TY - JOUR A1 - Vollert, F. A1 - Thomas, Maximilian A1 - Kromm, Arne A1 - Gibmeier, J. T1 - Solidification Cracking Assessment of LTT Filler Materials by Means of Varestraint Testing and μCT N2 - Investigations of the weldability of metals often deal with hot cracking, as one of the most dreaded imperfections during weld fabrication. The hot cracking investigations presented in this paper were carried out as part of a study on the development of low transformation temperature (LTT) weld filler materials. These alloys allow to mitigate tensile residual stresses that usually arise during welding using conventional weld filler materials. By this means, higher fatigue strength and higher lifetimes of the weld can be achieved. However, LTT weld filler materials are for example, high-alloyed Cr/Ni steels that are susceptible to the formation of hot cracks. To assess hot cracking, we applied the standardized modified varestraint transvarestraint hot cracking test (MVT), which is well appropriate to evaluate different base or filler materials with regard to their hot cracking susceptibility. In order to consider the complete material volume for the assessment of hot cracking, we additionally applied microfocus X-ray computer tomography (μCT). It is shown that by a suitable selection of welding and MVT parameter the analysis of the complete 3D hot crack network can provide additional information with regard to the hot cracking model following Prokhorov. It is now possible to determine easy accessible substitute values (e.g., maximum crack depth) for the extent of the Brittleness Temperature Range (BTR) and the minimum critical strain Pmin. KW - LTT weld filler materials KW - μCT-analysis KW - Hot cracking KW - Varestraint test PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509126 DO - https://doi.org/10.3390/ma13122726 VL - 13 IS - 12 SP - 2726 PB - MDPI AN - OPUS4-50912 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fahrbach, M. A1 - Friedrich, Sebastian A1 - Cappella, Brunero A1 - Peiner, Erwin T1 - Calibrating a high-speed contact-resonance profilometer N2 - A European EMPIR project, which aims to use large-scale piezoresistive microprobes for contact resonance applications, a well-established measurement mode of atomic force microscopes (AFMs), is being funded. As the probes used in this project are much larger in size than typical AFM probes some of the simplifications and assumptions made for AFM probes are not applicable. This study presents a guide on how to systematically create a model that replicates the dynamic behavior of microprobes, including air damping, nonlinear sensitivities, and frequency dependencies. The model is then verified by analyzing a series of measurements. KW - Piezoresistive cantilever KW - AFM KW - contact resonance PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509899 DO - https://doi.org/10.5194/jsss-9-179-2020 VL - 9 SP - 179 EP - 187 PB - Copernicus Publications AN - OPUS4-50989 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reichelt, Manuel A1 - Cappella, Brunero T1 - Influence of relative humidity on wear of self-mated 100 Cr6 steel N2 - The influence of relative humidity on friction and wear is subject of several studies in the last decades. A comprehensive understanding of physical and chemical phenomena affecting the tribology is hampered by the lack of reproducible experimental results, by the large number of variables, and by several difficulties in the detection of tribochemical processes and products. In the present work, we analyze the wear coefficient and the wear volumes of 686 unlubricated tests performed on different oscillating tribometers with 100Cr6 balls on 100Cr6 planes at different relative humidity. Aim of this work is to assess the repeatability and reproducibility of data, to determine the dependence of the wear coefficient on the relative humidity, to understand the underlying physicochemical phenomena and to build three dimensional maps of the wear coefficient as a function of both humidity and the product of normal force and sliding distance. KW - Wear KW - 100Cr6 KW - Relative humidity PY - 2020 DO - https://doi.org/10.1016/j.wear.2020.203239 VL - 450-451 SP - 203239 AN - OPUS4-50583 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Florian, Camilo A1 - Wonneberger, R. A1 - Undisz, A. A1 - Kirner, Sabrina V. A1 - Wasmuth, Karsten A1 - Spaltmann, Dirk A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Chemical effects during the formation of various types of femtosecond laser-generated surface structures on titanium alloy N2 - In this contribution, chemical, structural, and mechanical alterations in various types of femtosecond laser-generated surface structures, i.e., laser-induced periodic surface structures (LIPSS, ripples), Grooves, and Spikes on titanium alloy, are characterized by various surface analytical techniques, including X-ray diffraction and glow-discharge optical emission spectroscopy. The formation of oxide layers of the different laser-based structures inherently influences the friction and wear performance as demonstrated in oil-lubricated reciprocating sliding tribological tests (RSTTs) along with subsequent elemental mapping by energy-dispersive X-ray analysis. It is revealed that the fs-laser scan processing (790 nm, 30 fs, 1 kHz) of near-wavelength-sized LIPSS leads to the formation of a graded oxide layer extending a few hundreds of nanometers into depth, consisting mainly of amorphous oxides. Other superficial fs-laser-generated structures such as periodic Grooves and irregular Spikes produced at higher fluences and effective number of pulses per unit area present even thicker graded oxide layers that are also suitable for friction reduction and wear resistance. Ultimately, these femtosecond laser-induced nanostructured surface layers efficiently prevent a direct metal-to-metal contact in the RSTT and may act as an anchor layer for specific wear-reducing additives contained in the used engine oil. KW - Laser-induced oxide layer KW - Laser-induced periodic surface strctures (LIPSS) KW - Femtosecond laser processing KW - Tribology KW - Surface processing PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-505660 DO - https://doi.org/10.1007/s00339-020-3434-7 SN - 0947-8396 SN - 1432-0630 VL - 126 IS - 4 SP - 266 PB - Springer Nature Switzerland AG AN - OPUS4-50566 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vollert, F. A1 - Thomas, Maximilian A1 - Kromm, Arne A1 - Gibmeier, J. T1 - Hot crack assessment of LTT welds using μCT N2 - Investigations on weldability often deal with hot cracking, as one of the most popular failure during weld fabrication. The modified varestraint transvarestraint hot cracking test (MVT) is well known for the assessment of the hot cracking susceptibility of materials. The shortcoming of this approach is that the information is only from the very near surface region, which inhibits access to the characteristic of the hot crack network in the bulk. Here, we report about a new approach, illustrated in the example of low transformation temperature (LTT) weld filler materials, to monitor the entire 3D hot crack network after welding by means of microfocus X-ray computer tomography (μCT). T2 - 10th Conference on Industrial Computed Tomography (iCT 2020) CY - Wels, Austria DA - 04.02.2020 KW - Varestraint testing KW - LTT weld filler materials KW - Hot cracking KW - Welding KW - μCT-analysis PY - 2020 DO - https://doi.org/https://doi.org/10.58286/25121 SN - 1435-4934 VL - 25 IS - 2 SP - 1 EP - 7 PB - NDT.net CY - Kirchwald AN - OPUS4-50341 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reichelt, Manuel A1 - Cappella, Brunero T1 - Comparative analysis of error sources in the determination of wear volumes of oscillating ball-on-plane tests N2 - The accurate determination of wear volumes is a prerequisite for the study of numerous tribological phenomena. Wear volumes can be measured with different techniques or else be calculated starting from some quantities measured from the wear scar. Advantages and drawbacks of the measuring techniques are shown by means of wear scars and calottes resulting from ball-on-plane tests with 100Cr6 specimens. When measuring wear volumes, white light interferometry results to be one of the most suitable techniques. When wear volumes are calculated, errors result mainly from two sources: (1) the arbitrary choice of one or few line profiles for the determination of the width and of the planimetric wear, and (2) approximations in the calculation, which are even necessary when values of the wear volumes of the single tribological partners and not only the total volume are of interest. The effect of both error sources on the accuracy in the determination of wear volumes is characterized and elucidated by examples. It is found that errors due to approximations are negligible when compared to errors due to the arbitrary choice of one line profile. KW - Error sources analysis KW - White light interferometry KW - Statistical analysis KW - AFM KW - Wear KW - Oscillating ball-on-disc test PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-508407 DO - https://doi.org/10.3389/fmech.2020.00025 VL - 6 SP - Article 25 AN - OPUS4-50840 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zerbst, Uwe T1 - Application of fracture mechanics to welds with crack origin at the weld toe—a review. Part 2: welding residual stresses. Residual and total life assessment N2 - The two-part paper series provides an overview on the state-of-the-art in the application of engineering fracture mechanics to weldments limited to butt and fillet welds with crack initiation at weld toes. In the present second part, one focus is on welding residual stresses, their characteristics and stability under cyclic loading and their effect on structural integrity. Subsequently, features will be addressed which are essential for applying fracture mechanics to overall fatigue life and fatigue strength considerations of weldments. These comprise fatigue life relevant initial crack sizes and multiple crack initiation and Propagation due to various stress peaks along the weld toe. A concept is briefly introduced which covers all these aspects. KW - Fracture mechanics KW - Welding residual stresses KW - Multiple crack propagation KW - Fatigue strength PY - 2020 DO - https://doi.org/10.1007/s40194-019-00816-y VL - 64 IS - 1 SP - 151 EP - 169 PB - Springer AN - OPUS4-50263 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Spranger, Felix A1 - Schirdewahn, S. A1 - Kromm, Arne A1 - Merklein, M. A1 - Hilgenberg, Kai T1 - On the influence of TiB2, TiC, and TiN hard particles on the microstructure of localized laser dispersed AISI D2 tool steel surfaces N2 - The control of friction and wear is a major concern in many industrial applications. A promising method for tailored surface modification is the so-called laser implantation technique. This method combines surface texturing and material optimization in one processing step by a localized dispersing of hard ceramic particles using pulsed laser radiation. Wear resistant, protruding micrometric features (implants) with defined geometry can be created in a deterministic pattern where needed on highly stressed surfaces, i.e., on forming or cutting tools. However, in order to maintain the implants over the tool’s lifetime, a suitable selection of hard ceramic particles is a prerequisite. They must provide a defect-free metal matrix composite with a high share of homogeneously distributed particles and, especially, high implant hardness. In this study, TiN, TiC, and TiB2 hard particles were compared as implant materials for the first time. By a systematic variation of pulse power and pulse duration, their dispersing behavior and influence on the material properties of AISI D2 tool steel were investigated. Although all powder materials had grain sizes smaller than 10 μm, it was possible to disperse them by pulsed laser radiation and to obtain defect-free protruding implants. The highest share of dispersed particles (∼64%) was observed for TiB2. By scanning electron microscopy and energy dispersive x-ray spectroscopy, it was also shown that a significant share of the preplaced particles was dissolved by the laser beam and precipitated as nanometer sized particles within the matrix during solidification. These in situ formed particles have a decisive influence on the material properties. While the TiN and TiC implants have shown maximum hardness values of 750 and 850 HV1, the TiB2 implants have shown the highest hardness values with more than 1600 HV1. By x-ray diffraction, it was possible to ascribe the lower hardness values of TiC and TiN implants to high amounts of retained austenite in the metal matrix. By implanting TiB2, the formation of retained austenite was successfully suppressed due to the in situ formation of TiC particles, which was proven by electron backscatter diffraction. In conclusion, all the implant materials are basically suitable for laser implantation on AISI D2 tool steel. However, TiB2 has shown the most promising results. T2 - ICALEO 2019 CY - Orlando, FL, USA DA - 07.10.2019 KW - Laser implantation KW - Surface texturing KW - AISI D2 KW - TiB2 KW - TiN KW - TiC KW - Retained Austenite KW - Localized laser dispersing PY - 2020 DO - https://doi.org/10.2351/7.0000059 VL - 32 IS - 2 SP - 022028 EP - 022028-9 PB - AIP Publishing AN - OPUS4-50712 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schirdewahn, S. A1 - Spranger, Felix A1 - Hilgenberg, Kai A1 - Merklein, M. T1 - Localized Laser Dispersing of Titanium-Based Particles for Improving the Tribological Performance of Hot Stamping Tools N2 - Within the scope of this work, a new surface engineering technology named laser implantation has been investigated, in order to improve the tribological performance of hot stamping tools. This technique is based on manufacturing highly wear-resistant, separated, and elevated microfeatures by embedding hard ceramic particles into the tool surface via pulsed laser radiation. Hence, the topography and material properties of the tool are modified, which influences the thermal and tribological interactions at the blank-die interface. To verify these assumptions and to clarify the cause–effect relations, different titanium-based particles (TiB2, TiC, TiN) were laser-implanted and subsequently analyzed regarding to their geometrical shape and mechanical properties. Afterwards, quenching tests as well as tribological experiments were carried out by using titanium-diboride as the most promising implantation material for reducing the tribological load due to high hardness value of the generated implants. Compared to conventional tooling systems, the modified tool surfaces revealed a significantly higher wear resistance as well as reduced friction forces while offering the possibility to adjust the thermal interactions at the blank-die interface. Based on these results, a tailored tool surface modification can be pursued in future research work, in order to enhance the effectiveness of the hot stamping technology. KW - Hot stamping KW - Tribology KW - Surface modification KW - Localized laser dispersing PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-510981 DO - https://doi.org/10.3390/jmmp4030068 VL - 4 IS - 3 SP - 68 PB - MDPI AN - OPUS4-51098 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Sebastian A1 - Cappella, Brunero T1 - Application of contact-resonance AFM methods to polymer samples N2 - Contact-resonance AFM (CR-AFM) has been used in recent years for the measurement of mechanical properties. Compared with other techniques, CR-AFM has a much shorter acquisition time, compensating the incomplete theoretical understanding of the underlying physical phenomena. In the present paper, we propose a procedure, which allows to determine the elastic modulus of the sample as a parameter of the fit of the CR frequency as a function of the load. It is concluded that CR measurements are not appropriate for polymer samples. Major drawbacks are the bad resolution for moduli lower than ca. 10 GPa and the lack of a comprehensive physical model. KW - Atomic force microscopy KW - Contact resonance KW - Mechanical properties KW - Polymers KW - Wear PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-515621 DO - https://doi.org/10.3762/bjnano.11.154 VL - 11 SP - 1714 EP - 1727 AN - OPUS4-51562 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Genga, R. M. A1 - Rokebrand, P. A1 - Cornish, L. A. A1 - Nelwalani, N. A1 - Brandt, Guido A1 - Kelling, Norbert A1 - Woydt, Mathias A1 - Janse van Vuuren, A. A1 - Polese, C. T1 - High-temperature sliding wear, elastic modulus and transverse rupture strength of Ni bonded NbC and WC cermets N2 - The effects of rapid pulse electric current sintering (PECS), substitution of WC by NbC and Co by Ni, and carbide additives (TiC and Mo2C) on the microstructure, elastic modulus, B3B transverse rupture strength (TRS) and high temperature sliding wear on WC-Co, WC-Ni, NbC-Co and NbC-Ni cermets were studied. High temperature sliding wear tests were carried out using a ball-on-disk tribometer, with a 10 N force, at a sliding speed of 1.34 m/s for 0.8 km (10 min) and 2.4 km (30 min), using 100Cr6 (AISI 52100) steel balls at 400 °C and 0% humidity. Additions of TiC and Mo2C to NbC-12Ni improved the sliding wear resistance, with TiC having the greater effect, reducing the sample wear rate by over 30% from 15.1×10−6mm3/N·m to 9.4×10−6mm3/N·m after sliding distance of 2.4 km. Generally, the LPS samples had lower wear volumes than the corresponding SPS samples, due to higher K1c and TRS. KW - Pulse electric current sintering KW - Niobium carbide KW - Nickel KW - Molybdenum carbide KW - Titanium carbide PY - 2020 DO - https://doi.org/10.1016/j.ijrmhm.2019.105143 SN - 0263-4368 VL - 87 SP - 105143 PB - Elsevier Ltd. AN - OPUS4-51473 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schirdewahn, S. A1 - Spranger, Felix A1 - Hilgenberg, Kai A1 - Merklein, M. T1 - Localized dispersing of TiB2 and TiN particles via pulsed laser radiation for improving the tribological performance of hot stamping tools N2 - The aim of this study is to increase the tribological performance of hot stamping tools by using a laser implantation process. This technique allows the fabrication of separated, elevated and dome-shaped microfeatures on the tool surface in consequence of a localized dispersing of ceramic particles via pulsed laser radiation. Hence, the topography and material properties of the tool are modified, which influences the tribological interactions at the blank-die interface. However, an appropriate selection of ceramic particles is an essential prerequisite, in order to obtain tailored and highly wear resistant surface features. In this regard, different titanium-based hard particles (TiB2 and TiN) were laser-implanted on hot working tool specimens and subsequently tested by means of a modified pin-on-disk test regarding to their wear and friction behavior. KW - Surface modification KW - Tribology KW - Laser implantation KW - Hot working tool steel KW - Hot stamping PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-514171 DO - https://doi.org/10.1016/j.procir.2020.09.069 VL - 94 SP - 901 EP - 904 PB - Elsevier B.V. AN - OPUS4-51417 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rawat, S. S. A1 - Harsha, A. P. A1 - Khatri, O. P. A1 - Wäsche, Rolf T1 - Pristine, reduced, and alkylated graphene oxide as additives to paraffin grease for enhancement of tribological properties N2 - Pristine, reduced, and alkylated graphene oxides are applied as lubricating additives in paraffin grease. It has revealed that their crystalline structure governs the tribological properties of grease for steel tribo-pair. The microstructural analyses of grease samples showed that a loose fiber network of soap in the presence of graphene-based additive allows their facile release for efficient lubrication. The surface analyses based on the microscopic and elemental mapping show the development of a graphene-derived protective film on the worn scars, which protected the tribo-surfaces and subsided the wear. The reduced graphene oxide (rGO) with the interlamellar distance of 0.35 nm in the (002) plane provided minimum resistance to shear and exhibited maximum reduction in coefficient of friction (COF) for the paraffin grease. The presence of oxygen functionalities in the basal of pristine and alkylated graphene oxide (GO) compromised the interlamellar shearing under tribo-stress; consequently, higher COF than that of rGO. KW - Coefficient of friction KW - Graphene oxide KW - Grease KW - Nanoadditive KW - Tribo-film KW - Wear KW - Boundary lubrication KW - Grease lubrication KW - Lubricant additives KW - Lubricants PY - 2021 DO - https://doi.org/10.1115/1.4047952 VL - 143 IS - 2 SP - 021903-1 EP - 021903-11 PB - ASME AN - OPUS4-51170 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - El-Batahgy, A. A1 - Saiyah, A. A1 - Khafagi, S. A1 - Gumenyuk, Andrey A1 - Gook, S. A1 - Rethmeier, Michael T1 - Shielded metal arc welding of 9%Ni steel using matching ferritic filler metal N2 - Motivated by the tensile strength loss of 9%Ni steel arc welded joints made using Ni-based austenitic filler metals, the feasibility of maintaining the tensile strength using matching ferritic filler metal has been demonstrated. In comparison with shielded metal arc welded joint made using Ni-based austenitic electrode ENiCrMo-6, higher tensile strength comparable to that of the base metal was obtained using matching ferritic electrode. Besides, sufficient impact toughness energies with much lower mismatch were obtained for weld metal and heat-affected zone. Welded joint with a lower mechanical mismatching is of considerable importance for achieving acceptable combination of tensile strength and impact toughness.Abetter combination of These mechanical properties is ensured by applying a post weld heat treatment. KW - Mechanical mismatching KW - Mechanical properties KW - Microstructure KW - Austenitic welding electrode KW - Matching ferritic welding electrode PY - 2020 DO - https://doi.org/10.1080/13621718.2020.1846936 SN - 1362-1718 SP - 1 EP - 7 PB - Taylor & Francis AN - OPUS4-51835 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pignatelli, Giuseppe T1 - Optical Sensor for Monitoring Quality of 3D Metal Printing N2 - Additive Manufacturing (AM) becomes widespread in many technological fields including the precise machining of steel. To assure quality of final products, thorough monitoring of online process is required. We test several monitoring techniques during the AM printing to quickly detect and possibly correct flaws while building a workpiece. Here we show how optical emission spectroscopy can be used to recognize defects that are artificially introduced on a steel printing substrate. T2 - Scix 2020 CY - Online meeting DA - 12.10.2020 KW - Additive manufacturing KW - Spectroscopy KW - Analytical chemistry PY - 2020 AN - OPUS4-51858 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schürmann, K. T1 - Experimental investigations on the fatigue resistance of automatically welded tubular X-joints for jacket support structures N2 - The development within the offshore wind sector towards more powerful turbines combined with increasing water depth for new wind parks is challenging both the designer as well as the manufacturer of bottom fixed support structures. Besides XL-monopiles, the market developed an innovative and economic jacket support structure which is based on automatically manufactured tubular joints combined with standardized pipes. Besides the improvements for a serial manufacturing process the automatically welded tubular joints show a great potential in terms of fatigue resistance e.g. due to a smooth weld geometry without sharp notches. However, these benefits are not considered yet within the fatigue design process of automatically manufactured jacket substructures according to current standards due to the lack of suitable S-N curves. Therefore, 32 axial fatigue tests on single and double-sided automatically welded tubular X-joints have been performed to determine a new hot spot stress related S-N curve. Based on these constant amplitude fatigue tests a new S-N curve equal to a FAT 126 curve was computed which implicitly includes the benefits of the automatically welding procedure. T2 - EERA DeepWind 2020 CY - Trondheim, Norway DA - 15.01.2020 KW - Notch stress approach KW - Tubular X-joints KW - Automated manufacturing KW - Fatigue tests KW - Structural stress approach PY - 2020 AN - OPUS4-51873 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yu, C.-H. A1 - Peng, R. L. A1 - Luzin, V. A1 - Sprengel, Maximilian A1 - Calmunger, M. A1 - Lundgren, J.-E. A1 - Brodin, H. A1 - Kromm, Arne A1 - Moverare, J. T1 - Thin-wall effects and anisotropic deformation mechanisms of an additively manufactured Ni-based superalloy N2 - Laser powder bed fusion (LPBF) of Ni-based superalloys shows great potential for high temperature applications, for example, as a burner repair application for gas turbines where the thin-walled structure is important. It motivates this work to investigate the evolution of microstructure and the anisotropic mechanical behavior when plate-like specimens are built with a thickness from 4 mm down to 1 mm. By performing texture analysis using neutron diffraction, a clear transition in fiber texture from <011> to <001> is indicated when the specimen becomes thinner. The residual stress shows no thickness dependence, and at the subsurface the residual stress reaches the same level as the yield strength. Due to the rough as-built surface, a roughness compensation method for mechanical properties of thin-walled structures is outlined and demonstrated. Tensile tests from room temperature up to 700 ◦C have been carried out. Anisotropic mechanical behavior is found at all temperatures, which is strongly related to the anisotropic texture evolution. Stronger texture evolution and grain rotations are discovered when the tensile loading is applied along the building direction. The mechanical behavior has been compared to a wrought material, where the high dislocation density and the subgrain structure of the LPBF material result in a higher yield strength. Combining the statistical texture analysis by neutron diffraction with mechanical testing, EBSD grain orientation mapping and the investigation of dislocation structures using transmission electron microscopy, this work illustrates the significance of texture for the thin-wall effect and anisotropic mechanical behavior of LPBF materials. KW - Hastelloy X KW - Hot tensile test KW - Crystallographic texture KW - Roughness KW - Residual stress KW - Dislocation density PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-518759 DO - https://doi.org/10.1016/j.addma.2020.101672 VL - 36 SP - 101672 PB - Elsevier B.V. AN - OPUS4-51875 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heßmann, Jennifer A1 - Bachmann, Marcel A1 - Hilgenberg, Kai T1 - Numerical and experimental investigation of controlled weld pool displacement by electromagnetic forces for joining dissimilar materials N2 - In order to reduce CO2 emissions, an increasing interest in lightweight construction exists in the automotive industry, especially the multi-material-design approach. The main construction materials here are steels and aluminium alloys. Due to their different physical material properties and limited mutual solubility, these two materials cannot be joined thermally without difficulty. This paper presents a new joining approach for dissimilar materials. It uses electromagnetic displacement of a laser-generated melt pool to produce overlap joints between 1 mm steel (1.0330) and 2 mm aluminium alloy (EN AW 5754). Contactless induced Lorentz forces are generated by an alternating current (AC) magnet system. The controlled displacement of the aluminium alloy melt into the hole of the overlying steel sheet is investigated through numerical and experimental studies. The numerical results are compared with cross sections and thermocouple measurements. For the first time, it is possible to achieve a reproducible controlled melt pool displacement on thin sheets to produce overlap joints between dissimilar materials. KW - Displacement KW - Laser beam welding KW - Dissimilar materials KW - Joining technology KW - Electromagnetic field KW - Lorentz force KW - Numerical investigation PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-516640 DO - https://doi.org/10.3390/met10111447 VL - 10 IS - 11 SP - 1447 EP - 1462 PB - MDPI CY - Basel, Schweiz AN - OPUS4-51664 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schridewahn, S. A1 - Spranger, F. A1 - Hilgenberg, Kai A1 - Merklein, M. T1 - Laser Implantation of Niobium and Titanium-Based Particles on Hot Working Tool Surfaces for Improving the Tribological Performance within Hot Stamping N2 - Within the scope of this work, a laser implantation process has been used, in order to improve the tribological performance of hot stamping tools. This surface engineering Technology enables the generation of dome-shaped, elevated and highly wear resistant microfeatures on tool surfaces in consequence of a localized dispersing of hard ceramic particles via pulsed laser radiation. As a result, the topography and material properties of the tool and thus the tribological interactions at the blank-die interface are locally influenced. However, a suitable selection of hard ceramic particles is imperative for generating defect-free surface features with a high share of homogenously disturbed particles. For this purpose, different niobium (NbB2 and NbC) as well as titanium-based (TiB2 and TiC) materials were embedded on hot working tool specimens and subsequently analyzed with regard to their resulting shape and mechanical properties. Afterwards, modified pin-on-disk tests were carried out by using conventional and laser-implanted tool surfaces, in order to evaluate the wear and friction behavior of both tooling systems. KW - Surface modification KW - Triobology KW - Laser implantation PY - 2020 DO - https://doi.org/10.4028/www.scientific.net/DDF.404.117 SN - 1662-9507, VL - 404 SP - 117 EP - 123 PB - Trans Tech Publications Ltd. AN - OPUS4-53690 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Spaltmann, Dirk T1 - Trusted Qualification - On the need for procedures to harmonize tribological testing N2 - In order to shorten time to market of products and to support new developments, the European Community is funding a HORIZON 2020 project called i-TRIBOMAT. In the field of tribology, renowned institutions combine their testing and analytical capabilities to provide the respective services. The later will be offered in Europe via a Single-Entry Point (SEP). Due to this combination of services, a testbed is created consisting of more than 100 tribometers. Thus, a large variety of testers exists, either commercially available or in-house built. Each tester is optimised to simulate a specific tribological contact situation. Currently, there is no standard available for the design of such testers. Especially, the way forces (normal load, friction force) and distances (e.g. stroke, linear wear) are measured, recorded and pre-processed differs from type to type. These forces and distances are essential for the determination of wear/ wear rates and coefficients of friction (COF), the core results of tribo-tests. This matter is complicated by the fact that e.g. for reciprocating motion, there are at least four different ways to determine COF. Depending on the testing conditions, these ways can lead to considerably different results. Currently, it is not obligatory to specify the method used for determining the COF. In order to make data comparable, there is a need for measures which ensure that each tribometer is delivering similar, at best the same results under the same test conditions, irrespective of its manufacturer, design, location, determination method and even operator. The way forward are improved Round-Robin tests. First results and other challenges faced by creating comparable tribological data will be considered in the present contribution. T2 - LUBMAT 2020 CY - Online meeting DA - 15.12.2020 KW - I-TRIBOMAT KW - Tribo-tests KW - Tribological data PY - 2020 AN - OPUS4-51981 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hilgenberg, Kai T1 - Additive Manufacturing: Opportunities and challenges for NDT N2 - Additive manufacturing processes are increasingly being used in industrial applications. Especially powder bed fusion processes are of high interest due to their capability to economically produce individual, highly complex and functionally integrated components in small batches. However, the quality assurance of these components remains a challenge. Internal defects and undesirable microstructures and surface conditions can deteriorate the mechanical properties. Especially for use in safety-relevant applications, new design and inspection concepts are needed that take these factors into account. This talk presents typical defects and microstructure phenomena resulting from the laser powder bed fusion process and identifies challenges and opportunities for non-destructive testing from a manufacturing engineering perspective. In particular, the possibility of a process-integrated quality control is shown based on current research results. T2 - The 13th International Symposium on NDT in Aerospace 2021 CY - Online meeting DA - 05.10.2021 KW - Additive manufacturing KW - Laser powder bed fusion KW - In-situ monitoring PY - 2021 AN - OPUS4-53484 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Griesche, Axel A1 - Pfretzschner, B. A1 - Taparli, Ugur Alp A1 - Kardjilov, N. T1 - Time-Resolved Neutron Bragg-Edge Imaging: A Case Study by Observing Martensitic Phase Formation in Low Temperature Transformation (LTT) Steel during GTAW N2 - Polychromatic and wavelength-selective neutron transmission radiography were applied during bead-on-plate welding on 5 mm thick sheets on the face side of martensitic low transformation temperature (LTT) steel plates using gas tungsten arc welding (GTAW). The in situ visualization of austenitization upon welding and subsequent α’-martensite formation during cooling could be achieved with a temporal resolution of 2 s for monochromatic imaging using a single neutron wavelength and of 0.5 s for polychromatic imaging using the full spectrum of the beam (white beam). The spatial resolution achieved in the experiments was approximately 200 µm. The transmitted monochromatic neutron beam intensity at a wavelength of λ = 0.395 nm was significantly reduced during cooling below the martensitic start temperature Ms since the emerging martensitic phase has a ~10% higher attenuation coefficient than the austenitic phase. Neutron imaging was significantly influenced by coherent neutron scattering caused by the thermal motion of the crystal lattice (Debye–Waller factor), resulting in a reduction in the neutron transmission by approx. 15% for monochromatic and by approx. 4% for polychromatic imaging. KW - Austenite-to-martensite transformation KW - Neutron radiography KW - Bragg-edge imaging KW - Gas tungsten arc welding (GTAW) KW - Debye–Waller factor KW - Low transformation temperature (LTT) steel PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-538016 DO - https://doi.org/10.3390/app112210886 VL - 11 IS - 22 SP - 10886 PB - MDPI CY - Basel AN - OPUS4-53801 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ivanov, S. A1 - Gushchina, M. A1 - Artinov, Antoni A1 - Khomutov, M. A1 - Zemlyakov, E. T1 - Effect of Elevated Temperatures on the Mechanical Properties of a Direct Laser Deposited Ti-6Al-4V N2 - In the present work, the mechanical properties of the DLD-processed Ti-6Al-4V alloy were obtained by tensile tests performed at different temperatures, ranging from 20 °C to 800 °C. Thereby, the process conditions were close to the conditions used to produce large-sized structures using the DLD method, resulting in specimens having the same initial martensitic microstructure. According to the obtained stress curves, the yield strength decreases gradually by 40% when the temperature is increased to 500 °C. Similar behavior is observed for the tensile strength. However, further heating above 500 °C leads to a significant increase in the softening rate. It was found that the DLD-processed Ti-6Al-4V alloy had a Young’s modulus with higher thermal stability than conventionally processed alloys. At 500 °C, the Young’s modulus of the DLD alloy was 46% higher than that of the wrought alloy. The influence of the thermal history on the stress relaxation for the cases where 500 °C and 700 °C were the maximum temperatures was studied. It was revealed that stress relaxation processes are decisive for the formation of residual stresses at temperatures above 700 °C, which is especially important for small-sized parts produced by the DLD method. The coefficient of thermal expansion was investigated up to 1050 °C. KW - Direct laser deposition KW - Ti-6Al-4V KW - Mechanical properties KW - Microstructure KW - Stress relaxation KW - Elevated temperatures PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-538025 DO - https://doi.org/10.3390/ma14216432 SN - 1996-1944 VL - 14 IS - 21 SP - 1 EP - 17 PB - MDPI CY - Basel, Switzerland AN - OPUS4-53802 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Carstensen, Niels T1 - Generation of Tribosystems by Additive Surface Treatment on Tool Steel Substrate N2 - Laser implantation aims at reducing friction and wear on highly stressed surfaces in forming processes. Especially the hot stamping process that is used as a resource efficient process for manufacturing geometrical complex and high-strength structures, exhibits severe wear and high friction during the forming operation. The laser implantation process addresses this problem by combining two different approaches (surface modification and surface structuring) in surface technology by creating elevated, highly wear-resistant micro-features to influence the tribological performance. Pure TiB2 implants have shown to reduce tool-sided wear significally and improve the part formability by reducing local necking in deep drawing tests. Within the scope of this work, TiB2-TiC and TiB2-TaC hard material mixtures are implanted on X38CrMoV5-3 hot work tool steel. The aim is to investigate how the implant material properties can be influenced by the application of different mixing ratios of hard material mixtures under the specific variation of the process parameters. Distinct implant formations are tested on a novel test apparatus to examine the influence on the tribological properties. From the analyses of the implant properties by hardness measurements, light microscopic images, EDX and XRD analyses process parameter ranges are identified to produce defect-free dome- and ring-shaped implants. The specific process parameters (pulse power, pulse duration, mixing ratio and coating thickness) can be used for the determination of the implant geometry (height, width and depth). The tribological tests exhibit improved friction and wear properties. Based on these results, a tribosystem manufactured by this additive surface treatment technology shows great potential to enhance the effectiveness of the hot stamping process. T2 - Friction 2021 CY - Sankt Augustin, Germany DA - 18.11.2021 KW - Laser implantation KW - Surface modification KW - Additive surface treatment KW - Hot stamping KW - Tool steel PY - 2021 AN - OPUS4-53809 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kempf, A. T1 - Correlation between quasistatic und fatigue properties of additively manufactured AlSi10Mg using Laser Powder Bed Fusion N2 - In order to find a resource efficient approach for the fatigue lifetime prediction of laser powder bed fusion (L-PBF) processed AlSi10Mg material, results of tensile and fatigue tests were compared. The specimens were manufactured with three different L-PBF machines and studied in different heat treatment conditions (as-built, annealed, T6 heat treated). The investigations showed that the high attainable tensile strength properties after the manufacturing process are not beneficial in the high cycle fatigue (HCF) regime. In contrast, the applied heat treatments, which lead typically to a decrease of ultimate tensile strength, improved dramatically the fatigue behavior. Additionally, a clear correlation between the elongation at fracture and HCF resistance has been found for individual heat treatment conditions. This empiric relationship provides an estimation of the fatigue resistance in the presence of material defects and can be implemented in part and process approvals. T2 - Fatigue Design 2021 CY - Online meeting DA - 17.11.2021 KW - Additive Manufacturing KW - Laser powder bed fusion KW - AlSi10Mg KW - Tensile properties KW - Fatigue properties PY - 2021 AN - OPUS4-53792 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Artinov, Antoni T1 - Numerical study of the bulging effect in deep penetration laser beam welding N2 - This article is devoted to the study of the bulging effect in deep penetration laser beam welding. The numerical results of the investigations are based upon experimental results from previous studies to reveal the relationship between the bulging effect and the hot cracking formation, as well as the mixing of alloying elements in the weld pool. The widening of the molten pool in its center area can be observed in full penetration as well as in partial penetration welds on 8 mm and 12 mm thick structural steel plates, respectively. The weld pool shape is extracted from the simulations to evaluate the extent of the necking of the solidification line as well as the bulging phenomena and its influence on the hot cracking phenomena. Relying on an earlier numerical study utilizing a fixed keyhole, simulation models considering a dynamic keyhole are developed thereto. Additionally, the mixing behavior of alloying elements during partial penetration is investigated. The link between the bulge and the studied phenomena is found to be significant. T2 - Lasers in Manufacturing Conference 2021 CY - Online meeting DA - 21.06.2021 KW - Deep penetration laser beam welding KW - Welding simulation KW - Solidification cracking KW - Bulging effect PY - 2021 AN - OPUS4-52847 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fabry, Çağtay T1 - WelDX – progress report on the welding data exchange format N2 - The presentation shows the current development status of the Welding Data Exchange (weldx) format based on the Advanced Scientific Data Format (ASDF). The use of a complete single pass arc welding experiment example stored in a single weldx file and validated against a predefined schema definition is presented. The example includes generic experimental metadata, the workpiece geometry and materials definition following associated standards, the weld process spatial movement description, the welding process parameter descriptions and welding process measurements. The inclusion of 3D scan data of the workpiece description is also included. The full code and data is available on GitHub: https://github.com/BAMWelDX/IIW2021_joint_intermediate_CXII T2 - IIW joint intermediate meeting Comm. I,IV,XII,SG212 2021 CY - Online meeting DA - 30.03.2021 KW - WelDX KW - Research data management KW - Open science KW - Arc welding KW - Digitalization PY - 2021 AN - OPUS4-52661 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kempf, A. A1 - Hilgenberg, Kai T1 - Influence of heat treatments on AlSi10Mg specimens manufactured with different laser powder bed fusion machines N2 - Mechanical properties such as ultimate tensile strength, yield strength, and tensile elongation of parts manufactured with Laser Powder Bed Fusion (L-PBF) can differ significantly after the building process limiting the advantage of production flexibility of that technology. At this background, the present work investigated the influence of post process heat treatments (HT) on microstructure, hardness, and tensile properties of AlSi10Mg specimens in different As-built (AB) conditions. For this purpose, two superordinate aspects were covered within this study. Firstly, various HTs were performed on specimens built-up with the same L-PBF machine applying the same parameter set-up. Results of tensile tests and hardness measurements were discussed considering the microstructural changes examined with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy as well as X-ray diffraction, and gathered in a material data map. Based on the observed microstructural changes and a calculated quality index which comprises strength and ductility properties, three HTs were selected for the second part of this work. Therein, the effect of these HTs on specimens fabricated with overall three L-PBF machines working with different raw materials, process parameters, and build-up strategies was studied. Specimens characterization included porosity measurements, the evaluation of material defects, microstructure analysis via SEM, hardness measurements, and tensile tests. It was found that strength properties in the AB condition revealed appreciable deviations: Values of yield strength and ultimate tensile strength were from 228 to 292 MPa and from 346 to 484 MPa, respectively. Whereas heat treated specimens at 300 °C for 0.5 as well as 2 h only exhibited slight differences in strength, a complete homogenization of strength properties was obtained after conducting a T6 HT. Nevertheless, ductility was not homogenized after heat treating caused by the presence of material defects such as keyhole pores and lack of fusion defects. It was shown that even slight differences in porosity determined in cross-sections can significantly affect ductility properties. KW - Laser powder bed fusion PY - 2021 DO - https://doi.org/10.1016/j.msea.2021.141371 SN - 0921-5093 VL - 818 SP - 141371 PB - Elsevier B.V. CY - Berlin AN - OPUS4-52741 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fahrbach, M. A1 - Friedrich, Sebastian A1 - Behle, H. A1 - Xu, Min A1 - Cappella, Brunero A1 - Brand, U. A1 - Peiner, E. T1 - Customized piezoresistive microprobes for combined imaging of topography and mechanical properties N2 - Customized piezoresistive cantilever microprobes with a deflection range of 120 μm and silicon tips of 100 μm height were operated in a Cypher AFM showing their functionality for measuring topography together with stiffness, adhesion, and viscoelastic properties of thin films. KW - Cantilever microprobe KW - Piezoresistive KW - Atomic force microscopy KW - Force-distance curves KW - Contact resonance KW - Lubricants PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-524225 DO - https://doi.org/10.1016/j.measen.2021.100042 VL - 15 SP - 100042 PB - Elsevier Ltd. AN - OPUS4-52422 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Werner, Tiago T1 - Short fatigue crack propagation in additively manufactured stainless steel 316L N2 - Fracture mechanics is a key to fatigue assessment in AM metal components. Short fatigue cracks are initiated at defects and pronounced surface roughness intrinsic to AM. The subsequent crack-propagation is strongly influenced by microstructural interactions and the build-up of crack-closure. The aim of the present study is to give an insight into short-crack propagation in AM-metals. Fatigue crack propagation resistance curves were determined experimentally for AISI 316L manufactured by Laser Powder Bed Fusion (L-PBF) which was heat treated at three different temperatures. Differences in the build-up of the fatigue-crack propagation threshold in between the L-PBF specimens and compared to wrought material are due to the residual stress states, a pronounced roughness of the crack-faces in the L-PBF specimens and phase transformation in the vicinity of the crack-tip, resulting in increased crack-closure. This, together with crack-branching found along the crack path, enhances the resistance to the propagation of fatigue cracks. T2 - In-situ Monitoring and Microstructure Development in Additive Manufactured Alloys CY - Online meeting DA - 19.04.2021 KW - AM KW - Cyclic R-Curve KW - Fatigue Crack Propagation PY - 2021 AN - OPUS4-52587 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ayerdi, J. J. A1 - Aginagalde, A. A1 - Llavori, I. A1 - Bonse, Jörn A1 - Spaltmann, Dirk A1 - Zabala, A. T1 - Ball-on-flat linear reciprocating tests: Critical assessment of wear volume determination methods and suggested improvements for ASTM N2 - In the present work it was shown the importance of the correct selection, implementation, and reporting of wear volume computation method and quanitifies the potential errors. KW - Wear KW - Sliding KW - Surface KW - Analysis KW - ASTM KW - D7755-11 PY - 2021 DO - https://doi.org/10.1016/j.wear.2021.203620 VL - 470-471 SP - 3620 AN - OPUS4-52080 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reichelt, Manuel A1 - Cappella, Brunero T1 - Large scale multi-parameter analysis of wear of self-mated 100Cr6 steel - A study of the validity of Archard's law N2 - Considerable scattering of experimental wear results affects seriously the evaluation of repeatability and reproducibility of tribological measurements and hampers detecting, studying, and verifying tribological laws. An accurate characterization of the statistics of results, the detection of the influence of operating parameters, and the verification of equations describing tribological phenomena can be achieved only through the analysis of large datasets with wide variation of parameters. Taking advantage of more than 400 experiments performed with the same material pairing under the same conditions on four different tribometers, the repeatability and reproducibility of volumetric wear measurements has been evaluated using Welch's test. By testing Archard's law over seven orders of magnitude of sFN, it was found that this law is not universally valid and that, under certain conditions, the wear coefficient depends on sFN itself. KW - Wear KW - Archard's law KW - 100Cr6 steel KW - Scattering PY - 2021 DO - https://doi.org/10.1016/j.triboint.2021.106945 VL - 159 SP - 6945 PB - Elsevier Ltd. AN - OPUS4-52244 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heßmann, Jennifer T1 - Joining dissimilar materials a new approach based on laser beam welding and melt displacement by electromagnetic forces N2 - In order to reduce weight of vehicles, the interest in multi-material-design has been growing within the last few years. For vehicles the combination of steel and aluminium alloys offers the most promising compromise between weight, strength and formability. Thermal joining of these dissimilar materials is still a challenge to overcome. A possible approach is a new joining technology, whereby a combination of laser beam welding and contactless induced electromagnetic forces are used to displace the generated melt of one joining partner into a notch of the other. This paper presents the working principle and shows numerical analyses to improve the understanding of this joining process. The simulations help to calculate the thermal development of the joining partners, which is important for the formation of intermetallic phases. Furthermore, the calculation of the time required for a complete displacement is possible. The numerical results are validated by experimental results. T2 - LiM 2021 CY - Online meeting DA - 21.06.2021 KW - Joining dissimilar materials KW - Laser beam welding KW - Electromagnetic forces KW - Steel and aluminium PY - 2021 AN - OPUS4-52977 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heßmann, Jennifer A1 - Bachmann, Marcel A1 - Hilgenberg, Kai T1 - Joining dissimilar materials a new approach based on laser beam welding and melt displacement by electromagnetic forces N2 - In order to reduce weight of vehicles, the interest in multi-material-design has been growing within the last few years. For vehicles the combination of steel and aluminium alloys offers the most promising compromise between weight, strength and formability. Thermal joining of these dissimilar materials is still a challenge to overcome. A possible approach is a new joining technology, whereby a combination of laser beam welding and contactless induced electromagnetic forces are used to displace the generated melt of one joining partner into a notch of the other. This paper presents the working principle and shows numerical analyses to improve the understanding of this joining process. The simulations help to calculate the thermal development of the joining partners, which is important for the formation of intermetallic phases. Furthermore, the calculation of the time required for a complete displacement is possible. The numerical results are validated by experimental results. T2 - LiM 2021 CY - Online meeting DA - 21.06.2021 KW - Joining dissimilar materials KW - Laser beam welding KW - Electromagnetic forces KW - Steel and aluminium PY - 2021 SP - 1 EP - 9 PB - Wissenschaftliche Gesellschaft Lasertechnik e.V. (WLT) AN - OPUS4-52978 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heßmann, Jennifer A1 - Hilgenberg, Kai A1 - Bachmann, Marcel T1 - An electromagnetic approach to dissimilar metal welding N2 - To save weight without affecting the functional properties of vehicles, heavy materials must be replaced with lighter alternatives.Modern lightweight concepts have therefore been developed, featuring multi-material designs that require the joining of dissimilar materials.One new possible approach for the joining of dissimilar metals is based on laser welding and melt displacement by contactless induced electromagnetic forces. KW - Joining dissimilar materials KW - Laser beam welding KW - Electromagnetic forces KW - Steel and aluminium PY - 2021 SP - 1 EP - 5 AN - OPUS4-53373 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cappella, Brunero A1 - Reichelt, Manuel T1 - Origin of lognormal distribution of wear coefficient values N2 - Wear test results exhibit often large scattering. Hence, the study of spreading of experimental results requires big datasets. In various studies, wear coefficients were found to have lognormal distributions. Therefore, it was supposed that the wear coefficient is affected by two normally distributed variables, which combine through a product. In the present study, we demonstrate that a lognormal distribution may arise from a nonconstant wear coefficient, too, i.e., when a system does not follow Archard’s law. KW - Wear KW - Archard's law KW - Statistical distributions KW - Spreading PY - 2021 DO - https://doi.org/10.1016/j.triboint.2021.107207 SN - 0301-679X VL - 164 PB - Elsevier Ltd. AN - OPUS4-53100 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schirdewahn, S. A1 - Spranger, Felix A1 - Hilgenberg, Kai A1 - Merklein, M. T1 - Investigation of the thermal and tribological performance of localized laser dispersed tool surfaces under hot stamping conditions N2 - In the automotive industry, hot stamping has been established as a key technology for manufacturing safety-relevant car body components with high strength-to-weight ratio. However, hot stamping tools are stressed by cyclic thermo-mechanical loads, which leads to severe wear and high friction during the forming operation. Consequently, the quality of the parts, the durability of the tools and the efficiency of the process are negatively affected. Within the scope of this work, a promising approach named laser implantation process has been investigated for improving the tribological behavior of hot stamping tools. This technique enables the fabrication of highly wear resistant, separated and elevated micro-features by embedding hard ceramic particles into the tool via pulsed laser radiation. Hence, highly stressed tool areas can be modified, which influences the thermal and tribological interactions at the blank-die interface. To clarify these cause-effect relations, numerical simulations, quenching tests as well as tribological investigations have been conducted. In this context, laser-implanted tools reveal a significantly improved tribological performance while offering the possibility to adjust the thermal properties within hot stamping. Based on these results, a tailored tool modification can be pursued in future research work, in order to enhance the effectiveness of hot stamping tooling systems. KW - Hot stamping KW - Laser Implantation KW - Surface structuring KW - Wear KW - Friction PY - 2021 DO - https://doi.org/10.1016/j.wear.2021.203694 VL - 476 SP - 1 EP - 11 PB - Elsevier B.V. AN - OPUS4-52988 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Werner, Tiago T1 - Comparison of the fatigue behavior of wrought and additively manufactured AISI 316L N2 - Additively Manufactured (AM) parts are still far from being used in safety-relevant applications, mainly due to a lack of understanding of the feedstock-process-propertiesperformance relationship. This work aims at providing a characterization of the fatigue behavior of the additively manufactured AISI 316L austenitic stainless steel and a direct comparison with the fatigue performance of the wrought steel. A set of specimens has been produced by laser powder bed fusion (L-PBF) and a second set of specimens has been machined out of hot-rolled plates. The L-PBF material shows a higher fatigue limit and better finite life performance compared to the wrought material, accompanied by an extensive amount of cyclic softening. T2 - Fatigue Design 2021 CY - Online meeting DA - 17.11.2021 KW - Additive Manufacturing KW - AM KW - 316L KW - Fatigue KW - High Cycle Fatigue KW - Low Cycle Fatigue PY - 2021 AN - OPUS4-53780 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kröll, Mirco T1 - Effects of harmonised procedures in (digital) Tribology N2 - The talk presents the work on digitalisation in tribology and the harmonised procedures developed in i-Tribomat. T2 - NanoMECommons workshop "Materials characterization challenges to support the industry transition in the digital era CY - Online meeting DA - 13.12.2021 KW - Tribology KW - i-TRIBOMAT KW - Characterization KW - Digitalisation PY - 2021 AN - OPUS4-54192 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ivanov, S. A1 - Artinov, Antoni A1 - Zemlyakov, E. A1 - Karpov, I. A1 - Rylov, S. A1 - Em, V. T1 - Spatiotemporal Evolution of Stress Field during Direct Laser Deposition of Multilayer Thin Wall of Ti-6Al-4V N2 - The present work seeks to extend the level of understanding of the stress field evolution during direct laser deposition (DLD) of a 3.2 mm thick multilayer wall of Ti-6Al-4V alloy by theoretical and experimental studies. The process conditions were close to the conditions used to produce large-sized structures by the DLD method, resulting in specimens having the same thermal history. A simulation procedure based on the implicit finite element method was developed for the theoretical study of the stress field evolution. The accuracy of the simulation was significantly improved by using experimentally obtained temperature-dependent mechanical properties of the DLD-processed Ti-6Al4V alloy. The residual stress field in the buildup was experimentally measured by neutron diffraction. The stress-free lattice parameter, which is decisive for the measured stresses, was determined using both a plane stress approach and a force-momentum balance. The influence of the inhomogeneity of the residual stress field on the accuracy of the experimental measurement and the validation of the simulation procedure are analyzed and discussed. Based on the numerical results it was found that the non-uniformity of the through-thickness stress distribution reaches a maximum in the central cross-section, while at the buildup ends the stresses are distributed almost uniformly. The components of the principal stresses are tensile at the buildup ends near the substrate. Furthermore, the calculated equivalent plastic strain reaches 5.9% near the buildup end, where the deposited layers are completed, while the plastic strain is practically equal to the experimentally measured ductility of the DLD-processed alloy, which is 6.2%. The experimentally measured residual stresses obtained by the force-momentum balance and the plane stress approach differ slightly from each other. KW - Direct laser deposition KW - Finite element simulation KW - Neutron diffraction KW - Residual stresses KW - Ti-6Al-4V KW - Mechanical properties PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-542444 DO - https://doi.org/10.3390/ma15010263 VL - 15 IS - 263 SP - 1 EP - 20 PB - MDPI AN - OPUS4-54244 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kempf, Andreas A1 - Kruse, Julius A1 - Madia, Mauro A1 - Hilgenberg, Kai T1 - Correlation between quasistatic und fatigue properties of additively manufactured AlSi10Mg using Laser Powder Bed Fusion N2 - In order to find a resource efficient approach for the fatigue lifetime prediction of laser powder bed fusion (L-PBF) processed AlSi10Mg material, results of tensile and fatigue tests were compared. The specimens were manufactured with three different L-PBF machines and studied in different heat treatment conditions (as-built, annealed, T6 heat treated). The investigations showed that the high attainable tensile strength properties after the manufacturing process are not beneficial in the high cycle fatigue (HCF) regime. In contrast, the applied heat treatments, which lead typically to a decrease of ultimate tensile strength, improved dramatically the fatigue behavior. Additionally, a clear correlation between the elongation at fracture and HCF resistance has been found for individual heat treatment conditions. This empiric relationship provides an estimation of the fatigue resistance in the presence of material defects and can be implemented in part and process approvals. T2 - FATIGUE DESIGN 2021 CY - Online meeting DA - 17.11.2021 KW - Additive Manufacturing KW - Laser powder bed fusion KW - AlSi10Mg KW - Tensile properties KW - Fatigue properties PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-544921 DO - https://doi.org/10.1016/j.prostr.2022.03.009 SN - 2452-3216 VL - 38 SP - 77 EP - 83 PB - Elsevier B.V. AN - OPUS4-54492 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Werner, Tiago A1 - Madia, Mauro A1 - Zerbst, Uwe T1 - Comparison of the fatigue behavior of wrought and additively manufactured AISI 316L N2 - Additive manufacturing (AM) is becoming increasingly important in engineering applications due to the possibility of producing components with a high geometrical complexity allowing for optimized forms with respect to the in-service functionality. Despite the promising potential, AM components are still far from being used in safety-relevant applications, mainly due to a lack of understanding of the feedstock-process-properties-performance relationship. This work aims at providing a full characterization of the fatigue behavior of the additively manufactured AISI 316L austenitic stainless steel and a direct comparison with the fatigue performance of the wrought steel. To this purpose, a set of specimens has been produced by laser powder bed fusion (L-PBF) and subsequently heat treated at 900 °C for 1 hour for complete stress relief, whereas a second set of specimens has been machined out of hot-rolled plates. Low cycle fatigue (LCF) and high cycle fatigue (HCF) tests have been conducted for characterizing the fatigue behavior. The L-PBF material had a higher fatigue limit and better finite life performance compared to wrought material. Both, LCF and HCF-testing revealed an extensive cyclic softening. T2 - FATIGUE DESIGN 2021 CY - Online meeting DA - 17.11.2021 KW - Additive manufacturing KW - L-PBF KW - 316L KW - Fatigue KW - LCF KW - HCF PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-544952 DO - https://doi.org/10.1016/j.prostr.2022.03.056 SN - 2452-3216 VL - 38 SP - 554 EP - 563 PB - Elsevier B.V. AN - OPUS4-54495 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schirdewahn, S. A1 - Spranger, Felix A1 - Hilgenberg, Kai A1 - Merklein, M. T1 - Tribological and thermal behavior of laser implanted tool surfaces for hot stamping AlSi coated 22MnB5 sheets N2 - In the automotive industry, the development of electrically powered vehicles has become a major forward-looking topic. For improving the range and thus the efficiency of electric cars, lightweight construction has gained even more importance. In this regard, hot stamping has been established as a suitable and resource efficient process to manufacture high-strength and lightweight body-in-white components. This method combines hot forming and quenching of boron-manganese steel 22MnB5 in a single process step. As a result, complex structures with thin sheet thicknesses and high ultimate tensile strength up to 1500 MPa are generated. However, the use of lubricants is not possible at elevated temperatures, which subsequently leads to high thermo-mechanical tool stresses. As a side effect, high friction and severe wear occur during the forming process, which affect the resulting part quality and maximum tool life. Therefore, the aim of this study is to improve the tribological performance of hot stamping tools by using a laser implantation process. This technique is based on manufacturing highly wear resistant, separated and elevated structures in micrometer range by embedding hard ceramic particles into the tool material via pulsed laser radiation. As a result, highly stressed areas on the tool surface can be modified locally, which in turn influence the tribological and thermal behavior during the forming process. In this regard, laser implanted and conventionally tool surfaces were investigated under hot stamping conditions. A modified pin-on-disk test was used to analyze the friction coefficient and occuring wear mechanisms. Furthermore, quenching tests as well as hardness measurements were carried out to gain in-depth knowledge about the cooling behavior of the modified tool surfaces and its impact to the resulting mechanical part properties. KW - Laser implantation KW - Laser dispersing KW - Surface structuring KW - Hot stamping PY - 2022 DO - https://doi.org/10.4028/p-e4i60t SN - 1662-9507 IS - 414 SP - 69 EP - 74 PB - Trans Tech Publications CY - Baech AN - OPUS4-54302 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kröll, Mirco T1 - Trusted tribological materials characterisation services N2 - Renowed institutions in various European countries combine their tribo-testing as well as analytical and characterisation capabilities for the European Tribology Centre. This foundation of one of the largest Open Innovative Test Beds for tribological services, the aim of the European Horizon 2020 project i-TRIBOMAT, places certain demands on the comparability of the test equipment and execution process. T2 - 23rd International Colloquium Tribology at TAE CY - Online meeting DA - 25.01.2022 KW - Tribology KW - i-TRIBOMAT KW - Characterisation KW - Digitalisation KW - Harmonisation KW - Round robin tests KW - Interlaboratory tests PY - 2022 AN - OPUS4-54291 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kröll, Mirco A1 - Grundtner, R. A1 - Newrkla, K. A1 - Spaltmann, Dirk A1 - Pagano, F. A1 - Pinedo, B. A1 - Nyberg, E. A1 - Söderfjäll, M. A1 - Heino, V. A1 - Ronkainen, H. ED - Topolovec-Miklozic, K. ED - Pauschitz, A. ED - Fatemi, A. T1 - Trusted tribological materials characterisation services N2 - Renowed institutions in various European countries combine their tribo-testing as well as analytical and characterisation capabilities for the European Tribology Centre. This foundation of one of the largest Open Innovative Test Beds for tribological services, the aim of the European Horizon 2020 project i-TRIBOMAT, places certain demands on the comparability of the test equipment and execution process. T2 - 23rd International Colloquium Tribology at TAE CY - Online meeting DA - 25.01.2022 KW - Tribology KW - i-TRIBOMAT KW - Characterisation KW - Digitalisation KW - Harmonisation KW - Round robin tests KW - Interlaboratory tests PY - 2022 SN - 978-3-8169-3547-6 SP - 503 EP - 505 PB - Narr Francke Attempto Verlag CY - Tübingen AN - OPUS4-54293 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Duarte, Larissa T1 - Fracture mechanics fatigue life assessmente based on effective crack propagation data obtained at closure-free conditions N2 - The use of effective crack propagation data, i.e. not affected by the crack closure mechanisms, is proposed as a reliable and robust alternative for the fatigue life assessment of cyclically loaded components. T2 - 43rd Materials Mechanics Seminar CY - Sani, Greece DA - 05.06.2022 KW - Effective crack propagation data KW - Crack-closure KW - Component assessment PY - 2022 AN - OPUS4-55044 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fabry, Çağtay T1 - Multi-Layer welding data analysis and open data approach using WelDX N2 - The talk motivates and introduces the WelDX project and the proposed solutions for current challenges in the field of research data management and Open Science practices in welding research. Using an exemplary welding dataset based on the joint and welding process design of offshore structures, advanced data fusion and analysis capabilities are demonstrated. The dataset shown consists of a complex welding sequence covering multiple weld layers with varying process parameters and adaptive weaving motions to cover manufacturing tolerances. In the presentation, an interactive exploration of the dataset contents in the spatial domain is presented. Furthermore, transformation between spatial and time domain of the data is demonstrated. In addition to data gathered during the welding process, the integration of downstream testing data and results is also explained. For demonstration, integration of weld seam cross section images and Vickers hardness mapping test results into the dataset are explained an demonstrated. The testing data is set into context with the welding process information. Finally, implications for advancements in research data management for WAAM and AI applications are discussed. T2 - The 75th IIW Annual Assembly and International Conference CY - Tokyo, Japan DA - 17.07.2022 KW - WelDX KW - Research data management KW - Open science KW - Arc welding KW - Digital transformation PY - 2022 AN - OPUS4-55354 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, Xiangmeng A1 - Bachmann, Marcel A1 - Artinov, Antoni A1 - Rethmier, Michael T1 - A study of the magnetohydrodynamic effect on keyhole dynamics and defect mitigation in laser beam welding N2 - In this paper, the highly transient keyhole dynamics, e.g., laser absorption, keyhole geometry, and fluctuation, etc., under a magnetic field are investigated using an experimental approach and multi-physical modeling. The model provides accurate predictions to the variation of penetration depth and weld pool profiles caused by the MHD effect, which is validated by the measurements of optical micrographs and in-situ metal/glass observation. The micro-X-ray computed tomography shows a remarkable reduction of keyhole-induced porosity with the magnetic field. The correlation between the porosity mitigation and the weld pool dynamics influenced by the magnetic field is built comprehensively. It is found that the magnetic field gives a direct impact on the laser energy absorption at the keyhole front wall by changing the protrusion movement. The porosity mitigation comes from multiple physical aspects, including keyhole stabilization, widening of the bubble floating channel, and the electromagnetic expulsive force. Their contributions vary according to the bubble size. The findings provide a deeper insight into the relationship between electromagnetic parameters, keyhole dynamics, and suppression of keyhole-relevant defects. KW - Laser beam welding (LBW) KW - Keyhole dynamics KW - Porosity KW - Magnetohydrodynamics (MHD) KW - X-ray computed tomography KW - Multi-physical modeling PY - 2022 DO - https://doi.org/10.1016/j.jmatprotec.2022.117636 SN - 0924-0136 VL - 307 SP - 117636 PB - Elsevier B.V. AN - OPUS4-55378 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kröll, Mirco T1 - Effects of harmonised procedures in tribology testing N2 - i-TRIBOMAT will provide the world's first Open Innovation Test Bed dedicated to analysing and simulating materials in tribological systems. In order to make necessary results of tribological tests comparable, harmonised ways to produce data are mandatory. Many sources influence the outcome of a Tribological test. Different approaches of institutes were evaluated in best practices via quality management tools minimising the impact on results. T2 - 7th World Tribology Congress - WTC 2022 CY - Lyon, France DA - 11.07.2022 KW - Tribology KW - i-TRIBOMAT KW - Characterisation KW - Digitalisation KW - Harmonisation KW - Round robin tests KW - Interlaboratory tests PY - 2022 AN - OPUS4-55317 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Spaltmann, Dirk T1 - Tribological performance of FS-laser-induced periodic surface structures on titanium alloy against different counter-body materials using a ZDDP lubricant additive N2 - In this study the so-called laser-induced periodic surface structures (LIPSS, ripples) were produced on titanium alloy (Ti6Al4V) surfaces upon scan processing in air by a Ti:sapphire femtosecond (fs) laser. The tribological performance of the resulting surfaces was qualified in linear reciprocating sliding tribological tests (RSTT) against balls made of different materials (100Cr6 steel/Al2O3/Si3N4) using different oil-based lubricants. The admixture of the additive 2-ethylhexylzinc-dithiophosphate (ZDDP) to a base oil containing only anti-oxidants and temperature stabilizers disclosed the synergy of the additive with the laser-oxidized nanostructures. This interplay between the laser-textured sample topography and the local chemistry in the tribological contact area reduces friction and wear. T2 - 7th World Tribology Congress - WTC 2022 CY - Lyon, France DA - 11.07.2022 KW - Lubricant additives KW - Laser-induced periodic surface structures (LIPSS) KW - Wear KW - Friction PY - 2022 AN - OPUS4-55318 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zabala, A. T1 - Ball-on-flat linear reciprocating tests: Critical assessment of wear volume determination methods N2 - This work presents a critical assessment of wear volume determination methods for ball-on-flat linear reciprocating sliding tribological tests. T2 - 7th World Tribology Congress - WTC 2022 CY - Lyon, France DA - 11.07.2022 KW - Wear KW - Sliding KW - Surface KW - Analysis PY - 2022 AN - OPUS4-55319 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Woydt, M. T1 - Slip-rolling resistant steel alloys up to P0max = 3,920 MPa under lubricated conditions N2 - Downsizing (power-to-weight ratio) and higher speeds lead to a rise in Hertzian contact pressures in combination with an increase in surface or oil temperatures. Under such conditions, commonly used bearing steels, such as 100Cr6, reach their limits, creating a demand for alternative slip-rolling resistant steel alloys. The present work therefore compares the slip-rolling performance of various steel types with Maraging- and PM-type steel alloys in the Hertzian contact pressure range up to P0max of 4 GPa. T2 - 7th World Tribology Congress - WTC 2022 CY - Lyon, France DA - 11.07.2022 KW - Steel KW - Alloy KW - Slip-rolling KW - Friction KW - Wear rate KW - Contact pressure PY - 2022 AN - OPUS4-55320 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Roveda, Ilaria T1 - Investigation of residual stresses and microstructure effects on the fatigue behaviour of a L-PBF AlSi10Mg alloy N2 - Laser Powder Bed Fusion (L-PBF) allow the fabrication of lightweight near net shape AlSi10Mg components attractive to the aerospace, automotive, biomedical and military industries. During the build-up process, high cooling rates occur. Thus, L-PBF AlSi10Mg alloys exhibit a Si-nanostructure in the as-built condition, which leads to superior mechanical properties compared to conventional cast materials. At the same time, such high thermal gradients generally involve a deleterious residual stress (RS) state that needs to be assessed during the design process, before placing a component in service. To this purpose post-process heat treatments are commonly performed to relieve detrimental RS. In this contribution two low-temperature stress-relief heat treatments (SRHT) are studied and compared with the as-built state: a SRHT at 265°C for 1 hour and a SRHT at 300°C for 2 hours. At these temperatures microstructural changes occur. In the as-built state, Si atoms are supersaturated in the α-aluminium matrix, which is enveloped by a eutectic Si-network. At 265°C the Si precipitation from the matrix to the pre-existing network is triggered. Thereafter, above 295°C the fragmentation and spheroidization of the Si branches takes place, presumably by Al–Si interdiffusion. After 2 hours the original eutectic network is completely replaced by uniformly distributed blocky particles. The effect of the heat and the microstructure modification on the RS state and the fatigue properties is investigated. Energy dispersive x-ray and neutron diffraction are combined to investigate the near-surface and bulk RS state of a L-PBF AlSi10Mg material. Differences in the endurance limit are evaluated experimentally by high cycle fatigue (HCF) tests and cyclic R-curve determination. T2 - 43rd Materials Mechanics Seminar CY - Sani, Chalkidiki, Greece DA - 05.06.2022 KW - AlSi10Mg KW - Fatigue KW - Neutron diffraction KW - X-ray diffraction PY - 2022 AN - OPUS4-55090 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübler, Daniela A1 - Gradt, Thomas T1 - Effect of different binders and secondary carbides on NbC cermets T1 - Einfluss unterschiedlicher Binder und Sekundärkarbide auf NbC-Hartmetalle N2 - Due to the rapidly increasing price of tungsten carbide and the significant health risks associated with the wear products of WC-Co (Co3O4 and Wo3), an alternative is required. Niobium carbide (NbC) is well suited as a cutting tool due to its high melting point and low solubility in iron. So far, NbC-Ni cermets best met the requirements of high hardness and toughness. Various secondary carbides such as VC, Mo2C, TiC, but also WC were added to further improve the hardness. N2 - Aufgrund des rasanten Preisanstiegs von Wolframcarbid und signifikanter Gesundheitsrisiken, die mit den Verschleißprodukten von WC-Co-Hartmetallen (Co3O4 and Wo3) einhergehen, wird eine Alternative benötigt. Niobcarbid (NbC) ist als Zerspanwerkzeug aufgrund seiner hohen Schmelztemperatur und seiner geringen Löslichkeit in Eisen gut geeignet. Im Vergleich zu reinem NbC, führte eine vollständige Substitution von WC zu NbC-Co zu einem Anstieg der Zähigkeit und Festigkeit. Als alternative Binder wurden anschließend Nickel- und Eisengebundene Binder untersucht. Obwohl eisengebundene Hartmetalle im Vergleich zu NbC-Ni Hartmetallen eine ökonomische und kostengünstigere Alternative darstellen würden, zeigten sie einen höheren Reibkoeffizienten und eine höhere Verschleißrate. Bisher erfüllen die NbC-Ni-Hartmetalle die Anforderungen hinsichtlich einer hohen Härte und Zähigkeit am besten. Verschiedene Sekundärkarbide, wie VC, Mo2C, TiC, aber auch WC wurden zusätzlich hinzugefügt, um die Härte weiter zu steigern. Elementanalysen der NbC-Ni-MeC Hartmetalle (Me = Metall) zeigten, dass der Binder eine kubisch-flächenzentrierter Mischkristall ist, während die NbC Phase ein Mischkristall des Typs (Nb, Me)C ist. KW - Niobium carbide (NbC) KW - Cutting tool KW - Binders PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-547202 DO - https://doi.org/10.1007/s10010-022-00583-1 SN - 0015-7899 VL - 86 IS - 2 SP - 197 EP - 211 PB - Springer CY - Berlin AN - OPUS4-54720 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kröll, Mirco T1 - On the challenges in achieving comparable and reproducible tribological model tests N2 - An infrastructure of more than 100 tribometers (for The European Tribology Centre i-TRIBOMAT) requires procedures which ensure that the respective results are characteristic as well as descriptive, trustworthy, comparable, and reproducible. T2 - Tribology International Conference 2022 (SETCOR) CY - Barcelona, Spain DA - 28.04.2022 KW - Tribology KW - i-TRIBOMAT KW - Characterisation KW - Digitalisation KW - Harmonisation KW - Round robin tests KW - Interlaboratory tests PY - 2022 AN - OPUS4-54754 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zhu, Jiangchao T1 - Burst behaviours of aero-engine turbine disk at overspeed conditions N2 - This presentation focuses on the basic ideas and current status of the development of an arithmetical method to predict the failure rotational speed of turbine disks. The certification specification requires that a gas turbine aero-engine must hold 5 minutes at overspeed conditions without critical failure. Therefore, instead of experimental proof from spin-tests using test-disks similar to engine components, it is considered to use simple specimen with similar test conditions compared to real overspeed scenarios. These test conditions, or stress fields are determined using arithmetical method, e.g. finite element method, with consideration of fracture mechanics under quasi-static conditions with a given rotational speed. Failure modes like hoop burst and rim peeling are considered during determination of stress fields. Various crack-tip parameters are used to explore the similarity of stress field between simple specimen and real overspeed scenarios. Additionally, probabilistic aspects and the implementation of a global stability criterion for overspeed analysis are also considered. T2 - 43rd Materials Mechanics Seminar CY - Sani, Chalkidiki, Greece DA - 06.06.2022 KW - Structural integrity KW - Fracture mechanics KW - Turbine disk KW - Overspeed PY - 2022 AN - OPUS4-55081 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zhu, Jiangchao T1 - Fracture mechanics-based structural integrity assessment of aero-engine turbine disks under overspeed conditions N2 - Aero-engine turbine disks are safety-relevant components which are operated under high thermal and mechanical stress conditions. The actual part qualification and certification procedures make use of spin-tests conducted on production-similar disks. While these tests provide, on the one hand, a reliable definition of the critical conditions for real components, on the other hand they represent a relevant cost item for engine manufacturers. The aim of this work is to present part of a fracture mechanics-based procedure under development which aims at replacing the tests on production-similar disks with lab tests on fracture mechanics specimens. In particular, the rim-peeling failure mode is considered as case study. A semi-circular surface crack is modelled at the most stressed region at the diaphragm of a turbine disk, with the crack plane perpendicular to the radial direction. The crack is therefore subjected to a biaxial stress state and grows under increasing rotational speed until it triggers the rim-peeling failure. The finite element simulation of the cracked disk considers the real thermal and mechanical loading conditions. In order to design a lab representative specimen, beside the crack driving force, expressed in terms of J-integral, also the constraint to plastic deformation e.g., stress triaxiality, at the crack-tip must be similar for the same crack in the specimen and in the disk. This has been achieved and as expected, both the highest J-integral and constraint factor are calculated at the same location along the crack front for both disk and specimen. The results of the structural integrity assessment in the form of a Failure Assessment Diagram (FAD) show good agreement between designed specimen and disk both in terms of expected failure mode and value of the critical speed. Probabilistic aspects are also considered in the calculations. T2 - Turbo Expo 2022 CY - Rotterdam, Netherlands DA - 13.06.2022 KW - Structural integrity KW - Fracture mechanics KW - Turbine disk KW - Overspeed PY - 2022 AN - OPUS4-55082 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gook, S. A1 - El-Sari, B. A1 - Biegler, M. A1 - Rethmeier, Michael A1 - Lichtenthäler, F. A1 - Stark, M. T1 - Multiple-wire submerged arc welding of high-strength fine-grained steels N2 - Ensuring the required mechanical-technological properties of welds is a critical issue in the application of multi-wire submerged arc welding processes for welding high-strength fine-grained steels. Excessive heat input is one of the main causes for microstructural zones with deteriorated mechanical properties of the welded joint, such as a reduced notched impact strength and a lower structural robustness. A process variant is proposed which reduces the weld volume as well as the heat input by adjusting the welding wire configuration as well as the energetic parameters of the arcs, while retaining the advantages of multiwire submerged arc welding such as high process stability and production speed. KW - Submerged arc welding KW - High-strength fine-grained steels KW - Mechanical properties of the joints KW - Energy parameters of the arc PY - 2022 DO - https://doi.org/10.37434/tpwj2022.01.02 SN - 0957-798X IS - 1 SP - 9 EP - 13 PB - Paton Publishing House CY - Kiev AN - OPUS4-54701 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scheuschner, Nils T1 - In-situ Monitoring of PBF-LB/M by thermography, optical tomography, melt-pool-monitoring and eddy current N2 - The formation of defects such as keyhole pores is a major challenge for the production of metal parts by Laser Powder Bed Fusion (LPBF). The LPBF process is characterized by a large number of influencing factors which can be hard to quantify. Machine Learning (ML) is a prominent tool to predict the outcome of complex processes on the basis of different sensor data. In this study, a ML model for defect prediction is created using thermographic image features as input data. As a reference, the porosity information calculated from an x-ray Micro Computed Tomography (µCT) scan of the produced specimen is used. Physical knowledge about the keyhole pore formation is incorporated into the model to increase the prediction accuracy. From the prediction result, the quality of the input data is evaluated and future demands on in-situ monitoring of LPBF processes are formulated. T2 - AM Bench 2022 CY - Bethesda, Washingthon DC, USA DA - 15.08.2022 KW - Additive Manufacturing KW - Thermography KW - Additive Fertigung KW - Thermografie PY - 2022 AN - OPUS4-55854 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Grimault de Freitas, Tomás T1 - Utilization of the Tubular Specimen Technique for the Qualification of Metallic Materials for Hydrogen Technologies N2 - As the world shifts to a decarbonized economy, the demand for hydrogen-based technologies is rapidly increasing. In order to make optimal use of hydrogen as an energy carrier, the infrastructure for hydrogen storage and transport in particular, must meet high technical safety standards. The indispensable basis for such safety assessments are the material properties, which must be evaluated under operating conditions that are as real as possible. The conventional method for the assessment of the material properties in gaseous hydrogen is conducted by testing materials in high-pressure hydrogen gas in a pressure vessel (autoclave). It is an established method that allows to perform common standardized tests such as tensile, fatigue and crack growth tests under varying hydrogen conditions. However, this method is complex and entails high costs due to extensive safety regulations. The hollow specimen technique is a more efficient test method, which can be used to assess the mechanical properties of materials under high-pressure hydrogen gas. The procedure is conducted by enclosing high-pressure gas into a hole along the axis of the tensile test specimen. Recently, this method has been successfully performed at pressures up to 1000 bar and over a wide range of temperatures. Due to the low hydrogen volume needed, this method requires minimal safety regulation; therefore, the costs are reduced when compared to the conventional autoclave technique. This method is now in a standardization process, which has been initiated by Japan as a new working package in ISO (TC 164/SC 1/WG 9). The following contribution presents preliminary results obtained testing common grades of metastable austenitic stainless steel. For this purpose, the mechanical properties and fracture surface of solid and tubular specimens were assessed and compared using slow strain rate tensile (SSRT) test as part of the preliminary work at the Fraunhofer IWM. In a similar way, pipeline steels evaluated under hydrogen atmospheres using the geometry adapted by BAM will be presented. Within the framework of the TransHyDE flagship project, more results with the goal of supporting the standardization of the hollow specimen technique are expected to be obtained. T2 - ZwickRoell Forum for High-Temperature Testing CY - Fürstenfeld, Austria DA - 03.05.2023 KW - Hydrogen KW - H2Hohlzug KW - TransHyDE KW - Tubular specimen technique KW - Innovation PY - 2023 AN - OPUS4-57417 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scheuschner, Nils T1 - In-situ monitoring of the laser powder bed fusion process by thermography, optical tomography and melt pool monitoring for defect detection N2 - For the wide acceptance of the use of additive manufacturing (AM), it is required to provide reliable testing methods to ensure the safety of the additively manufactured parts. A possible solution could be the deployment of in-situ monitoring during the build process. However, for laser powder bed fusion using metal powders (PBF-LB/M ) only a few in-situ monitoring techniques are commercially available (optical tomography, melt pool monitoring) but not researched to an extent that allows to guarantee the adherence to strict quality and safety standards. In this contribution, we present results of a study of PBF-LB/M printed parts made of the nickel-based superalloy Haynes 282. The formation of defects was provoked by local variations of the process parameters and monitored by thermography, optical tomography and melt pool monitoring. Afterwards, the defects were characterized by computed tomography (CT) to identify the detection limits of the used in-situ techniques. T2 - LiM Conference 2023 - Lasers in Manufacturing CY - Munich, Germany DA - 26.06.2023 KW - Thermography KW - High temperature alloys KW - Additive Manufacturing KW - PBF-LB/M PY - 2023 AN - OPUS4-57947 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Woitzek, Andreas A1 - Kasch, Thomas A1 - Kittler-Packmor, Kai ED - Steinberg, Th. A. ED - Chiffoleau, G. J. T1 - New large-scale 750 bar Oxygen Pressure Surge Test Facility N2 - The Oxygen Pressure Surge Test (OPST) is considered to be best practice for evaluating the burn out safety of plant components and testing the compatibility of nonmetallic materials for oxygen service. Nevertheless, there are only a few laboratories worldwide performing the OPST. The Federal Institute for Materials Research and Testing (BAM) already operates oxygen pressure surge test facilities with maximum OPST pressures of 450 bar. However, to ensure technical innovation and to enhance research and development, the decision was made to develop a new and large-scale oxygen pressure surge test facility. Due to the size and the high potential impact energies, the test facility is located outside of Berlin at BAM Test Site for Technical Safety (TTS), where large scale testing is carried out. In addition to an intended maximum OPST pressure of 750 bar, there is the possibility of testing industrial equipment with large inner volumes and diameters. The new quick opening valve constitutes the core of the system and was developed by BAM. It allows to perform tests with the standardized pressure rise times of 15 ms to 20 ms or with adjustable pressure rise times at higher or lower values. As a result, it is possible to provide customized test parameters for specific practical applications as well as research projects. This presentation shows the status quo of this unique test facility, its performance, its technical specifications, and its new possibilities for research and development for a long term enhancement of burn out safety in oxygen application. KW - Oxygen pressure surge test KW - Adiabatic compression KW - Burn out safety KW - Innovation in OPST facility KW - Adjustable pressure rise time PY - 2021 SN - 978-0-8031-7698-0 DO - https://doi.org/10.1520/STP1626-EB SN - 0899-6652 VL - STP 1626 - 15 SP - 326 EP - 340 PB - ASTM International CY - West Conshohocken, PA, USA AN - OPUS4-54889 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kröll, Mirco T1 - Benefits of novel tools open to Industry from Open Innovation Testbeds. Effects of harmonised procedures in (digital) Tribology N2 - The work on Tribology, digitalisation, and the harmonised procedures developed in i-TRIBOMAT Open Innovation Testbed was presented. The project develops procedures and shares ideas on how to deal with characterisation techniques and provide services to end users in different places and locations, which is realised by adopting a common and widely agreed procedures. i-TRIBOMAT is active also via YouTube platform to enhance communication and spread the word amongst the interested parties and society. T2 - Workshop of NanoMECommons project: "Materials characterisation challenges to support the industry transition in the digital era" CY - Online meeting DA - 13.12.2021 KW - Tribology KW - i-TRIBOMAT KW - Characterisation KW - Digitalisation KW - Interoperability KW - Harmonisation KW - Green Deal PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-548909 DO - https://doi.org/10.5281/zenodo.6339985 SP - 14 EP - 17 AN - OPUS4-54890 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heßmann, Jennifer T1 - Meeting the challenge of thermal joining of steel and aluminum using a new approach based on melt displacement by electromagnetic forces N2 - Environmental protection, resource conservation and CO2 reduction require new joining concepts for effective multi-material design in automotive lightweight construction. The thermal joining of dissimilar materials, especially the combination of aluminum alloys and steel, is associated with difficulties. Different material properties, such as melting point and coefficient of thermal expansion, complicate joining processes. Furthermore, the insolubility between these materials results in the formation of intermetallic phases. These brittle phases reduce the load-bearing capacity and quality of the joints. The thickness of the intermetallic phases should not reach the critical value of 10 μm to ensure good mechanical properties of the joint. It is known that a two-phase reaction layer consisting of Al5Fe2 and Al3Fe (also known as Al13Fe4) forms at the interface between solid steel and liquid aluminum. Due to high cooling rates, as it is the case in laser beam welding, metastable intermetallic compounds can form different from the equilibrium state. The formation of the intermetallic reaction layer is a diffusion-controlled process. So, it is only possible to control the growth of these phases. This problem has led to use joining methods that do not require the melting of both joining partners. A promising joining method is laser beam welding-brazing, whereby only one joining partner is melted and wets the solid joining partner. Conventional laser beam welding-brazing only results in material-fit joints and often requires the use of expensive filler materials. An additional form-fit could optimize the mechanical performance of the joint. For this reason, a new joining method for overlap configurations of dissimilar materials was developed. A laser beam melts the lower joining partner through a cavity of the upper joining partner. The created melt pool is moved upwards into the cavity of the upper joining partner due to contactless induced Lorentz forces of an AC-magnetic system. The displaced melt creates a form- and material-fit joint after solidification. The advantage of this joining technology is the absence of filler materials, flux agents and expensive auxiliary joining elements. T2 - 5th International Conference Hybrid 2022 - Materials and Structures CY - Leoben, Austria DA - 20.07.2022 KW - Joining dissimilar materials KW - Laser beam welding KW - Electromagnetic forces KW - Steel and aluminium PY - 2022 AN - OPUS4-55534 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heßmann, Jennifer A1 - Hilgenberg, Kai ED - Hausmann, J. M. T1 - Meeting the challenge of thermal joining of steel and aluminum using a new approach based on melt displacement by electromagnetic forces N2 - Environmental protection, resource conservation and CO2 reduction require new joining concepts for effective multi-material design in automotive lightweight construction. The thermal joining of dissimilar materials, especially the combination of aluminum alloys and steel, is associated with difficulties. Different material properties, such as melting point and coefficient of thermal expansion, complicate joining processes. Furthermore, the insolubility between these materials results in the formation of intermetallic phases. These brittle phases reduce the load-bearing capacity and quality of the joints. The thickness of the intermetallic phases should not reach the critical value of 10 μm to ensure good mechanical properties of the joint. It is known that a two-phase reaction layer consisting of Al5Fe2 and Al3Fe (also known as Al13Fe4) forms at the interface between solid steel and liquid aluminum. Due to high cooling rates, as it is the case in laser beam welding, metastable intermetallic compounds can form different from the equilibrium state. The formation of the intermetallic reaction layer is a diffusion-controlled process. So, it is only possible to control the growth of these phases. This problem has led to use joining methods that do not require the melting of both joining partners. A promising joining method is laser beam welding-brazing, whereby only one joining partner is melted and wets the solid joining partner. Conventional laser beam welding-brazing only results in material-fit joints and often requires the use of expensive filler materials. An additional form-fit could optimize the mechanical performance of the joint. For this reason, a new joining method for overlap configurations of dissimilar materials was developed. A laser beam melts the lower joining partner through a cavity of the upper joining partner. The created melt pool is moved upwards into the cavity of the upper joining partner due to contactless induced Lorentz forces of an AC-magnetic system. The displaced melt creates a form- and material-fit joint after solidification. The advantage of this joining technology is the absence of filler materials, flux agents and expensive auxiliary joining elements. T2 - 5th International Conference Hybrid 2022 - Materials and Structures CY - Leoben, Austria DA - 20.07.2022 KW - Joining dissimilar materials KW - Laser beam welding KW - Electromagnetic forces KW - Steel and aluminium PY - 2022 SN - 978-3-88355-426-6 SP - 6 EP - 8 PB - Deutsche Gesellschaft für Materialkunde (DGM) CY - Sankt Augustin AN - OPUS4-55536 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Michler, T. A1 - Grimault de Freitas, Tomás A1 - Oesterlin, H. A1 - Fischer, C. A1 - Wackermann, K. A1 - Ebling, F. T1 - Tensile testing in high pressure gaseous hydrogen using conventional and tubular specimens: Austenitic stainless steels N2 - Eight commercial austenitic stainless steels were tensile tested in reference atmosphere, in gaseous high-pressure hydrogen and in gaseous hydrogen precharged condition using conventional (CS) and tubular specimens (TS). For all configurations, 0.2 yield strength and ultimate tensile strength were comparable. In reference atmosphere, reduction of area of CS was higher compared to TS, whereas in gaseous high pressure hydrogen reduction of area of CS was lower compared to TS. In gaseous hydrogen precharged condition reduction of area of CS and TS were comparable for the severely affected grades. The differences in necking behavior between CS and TS are explained by different competitions between necking and hydrogen assisted crack initiation and growth especially for the tests in high pressure hydrogen gas. KW - Hydrogen KW - Hydrogen Embrittlement KW - Tensile Test KW - Conventional and Tubular Specimen KW - Austenitic Stainless Steel KW - High Pressure Gaseous Hydrogen PY - 2023 DO - https://doi.org/10.1016/j.ijhydene.2023.03.248 SN - 0360-3199 VL - 48 IS - 65 SP - 25609 EP - 25618 PB - Elsevier BV AN - OPUS4-58185 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kröll, Mirco T1 - On the quality of wear volume data of laboratory model tests N2 - European tribological research organisations unify their capabilities for the European Tribology Centre (https://www.i-tribomat.eu/). At its core is a database, which data are made comparable and trusted via harmonised procedures for their generation. This contribution will focus on wear volume data. T2 - 63. Tribologie-Fachtagung 2022 CY - Göttingen, Germany DA - 27.09.2022 KW - Tribology KW - i-TRIBOMAT KW - Characterisation KW - Digitalisation KW - Harmonisation KW - Round robin tests KW - Interlaboratory tests KW - Wear volume PY - 2022 AN - OPUS4-55880 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kröll, Mirco A1 - Grundtner, R. A1 - Newrkla, K. A1 - Pagano, F. A1 - Nyberg, E. A1 - Heino, V. A1 - Spaltmann, Dirk T1 - On the quality of wear volume data of laboratory model tests N2 - European tribological research organisations unify their capabilities for the European Tribology Centre (https://www.i-tribomat.eu/). At its core is a database, which data are made comparable and trusted via harmonised procedures for their generation. This contribution will focus on wear volume data. T2 - 63. Tribologie-Fachtagung 2022 CY - Göttingen, Germany DA - 26.09.2022 KW - Tribology KW - i-TRIBOMAT KW - Characterisation KW - Digitalisation KW - Harmonisation KW - Round robin tests KW - Interlaboratory tests KW - Wear volume PY - 2022 SN - 978-3-9817451-7-7 SP - 192 EP - 194 PB - Gesellschaft für Tribologie e.V. AN - OPUS4-55881 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Griesche, Axel A1 - Pfretzschner, Beate A1 - Taparli, Ugur Alp A1 - Kardjilov, N. T1 - Time-Resolved Neutron Bragg-Edge Imaging: A Case Study by Observing Martensitic Phase Formation in Low Temperature Transformation (LTT) Steel during GTAW N2 - Polychromatic and wavelength-selective neutron transmission radiography were applied during bead-on-plate welding on 5 mm thick sheets on the face side of martensitic low transformation temperature (LTT) steel plates using gas tungsten arc welding (GTAW). The in situ visualization of austenitization upon welding and subsequent α’-martensite formation during cooling could be achieved with a temporal resolution of 2 s for monochromatic imaging using a single neutron wavelength and of 0.5 s for polychromatic imaging using the full spectrum of the beam (white beam). The spatial resolution achieved in the experiments was approximately 200 µm. The transmitted monochromatic neutron beam intensity at a wavelength of λ = 0.395 nm was significantly reduced during cooling below the martensitic start temperature M s since the emerging martensitic phase has a ~10% higher attenuation coefficient than the austenitic phase. Neutron imaging was significantly influenced by coherent neutron scattering caused by the thermal motion of the crystal lattice (Debye–Waller factor), resulting in a reduction in the neutron transmission by approx. 15% for monochromatic and by approx. 4% for polychromatic imaging. KW - Neutron radiography KW - Debye–Waller factor KW - Austenite-to-martensite transformation KW - Low transformation temperature (LTT) steel KW - Bragg-edge imaging KW - Gas tungsten arc welding (GTAW) PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-559077 DO - https://doi.org/10.3390/app112210886 VL - 11 IS - 22 PB - MDPI AN - OPUS4-55907 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Herr, M. A1 - Borras, F. X. A1 - Spaltmann, Dirk A1 - Kröll, Mirco A1 - Pirker, F. A1 - Cihak-Bayr, U. T1 - How to create trusted tribological characterization data of soft polymers as input for FEM simulations? N2 - Soft polymers such as the investigated polyurethane, characterized by low Young’s moduli and prone to high shear deflection, are frequently applied in pneumatic cylinders. Their performance and lifetime without external lubrication are highly determined by the friction between seal and shaft and the wear rate. FEM simulation has established itself as a tool in seal design processes but requires input values for friction and wear depending on material, load, and velocity. This paper presents a tribological test configuration for long stroke, reciprocating movement, allowing the generation of data which meet the requirements of input parameters for FEM simulations without the geometrical influences of specific seal profiles. A numerical parameter study, performed with an FEM model, revealed the most eligible sample geometry as a flat, disc-shaped sample of the polymer glued on a stiff sample holder. At the same time, the study illustrates that the sensitivity of the contact pressure distribution to Poisson’s ratio and CoF can be minimized by the developed and verified setup. It ensures robust, reliable, and repeatable experimental results with uniform contact pressures and constant contact areas to be used in databases and FEM simulations of seals, enabling upscaling from generically shaped samples to complex seal profiles. KW - Tribologie KW - FEM KW - Simulation KW - Polymere KW - Charakterisierung KW - i-TRIBOMAT KW - Modellierung KW - Polyurethan KW - Dichtungen KW - Upscaling PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-567683 DO - https://doi.org/10.3390/ma16010131 SN - 1996-1944 VL - 16 IS - 1 SP - 1 EP - 20 PB - MDPI CY - Basel AN - OPUS4-56768 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bergant, M. A1 - Larrosa, N. A1 - Yawny, A. A1 - Madia, Mauro T1 - Short crack growth model for the evaluation of the fatigue strength of WAAM Ti-6Al-4V alloy containing pore-type defects N2 - The role of defects in the fatigue strength of Wire Arc Additively Manufactured (WAAMed) Ti-6Al-4V is analysed by means of the IBESS model, a fracture mechanics short crack growth approach based on the cyclic R-curve. Pores and crack-like defects are analysed. Estimations of the role of pore shape and size agree well with published fatigue data of WAAM Ti-6Al-4V with pores. The model is also used to explain the effect of fabrication defects on the scatter of experimental data. This demonstrates that short crack growth models represent a suitable engineering tool for the fatigue assessment of defective AM materials. KW - WAAM Ti-6Al-4V KW - Cyclic R-curve KW - IBESS model for short cracks KW - Kitagawa-Takahashi (K-T) diagram PY - 2023 DO - https://doi.org/10.1016/j.engfracmech.2023.109467 SN - 0013-7944 VL - 289 SP - 1 EP - 21 PB - Elsevier Ltd. AN - OPUS4-57963 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Grimault de Freitas, Tomás T1 - State of the Art in the Qualification of Metallic Materials for Hydrogen Technologies N2 - The hydrogen economy is one of the main solutions for achieving climate neutrality in Europe. Metallic materials, predominantly steels, are the most common structural materials in the various components along the hydrogen supply chain. Ensuring their sustainable and safe use in hydrogen technologies is a key factor in the ramp-up of the hydrogen economy. This requires extensive materials qualification, however, most of the accepted, and standardised test methods for determining the influence of gaseous hydrogen on metallic materials describe complex and costly procedures that are only available to a very limited extent worldwide (e.g., autoclave technique). The hollow specimen technique is presented as an alternative method that can overcome the limitations of current techniques and complement them. To standardise the technique, a process has been initiated by ISO in 2021. Knowledge gaps for tests with the technique in hydrogen have been identified by DIN. The H2HohlZug project, which falls under the umbrella of TransHyDE, aims to address the identified knowledge gaps and provide a foundation for a comprehensive standardisation of the hollow specimen technique. T2 - E-World Energy & Water CY - Essen, Germany DA - 20.02.2024 KW - Hydrogen KW - Hydrogen Embrittlement KW - Hollow Specimen Technique KW - High-Pressure Gaseous Hydrogen KW - Standardisation KW - H2HohlZug KW - TransHyDE PY - 2024 AN - OPUS4-59564 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kröll, Mirco T1 - Creating a Tribological Dataspace N2 - Dataspaces are a concept to share and distribute data. Introducing this concept in a tribological context will help to provide a wider availability of the domain a deeper understanding of tribological phenomena. T2 - Tribology Days 2023 CY - Hagen, Germany DA - 15.11.2023 KW - Tribology KW - i-TRIBOMAT KW - Dataspace KW - Digitalisation KW - Harmonisation KW - Database PY - 2023 AN - OPUS4-58901 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Srinivasan, Krishnanand A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Laser Metal Deposition of Rene 80 – Microstructure and Solidification Behaviour Modelling N2 - New developments in nickel-based superalloys and production methods, such as the use of additive manufacturing (AM), can result in innovative designs for turbines. It is crucial to understand how the material behaves during the AM process to advance industrial use of these techniques. An analytical model based on reaction-diffusion formalism is developed to better explain the solidification behavior of the material during laser metal deposition (LMD). The well-known Scheil-Gulliver theory has some drawbacks, such as the assumption of equilibrium at the solid-liquid interface, which is addressed by this method. The solidified fractions under the Scheil model and the pure equilibrium model are calculated using CALPHAD simulations. Differential scanning calorimeter is used to measure the heat flow during the solid-liquid phase transformation, the result of which is further converted to solidified fractions. The analytical model is compared with all the other models for validation. T2 - Lasers in Manufacturing Conference 2023 CY - Munich, Germany DA - 26.06.2023 KW - Additive manufacturing KW - Laser metal deposition KW - Solidification behaviour KW - Analytical model KW - Nickel-based superalloy PY - 2023 SP - 1 EP - 10 AN - OPUS4-58612 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Üstündag, Ömer T1 - High-power hybrid laser arc welding of thick materials with electromagnetic weld pool support N2 - In addition to the many advantages of deep penetration, increased welding speed and a low sensitivity to manufacturing tolerances such as gap and edge offset, the hybrid laser arc welding (HLAW) process is used increasingly in industrial applications such as shipbuilding or pipeline manufacturing. Nonetheless, thick-walled sheets with a wall thickness of 20 mm or more are still multi-pass welded using the arc welding process, due to increased process instability by increasing laser power. Welding at reduced speed, especially in a flat position, leads to an irregular formation of the root part such as dropping. The hydrostatic pressure exceeds the surface tension, which decreases with increasing seam width. In order to prevent gravity drop-outs, the use of a melt pool support is necessary. Usual weld pool supports such as ceramic or powder supports require time-consuming mechanical detachment. The electromagnetic weld pool support system, which is described in this study, operates without contact and based on generating Lorentz forces in the weld pool. An externally applied oscillating magnetic field induces eddy currents and generates an upward directed Lorentz force, which counteracts the hydrostatic pressure. This allows single-pass welds up to 30 mm by hybrid laser arc welding process with a 20-kW fibre laser. Moreover, it is favoured by the diminished welding speed the cooling rate which leads to an improvement of the mechanical-technological properties of the seams – the lower formation of martensite in the microstructure enables better Charpy impact toughness. The electromagnetic weld pool support extends the limitation of the laser hybrid welding process in the thick sheet area. By adapting the electromagnetic weld pool support to the laser and laser hybrid welding process, the application potential of these technologies for industrial implementation can be drastically increased. T2 - 23rd Technical Conference on Welding and Joining Technologies CY - Irun, Spain DA - 07.03.2023 KW - Laser hybrid welding KW - Thick-walled steel KW - Electromagnetic backing KW - High-power laser PY - 2023 AN - OPUS4-58613 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Üstündag, Ömer T1 - Influence of shielding gas on filler wire mixing at laser hybrid welding of thick high strength steels N2 - The laser hybrid welding process offers many advantages during welding oft hick-walled steels, such as the increased penetration depth and, thus, reduced number of layers, reduced heat input and decreased distortion compared to arc-based welding processes. Especially, when welding high-strength steels (HSS), the reduced heat input plays an essential role. However, a major challenge when laser hybrid welding of thick-walled steels is the limited filler wire mixing over the entire seam thickness, which can lead to changed mechanical properties over the depth. To overcome this issue, the add of oxygen into the shielding gas and its influence on the filler wire mixing and finally to the mechanical properties were investigated within this work. Therefore, 20 mm thick S690QL steels were laser hybrid welded in a single-pass. A contactless electromagnetic backing was used to avoid sagging. The admixture of oxygen was performed by a gas mixer, where the oxygen content was varied between 0 % and 7.2 %. The experiments were also accompanied by laser beam welding tests in steel/glass configuration, where the melt pool geometry as well as the melt flow characteristics were captured by a high-speed camera. It can be concluded, that adding of 2 % to 4 % oxygen into the shielding gas had a positive effect on the filler wire mixing, were up to a depth of 18 mm elements of the filler wire could be observed. T2 - 19th Nordic Laser Material Processing Conference CY - Turku, Finland DA - 22.08.2023 KW - Laser hybrid welding KW - Electromagnetic backing KW - Shielding gas KW - Charpy impact toughness KW - Thick-plate welding KW - Filler wire mixing PY - 2023 AN - OPUS4-58615 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Üstündag, Ömer T1 - Process advantages of laser hybrid welding compared to conventional arc-based welding processes for joining thick steel structures of wind tower N2 - The most common welding processes when joining thick-walled steels in the industry are arc-based welding processes such as GMAW or SAW. For this purpose, the sheets are joined in multi-layer technique, which can lead to productivity losses due to high welding times. The process-specific challenges in welding thick steels using multi-layer technique relate to the high heat input from the process. Therefore, alternative welding processes are being actively sought. A suitable alternative is provided by beam-based welding processes such as the laser beam or laser hybrid welding processes, which are characterized by deep penetration welds and lower heat input. With implementation of the laser hybrid welding process in the heavy industry, such as the wind tower industry, economic benefits can be reached such as the increase in productivity by reducing the layer number, and the lower consumption of filler material and energy. When comparing SAW welded 25 mm thick steels in five to six layers and single-pass laser hybrid welding, the welding time can be reduced more than 80 % and the costs of filler material, flux and energy can be saved up to 90 %. However, the industrial use of the laser hybrid welding process is still limited to applications, where the material thickness does not exceed 15 mm due to some process-specific challenges such as the sagging, sensitivity to manufacturing tolerances such as gaps and misalignment, limited filler wire mixing, and deteriorated mechanical properties resulting from high cooling rates. To overcome these challenges, an electromagnetic backing was used within the framework of this work, which works contactless and is based on an externally applied AC magnetic field. Eddy currents are induced due to the oscillating magnetic field, and an upward-oriented Lorentz force is generated to counteract the droplets formed due to gravitational forces. It allows to weld up to 30 mm thick structural steels in a single-pass with a 20-kW fiber laser system. Additionally, the gap bridgeability and the misalignment of edges were increased to 2 mm when welding 20 mm thick steels. With the aid of the AC magnetic field, a vortex was formed in the weld root, which had a positive effect on the filler wire mixing. A further significant advantage of the EM backing was the possibility to expand the process parameter window to maintain desired cooling times and mechanical properties, without suffering adverse effects concerning the root quality of the weld. T2 - 19th Nordic Laser Material Processing Conference CY - Turku, Finland DA - 22.08.2023 KW - Laser hybrid welding KW - Wind energy PY - 2023 AN - OPUS4-58616 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Drendel, Jan A1 - Logvinov, Ruslan A1 - Heinrichsdorff, Frank A1 - Hilgenberg, Kai T1 - Simulation-based controlling of local surface temperature in laser powder bed fusion using the process laser N2 - State-of-the-art laser powder bed fusion (PBF-LB/M) machines allow pre-heating of the substrate plate to reduce stress and improve part quality. However, two major issues have been shown in the past: First, with increasing build height the apparent pre-heat temperature at the surface can deviate drastically from the nominal pre-heat temperature in the substrate plate. Second, even within a single layer the local surface pre-heat temperature can show large gradients due to thermal bottlenecks in the part geometry underneath the top surface. Both lead to unwanted changes in microstructure or defects in the final parts. In this study, a first attempt is taken to show the feasibility of pre-heating the top surface with the onboard laser beam to overcome the mentioned issues. A single layer of a group of three parts built from IN718 to a height of 33.5 mm is pre-heated in a commercially available PBF-LB/M machine to an average steady state surface temperature of 200 °C using the onboard laser beam. The parts are continuously heated, omitting powder deposition and melting step. Temperatures are measured by thermocouples underneath the surface. The experiments are supported by a thermal finite element (FE) model that predicts the temperature field in the parts. When heating the parts uniformly with the laser beam, differences in surface temperatures as large as 170 K are observed. To overcome this inhomogeneity, the heat flux supplied by the laser beam is modulated. An optimized, spatial heat flow distribution is provided by the thermal FE model and translated into a scan pattern that reproduces the optimized heat distribution on the PBF-LB/M machine by locally modulating hatch distance and scan velocity. This successfully reduces the differences in surface temperature to 20 K. Thermographic imaging shows that a homogeneous surface temperature can be achieved despite the localized heat input by the beam. The potential for industrial application of the optimized laser-heating technique is discussed. KW - Additive Manufacturing KW - Simulation KW - Surface temperature KW - Laser powder bed fusion PY - 2023 DO - https://doi.org/10.1016/j.addma.2023.103854 SN - 2214-8604 VL - 78 SP - 1 EP - 16 PB - Elsevier B.V. AN - OPUS4-58825 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ayerdi Gomez, A. A1 - Slachciak, Nadine A1 - Zubia Aranburu, J. A1 - Zabala, A. A1 - Aginagalde, A. A1 - Bonse, Jörn A1 - Spaltmann, Dirk T1 - Improvement of the tribological performance of titanium alloy using FS-laser-induced periodic surface structures in combination with ZDDP and ionic liquid lubricant additives N2 - The performance of titanium alloy (Ti6Al4V) surfaces was investigated in lubricated reciprocating sliding tribological tests (RSTT). Special emphasis was laid on the effect of surface nanostructures in area of contact on the respective friction and wear behaviour. These so-called laser-induced periodic surface structures (LIPSS, ripples) were produced on the titanium alloy surface upon scan processing in air by an ultrashort pulsed femtosecond (fs) laser. As lubricant served two types of base oils, a pure polyalcylene-glycol, and an SAE 0W30 oil containing only antioxidants and temperature stabilizers. Tribological tests were carried out on polished as well as LIPSS covered areas using both types of base oil. A test metrics was established, combining the additive 2-ethylhexyl-zincdithiophosphate (ZDDP) or the ionic liquid [P6,6,6,14] [DEHP] (98% purity) with the respective base oils. The test metrics also considered the orientation of motion with respect to the orientation of the structures formed on the surface. Results are presented which show that the interplay between LIPSS and the local chemistry formed by the respective additives is beneficial for the tribological behaviour of the titanium alloy. Certain combinations of base oil, additive and LIPSS reduced friction and wear significantly in the tribological contact. T2 - 64. Tribologie-Fachtagung CY - Göttingen, Germany DA - 25.09.2023 KW - TiAl64V KW - 100Cr6 KW - Friction KW - Wear KW - LIPSS KW - Lubrication KW - PAG KW - Ionic liquid PY - 2023 SP - 1 EP - 5 AN - OPUS4-58642 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael A1 - Artinov, Antoni A1 - Meng, Xiangmeng A1 - Bakir, Nasim A1 - Üstündag, Ömer A1 - Bachmann, Marcel A1 - Gumenyuk, Andrey T1 - The bulging effect and its relevance in high power laser beam welding N2 - The present work deals with the recently confirmed widening of the weld pool interface, known as a bulging effect, and its relevance in high power laser beam welding. A combined experimental and numerical approach is utilized to study the influence of the bulge on the hot cracking formation and the transport of alloying elements in the molten pool. A technique using a quartz glass, a direct-diode laser illumination, a high-speed camera, and two thermal imaging cameras is applied to visualize the weld pool geometry in the longitudinal section. The study examines the relevance of the bulging effect on both, partial and complete penetration, as well as for different sheet thicknesses ranging from 8 mm to 25 mm. The numerical analysis shows that the formation of a bulge region is highly dependent on the penetration depth and occurs above 10 mm penetration depth. The location of the bulge correlates strongly with the cracking location. The obtained experimental and numerical results reveal that the bulging effect increases the hot cracking susceptibility and limits the transfer of alloying elements from the top of the weld pool to the weld root. T2 - 1st Annual Assembly and Conference of The Welding Federation of Africa (TWF-Africa) CY - Cairo, Egypt DA - 14.03.2023 KW - Laser beam welding KW - Melt pool dinamics PY - 2023 AN - OPUS4-58695 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, Xiangmeng A1 - Putra, Stephen Nugraha A1 - Bachmann, Marcel A1 - Rethmier, Michael T1 - Influence of the spatial laser energy absorption on the molten pool dynamics in high-power laser beam welding N2 - The spatial laser energy absorption inside the keyhole is decisive for the dynamic molten pool behaviors and the resultant weld properties in high-power laser beam welding (LBW). In this paper, a numerical simulation of the LBW process, considering the 3D transient heat transfer, fluid flow, and keyhole dynamics, is implemented, in which the free surface is tracked by the volume-of-fluid algorithm. The underlying laser-material interactions, i.e., the multiple reflections and Fresnel absorption, are considered by an advanced ray-tracing method based on a localized level-set strategy and a temperature-dependent absorption coefficient. The laser energy absorption is analyzed from a time-averaged point of view for a better statistical representation. It is found for the first time that a significant drop in the time-averaged laser energy absorption occurs at the focus position of the laser beam and that the rest of the keyhole region has relatively homogeneous absorbed energy. This unique absorption pattern may lead to a certain keyhole instability and have a strong correlation with the detrimental bulging and narrowing phenomena in the molten pool. The influence of different focus positions of the laser beam on the keyhole dynamics and molten pool profile is also analyzed. The obtained numerical results are compared with experimental measurements to ensure the validity of the proposed model. KW - Laser beam welding KW - Laser energy absorption KW - Molten pool KW - Keyhole dynamics KW - Numerical modeling PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-587531 DO - https://doi.org/10.2351/7.0001078 SN - 1042-346X VL - 35 IS - 4 SP - 1 EP - 8 PB - AIP Publishing AN - OPUS4-58753 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meng, Xiangmeng A1 - Putra, Stephen Nugraha A1 - Bachmann, Marcel A1 - Rethmier, Michael T1 - Influence of the spatial laser energy absorption on the molten pool dynamics in high-power laser beam welding N2 - The spatial laser energy absorption inside the keyhole is decisive for the dynamic molten pool behaviors and the resultant weld properties in high-power laser beam welding (LBW). In this paper, a numerical simulation of the LBW process, considering the 3D transient heat transfer, fluid flow, and keyhole dynamics, is implemented, in which the free surface is tracked by the volume-of-fluid algorithm. The underlying laser-material interactions i.e., the multiple reflections and Fresnel absorption, are considered by an advanced ray-tracing method based on a localized Level-Set strategy and a temperature-dependent absorption coefficient. The laser energy absorption is analyzed from a time-averaged point of view for a better statistical representation. It is found for the first time that a noticeable drop of the time-averaged laser energy absorption occurs at the focus position of the laser beam, and the rest region of the keyhole has relatively homogenous absorbed energy. This unique absorption pattern may lead to a certain keyhole instability and have a strong correlation with the detrimental bulging and narrowing phenomena in the molten pool. The influence of the different focus positions of the laser beam on the keyhole dynamics and molten pool profile is also analyzed and compared. The obtained numerical results are compared with experimental measurements to assure the validity of the proposed model. T2 - International Congress of Applications of Lasers & Electro-Optics 2023 CY - Chicago, USA DA - 16.10.2023 KW - Laser beam welding KW - laser energy absorption KW - molten pool KW - keyhole dynamics KW - numerical modeling PY - 2023 SP - 1 EP - 8 AN - OPUS4-58754 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meng, Xiangmeng A1 - Putra, Stephen Nugraha A1 - Bachmann, Marcel A1 - Rethmier, Michael T1 - The influence of the spatial laser energy absorption on the molten pool dynamics in high power laser beam welding N2 - The spatial laser energy absorption inside the keyhole is decisive for the dynamic molten pool behaviors and the resultant weld properties in high-power laser beam welding (LBW). In this paper, a numerical simulation of the LBW process, considering the 3D transient heat transfer, fluid flow, and keyhole dynamics, is implemented, in which the free surface is tracked by the volume-of-fluid algorithm. The underlying laser-material interactions i.e., the multiple reflections and Fresnel absorption, are considered by an advanced ray-tracing method based on a localized Level-Set strategy and a temperature-dependent absorption coefficient. The laser energy absorption is analyzed from a time-averaged point of view for a better statistical representation. It is found for the first time that a noticeable drop of the time-averaged laser energy absorption occurs at the focus position of the laser beam, and the rest region of the keyhole has relatively homogenous absorbed energy. This unique absorption pattern may lead to a certain keyhole instability and have a strong correlation with the detrimental bulging and narrowing phenomena in the molten pool. The influence of the different focus positions of the laser beam on the keyhole dynamics and molten pool profile is also analyzed and compared. The obtained numerical results are compared with experimental measurements to assure the validity of the proposed model. T2 - International Congress of Applications of Lasers & Electro-Optics 2023 CY - Chicago, Illinois, USA DA - 16.10.2023 KW - Laser beam welding KW - Laser energy absorption KW - Molten pool KW - Keyhole dynamics KW - Numerical modeling PY - 2023 AN - OPUS4-58755 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Epperlein, Martin A1 - Hilgenberg, Kai A1 - Hellfritz, Benjamin A1 - Löffler, Frank T1 - Digitisation of the quality infrastructure - using the example of additive manufacturing N2 - Rapidly advancing technologies and progressive digitisation are posing challenges to the established quality infrastructure (QI). In response, the key stakeholders of the German QI established the initiative QI-Digital aimed at developing new solutions for modern quality assurance. One of the central use cases herein is quality assurance for additive manufacturing, in which a fully interlinked additive manufacturing process chain is established. The intention is to collect and process data from each production step, allowing for a comprehensive digital view of the physical material flow. Within this process chain, prototypes of digital QI tools like machine readable standards and digital quality certificates are being demonstrated, tested, and evolved. This is complemented by research on the process level, comprising the evaluation and refinement of methods for in-situ and ex-situ quality assurance, as well as algorithms for registration, reduction, and analysis of process data. This paper presents the status, goals, and vision for the QI-Digital use case additive manufacturing. T2 - Metal Additive Manufacturing Conference 2023 CY - Wien, Austria DA - 17.10.2023 KW - Additive Manufacturing KW - Digitalisation KW - Quality Assurance PY - 2023 SP - 96 EP - 104 CY - Wien AN - OPUS4-58628 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Epperlein, Martin T1 - Digitisation of the quality infrastructure - Using the example of additive manufacturing N2 - Rapidly advancing technologies and progressive digitisation are posing challenges to the established quality infrastructure (QI). In response, the key stakeholders of the German QI established the initiative QI-Digital aimed at developing new solutions for modern quality assurance. One of the central use cases herein is quality assurance for additive manufacturing, in which a fully interlinked additive manufacturing process chain is established. The intention is to collect and process data from each production step, allowing for a comprehensive digital view of the physical material flow. Within this process chain, prototypes of digital QI tools like machine readable standards and digital quality certificates are being demonstrated, tested, and evolved. This is complemented by research on the process level, comprising the evaluation and refinement of methods for in-situ and ex-situ quality assurance, as well as algorithms for registration, reduction, and analysis of process data. This paper presents the status, goals, and vision for the QI-Digital use case additive manufacturing. T2 - Metal Additive Manufacturing Conference 2023 CY - Vienna, Austria DA - 17.10.2023 KW - Additive Manufacturing KW - Digitalisation KW - Quality Assurance PY - 2023 AN - OPUS4-58629 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yang, Chunliang A1 - Yan, Fan A1 - Meng, Xiangmeng A1 - Putra, Stephen Nugraha A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Phase-field simulation of the dendrite growth in aluminum alloy AA5754 during alternating current electromagnetic stirring laser beam welding N2 - Electromagnetic stirring is known to promote material flow, reduce porosity, uniform elements distribution, and refine grain in laser beam welding (LBW), which enhances the applicability of LBW in various industries. In this study, a phase-field model of dendrite growth in AA5754 Al alloy electromagnetic stirring laser beam welding was established. The model considered the thermal electromagnetic Lorentz force resulting from the interaction between the electric field generated by the Seebeck effect and the magnetic field, as well as the temperature gradient and solidification rate of the solidification interface obtained from the computational fluid dynamics electromagnetic stirring LBW model. The variation rules of dendrite growth with different magnetic parameters and effects are analyzed. Comprehensively, the magnetic field promotes the solidification rate, thus promoting interfacial instability and a large magnetic flux density leads to a faster interface instability. The solidification rate as well as the temperature gradient affect the growth rate, and the accelerated growth caused by the so lidification rate with a high frequency and a large magnetic flux density effectively inhibits the slow growth caused by the temperature gradient. The thermal electromagnetic Lorentz force is the main factor for the branch increment at low frequencies, while both thermal electromagnetic Lorentz force and temperature gradient in crease the number of branches at high frequencies. The calculated average branch numbers considering various factors in the stable stage under different magnetic parameters were consistent with the results of the scanning electron microscope tests. KW - Laser beam welding KW - Electromagnetic KW - Aluminum alloys KW - Phase field method KW - Dendrite growth PY - 2024 DO - https://doi.org/10.1016/j.ijheatmasstransfer.2023.124754 SN - 0017-9310 VL - 218 SP - 1 EP - 16 PB - Elsevier Ltd. AN - OPUS4-58489 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Poka, Konstantin A1 - Merz, Benjamin A1 - Epperlein, Martin A1 - Hilgenberg, Kai T1 - Integration of the whole digital chain in a unique file for PBF-LB/M: practical implementation within a digital thread and its advantages N2 - The industrialization of AM is only possible by creating synergy with the tools of Industry 4.0. The system technology of Powder Bed Fusion with Laser beam of Metals (PBF-LB/M) reached a level of high performance in terms of process stability and material spectrum in the past years. However, the digital process chain, starting from CAD via CAM and plant-specific compila-tion of the manufacturing file exhibits media disruptions. The consequence is a loss of metadata. A uniform data scheme of simulation for Design for Additive Manufacturing (DfAM), the PBF-LB/M process itself and quality assurance is currently not realized within industry. There is no entity in the common data flows of the process chains, that enables the integration of these functionalities. As part of the creation of a digital quality infrastructure in the QI-Digital pro-ject, an integration of the CAD/CAM chain is being established. The outcome is a file in an advanced commercially available format which includes all simula-tions and manufacturing instructions. The information depth of this file extends to the level of the scan vectors and allows the automatic optimization and holis-tic documentation. In addition, the KPI for the economic analysis are generated by compressing information into a unique file combined with the application of a digital twin. The implementation and advantages of this solution are demon-strated in a case study on a multi-laser PBF-LB/M system. A build job contain-ing a challenging geometry is thermally simulated, optimized, and manufac-tured. To verify its suitability for an Additive Manufacturing Service Platform (AMSP), the identical production file is transferred to a PBF-LB/M system of another manufacturer. Finally, the achieved quality level of the build job is evaluated via 3D scanning. This evaluation is carried out in the identical entity of the production file to highlight the versatility of this format and to integrate quality assurance data. T2 - Additive Manufacturing for Products and Applications 2023 CY - Lucerne, Switzerland DA - 11.09.2023 KW - Laser Powder Bed Fusion KW - Digital Twin KW - Data Integrity KW - Process Chain Integration KW - Computer Aided Manufacturing PY - 2023 SN - 978-3-031-42982-8 DO - https://doi.org/10.1007/978-3-031-42983-5_7 SN - 2730-9576 VL - 3 SP - 91 EP - 114 PB - Springer CY - Cham AN - OPUS4-58363 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scheuschner, Nils A1 - Heinrichsdorff, F. A1 - Oster, Simon A1 - Uhlmann, E. A1 - Polte, J. A1 - Gordei, A. A1 - Hilgenberg, Kai T1 - In-situ monitoring of the laser powder bed fusion process by thermography, optical tomography and melt pool monitoring for defect detection N2 - For the wide acceptance of the use of additive manufacturing (AM), it is required to provide reliable testing methods to ensure the safety of the additively manufactured parts. A possible solution could be the deployment of in-situ monitoring during the build process. However, for laser powder bed fusion using metal powders (PBF-LB/M) only a few in-situ monitoring techniques are commercially available (optical tomography, melt pool monitoring), which have not been researched to an extent that allows to guarantee the adherence to strict quality and safety standards. In this contribution, we present results of a study of PBF-LB/M printed parts made of the nickel-based superalloy Haynes 282. The formation of defects was provoked by local variations of the process parameters and monitored by thermography, optical tomography and melt pool monitoring. Afterwards, the defects were characterized by computed tomography (CT) to identify the detection limits of the used in-situ techniques. T2 - Lasers in Manufacturing Conference 2023 CY - Munich, Germany DA - 26.06.2023 KW - Thermography KW - Optical tomography KW - Melt-pool-monitoring KW - Laser powder bed fusion KW - Haynes 282 KW - Additive Manufacturing PY - 2023 UR - https://www.wlt.de/lim2023-proceedings/system-engineering-and-process-control SP - 1 EP - 10 AN - OPUS4-58466 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhang, X. A1 - Shi, L. A1 - Wu, C. A1 - Yang, Chunliang A1 - Gao, S. T1 - Multi-phase modelling of heat and mass transfer during Ti/Al dissimilar friction stir welding process N2 - Friction stir welding (FSW) has the capacity to join the Al/Ti dissimilar structures with superior mechanical properties. The microstructures and mechanical characteristics of Al/Ti dissimilar FSW joints are determined by the heat and mass transfer during the welding process. However, a quantitative study of the Al/Ti dissimilar FSW process is lacking. Therefore, using the computational fluid dynamics (CFD) and volume of fluid (VOF) approach, a multi-phase model was constructed for quantitatively analyzing the heat and mass transfer behaviour in dissimilar FSW of TC4 titanium alloy and AA2024-T4 aluminium alloy. The mixed material was treated as a functionally graded material (FGM) to compute the thermophysical characteristics at the weld nugget zone (WNZ). Due to the vast disparity in the thermophysical characteristics of aluminum and titanium alloy, the temperature field in Al/Ti dissimilar FSW was severely asymmetric. The temperature of titanium alloy on the advancing side (AS) was higher than that of aluminium alloy on the retreating side (RS) at the same distance from the tool centre line near the tool shoulder, but it was lower than that of aluminium alloy on the RS without the influence of the shoulder. Due to the high flow stress of titanium alloy, plastic material flow mostly occurred on the RS of aluminium alloy in the Al/Ti dissimilar FSW, with its percentage exceeding 80%. This model was validated by experiment results. KW - Dissimilar friction stir welding KW - Al/Ti dissimilar joints KW - Temperature distribution KW - Heat generation KW - Plastic material flow PY - 2023 DO - https://doi.org/10.1016/j.jmapro.2023.03.037 SN - 2212-4616 VL - 94 SP - 240 EP - 254 PB - Elsevier Ltd. AN - OPUS4-57265 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schneider, M. A1 - Schlingmann, T. A1 - Schmidt, J. A1 - Bettge, Dirk A1 - Hilgenberg, Kai A1 - Binder, M. A1 - Klöden, B. T1 - A Round Robin Test To Investigate The Printing Quality Of PBF LB/M Processed AlSi10Mg N2 - When it comes to higher accuracies, new technologies and real applications in additive manufacturing, there is one topic which cannot be avoided: The material response on the chosen processing parameters and its agreement and correspondence with literature data of the wrought material grade counterpart. In industrial Additive Manufacturing (AM) standards in terms of printing parameters, protection gas atmospheres or powder handling instructions are not obligatory. Therefore, the question must be answered whether the AM process is reproducible and reliable over different printing companies. This was the motivation to realize a round robin test between 8 European printing companies and academic partners. The consortium had printed and tested fatigue and tensile testing bars under plant-specific conditions. A commonly used cast aluminum alloy, AlSi10Mg, was chosen as test material for the PBF-LB/M process. Differences of the results between the partners and the scatter itself were discussed in detail. T2 - World PM2022 CY - Lyon, France DA - 09.10.2022 KW - Additive manufacturing KW - AlSi10Mg KW - Laser powder bed fusion KW - Round robin KW - Reproducibility PY - 2022 AN - OPUS4-56303 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schneider, M. A1 - Schlingmann, T. A1 - Schmidt, J. A1 - Bettge, Dirk A1 - Hilgenberg, Kai A1 - Binder, M. A1 - Klöden, B. T1 - A Round Robin Test To Investigate The Printing Quality Of PBF-LB/M Processed AlSi10Mg N2 - When it comes to higher accuracies, new technologies and real applications in additive manufacturing, there is one topic which cannot be avoided: The material response on the chosen processing parameters and its agreement and correspondence with literature data of the wrought material grade counterpart. In industrial Additive Manufacturing (AM) standards in terms of printing parameters, protection gas atmospheres or powder handling instructions are not obligatory. Therefore, the question must be answered whether the AM process is reproducible and reliable over different printing companies. This was the motivation to realize a round robin test between 8 European printing companies and academic partners. The consortium had printed and tested fatigue and tensile testing bars under plant-specific conditions. A commonly used cast aluminum alloy, AlSi10Mg, was chosen as test material for the PBF-LB/M process. Differences of the results between the partners and the scatter itself were discussed in detail. T2 - World PM2022 CY - Lyon, France DA - 09.10.2022 KW - Additive manufacturing KW - Round robin KW - Reproducibility KW - Laser powder bed fusion KW - AlSi10Mg PY - 2022 SN - 978-1-899072-54-5 SP - 1 EP - 10 PB - European Powder Metallurgy Association (EPMA) AN - OPUS4-56304 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bachmann, Marcel A1 - Meng, Xiangmeng A1 - Artinov, Antoni A1 - Rethmeier, Michael T1 - Evaluation of narrowed weld pool shapes and their effect on resulting potential defects during deep penetration laser beam welding N2 - This study presents mechanisms of the evolution of a narrowed region in the weld pool center during deep penetration laser beam welding. In numerous numerical studies presented in this study, it was also found that the local reduction of the weld pool size can cause detrimental effects on the melt flow behavior and the resulting properties of the welds. A particularly large influence of this effect was identified in three aspects. Firstly, the local variation of the solidification sequence of the weld pool causes an increase in the hot-cracking susceptibility due to a locally delayed solidification. Secondly, it was proven that a change in the local length and width of the weld pool is associated with an adverse impact on the potential flow routes of the molten material that induces stronger local variations of its solidification. Thus, the element mixing, e.g. during the welding with filler materials, is blocked. This leads to a non-homogeneous chemical composition of the final weld and can cause undesired effects on the final material properties. Finally, another observed effect is related to the reduced ability of process pores to reach the top surface. As this type of porosity is usually produced around the keyhole tip, the change of the fluid flow regime above this area plays a significant role in determining the final path of the pores until the premature solidification in the middle of the weld pool captures them. This study summarizes mainly numerical results which were supported by selected experimental validation results. T2 - International Congress of Applications of Lasers & Electro-Optics 2022 CY - Orlando, FL, USA DA - 17.10.2022 KW - Weld pool shape KW - Laser beam welding KW - Solidification KW - Porosity KW - Numerical process simulation PY - 2022 SP - 1 AN - OPUS4-56532 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Harsha, A. P. A1 - Wäsche, Rolf A1 - Joyce, T. J. T1 - Friction and wear of two polyethylenes under different tribological contact conditions N2 - Tribological properties of ultrahigh-molecular weight polyethylene (UHMWPE) and cross-linked polyethylene (XLPE) were studied in two different wear modes. Firstly, reciprocating sliding wear studies under non-conformal contact investigated the effects of counterface surface roughness (polished, lapped and ground) of Ti6Al4V on the friction and wear of the polyethylenes. Secondly, two-body abrasive wear studies in conformal contact against different abrasive grit size papers were also carried out to ascertain the wear sensitivity of the polyethylenes under these adverse conditions. Wear mechanisms were studied using optical and scanning electron micrographs. The results of the reciprocating sliding wear studies showed that surface roughness of the counterface influenced friction and wear characteristics although no correlation was found between the coefficient of friction and specific wear rate. XLPE demonstrated wear sensitivity, particularly under severe abrasive wear condition. The results indicated that the performance of the polyethylenes greatly depends upon the tribological system under which it is operating. KW - Abrasive wear KW - Polyethylene KW - Reciprocating sliding wear KW - Surface roughness KW - Wear mechanism PY - 2021 DO - https://doi.org/10.1177/0967391120920130 SN - 0967-3911 SN - 1478-2391 VL - 29 IS - 5 SP - 393 EP - 404 PB - Sage Publishing CY - London AN - OPUS4-56903 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Diller, Johannes A1 - Siebert, Ludwig A1 - Winkler, Michael A1 - Siebert, Dorina A1 - Blankenhagen, Jakob A1 - Wenzler, David A1 - Radlbeck, Christina A1 - Mensinger, Martin T1 - An integrated approach for detecting and classifying pores and surface topology for fatigue assessment 316L manufactured by powder bed fusion of metals using a laser beam using μ$$ \mu $$CT and machine learning algorithms N2 - AbstractThis research aims to detect and analyze critical internal and surface defects in metal components manufactured by powder bed fusion of metals using a laser beam (PBF‐LB/M). The aim is to assess their impact on the fatigue behavior. Therefore, a combination of methods, including image processing of micro‐computed tomography (CT) scans, fatigue testing, and machine learning, was applied. A workflow was established to contribute to the nondestructive assessment of component quality and mechanical properties. Additionally, this study illustrates the application of machine learning to address a classification problem, specifically the categorization of pores into gas pores and lack of fusion pores. Although it was shown that internal defects exhibited a reduced impact on fatigue behavior compared with surface defects, it was noted that surface defects exert a higher influence on fatigue behavior. A machine learning algorithm was developed to predict the fatigue life using surface defect features as input parameters. KW - Fatigue KW - Machine learning KW - Micro-computed tomography KW - Powder bed fusion of metals using a laser beam KW - Quality assurance PY - 2024 DO - https://doi.org/10.1111/ffe.14375 SN - 8756-758X SP - 1 EP - 16 PB - John Wiley & Sons Ltd. AN - OPUS4-60593 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Brunner-Schwer, Christian T1 - How innovative welding technology can speed up the wind tower manufacturing process eightfold N2 - In the wind industry, a great deal of welding is required for the manufacture of foundation structures, floating platforms and towers. The poster illustrates how this welding process can be realised much more efficiently with the help of electromagnetic weld pool backing. T2 - Wind Europe Annual Event 2024 CY - Bilbao, Spain DA - 20.03.2024 KW - Schweißen KW - Laserschweißen KW - Windeneergie PY - 2024 AN - OPUS4-60604 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krankenhagen, Rainer T1 - Thermographic Investigation of the Anisotropic Behaviour of Additively Manufactured AISI 316 Steel using DED-arc N2 - Additive manufacturing is one of the most promising techniques for industrial production and maintenance, but the specifics of the layered structure must be considered. The Direct Energy Deposition-Arc process enables relatively high deposition rates, which is favourable for larger components. For this study, specimens with different orientations were prepared from one AISI316 steel block – parallel and orthogonal to the deposition plane. Quasistatic tensile loading tests were carried out, monitored by an infrared camera. The obtained surface temperature maps revealed structural differences between both orientations. The consideration of surface temperature transients yields more details about the behaviour of the material under tensile loading than the conventional stress-strain-curve. These preliminary investigations were supplemented by thermographic fatigue trials. Although the anisotropy was also observed during fatigue loading the fatigue behaviour in general was the same, at least for both inspected specimens. The presented results demonstrate the abilities and the potential of thermographic techniques for tensile tests. T2 - 17th Quantitative Infrared Thermography Conference CY - Zagreb, Croatia DA - 01.07.2024 KW - Thermoelastic effect KW - Thermoplastic effect KW - Thermal stress analysis PY - 2024 AN - OPUS4-60574 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schob, Daniela T1 - Deformation-Induced Martensitic Transformation in Fused Filament Fabricated Austenitic Stainless Steels During Tension at Wide Range of Temperatures. Part 2: Numerical Simulation N2 - Structural components of superconducting magnets (e.g., collars, bladders, or keys) with complex shapes, operating at cryogenic temperatures (4K, 77K), as well as additional elements of tanks for storing liquid hydrogen (20K), such as hoses and valves, are made of austenitic steel. With conventional manufacturing technologies, complex geometries are difficult to manufacture. In contrast, additive manufacturing offers the possibility of easier production of complex geometries, although the knowledge about the material behavior is not yet comprehensively available. The scientific objective of the project is the experimental identification and numerical simulation of the evolution of the deformation-induced martensitic transformation and the prediction of the material behavior of Fused Filemant Fabricated (FFF) 316L for cryogenic applications. The material behavior of FFF-316L under tensile stress at both room temperature and 77K was characterized. Utilizing experimental data and microstructure analysis through scanning electron microscopy, a comprehensive material model [1] was used. This constitutive model is centered on the deformation-induced martensitic transformation at both ambient and cryogenic temperatures. The linear kinetic law of evolution of deformation-induced phase transformation in ASS is adopted [1]. It posits that the phase transformation is driven by the accumulated plastic strain. The model intricately links the intensity of plastic deformation to the phase transformation, employing a mixed kinematic/isotropic linear plastic hardening approach based on Mori-Tanaka homogenization. A numerical results will be verified experimentaly at room and at 77K. T2 - 43rd Solid Mechanics Conference CY - Wroclaw, Poland DA - 16.09.2024 KW - Phase transformation KW - Deformation-induced martensitic transformation KW - 316L KW - Fused Deposition Modelling PY - 2024 AN - OPUS4-61181 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zhu, Jiangchao A1 - Madia, Mauro A1 - Schurig, M. A1 - Schlums, H. A1 - Zerbst, Uwe T1 - Fracture mechanics-based structural integrity assessment of aeroengine turbine disks under overspeed conditions N2 - Aero-engine turbine disks are safety-relevant components which are operated under high thermal and mechanical stress conditions. The actual part qualification and certification procedures make use of spin-tests conducted on productionsimilar disks. While these tests provide, on the one hand, a reliable definition of the critical conditions for real components, on the other hand they represent a relevant cost item for engine manufacturers. The aim of this work is to present part of a fracture mechanics-based procedure under development which aims at replacing the tests on production-similar disks with lab tests on fracture mechanics specimens. In particular, the rimpeeling failure mode is considered as case study. A semi-circular surface crack is modelled at the most stressed region at the diaphragm of a turbine disk, with the crack plane perpendicular to the radial direction. The crack is therefore subjected to a biaxial stress state and grows under increasing rotational speed until it triggers the rim-peeling failure. The finite element simulation of the cracked disk considers the real thermal and mechanical loading conditions. In order to design a lab representative specimen, beside the crack driving force, expressed in terms of � -integral, also the constraint to plastic deformation e.g., stress triaxiality, at the crack-tip must be similar for the same crack in the specimen and in the disk. This has been achieved and as expected, both the highest � -integral and constraint factor are calculated at the same location along the crack front for both disk and specimen. The results of the structural integrity assessment in the form of a Failure Assessment Diagram (FAD) show good agreement between designed specimen and disk both in terms of expected failure mode and value of the critical speed. Probabilistic aspects are also considered in the calculations. T2 - ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition (GT2022) CY - Rotterdam, The Netherlands DA - 13.06.2022 KW - Fracture mechanics KW - Burst KW - Turbine disk PY - 2022 SP - 1 EP - 7 PB - ASME AN - OPUS4-55903 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Braun, T. T1 - Evaluation of electric conductivity and mechanical load capacity of copper deposits for application in large winding components for electrical high-voltage machines made with cold spray additive manufacturing N2 - In line with the industrial trend of additive manufacturing, cold spray as a non-laser-based process is becoming increasingly important for many fields of application. For the evaluation of additive manufacturing of winding components made of copper for large electrical high-voltage machines, material and component properties such as electrical conductivity, mechanical load capacity and the component size that can be produced are of particular importance. In this context, the cold spray process offers advantages over laser-based additive manufacturing processes such as laser powder bed fusion (LPBF) or laser cladding by using the kinetic energy of the copper powder particles to generate particle cohesion. To investigate the electrical conductivity as well as the mechanical load capacity of cold spray parts, specimens were machined out of cold sprayed bulk copper deposits. The characteristic values were obtained with regard to the direction of deposition, which is defined by the direction of the robot’s movement. Thus, for the investigation of the component properties, specimens were provided that had been produced both longitudinally and transversely as well as orthogonally to the direction of deposition. The results of the investigations show that both the electrical conductivity and the mechanical load capacity of the specimen have a strong preferential direction of the specimen orientation with respect to the direction of deposition. Furthermore, it could be shown that by increasing the deposition height, there is an increasing oxygen content in the sample material, combined with increasingly significant defect networks. These effects have a negative impact on the electrical conductivity as well as on the mechanical load capacity. As a conclusion, further need for investigation is identified in the optimization of the process parameters as well as in the deposition strategy for the additive manufacturing of large-volume components with cold spray. T2 - ITSC 2022 CY - Vienna, Austria DA - 04.05.2022 KW - Cold Spray KW - Copper powder particles KW - Electrical conductivity KW - Large electrical high-voltage machine PY - 2022 AN - OPUS4-56127 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Braun, T. A1 - Uhlmann, E. A1 - Häcker, Ralf A1 - Jäger, M. A1 - Rauch, H. A1 - Kondas, J. A1 - Brach, K. A1 - Singh, R. T1 - Evaluation of electric conductivity and mechanical load capacity of copper deposits for application in large winding components for electrical high-voltage machines made with cold spray additive manufacturing N2 - In line with the industrial trend of additive manufacturing, cold spray as a non-laser-based process is becoming increasingly important for many fields of application. For the evaluation of additive manufacturing of winding components made of copper for large electrical high-voltage machines, material and component properties such as electrical conductivity, mechanical load capacity and the component size that can be produced are of particular importance. In this context, the cold spray process offers advantages over laser-based additive manufacturing processes such as laser powder bed fusion (LPBF) or laser cladding by using the kinetic energy of the copper powder particles to generate particle cohesion. To investigate the electrical conductivity as well as the mechanical load capacity of cold spray parts, specimens were machined out of cold sprayed bulk copper deposits. The characteristic values were obtained with regard to the direction of deposition, which is defined by the direction of the robot’s movement. Thus, for the investigation of the component properties, specimens were provided that had been produced both longitudinally and transversely as well as orthogonally to the direction of deposition. The results of the investigations show that both the electrical conductivity and the mechanical load capacity of the specimen have a strong preferential direction of the specimen orientation with respect to the direction of deposition. Furthermore, it could be shown that by increasing the deposition height, there is an increasing oxygen content in the sample material, combined with increasingly significant defect networks. These effects have a negative impact on the electrical conductivity as well as on the mechanical load capacity. As a conclusion, further need for investigation is identified in the optimization of the process parameters as well as in the deposition strategy for the additive manufacturing of large-volume components with cold spray. T2 - ITSC 2022 CY - Wien, Austria DA - 04.05.2022 KW - Cold Spray KW - Electrical conductivity KW - Copper powder particles KW - Large electrical high-voltage machine PY - 2022 SP - 1 EP - 7 AN - OPUS4-56108 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -