TY - CONF A1 - Mishurova, Tatiana T1 - 3D imaging and residual stress analysis of AM materials at BAM N2 - The overview of the activity of group 8.5 Micro-NDT (BAM, Belin, Germany) in the field of additively manufacturing material characterization will be presented. The research of our group is focused on the 3D imaging of AM materials by means of X-ray Computed Tomography at the lab and at synchrotron, and the residual stress characterization by diffraction (nondestructive technique). T2 - Seminar at Chalmers University and Centre for Additive Manufacture (CAM2) CY - Gothenburg, Sweden DA - 19.05.2022 KW - Additive manufacturing KW - Laser powder bed fusion KW - Residual stress KW - Computed tomography KW - Synchrotron X-ray diffraction KW - X-ray refraction PY - 2022 AN - OPUS4-55019 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana A1 - Serrano Munoz, Itziar T1 - Multiscale residual stress analysis and synchrotron X-ray refraction of additively manufactured parts N2 - The overview of the activity of group 8.5 Micro-NDT (BAM, Belin, Germany) in the field of additively manufacturing material characterization will be presented. The challenges in the residual stress analysis of AM components are discussed on the basis on the show studies performed in BAM. Also, the synchrotron X-ray refraction technique, available in BAM, is presented, showing example of in-situ heating test of Al10SiMg AM material. T2 - Seminar at Grenoble INP, Science et Ingénierie des Matériaux et Procédés (SIMaP) CY - Grenoble, France DA - 01.07.2022 KW - Additive manufacturing KW - Residual stress KW - X-ray refraction KW - Computed tomography PY - 2022 AN - OPUS4-55232 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Mehta, Bharat A1 - Nyborg, L. A1 - Virtanen, E. A1 - Markötter, Henning A1 - Hryda, E. A1 - Bruno, Giovanni T1 - Failure Mechanisms Investigation by Means of in-situ Synchrotron Computed Tomography in Aluminum MMC-based Alloy Tailored for Additive Manufacturing (AM) N2 - Most of the Al alloys used in additive manufacturing (AM), in particular Laser Powder Bed Fusion (LPBF), do not exceed a strength of 200 MPa, whereas conventionally high-performance alloys exhibit strengths exceeding 400 MPa. The availability of such Al alloys in AM is limited due to difficulties in printability, requiring synergetic material and AM process development to satisfy harsh processing conditions during LPBF [1]. One approach is the addition of reinforcement to the based powder, allowing tailoring composition and properties of a Metal Matrix Composite (MMC) by AM. Still, the effect of the reinforcement on the resulting mechanical properties must be studied to understand the performance and limits of the newly developed material. The goal of this work was to investigate the failure mechanism of LPBF Al-based MMC material using in-situ Synchrotron X-ray Computed Tomography (SXCT) during mechanical testing. T2 - International conference on tomography of material and structures CY - Grenoble, France DA - 27.06.2022 KW - Additive manufacturing KW - Laser powder bed fusion KW - Al alloy KW - MMC PY - 2022 AN - OPUS4-55228 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana A1 - Serrano Munoz, Itziar A1 - Markötter, Henning A1 - Mehta, Bharat A1 - Hryha, Eduard A1 - Bruno, Giovanni T1 - In-situ imaging of additively manufactured alloys at the BAMline N2 - In this work, we present the recent in-situ imaging developments at the BAMline (of synchrotron BESSY II, HZB), focused on the in-situ characterization and understanding of microstructural evolution of additively manufactured materials subjected to different environments. Two show cases are presented. In the first, X-ray refraction radiography (SXRR) was combined with in-situ heat treatment to monitor the microstructural evolution as a function of temperature in a laser powder bed fusion (LPBF) manufactured AlSi10Mg alloy. We show that SXRR allows detecting the changes in the Si-phase morphology upon heating using statistically relevant volumes. SXRR also allows observing the growth of pores (i.e., thermally induced porosity), usually studied via X-ray computed tomography (XCT), but using much smaller fields-of-view. In the second case study, XCT was combined with in-situ tensile test to investigate the damage mechanism in a LPBF Aluminum Metal Matrix Composite (MMC). In-situ SXCT test disclosed the critical role of the defects in the failure mechanism along with pre-cracks in the reinforcement phase of MMC. We found that cracks were initiated from lack-of-fusion defects and propagated through coalescence with other defects. T2 - New Frontiers in Materials Design for Laser Additive Manufacturing CY - Montabaur, Germany DA - 22.05.22 KW - Additive manufacturing KW - Laser powder bed fusion KW - Synchrotron X-ray computed tomography KW - Synchrotron X-ray Refraction PY - 2022 AN - OPUS4-54900 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Voloskov, B. A1 - Mishurova, Tatiana A1 - Evlashin, S. A1 - Akhatov, I. A1 - Bruno, Giovanni A1 - Sergeichev, I. T1 - Artificial Defects in 316L Stainless Steel Produced by Laser Powder Bed Fusion: Printability, Microstructure, and Effects on the Very-High-Cycle Fatigue Behavior JF - Advanced Engineering Materials N2 - The printability of artificial defects inside the additively manufactured laser powder bed fusion (LPBF) 316L stainless steel is investigated. The printing parameters of the LPBF process are optimized to produce artificial defects with reproducible sizes at desired positions while minimizing redundant porosity. The smallest obtained artificial defect is 90 μm in diameter. The accuracy of the geometry of the printed defect depends on both the height and the diameter in the input model. The effect of artificial defects on the very-high-cycle fatigue (VHCF) behavior of LPBF 316L stainless steel is also studied. The specimens printed with artificial defects in the center are tested under VHCF using an ultrasonic machine. Crack initiation is accompanied by the formation of a fine granular area (FGA), typical of VHCF. Despite the presence of relatively large artificial defects, FGA formation is observed around accidental natural printing defects closer to the surface, which can still be considered as internal. The causes for this occurrence are discussed. KW - Additive manufacturing KW - Laser powder bed fusion KW - X-ray computed tomography KW - VHCF PY - 2022 DO - https://doi.org/10.1002/adem.202200831 SP - 1 EP - 13 PB - Wiley VHC-Verlag AN - OPUS4-56109 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Mehta, B. A1 - Nyborg, L. A1 - Virtanen, E. A1 - Markötter, Henning A1 - Hryha, E. A1 - Bruno, Giovanni T1 - Failure Mechanisms Investigation by Means of in-situ Synchrotron Computed Tomography in Aluminum MMC-based Alloy Tailored for Additive Manufacturing (AM) N2 - The availability of high-performance Al alloys in AM is limited due to difficulties in printability, requiring both the development of synergetic material and AM process to mitigate problems such as solidification cracking during laser powder bed fusion (LPBF). The goal of this work was to investigate the failure mechanism in a LPBF 7017 Aluminium alloy + 3 wt% Zr + 0.5 wt% TiC. The processing leads to different categories of Zr-rich inclusions, precipitates and defects. T2 - Alloys for Additive Manufacturing Symposium 2022 (AAMS22) CY - Munich, Germany DA - 11.09.2022 KW - Additive manufacturing KW - Laser powder bed fusion KW - Synchrotron X-ray computed tomography KW - MMC PY - 2022 AN - OPUS4-56110 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Artzt, K. A1 - Haubrich, J. A1 - Sevostianov, I. A1 - Requena, G. A1 - Bruno, Giovanni T1 - Micromechanical behavior of annealed Ti-6Al-4V produced by Laser Powder Bed Fusion JF - European Journal of Materials N2 - The micromechanical behavior of an annealed Ti-6Al-4V material produced by Laser Powder Bed Fusion was characterized by means of in-situ synchrotron X-ray diffraction during a tensile test. The lattice strain evolution was obtained parallel and transversal to the loading direction. The elastic constants were determined and compared with the conventionally manufactured alloy. In the plastic regime, a lower plastic anisotropy exhibited by the lattice planes was observed along the load axis (parallel to the building direction) than in the transverse direction. Also, the load transfer from α to β phase was observed, increasing global ductility of the material. The material seems to accumulate a significant amount of intergranular strain in the transverse direction. KW - Additive manufacturing KW - Ti-6Al-4V KW - Anisotropy KW - Intergranular strain KW - Synchrotron X-ray diffraction PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-547406 DO - https://doi.org/10.1080/26889277.2022.2063763 VL - 2 IS - 1 SP - 186 EP - 201 PB - Taylor & Francis AN - OPUS4-54740 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Roveda, Ilaria A1 - Serrano Munoz, Itziar A1 - Mishurova, Tatiana A1 - Madia, Mauro A1 - Pirling, T. A1 - Evans, Alexander A1 - Klaus, M. A1 - Haubrich, J. A1 - Requena, G. A1 - Bruno, Giovanni T1 - Influence of a 265 °C heat treatment on the residual stress state of a PBF-LB/M AlSi10Mg alloy JF - Journal of materials science N2 - Laser Powder Bed Fusion (PBF-LB/M) additive manufacturing (AM) induces high magnitude residual stress (RS) in structures due to the extremely heterogeneous cooling and heating rates. As the RS can be deleterious to the fatigue resistance of engineering components, great efforts are focused on understanding their generation and evolution after post-process heat treatments. In this study, one of the few of its kind, the RS relaxation induced in an as-built PBF-LB/M AlSi10Mg material by a low-temperature heat treatment (265 °C for 1 h) is studied by means of X-ray and neutron diffraction. Since the specimens are manufactured using a baseplate heated up to 200 °C, low RS are found in the as-built condition. After heat treatment a redistribution of the RS is observed, while their magnitude remains constant. It is proposed that the redistribution is induced by a repartition of stresses between the a-aluminium matrix and the silicon phase, as the morphology of the silicon phase is affected by the heat treatment. A considerable scatter is observed in the neutron diffraction RS profiles, which is principally correlated to the presence (or absence) of pockets of porosity developed at the borders of the chessboard pattern. KW - Neutron diffraction KW - Additive manufacturing PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-565115 DO - https://doi.org/10.1007/s10853-022-07997-w SN - 1573-4803 VL - 57 SP - 22082 EP - 22098 PB - Springer Science + Business Media CY - Dordrecht AN - OPUS4-56511 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Khrapov, D. A1 - Paveleva, A. A1 - Kozadayeva, M. A1 - Evsevleev, Sergei A1 - Mishurova, Tatiana A1 - Bruno, Giovanni A1 - Surmenev, R. A1 - Koptyug, A. A1 - Surmeneva, M. T1 - Trapped powder removal from sheet-based porous structures based on triply periodic minimal surfaces fabricated by electron beam powder bed fusion JF - Materials Science & Engineering A N2 - Electron Beam Powder Bed Fusion-manufactured (E-PBF) porous components with narrow pores or channels and rough walls or struts can be filled with trapped powder after the manufacturing process. Adequate powder removal procedures are required, especially for high-density porous structures. In the present research, sheetbased porous structures with different thicknesses based on triply periodic minimal surfaces fabricated by EPBF were subjected to different post-processing methods, including a traditional powder recovery system for EPBF, chemical etching and ultrasound vibration-assisted powder removal. Wall thickness, internal defects, microstructure and morphology features, powder distribution inside the specimens, mechanical properties and deformation modes were investigated. A powder recovery system could not remove all residual powder from dense structures. In turn, chemical etching was effective for surface morphology changes and subsurface layers elimination but not for powder removal, as it affected the wall thickness, considerably influencing the mechanical properties of the whole structure. The ultrasound vibration method was quite effective for the removal of residual powder from sheet-based TMPS structures and without a severe degradation of mechanical properties. 10.1016/j.msea.2022.144479 Ultrasound vibration also caused grain refinement. KW - Additive manufacturing KW - Residual powder removal KW - Ti6Al4V alloy KW - Electron beam powder bed fusion KW - TPMS structures PY - 2023 DO - https://doi.org/10.1016/j.msea.2022.144479 VL - 862 SP - 1 EP - 16 PB - Elsevier B.V. AN - OPUS4-56564 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauzon, C. A1 - Mishurova, Tatiana A1 - Fischer, M. A1 - Ahlström, J. A1 - Fritsch, Tobias A1 - Bruno, Giovanni A1 - Hryha, Eduard T1 - Impact of contour scanning and helium-rich process gas on performances of Alloy 718 lattices produced by laser powder bed fusion JF - Materials & Design N2 - Contour scanning and process gas type are process parameters typically considered achieving second order effects compared to first order factors such as laser power and scanning speed. The present work highlights that contour scanning is crucial to ensure geometrical accuracy and thereby the high performance under uniaxial compression of complex Alloy 718 lattice structures. Studies of X-ray computed tomography visualizations of as-built and compression-strained structures reveal the continuous and smooth bending and compression of the walls, and the earlier onset of internal contact appearance in the denser lattices printed with contour. In contrast, the effect of addition of He to the Ar process gas appears to have limited influence on the mechanical response of the lattices and their microstructure as characterized by electron backscattered diffraction. However, the addition of He proved to significantly enhance the cooling rate and to reduce the amount of the generated spatters as evidenced by in situ monitoring of the process emissions, which is very promising for the process stability and powder reusability during laser powder bed fusion. KW - Additive manufacturing KW - Laser powder bed fusion KW - Gyroid lattice KW - Process atmosphere PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546632 DO - https://doi.org/10.1016/j.matdes.2022.110501 SN - 0264-1275 VL - 215 SP - 110501 PB - Elsevier Ltd. AN - OPUS4-54663 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - THES A1 - Mishurova, Tatiana T1 - Influence of residual stress and microstructure on mechanical performance of LPBF TI-6AL-4V N2 - Additive manufacturing technologies provide unique possibilities in the production of topologically optimized, near-net shape components. The main limiting factors affecting the structural integrity of Laser Powder Bed Fusion (LPBF) parts are manufacturing defects and residual stress (RS) because both of them are virtually inevitable. Taking into account the complex thermal history of LPBF materials, a prediction of the material behavior is not possible without experimental data on the microstructure, defect distribution, and RS fields. Therefore, this thesis aims to understand the factors that influence the LPBF Ti-6Al-4V material performance the most, covering both the production and the post-processing steps of manufacturing. Indeed, a parametric study on the influence of manufacturing process and post-processing on RS, defects and microstructure was performed. It was found that the volumetric energy Density (EV), commonly used for the LPBF process optimization, does neither consider the pore shapes and distribution, nor the influence of individual parameters on the volume fraction of pores. Therefore, it was recommended not to use EV without great care. It was shown that the Position on the base plate has a great impact on the amount of RS in the part. The micromechanical behavior of LPBF Ti-6Al-4V was also studied using in-situ Synchrotron X-ray diffraction during tensile and compression tests. Diffraction elastic constants (DEC), connecting macroscopic stress and (micro) strain, of the LPBF Ti-6Al-4V showed a difference from the DEC of conventionally manufactured alloy. This fact was attributed to the peculiar microstructure and crystallographic texture. It was therefore recommended to determine experimentally DECs whenever possible. Low Cycle Fatigue (LCF) tests at a chosen operating temperature were performed to evaluate the effect of post-treatment on the mechanical performance. Through the information on the microstructure, the mesostructure, and the RS, the LCF behavior was (indirectly) correlated to the process parameters. It was found that the fatigue performance of LPBF samples subjected to hot isostatic pressing is similar to that of hot-formed Ti-6Al-4V. The tensile RS found at the surface of LPBF as-built samples decreased the fatigue life compared to the heat-treated samples. The modification of the microstructure (by heat treatment) did not affect the Fatigue performance in the elastic regime. This shows that in the absence of tensile RS, the manufacturing defects solely control the failure of LPBF components and densification has the strongest effect on the improvement of the mechanical performance. KW - Additive manufacturing KW - Ti-6Al-4V KW - Residual stress KW - Computed tomography PY - 2021 SP - 1 EP - 143 CY - RWTH Aachen AN - OPUS4-54389 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröder, Jakob A1 - Evans, Alexander A1 - Mishurova, Tatiana A1 - Ulbricht, Alexander A1 - Sprengel, Maximilian A1 - Serrano Munoz, Itziar A1 - Fritsch, Tobias A1 - Kromm, Arne A1 - Kannengießer, Thomas A1 - Bruno, Giovanni T1 - Diffraction-Based Residual Stress Characterization in Laser Additive Manufacturing of Metals JF - Metals N2 - Laser-based additive manufacturing methods allow the production of complex metal structures within a single manufacturing step. However, the localized heat input and the layer-wise manufacturing manner give rise to large thermal gradients. Therefore, large internal stress (IS) during the process (and consequently residual stress (RS) at the end of production) is generated within the parts. This IS or RS can either lead to distortion or cracking during fabrication or in-service part failure, respectively. With this in view, the knowledge on the magnitude and spatial distribution of RS is important to develop strategies for its mitigation. Specifically, diffraction-based methods allow the spatial resolved determination of RS in a non-destructive fashion. In this review, common diffraction-based methods to determine RS in laser-based additive manufactured parts are presented. In fact, the unique microstructures and textures associated to laser-based additive manufacturing processes pose metrological challenges. Based on the literature review, it is recommended to (a) use mechanically relaxed samples measured in several orientations as appropriate strain-free lattice spacing, instead of powder, (b) consider that an appropriate grain-interaction model to calculate diffraction-elastic constants is both material- and texture-dependent and may differ from the conventionally manufactured variant. Further metrological challenges are critically reviewed and future demands in this research field are discussed. KW - Laser-based additive manufacturing KW - Residual stress analysis KW - X-ray and neutron diffraction KW - Diffraction-elastic constants KW - Strain-free lattice spacing PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-538054 DO - https://doi.org/10.3390/met11111830 VL - 11 IS - 11 SP - 1830 PB - MPDI CY - Basel AN - OPUS4-53805 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauzon, C. A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Dubiez-Le Goff, S. A1 - Murugesan, S. A1 - Bruno, Giovanni A1 - Hryha, E. T1 - Residual stresses and porosity in Ti-6Al-4V produced by laser powder bed fusion as a function of process atmosphere and component design JF - Additive Manufacturing N2 - The influence of the process gas, laser scan speed, and sample thickness on the build-up of residual stresses and porosity in Ti-6Al-4V produced by laser powder bed fusion was studied. Pure argon and helium, as well as a mixture of those (30% helium), were employed to establish process atmospheres with a low residual Oxygen content of 100 ppm O2. The results highlight that the subsurface residual stresses measured by X-ray diffraction were significantly lower in the thin samples (220 MPa) than in the cuboid samples (645 MPa). This difference was attributed to the shorter laser vector length, resulting in heat accumulation and thus in-situ stress relief. The addition of helium to the process gas did not introduce additional subsurface residual stresses in the simple geometries, even for the increased scanning speed. Finally, larger deflection was found in the cantilever built under helium (after removal from the baseplate), than in those produced under argon and an argon-helium mixture. This result demonstrates that complex designs involving large scanned areas could be subjected to higher residual stress when manufactured under helium due to the gas’s high thermal conductivity, heat capacity, and thermal diffusivity. KW - Additive manufacturing KW - Ti-6Al-4V KW - Residual stress KW - Process atmosphere KW - Helium PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-534209 DO - https://doi.org/10.1016/j.addma.2021.102340 VL - 47 SP - 2340 PB - Elsevier B.V. AN - OPUS4-53420 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Khrapov, D. A1 - Kozadayeva, M. A1 - Manabaev, K. A1 - Panin, A. A1 - Sjöström, W. A1 - Koptyug, A. A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Meinel, Dietmar A1 - Bruno, Giovanni A1 - Cheneler, D. A1 - Surmenev, R. A1 - Surmeneva, M. T1 - Different approaches for manufacturing Ti-6Al-4V alloy with triply periodic minimal surface sheet-based structures by electron beam melting JF - Materials N2 - Targeting biomedical applications, Triply Periodic Minimal Surface (TPMS) gyroid sheet-based structures were successfully manufactured for the first time by Electron Beam Melting in two different production Themes, i.e., inputting a zero (Wafer Theme) and a 200 µm (Melt Theme) wall thickness. Initial assumption was that in both cases, EBM manufacturing should yield the structures with similar mechanical properties as in a Wafer-mode, as wall thickness is determined by the minimal beam spot size of ca 200 µm. Their surface morphology, geometry, and mechanical properties were investigated by means of electron microscopy (SEM), X-ray Computed Tomography (XCT), and uniaxial tests (both compression and tension). Application of different manufacturing Themes resulted in specimens with different wall thicknesses while quasi-elastic gradients for different Themes was found to be of 1.5 GPa, similar to the elastic modulus of human cortical bone tissue. The specific energy absorption at 50% strain was also similar for the two types of structures. Finite element simulations were also conducted to qualitatively analyze the deformation process and the stress distribution under mechanical load. Simulations demonstrated that in the elastic regime wall, regions oriented parallel to the load are primarily affected by deformation. We could conclude that gyroids manufactured in Wafer and Melt Themes are equally effective in mimicking mechanical properties of the bones. KW - Electron beam melting KW - Scaffold KW - Lightweight structures KW - Computed tomography PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-531595 DO - https://doi.org/10.3390/ma14174912 SN - 1996-1944 VL - 14 IS - 17 SP - 1 EP - 21 PB - MDPI CY - Basel AN - OPUS4-53159 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Khimich, M. A. A1 - Prosolov, K. A. A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Monforte, X. A1 - Teuschl, A. H. A1 - Slezak, P. A1 - Ibragimov, E. A. A1 - Saprykin, A. A. A1 - Kovalevskaya, Z. G. A1 - Dmitriev, A. I. A1 - Bruno, Giovanni A1 - Sharkeev, Y. P. T1 - Advances in Laser Additive Manufacturing of Ti-Nb Alloys: From Nanostructured Powders to Bulk Objects JF - Nanomaterials N2 - The additive manufacturing of low elastic modulus alloys that have a certain level of porosity for biomedical needs is a growing area of research. Here, we show the results of manufacturing of porous and dense samples by a laser powder bed fusion (LPBF) of Ti-Nb alloy, using two distinctive fusion strategies. The nanostructured Ti-Nb alloy powders were produced by mechanical alloying and have a nanostructured state with nanosized grains up to 90 nm. The manufactured porous samples have pronounced open porosity and advanced roughness, contrary to dense samples with a relatively smooth surface profile. The structure of both types of samples after LPBF is formed by uniaxial grains having micro- and nanosized features. The inner structure of the porous samples is comprised of an open interconnected system of pores. The volume fraction of isolated porosity is 2 vol. % and the total porosity is 20 vol. %. Cell viability was assessed in vitro for 3 and 7 days using the MG63 cell line. With longer culture periods, cells showed an increased cell density over the entire surface of a porous Ti-Nb sample. Both types of samples are not cytotoxic and could be used for further in vivo studies. KW - Additive manufacturing KW - Biomaterials KW - Ti-Nb alloy KW - Nanostructured powder KW - Laser methods KW - Powder methods KW - Laser powder bed fusion PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-525344 DO - https://doi.org/10.3390/nano11051159 VL - 11 IS - 5 SP - 1159 PB - MDPI AN - OPUS4-52534 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Serrano Munoz, Itziar A1 - Ulbricht, Alexander A1 - Fritsch, Tobias A1 - Mishurova, Tatiana A1 - Kromm, Arne A1 - Hofmann, M. A1 - Wimpory, R. C. A1 - Evans, Alexander A1 - Bruno, Giovanni T1 - Scanning Manufacturing Parameters Determining the Residual Stress State in LPBF IN718 Small Parts JF - Advanced engineering materials N2 - The influence of scan strategy on the residual stress (RS) state of an as-built IN718 alloy produced by means of laser powder bed fusion (LPBF) is investigated. Two scan vector rotations (90°-alternation and 67°-rotation), each produced following two different scan vector lengths (long and short), are used to manufacture four rectangular prisms. Neutron diffraction (ND) and laboratory X-ray diffraction (XRD) techniques are used to map the bulk and surface RS state, respectively. The distortion induced upon removal from the baseplate is measured via profilometry. XRD measurements show that the two long scan vector strategies lead to higher RS when compared with the equivalent short scan vector strategies. Also, the 67°-rotation strategies generate lower RS than their 90°-alternation counterparts. Due to the lack of reliable stress-free d0 references, the ND results are analyzed using von Mises stress. In general, ND results show significant RS spatial non-uniformity. A comparison between ND and distortion results indicates that the RS component parallel to the building direction (Z-axis) has a predominant role in the Z-displacement. The use of a stress balance scheme allows to discuss the d0 variability along the length of the specimens, as well as examine the absolute RS state. KW - As-built LPBF IN718 alloy KW - Scan strategy influence KW - Neutron diffraction KW - Residual stress state KW - Stress balance condition KW - Distortion PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-526360 DO - https://doi.org/10.1002/adem.202100158 VL - 23 IS - 7 SP - 158 PB - Wiley AN - OPUS4-52636 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Serrano Munoz, Itziar A1 - Evans, Alexander A1 - Mishurova, Tatiana A1 - Sprengel, Maximilian A1 - Pirling, T. A1 - Kromm, Arne A1 - Bruno, Giovanni T1 - The importance of subsurface residual stress in laser powder bed fusion IN718 JF - Advanced engineering materials N2 - The residual stress (RS) in laser powder bed fusion (LPBF) IN718 alloy samples produced using a 67°-rotation scan strategy is investigated via laboratory X-ray diffraction (XRD) and neutron diffraction (ND). The location dependence of the strain-free (d₀) lattice spacing in ND is evaluated using a grid array of coupons extracted from the far-edge of the investigated specimen. No compositional spatial variation is observed in the grid array. The calculated RS fields show considerable non-uniformity, significant stress gradients in the region from 0.6 to 2 mm below the surface, as well as subsurface maxima that cannot be accounted for via XRD. It is concluded that failure to determine such maxima would hamper a quantitative determination of RS fields by means of the stress balance method. KW - Laser powder bed fusion KW - Neutron and X-ray diffraction KW - Residual stress analysis KW - Strain-free lattice references KW - Stress balance PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-532707 DO - https://doi.org/10.1002/adem.202100895 SN - 1615-7508 SN - 1527-2648 VL - 24 IS - 6 SP - 1 EP - 7 PB - Wiley-VCH CY - Weinheim AN - OPUS4-53270 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thiede, Tobias A1 - Cabeza, Sandra A1 - Mishurova, Tatiana A1 - Nadammal, Naresh A1 - Kromm, Arne A1 - Bode, Johannes A1 - Haberland, C. A1 - Bruno, Giovanni T1 - An assessment of bulk residual stress in selective laser melted Inconel 718 T2 - Proceedings ECNDT2018 N2 - Additive Manufacturing (AM) of metals has become industrially viable for a large variety of applications, including aerospace, automotive and medicine. Powder bed techniques such as Selective Laser Melting (SLM) based on layer-by-layer deposition and laser melt enable numerous degrees of freedom for the geometrical design. Developing during the manufacturing process, residual stresses may limit the application of SLM parts by reducing the load bearing capacity as well as induce unwanted distortion depending on the boundary conditions specified in manufacturing. The residual stress distribution in the bulk of IN718 elongated prisms produced by SLM was studied non-destructively by means of neutron diffraction. The samples with different scanning strategies, i.e. hatching length, were measured in as-build condition (on a build plate) and after removal from the build plate. The absolute values of all stress components decreased after removal from the build plate. Together with surface scan utilizing a coordinate-measuring machine (CMM), it is possible to link the stress release to the sample distortion. Obtained results indicated different residual stress states for each of the transversal, longitudinal and normal component depending on the thermal gradient in the respective direction. T2 - ECNDT 2018 CY - Göteborg, Sweden DA - 11.06.2018 KW - Residual stress KW - Selective laser melting KW - Neutron diffraction KW - IN718 PY - 2018 UR - http://cdn.ecndt2018.com/wp-content/uploads/2018/05/ecndt-0315-2018-File001.pdf SP - 1 AN - OPUS4-45325 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana A1 - Cabeza, Sandra A1 - Artzt, Katia A1 - Bruno, Giovanni A1 - Haubrich, Jan A1 - Requena, Guillermo T1 - Subsurface Residual Stress Analysis in Ti-6Al-4V Additive Manufactured Parts by Synchrotron X-ray Diffraction N2 - Synchrotron X-ray diffraction is a powerful non-destructive technique for the analysis of the material stress-state. High cooling rates and heterogeneous temperature distributions during additive manufacturing lead to high residual stresses. These high residual stresses play a crucial role in the ability to achieve complex geometries with accuracy since they can promote distortion of parts during manufacturing. Furthermore, residual stresses are critical for the mechanical performance of parts in terms of durability and safety. In the present study, Ti-6Al-4V bridge-like specimens were manufactured additively by selective laser melting (SLM) under different laser scanning speed conditions in order to compare the effect of process energy density on the residual stress state. Subsurface residual stress analysis was conducted by means of synchrotron X-ray diffraction in energy dispersive mode for three conditions: as-built on base plate, released from base plate, and after heat treatment on the base plate. The quantitative residual stress characterization shows a correlation with the qualitative bridge curvature method. Computed tomography (CT) was carried out to ensure that no stress relief took place owing to the presence of porosity. CT allows obtaining spatial and size pores distribution which helps in optimization of the SLM process. High tensile residual stresses were found at the lateral surface for samples in the as-built conditions. We observed that higher laser energy density during fabrication leads to lower residual stresses. Samples in released condition showed redistribution of the stresses due to distortion. T2 - ECNDT 2018 CY - Göteborg, Sweden DA - 11.06.2018 KW - Additive manufacturing KW - Selective laser melting KW - Residual stress KW - Computed tomography KW - Ti-6Al-4V PY - 2018 AN - OPUS4-45202 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana A1 - Artzt, Katia A1 - Bruno, Giovanni A1 - Requena, Guillermo A1 - Haubrich, Jan T1 - Subsurface residual stress analysis in Ti-6Al-4V additive manufactured parts by synchrotron x-ray diffraction T2 - Proceedings ECNDT2018 N2 - Synchrotron X-ray diffraction is a powerful non-destructive technique for the analysis of the material stress-state. High cooling rates and heterogeneous temperature distributions during additive manufacturing lead to high residual stresses. These high residual stresses play a crucial role in the ability to achieve complex geometries with accuracy since they can promote distortion of parts during manufacturing. Furthermore, residual stresses are critical for the mechanical performance of parts in terms of durability and safety. In the present study, Ti-6Al-4V bridge-like specimens were manufactured additively by selective laser melting (SLM) under different laser scanning speed conditions in order to compare the effect of process energy density on the residual stress state. Subsurface residual stress analysis was conducted by means of synchrotron X-ray diffraction in energy dispersive mode for three conditions: as-built on base plate, released from base plate, and after heat treatment on the base plate. The quantitative residual stress characterization shows a correlation with the qualitative bridge curvature method. Computed tomography (CT) was carried out to ensure that no stress relief took place owing to the presence of porosity. CT allows obtaining spatial and size pores distribution which helps in optimization of the SLM process. High tensile residual stresses were found at the lateral surface for samples in the as-built conditions. We observed that higher laser energy density during fabrication leads to lower residual stresses. Samples in released condition showed redistribution of the stresses due to distortion. T2 - 12th ECNDT 2018 CY - Göteborg, Sweden DA - 11.06.2018 KW - Additive manufacturing KW - Selective laser melting KW - Residual stress KW - Synchrotron X-ray diffraction KW - Ti-6Al-4V PY - 2018 UR - http://cdn.ecndt2018.com/wp-content/uploads/2018/05/ecndt-0213-2018-File001.pdf SP - 1 EP - 8 AN - OPUS4-45217 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni A1 - Thiede, Tobias A1 - Mishurova, Tatiana A1 - Kromm, Arne A1 - Nadammal, Naresh A1 - Bode, Johannes A1 - Cabeza, Sandra T1 - Influence of deposition hatch length on residual stress in selective laser melted Inconel 718 N2 - The present study aims to evaluate the bulk residual stresses in SLM parts by using neutron diffraction measurements performed at E3 line -BER II neutron reactor- of Helmholtz-Zentrum für Materialien und Energie (HZB) Berlin. Together with microstructure characterization and distortion measurements, it is possible to describe the stress state throughout the whole sample. The sample was measured in as-build condition (on a build plate) and after releasing from the build plate. The used material is the nickel based superalloy 718. This alloy is widely used in aerospace and chemical industries due to its superior corrosion and heat resistant properties. Obtained results indicated different residual stress states for each of the transversal, longitudinal and normal component. The normal and transversal component exhibits a rather compressive behavior while the longitudinal was tensile in the center part of the sample and became compressive towards the tip. As expected, the absolute values of all stress components decreased after releasing the sample from the building plate. A surface scan utilizing a coordinate-measuring machine (CMM) allowed us to present top surface distortion before and after releasing. The top surface showed a distortion around ±80µm after releasing. Microstructure evolution in the scanning-building cross-section is largely dominated by columnar grains. In addition, many small random orientated grains are prominent in the regions of a laser overlap during SLM. In summary, for the sample of superalloy 718 manufactured by SLM, a small distortion occurred when removing the sample from the build plate whereby the residual stress state decreases. Moreover, the observed columnar grains in the building direction could give a reason for the lowest stress values in that normal direction. However, the most important parameter controlling the residual stresses is the temperature gradient. Hence, future investigations are planned for a different scan strategy to distribute the laser impact in a more homogenous manner. T2 - WAM2018 CY - Grenoble, France DA - 09.04.2018 KW - Additive manufacturing KW - SLM KW - Residual stress KW - In718 PY - 2018 AN - OPUS4-44694 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishurova, Tatiana A1 - Cabeza, Sandra A1 - Thiede, Tobias A1 - Nadammal, Naresh A1 - Kromm, Arne A1 - Klaus, Manuela A1 - Genzel, Christoph A1 - Haberland, Christoph A1 - Bruno, Giovanni T1 - The influence of the support structure on residual stress and distortion in SLM Inconel 718 parts JF - Metallurgical and materials transactions A N2 - The effect of support structure and of removal from the base plate on the residual stress state in selective laser melted IN718 parts was studied by means of synchrotron X-ray diffraction. The residual stresses in subsurface region of two elongated prisms in as-built condition and after removal from the base plate were determined. One sample was directly built on a base plate and another one on a support structure. Also, the distortion on the top surface due to stress release was measured by contact profilometry. High tensile residual stress values were found, with pronounced stress gradient along the hatching direction. In the sample on support, stress redistribution took place after removal from the base plate, as opposed to simple stress relaxation for the sample without support. The sample on support structure showed larger distortion compared to sample without support. We conclude that the use of a support decreases stress values but stress-relieving heat treatments are still needed. KW - Additive manufacturing KW - SLM KW - Residual stress KW - Synchrotron X-ray diffraction KW - IN718 PY - 2018 DO - https://doi.org/10.1007/s11661-018-4653-9 SN - 1073-5623 VL - 49A IS - 7 SP - 3038 EP - 3046 PB - Springer Sciences & Business Media CY - New York, NY AN - OPUS4-45100 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni A1 - Mishurova, Tatiana A1 - Serrano Munoz, Itziar A1 - Ulbricht, Alexander A1 - Fritsch, Tobias A1 - Sprengel, Maximilian A1 - Evans, Alexander A1 - Kromm, Arne A1 - Madia, Mauro ED - Bruno, Giovanni T1 - A Critical Discussion on the Diffraction-Based Experimental Determination of Residual Stress in AM Parts T2 - Structural integrityofadditive manufactured materials and parts N2 - As opposed to reviewing results on experimental determination of residual stress by diffraction, this paper discusses the open issues when dealing with residual stress determination in additive manufactured parts, in particular those manufactured with laser powder bed fusion techniques. Three points are addressed in detail: (a) the proper determination of the strain-free reference d0, (b) the problem of the determination of the principal axes, and (c) the use of the correct diffraction elastic constants. It is shown that all methods to determine the strain-free reference d0 suffer from caveats, and care must be taken in evaluating the most suitable for the problem being tackled. In addition, it is shown that, in some systems, the principal axes do correspond to the geometrical axes of the specimen, but this needs to be systematically checked, especially in the case of uni- or bidirectional hatching strategies. Finally, the need to experimentally determine the proper diffraction elastic constants is underlined, especially in the case of strongly textured specimens, which again depends on the deposition strategy. T2 - ASTM ICAM 2020 – ASTM International Conference on Additive Manufacturing CY - Online meeting DA - 16.11.2020 KW - Additive Manufacturing KW - Diffraction KW - Residual Stress PY - 2020 DO - https://doi.org/10.1520/STP163120190148 VL - STP1631 SP - 122 EP - 138 PB - ASTM International CY - USA AN - OPUS4-51347 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Artzt, K. A1 - Mishurova, Tatiana A1 - Bauer, P.-P. A1 - Gussone, J. A1 - Barriobero-Vila, P. A1 - Evsevleev, Sergei A1 - Bruno, Giovanni A1 - Requena, G. A1 - Haubrich, J. T1 - Pandora’s Box–Influence of Contour Parameters on Roughness and Subsurface Residual Stresses in Laser Powder Bed Fusion of Ti-6Al-4V JF - Materials N2 - The contour scan strategies in laser powder bed fusion (LPBF) of Ti-6Al-4V were studied at the coupon level. These scan strategies determined the surface qualities and subsurface residual stresses. The correlations to these properties were identified for an optimization of the LPBF processing. The surface roughness and the residual stresses in build direction were linked: combining high laser power and high scan velocities with at least two contour lines substantially reduced the surface roughness, expressed by the arithmetic mean height, from values as high as 30 μm to 13 μm, while the residual stresses rose from ~340 to about 800 MPa. At this stress level, manufactured rocket fuel injector components evidenced macroscopic cracking. A scan strategy completing the contour region at 100 W and 1050 mm/s is recommended as a compromise between residual stresses (625 MPa) and surface quality (14.2 μm). The LPBF builds were monitored with an in-line twin-photodiode-based melt pool monitoring (MPM) system, which revealed a correlation between the intensity quotient I2/I1, the surface roughness, and the residual stresses. Thus, this MPM system can provide a predictive estimate of the surface quality of the samples and resulting residual stresses in the material generated during LPBF. KW - Additive manufacturing KW - Ti-6Al-4V KW - Contour scan strategy KW - Surface roughness KW - Melt pool monitoring KW - Residual stress KW - Synchrotron X-ray diffraction PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-510585 DO - https://doi.org/10.3390/ma13153348 VL - 13 IS - 15 SP - 3348 AN - OPUS4-51058 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishurova, Tatiana A1 - Sydow, B. A1 - Thiede, Tobias A1 - Sizova, I. A1 - Ulbricht, Alexander A1 - Bambach, M. A1 - Bruno, Giovanni T1 - Residual Stress and Microstructure of a Ti-6Al-4V Wire Arc Additive Manufacturing Hybrid Demonstrator JF - Metals N2 - Wire Arc Additive Manufacturing (WAAM) features high deposition rates and, thus, allows production of large components that are relevant for aerospace applications. However, a lot of aerospace parts are currently produced by forging or machining alone to ensure fast production and to obtain good mechanical properties; the use of these conventional process routes causes high tooling and material costs. A hybrid approach (a combination of forging and WAAM) allows making production more efficient. In this fashion, further structural or functional features can be built in any direction without using additional tools for every part. By using a combination of forging basic geometries with one tool set and adding the functional features by means of WAAM, the tool costs and material waste can be reduced compared to either completely forged or machined parts. One of the factors influencing the structural integrity of additively manufactured parts are (high) residual stresses, generated during the build process. In this study, the triaxial residual stress profiles in a hybrid WAAM part are reported, as determined by neutron diffraction. The analysis is complemented by microstructural investigations, showing a gradient of microstructure (shape and size of grains) along the part height. The highest residual stresses were found in the transition Zone (between WAAM and forged part). The total stress range showed to be lower than expected for WAAM components. This could be explained by the thermal history of the component. KW - Additive manufacturing KW - Neutron diffraction KW - Residual stress KW - Hybrid manufacturing KW - WAAM KW - Ti-6Al-4V PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-508245 DO - https://doi.org/10.3390/met10060701 VL - 10 IS - 6 SP - 701 PB - MDPI AN - OPUS4-50824 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishurova, Tatiana A1 - Bruno, Giovanni A1 - Evsevleev, Sergei A1 - Sevostianov, I. T1 - Determination of macroscopic stress from diffraction experiments: A critical discussion JF - Journal of Applied Physics N2 - The paper is motivated by some inconsistencies and contradictions present in the literature on the calculation of the so-called diffraction elastic constants. In an attempt at unifying the views that the two communities of Materials Science and Mechanics of Materials have on the subject, we revisit and define the terminology used in the field. We also clarify the limitations of the commonly used approaches and Show that a unified methodology is also applicable to textured materials with a nearly arbitrary grain shape. We finally compare the predictions based on this methodology with experimental data obtained by in situ synchrotron radiation diffraction on additively manufactured Ti-6Al4V alloy. We show that (a) the transverse isotropy of the material yields good agreement between the best-fit isotropy approximation (equivalent to the classic Kröner’s model) and the experimental data and (b) the use of a general framework allows the calculation of all components of the tensor of diffraction elastic constants, which are not easily measurable by diffraction methods. This allows us to extend the current state-of-the-art with a predictive tool. KW - Additive manufacturing KW - X-ray diffraction KW - Elastic constants KW - Stress concentration tensor PY - 2020 DO - https://doi.org/10.1063/5.0009101 VL - 128 IS - 2 SP - 025103 PB - AIP Publishing AN - OPUS4-50993 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Khrapov, D A1 - Koptyug, A. A1 - Manabaev, K. A1 - Léonard, Fabien A1 - Mishurova, Tatiana A1 - Bruno, Giovanni A1 - Cheneler, D. A1 - Loza, K. A1 - Epple, M. A1 - Surmenev, R. A1 - Surmeneva, M. T1 - The impact of post manufacturing treatment of functionally graded Ti6Al4V scaffolds on their surface morphology and mechanical strength JF - Journal of Material Research and Technology N2 - An ultrasonic vibration post-treatment procedure was suggested for additively manufac-tured lattices. The aim of the present research was to investigate mechanical properties andthe differences in mechanical behavior and fracture modes of Ti6Al4V scaffolds treated withtraditional powder recovery system (PRS) and ultrasound vibration (USV). Scanning electronmicroscopy (SEM) was used to investigate the strut surface and the fracture surface mor-phology. X-ray computed tomography (CT) was employed to evaluate the inner structure,strut dimensions, pore size, as well as the surface morphology of additively manufacturedporous scaffolds. Uniaxial compression tests were conducted to obtain elastic modulus,compressive ultimate strength and yield stress. Finite element analysis was performedfor a body-centered cubic (BCC) element-based model and for CT-based reconstructiondata, as well as for a two-zone scaffold model to evaluate stress distribution during elasticdeformation. The scaffold with PRS post treatment displayed ductile behavior, while USVtreated scaffold displayed fragile behavior. Double barrel formation of PRS treated scaffoldwas observed during deformation. Finite element analysis for the CT-based reconstructionrevealed the strong impact of surface morphology on the stress distribution in comparisonwith BCC cell model because of partially molten metal particles on the surface of struts,which usually remain unstressed. KW - Additive manufacturing KW - Electron beam melting KW - Computed tomography KW - FEM KW - Lattice structures PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-505960 DO - https://doi.org/10.1016/j.jmrt.2019.12.019 SN - 2238-7854 VL - 9 IS - 2 SP - 1866 EP - 1881 PB - Elsevier B.V. AN - OPUS4-50596 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana A1 - Artzt, K. A1 - Haubrich, J. A1 - Requena, G. A1 - Bruno, Giovanni T1 - New aspects about the search for the most relevant parameters optimizing SLM materials N2 - Using non-optimum combination of manufacturing parameters in selective laser melting (SLM) may lead to reduction of quality of component: defects generation, distortion of geometry and even cracking. Usually, the optimization of parameters is performed by changing volumetric energy density (Ev) and selecting parameters giving low porosity values. However, not only low porosity but also stable microstructure and low residual stresses will help to achieve advanced mechanical behavior of the component. In present work, we investigated cuboid-shaped Ti-6Al-4V samples produced with different manufacturing parameters. The parameters leading to the same Ev were considered as well as parameters which are not included in Ev. Residual stresses in subsurface region were investigated by synchrotron X-ray diffraction, which allows to penetrate around 100 µm from the surface therefore overcome the problem of high roughness of SLM components without additional sample preparation. Only tensile stresses were found along the building direction, that can play critical role especially during cyclic loading. The pore shape and spatial distribution obtained by computed tomography varied for samples produced with the same Ev. However, by using some process parameters it was possible to decrease residual stresses and obtain uniform α+β Ti microstructure and relatively low porosity. Additionally, it was found that not included in Ev (e.g., base plate position, focus distance) should be considered as additional manufacturing parameters during SLM process. T2 - ESIAM 2019 CY - Trondheim, Norway DA - 09.09.2019 KW - Additive manufacturing KW - Computed tomography KW - Residual stress PY - 2019 AN - OPUS4-49216 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Surmeneva, M. A1 - Koptyug, A. A1 - Khrapov, D. A1 - Ivanov, Yuriy A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Prymak, O. A1 - Loza, K. A1 - Epple, M. A1 - Bruno, Giovanni A1 - Surmenev, R. T1 - In situ synthesis of a binary Ti–10at% Nb alloy by electron beam melting using a mixture of elemental niobium and titanium powders JF - Journal of Materials Processing Technology N2 - This study reports the results of the preliminary assessment to fabricate Ti-10at% Nb alloy by electron beam melting (EBM®) from a blend of elemental Nb and Ti powders. The microstructure of the EBM-manufactured Ti-10at% Nb alloys is sensitive to the following factors: different sintering properties of Nb and Ti powders, powder particle properties, material viscosities at varying melt pool temperatures, β-stabilizer element content and the EBM® process parameters. Three phases were observed in as-manufactured Ti-10at% Nb alloy: μm-size Nb phase, a Nb-rich β-solid solution surrounding Nb phase, lamellar structured α-phase and β-solid solution with different distribution and volume fraction. Thus, the combination of powder particle characteristics, very short time material spends in molten condition and sluggish kinetics of mixing and diffusional process in Ti-Nb alloy results in heterogeneous microstructures depending on the local Nb content in the powder blend and the EBM® process conditions. KW - Additive manufacturing KW - Electron beam melting KW - Ti-Nb alloy KW - In situ alloying PY - 2020 DO - https://doi.org/10.1016/j.jmatprotec.2020.116646 VL - 282 SP - 116646 PB - Elsevier B.V. AN - OPUS4-50457 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröder, Jakob A1 - Mishurova, Tatiana A1 - Fritsch, Tobias A1 - Serrano Munoz, Itziar A1 - Evans, Alexander A1 - Sprengel, Maximilian A1 - Klaus, M. A1 - Genzel, C. A1 - Schneider, J. A1 - Bruno, Giovanni T1 - On the influence of heat treatment on microstructure and mechanical behavior of laser powder bed fused Inconel 718 JF - Materials Science & Engineering A N2 - A range of heat treatments have been developed for wrought Inconel 718 to obtain desired properties. For additively manufactured Inconel 718, the recently developed standard ASTM F3301 provides guidance for heat treatment of powder bed fusion specimens. Although this standard is based on standards developed for wrought Inconel 718, it does not include direct aging. Since direct aging reduces the number of processing steps, it can result in a post processing cost reduction if the desired properties are obtained. In this study, we characterized the microstructure and tensile behavior of Inconel 718 specimens produced by a laser powder bed fusion process. The specimens were heat treated according to two different routines after stress relieving: a full heat Treatment versus a one-step direct aging process. Differences in the resulting texture and grain morphology were observed. The ex-situ stress-strain behavior was broadly similar. However, a slight increase in yield strength was observed for the direct aged specimen. In order to understand this behavior, investigations with in-situ synchrotron Energy dispersive X-ray diffraction tensile testing revealed differences in the load partitioning among different Crystal directions. Importantly, the elastic anisotropy expressed by the magnitude of the diffraction elastic constants showed a dependency on the microstructures. KW - Electron microscopy KW - X-ray analysis KW - Inconel 718 KW - Additive Manufacturing KW - Mechanical behavior KW - Diffraction elastic constants PY - 2021 DO - https://doi.org/10.1016/j.msea.2020.140555 VL - 805 SP - 40555 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-52142 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Serrano Munoz, Itziar A1 - Fritsch, Tobias A1 - Mishurova, Tatiana A1 - Trofimov, Anton A1 - Apel, D. A1 - Ulbricht, Alexander A1 - Kromm, Arne A1 - Hesse, René A1 - Evans, Alexander A1 - Bruno, Giovanni T1 - On the interplay of microstructure and residual stress in LPBF IN718 JF - Journal of Material Science N2 - The relationship between residual stresses and microstructure associated with a laser powder bed fusion (LPBF) IN718 alloy has been investigated on specimens produced with three different scanning strategies (unidirectional Y-scan, 90° XY-scan, and 67° Rot-scan). Synchrotron X-ray energy-dispersive diffraction (EDXRD) combined with optical profilometry was used to study residual stress (RS) distribution and distortion upon removal of the specimens from the baseplate. The microstructural characterization of both the bulk and the nearsurface regions was conducted using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). On the top surfaces of the specimens, the highest RS values are observed in the Y-scan specimen and the lowest in the Rot-scan specimen, while the tendency is inversed on the side lateral surfaces. A considerable amount of RS remains in the specimens after their removal from the baseplate, especially in the Y- and Z-direction (short specimen Dimension and building direction (BD), respectively). The distortion measured on the top surface following baseplate thinning and subsequent removal is mainly attributed to the amount of RS released in the build direction. Importantly, it is observed that the additive manufacturing microstructures challenge the use of classic theoretical models for the calculation of diffraction elastic constants (DEC) required for diffraction-based RS analysis. It is found that when the Reuß model is used for the calculation of RS for different crystal planes, as opposed to the conventionally used Kröner model, the results exhibit lower scatter. This is discussed in context of experimental measurements of DEC available in the literature for conventional and additively manufactured Ni-base alloys. KW - L-PBF IN718 material KW - Effect of scanning strategies KW - Near-surface X-ray diffraction KW - Residual stress in AM KW - Distortion upon baseplate removal PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519460 DO - https://doi.org/10.1007/s10853-020-05553-y SN - 0022-2461 VL - 56 IS - 9 SP - 5845 EP - 5867 PB - Springer AN - OPUS4-51946 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishurova, Tatiana A1 - Artzt, K. A1 - Haubrich, J. A1 - Requena, G. A1 - Bruno, Giovanni T1 - Exploring the correlation between subsurface residual stresses and manufacturing parameters in laser powder bed fused Ti-6Al-4V JF - Metals N2 - Subsurface residual stresses (RS) were investigated in Ti-6Al-4V cuboid samples by means of X-ray synchrotron diffraction. The samples were manufactured by laser powder bed fusion (LPBF) applying different processing parameters, not commonly considered in open literature, in order to assess their influence on RS state. While investigating the effect of process parameters used for the calculation of volumetric energy density (such as laser velocity, laser power and hatch distance), we observed that an increase of energy density led to a decrease of RS, although not to the same extent for every parameter variation. Additionally, the effect of support structure, sample roughness and LPBF machine effects potentially coming from Ar flow were studied. We observed no influence of support structure on subsurface RS while the orientation with respect to Ar flow showed to have an impact on RS.We conclude recommending monitoring such parameters to improve part reliability and reproducibility. KW - Additive manufacturing KW - Synchrotron X-ray diffraction KW - Residual stress KW - Ti-6Al-4V PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-474281 DO - https://doi.org/10.3390/met9020261 SN - 2075-4701 VL - 9 IS - 2 SP - 261, 1 EP - 13 PB - MDPI AN - OPUS4-47428 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thiede, Tobias A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Serrano Munoz, Itziar A1 - Gollwitzer, Christian A1 - Bruno, Giovanni T1 - 3D shape analysis of powder for laser beam melting by synchrotron X-ray CT JF - Quantum Beam Science N2 - The quality of components made by laser beam melting (LBM) additive manufacturing is naturally influenced by the quality of the powder bed. A packing density <1 and porosity inside the powder particles lead to intrinsic voids in the powder bed. Since the packing density is determined by the particle size and shape distribution, the determination of these properties is of significant interest to assess the printing process. In this work, the size and shape distribution, the amount of the particle’s intrinsic porosity, as well as the packing density of micrometric powder used for LBM, have been investigated by means of synchrotron X-ray computed tomography (CT). Two different powder batches were investigated: Ti–6Al–4V produced by plasma atomization and stainless steel 316L produced by gas atomization. Plasma atomization particles were observed to be more spherical in terms of the mean anisotropy compared to particles produced by gas atomization. The two kinds of particles were comparable in size according to the equivalent diameter. The packing density was lower (i.e., the powder bed contained more voids in between particles) for the Ti–6Al–4V particles. The comparison of the tomographic results with laser diffraction, as another particle size measurement technique, proved to be in agreement. KW - Additive manufacturing KW - Laser beam melting KW - Synchrotron computed tomography KW - Powder analysis KW - Imaging PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-474070 DO - https://doi.org/10.3390/qubs3010003 SN - 2412-382X VL - 3 IS - 1 SP - 3, 1 EP - 12 PB - MDPI AN - OPUS4-47407 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kromm, Arne A1 - Cabeza, S. A1 - Mishurova, Tatiana A1 - Nadammal, Naresh A1 - Thiede, Tobias A1 - Bruno, Giovanni T1 - Residual Stresses in Selective Laser Melted Samples of a Nickel Based Superalloy T2 - Residual Stresses 2018 ECRS-10 N2 - Additive Manufacturing (AM) through the Selective Laser Melting (SLM) route offers ample scope for producing geometrically complex parts compared to the conventional subtractive manufacturing strategies. Nevertheless, the residual stresses which develop during the fabrication can limit application of the SLM components by reducing the load bearing capacity and by inducing unwanted distortion, depending on the boundary conditions specified during manufacturing. The present study aims at characterizing the residual stress states in the SLM parts using different diffraction methods. The material used is the nickel based superalloy Inconel 718. Microstructure as well as the surface and bulk residual stresses were characterized. For the residual stress analysis, X-ray, synchrotron and neutron diffraction methods were used. The measurements were performed at BAM, at the EDDI beamline of -BESSY II synchrotronand the E3 line -BER II neutron reactor- of the Helmholtz-Zentrum für Materialien und Energie (HZB) Berlin. The results reveal significant differences in the residual stress states for the different characterization techniques employed, which indicates the dependence of the residual state on the penetration depth in the sample. For the surface residual stresses, longitudinal and transverse stress components from X-ray and synchrotron agree well and the obtained values were around the yield strength of the material. Furthermore, synchrotron mapping disclosed gradients along the width and length of the sample for the longitudinal and transverse stress components. On the other hand, lower residual stresses were found in the bulk of the material measured using neutron diffraction. The longitudinal component was tensile and decreased towards the boundary of the sample. In contrast, the normal component was nearly constant and compressive in nature. The transversal component was almost negligible. The results indicate that a stress re-distribution takes place during the deposition of the consecutive layers. Further investigations are planned to study the phenomenon in detail. T2 - European Conference on Residual Stresses - ECRS10 CY - Leuven, Belgium DA - 11.09.2018 KW - Additive Manufacturing KW - Selective Laser Melting KW - Residual Stresses PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-459818 SN - 978-1-94529-189-0 SN - 978-1-94529-188-3 DO - https://doi.org/10.21741/9781945291890-41 SN - 2474-395X SN - 2474-3941 VL - 6 SP - 259 EP - 264 PB - Materials Research Forum LLC CY - Millersville, PA 17551, USA AN - OPUS4-45981 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana A1 - Thiede, Tobias A1 - Evsevleev, Sergei A1 - Serrano Munoz, Itziar A1 - Gollwitzer, Christian A1 - Bruno, Giovanni T1 - 3D Shape Analysis of Powder for Laser Beam Melting by Synchrotron X-ray CT N2 - The quality of components made by laser beam melting (LBM) additive manufacturing is naturally influenced by the quality of the powder bed. A packing density < 1 and porosity inside the powder particles lead to intrinsic voids in the powder bed. Since the packing density is determined by the particle size and shape distribution, the determination of these properties is of significant interest to assess the printing process. In this work, the size and shape distribution, the amount of particle’s intrinsic porosity as well as the packing density of micrometric powder used for LBM have been investigated by means of synchrotron X-ray computed tomography (CT). Two different powder batches were investigated: Ti-6Al-4V produced by plasma atomization and Stainless Steel 316L produced by gas atomization. Plasma atomization particles were observed to be more spherical in terms of the mean anisotropy compared to particles produced by gas atomization. The two kinds of particles are comparable in size according to the equivalent diameter. The packing density is lower (i.e. the powder bed contains more voids in between particles) for the Ti-6Al-4V particles. The comparison of the tomographic results with laser diffraction, as another particle size measurements techniques, proved agreement. T2 - User Meeting HZB 2018 CY - Berlin, BESSY II DA - 06.12.2018 KW - BAMline KW - Computed tomography KW - Laser beam melting KW - Powder PY - 2018 AN - OPUS4-46933 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thiede, Tobias A1 - Cabeza, S. A1 - Mishurova, Tatiana A1 - Nadammal, N. A1 - Kromm, Arne A1 - Bode, Johannes A1 - Haberland, C. A1 - Bruno, Giovanni T1 - Residual stress in selective laser melted Inconel 718: Influence of the removal from base plate and deposition hatch length JF - Materials, Performance & Characterization N2 - The residual stress distribution in IN718 elongated prisms produced by Selective Laser Melting was studied by means of neutron (bulk) and laboratory X-ray (surface) diffraction. Two deposition hatch lengths were considered. A horizontal plane near the top surface (perpendicular to the building direction) and a vertical plane near the lateral surface (parallel to the building direction) were investigated. Samples both in as-built (AB) condition and removed (RE) from the base plate were characterized. While surface stress fields seem constant for AB condition, X-ray diffraction shows stress gradients along the hatch direction in the RE condition. The stress profiles correlate with the distortion maps obtained by tactile probe measurements. Neutron diffraction shows bulk stress gradients for all principal components along the main sample directions. We correlate the observed stress patterns with the hatch length, i.e. with its effect on temperature gradients and heat flow. The bulk stress gradients partially disappear after removal from the baseplate. KW - Residual stress KW - Additive manufacturing KW - Neutron diffraction KW - Selective laser melting KW - Laboratory X-ray diffraction KW - Coordinate measurement machine KW - IN718 PY - 2018 DO - https://doi.org/10.1520/MPC20170119 SN - 2379-1365 VL - 7 IS - 4 SP - 717 EP - 735 PB - ASTM International CY - USA, West Conshohocken AN - OPUS4-46673 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishurova, Tatiana A1 - Artzt, K. A1 - Haubrich, J. A1 - Requena, G. A1 - Bruno, Giovanni T1 - New aspects about the search for the most relevant parameters optimizing SLM materials JF - Additive Manufacturing N2 - While the volumetric energy density is commonly used to qualify a process parameter set, and to quantify its influence on the microstructure and performance of additively manufactured (AM) materials and components, it has been already shown that this description is by no means exhaustive. In this work, new aspects of the optimization of the selective laser melting process are investigated for AM Ti-6Al-4V. We focus on the amount of near-surface residual stress (RS), often blamed for the failure of components, and on the porosity characteristics (amount and spatial distribution). First, using synchrotron x-ray diffraction we show that higher RS in the subsurface region is generated if a lower energy density is used. Second, we show that laser de-focusing and sample positioning inside the build chamber also play an eminent role, and we quantify this influence. In parallel, using X-ray Computed Tomography, we observe that porosity is mainly concentrated in the contour region, except in the case where the laser speed is small. The low values of porosity (less than 1%) do not influence RS. KW - Additive manufacturing KW - Selective laser melting KW - Residual stress KW - Computed tomography PY - 2019 DO - https://doi.org/10.1016/j.addma.2018.11.023 SN - 2214-8604 VL - 25 SP - 325 EP - 334 PB - Elsevier AN - OPUS4-46737 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nadammal, Naresh A1 - Mishurova, Tatiana A1 - Fritsch, Tobias A1 - Serrano Munoz, Itziar A1 - Kromm, Arne A1 - Haberland, C. A1 - Portella, Pedro Dolabella A1 - Bruno, Giovanni T1 - Critical role of scan strategies on the development of microstructure, texture, and residual stresses during laser powder bed fusion additive manufacturing JF - Additive Manufacturing N2 - Laser based powder bed fusion additive manufacturing offers the flexibility to incorporate standard and userdefined scan strategies in a layer or in between the layers for the customized fabrication of metallic components. In the present study, four different scan strategies and their impact on the development of microstructure, texture, and residual stresses in laser powder bed fusion additive manufacturing of a nickel-based superalloy Inconel 718 was investigated. Light microscopy, scanning electron microscopy combined with electron backscatter diffraction, and neutron diffraction were used as the characterization tools. Strong textures with epitaxially grown columnar grains were observed along the build direction for the two individual scan strategies. Patterns depicting the respective scan strategies were visible in the build plane, which dictated the microstructure development in the other planes. An alternating strategy combining the individual strategies in the successive layers and a 67◦ rotational strategy weakened the texture by forming finer microstructural features. Von Mises equivalent stress plots revealed lower stress values and gradients, which translates as lower distortions for the alternating and rotational strategies. Overall results confirmed the scope for manipulating the microstructure, texture, and residual stresses during laser powder bed fusion additive manufacturing by effectively controlling the scan strategies. KW - Additive manufacturing KW - Laser powder bed fusion KW - Nickel-based superalloys KW - Scan strategies KW - Residual stresses KW - Microstructure and texture PY - 2021 DO - https://doi.org/10.1016/j.addma.2020.101792 VL - 38 SP - 1792 PB - Elsevier B.V. AN - OPUS4-51944 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana A1 - Artzt, Katia A1 - Haubrich, Jan A1 - Requena, Guillermo A1 - Bruno, Giovanni A1 - Rehmer, Birgit T1 - Influence of residual stress and microstructure on mechanical performance of LPBF TI-6AL-4V N2 - Ti-6Al-4V alloy is intensively used in the aerospace industry because of its high specific strength. However, the application of Laser Powder Bed Fusion (LPBF) Ti-6Al-4V alloy for structurally critical load-bearing components is limited. One of the main limiting factors affecting the structural integrity, are manufacturing defects. Additionally, the high cooling rates associated with LPBF process result in the formation of large residual stress (RS) with complex fields. Such RS can cause cracking and geometrical distortions of the part even right after production. Also, the microstructure of LPBF Ti-6Al-4V in the as-built condition is significantly different from that of the conventionally produced alloy. All these factors affect the mechanical behavior of the material. Therefore, to improve the material performance it is important to evaluate the individual effect of RS, defects, and microstructure on fatigue life. To this aim Ti-6Al-4V LPBF material in as-built condition and subjected to different post-processing, including two heat treatments (for stress relief and microstructural modification) and Hot Isostatic Pressing (HIP, for densification), were investigated. Prior to Low Cycle Fatigue (LCF) tests at operating temperature (300°C), the microstructure (phases, crystallographic texture, and grain morphology), the mesostructure (defect shape and distribution), and subsurface RS on the LCF samples were investigated. It was found that the fatigue performance of HIPped samples is similar to that of conventionally produced Ti-6Al-4V. The tensile RS found at the surface of as-built samples decreased the fatigue life compared to heat-treated samples. Additionally, the modification of the microstructure (by heat treatment) did not affect the fatigue performance in the regime of mostly elastic strain. This shows that in the absence of tensile RS the manufacturing defects solely control the failure of LPBF components and densification has the strongest effect on the improvement of the mechanical performance. T2 - ASTM ICAM 2020 CY - Online meeting DA - 16.11.2020 KW - Additive manufacturing KW - Ti-6Al-4V KW - Computed tomography KW - Residual stress PY - 2020 AN - OPUS4-51695 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana A1 - Artzt, K. A1 - Rehmer, Birgit A1 - Avila, Luis A1 - Haubrich, J. A1 - Serrano Munoz, Itziar A1 - Requena, G. A1 - Bruno, Giovanni T1 - Separation of the impact of residual stress and microstructure on the fatigue performance of LPBF Ti-6Al-4V at elevated temperature (Keynote) N2 - Ti-6Al-4V alloy is intensively used in the aerospace industry because of its high specific strength. However, the application of Laser Powder Bed Fusion (LPBF) Ti-6Al-4V alloy for structurally critical load-bearing components is limited. One of the main limiting factors affecting the structural integrity, are manufacturing defects. Additionally, the high cooling rates associated with LPBF process result in the formation of large residual stress (RS) with complex fields. Such RS can cause cracking and geometrical distortions of the part even right after production. Also, the microstructure of LPBF Ti-6Al-4V in the as-built condition is significantly different from that of the conventionally produced alloy. All these factors affect the mechanical behavior of the material. Therefore, to improve the material performance it is important to evaluate the individual effect of RS, defects, and microstructure on fatigue life. To this aim Ti-6Al-4V LPBF material in as-built condition and subjected to different post-processing, including two heat treatments (for stress relief and microstructural modification) and Hot Isostatic Pressing (HIP, for densification), were investigated. Prior to fatigue tests at elevated temperature, the microstructure, the mesostructure, and subsurface RS on the fatigue samples were investigated. It was found that the fatigue performance of HIPped samples is similar to that of conventionally produced Ti-6Al-4V. The tensile RS found at the surface of as-built samples decreased the fatigue life compared to heat-treated samples. Additionally, the modification of the microstructure (by heat treatment) did not affect the fatigue performance in the regime of mostly elastic strain. This shows that in the absence of tensile RS the manufacturing defects solely control the failure of LPBF components and densification has the strongest effect on the improvement of the mechanical performance. T2 - EUROMAT 2021 CY - Online meeting DA - 12.09.2021 KW - Additive manufacturing KW - Ti-6Al-4V KW - Residual stress KW - Fatigue performance PY - 2021 AN - OPUS4-53278 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishurova, Tatiana A1 - Artzt, K. A1 - Rehmer, Birgit A1 - Haubrich, J. A1 - Avila, Luis A1 - Schoenstein, F. A1 - Serrano Munoz, Itziar A1 - Requena, G. A1 - Bruno, Giovanni T1 - Separation of the impact of residual stress and microstructure on the fatigue performance of LPBF Ti-6Al-4V at elevated temperature JF - International Journal of Fatigue N2 - Manufacturing defects, high residual stress (RS), and microstructures affect the structural integrity of laser powder bed fusion (LPBF) Ti-6Al-4V. In this study, the individual effect of these factors on fatigue performance at elevated temperature (300 °C) was evaluated. Material in as-built condition and subjected to post-processing, including two heat treatments and hot isostatic pressing, was investigated. It was found that in the absence of tensile RS, the fatigue life at elevated temperature is primary controlled by the defects; and densification has a much stronger effect than the considered heat treatments on the improvement of the mechanical performance. KW - Additive manufacturing KW - Ti-6Al-4V KW - Residual stress KW - Fatigue performance KW - Computed tomography PY - 2021 DO - https://doi.org/10.1016/j.ijfatigue.2021.106239 SN - 0142-1123 VL - 148 SP - 106239 PB - Elsevier Ltd. AN - OPUS4-52369 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fardan, Ahmed A1 - Fazi, Andrea A1 - Peng, Ru Lin A1 - Mishurova, Tatiana A1 - Thuvander, Mattias A1 - Bruno, Giovanni A1 - Brodin, Håkan A1 - Hryha, Eduard T1 - Fine-Tuning Melt Pools and Microstructures: Taming Cracks in Powder Bed Fusion—Laser Beam of a non-weldable Ni-base Superalloy JF - Materialia N2 - Powder Bed Fusion – Laser Beam (PBF-LB) of high γ’ strengthened Ni-base superalloys, such as CM247LC, is of great interest for high temperature applications in gas turbines. However, PBF-LB of CM247LC is challenging due to the high cracking susceptibility during PBF-LB processing (solidification cracking) and heat treatment (strain age cracking, mostly caused by residual stresses). This study focuses on understanding the impact of process parameters on microstructure, residual stresses and solidification cracking. Laser power (P), speed (v) and hatch spacing (h) were varied while the layer thickness (t) was fixed. The melt pool size and shape were found to be key factors in minimizing solidification cracking. Narrower and shallower melt pools, achieved using a low line energy density (LED = P/v ≤ 0.1 J/mm), gave low crack densities (0.7 mm/mm2). A tight hatch spacing (h = 0.03 mm) resulted in reduced lack of fusion porosity. Electron backscatter diffraction investigations revealed that parameters giving finer microstructure with 〈100〉crystallographic texture had low crack densities provided they were processed with a low LED. Atom probe tomography elucidated early stages of spinodal decomposition in the as-built condition, where Cr and Al cluster separately. The extent of spinodal decomposition was found to be affected by the LED and the hatch spacing. Samples with low LED and small hatch spacing showed higher degrees of spinodal decomposition. X-ray diffraction residual stress investigations revealed that the residual stress is proportional to the volumetric energy density (VED = P/(v. h. t)). Although low residual stresses can be achieved by using low VED, there is a high risk of lack of fusion. Hence, other parameters such as modified scan strategy, build plate pre-heating and pulsed laser mode, must be further explored to minimize the residual stresses to reduce the strain age cracking susceptibility. KW - Additive manufacturing KW - X-ray CT KW - Non-weldable superalloy KW - Solidification cracking PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597340 DO - https://doi.org/10.1016/j.mtla.2024.102059 SN - 2589-1529 VL - 34 IS - 102059 SP - 1 EP - 16 PB - Elsevier B.V. AN - OPUS4-59734 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana A1 - Bruno, Giovanni T1 - BAM activities in material characterization by advanced X-ray imaging N2 - The overview of the activity of Federal Institute for Material Research and Testing (BAM, Belin, Germany) in the field of additively manufacturing material characterization will be presented. The research of our group is focused on the 3D imaging of AM materials by means of X-ray Computed Tomography at the lab and at synchrotron, and the residual stress characterization by diffraction (nondestructive technique). Also, two successful research project in collaboration with CAM2, Sweden are presented. T2 - CAM2 Annual Meeting CY - Gothenburg, Sweden DA - 25.10.2023 KW - Additive manufacturing KW - Residual stress KW - X-ray computed tomography PY - 2023 AN - OPUS4-58828 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana A1 - Roveda, Ilaria A1 - Serrano Munoz, Itziar A1 - Evans, Alexander A1 - Bruno, Giovanni T1 - Effect of heat treatment on residual stress in additively manufactured AlSi10Mg N2 - Al-Si alloys produced by Laser Powder Bed Fusion (PBFLB) allow the fabrication of lightweight free-shape components. Due to the extremely heterogeneous cooling and heating, PBF-LB induces high magnitude residual stress (RS) and a fine Si microstructure. As the RS can be deleterious to the fatigue resistance of engineering components, great efforts are focused on understanding their evolution in as-built state (AB) and after post-process heat treatments (HT). RS in single edge notch bending (SENB) subjected to different HT are investigated (HT1: 1h at 265°C and HT2: 2h at 300°C). T2 - ESRF User Meeting 2023 CY - Grenoble, France DA - 07.02.2023 KW - Additive manufacturing KW - Laser powder bed fusion KW - Residual stress PY - 2023 AN - OPUS4-56982 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana T1 - 3D imaging and residual stress analysis for AM Materials N2 - The overview of the activity of Federal Institute for Material Research and Testing (BAM, Belin, Germany) in the field of additively manufacturing material characterization will be presented. The research of our group is focused on the 3D imaging of AM materials by means of X-ray Computed Tomography at the lab and at synchrotron, and the residual stress characterization by diffraction (nondestructive technique). T2 - Seminar at Integrated Additive Manufacturing center, Politecnico Torino CY - Turin, Italy DA - 14.02.2023 KW - Additive manufacturing KW - Laser powder bed fusion KW - Residual stress KW - Computed tomography KW - Synchrotron X-ray diffraction PY - 2023 AN - OPUS4-57047 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Khrapov, D. A1 - Kozadayeva, M. A1 - Koptyug, A. A1 - Mishurova, Tatiana A1 - Meinel, Dietmar A1 - Surmenev, R. A1 - Surmeneva, M. T1 - Geometrical features and mechanical properties of the sheet-based gyroid scaffolds with functionally graded porosity manufactured by electron beam melting JF - Materials Today Communications N2 - Functionally graded porous scaffolds (FGPS) constructed with pores of different size arranged as spatially continuous structure based on sheet-based gyroid with three different scaling factors of 0.05, 0.1 and 0.2 were produced by electron beam powder bed fusion. The pore dimensions of the obtained scaffolds satisfy the values required for optimal bone tissue ingrowth. Agglomerates of residual powder were found inside all structures, which required post-manufacturing treatment. Using X-ray Computed Tomography powder agglomerations were visualized and average wall thickness, wall-to-wall distances, micro- and macro-porosities were evaluated. The initial cleaning by powder recovery system (PRS) was insufficient for complete powder removal. Additional treatment by dry ultrasonic vibration (USV) was applied and was found successful for gyroids with the scaling factors of 0.05 and 0.1. Mechanical properties of the samples, including quasi-elastic gradients and first maximum compressive strengths of the structures before and after USV were evaluated to prove that additional treatment does not produce structural damage. The estimated quasi-elastic gradients for gyroids with different scaling factors lie in a range between 2.5 and 2.9 GPa, while the first maximum compressive strength vary from 52.5 for to 59.8 MPa, compressive offset stress vary from 46.2 for to 53.2 MPa. KW - Additive manufacturing KW - Electron beam KW - Powder bed fusion KW - Triply periodic minimal surfaces KW - Functionally graded porous scaffolds KW - X-ray computed tomography PY - 2023 DO - https://doi.org/10.1016/j.mtcomm.2023.106410 SN - 2352-4928 VL - 35 SP - 1 EP - 9 PB - Elsevier Ltd. AN - OPUS4-57682 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana T1 - Failure Mechanisms Investigation by Means of in-situ Synchrotron Computed Tomography in Aluminum MMC-based Alloy Tailored for Additive Manufacturing N2 - Synchrotron X-ray computed tomography (SXCT) at BAMline has been paired with in-situ tensile loading to monitor damage evolution in LPBF Metal Matrix Composite (MMC) 7017 Aluminium alloy + 3 wt% Zr + 0.5 wt% TiC. The processing of the material leads formation to different categories of Zr-rich inclusions, precipitates and defects. In-situ SXCT test disclosed the critical role of the pre-cracks in the reinforcement phases in the failure mechanisms of LPBF MMC. The damage was initiated from lack-of-fusion defects and cracks propagated through coalescence with other defects. T2 - HZB Uer Meeting 2023 CY - Berlin, Germany DA - 22.06.23 KW - Additive manufacturing KW - BAMline KW - Synchrotron X-ray computed tomography KW - in-situ PY - 2023 AN - OPUS4-57801 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mehta, B. A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Markötter, Henning A1 - Bruno, Giovanni A1 - Hryha, E. A1 - Nyborg, L. A1 - Virtanen, E. T1 - Microstructure, mechanical properties and fracture mechanisms in a 7017 aluminium alloy tailored for powder bed fusion – laser beam JF - Materials and Design N2 - This study addressed a 7017 Al-alloy tailored for powder bed fusion – laser beam (PBF-LB) process. The alloy was prepared by mixing 3 wt% Zr and 0.5 wt% TiC powder to standard pre-alloyed 7017 grade aluminium powder. This made printing of the alloys possible avoiding solidification cracking in the bulk and achieving high relative density (99.8 %). Such advanced alloys have significantly higher Young’s modulus (>80 GPa) than conventional Al-alloys (70–75 GPa), thus making them attractive for applications requiring high stiffness. The resulting microstructure in as-printed condition was rich in particles originating from admixed powders and primary precipitates/inclusions originating from the PBF-LB process. After performing a T6-like heat treatment designed for the PBF-LB process, the microstructure changed: Zr-nanoparticles and Fe- or Mg/Zn- containing precipitates formed thus providing 75 % increase in yield strength (from 254 MPa to 444 MPa) at the cost of decreasing ductility (∼20 % to ∼9 %). In-situ tensile testing combined with SXCT, and ex-situ tensile testing combined with fracture analysis confirmed that the fracture initiation in both conditions is highly dependent on defects originated during printing. However, cracks are deflected from decohesion around Zr-containing inclusions/precipitates embedded in the Al-matrix. This deflection is seen to improve the ductility of the material. KW - Additive manufacturing KW - Powder bed fusion Laser beam KW - X-ray computed tomography KW - Strengthening mechanisms KW - Crack propagation KW - Zirconium PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-568243 DO - https://doi.org/10.1016/j.matdes.2023.111602 SN - 0264-1275 VL - 226 SP - 1 EP - 14 PB - Elsevier Science CY - Amsterdam [u.a.] AN - OPUS4-56824 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Piault, Pierre A1 - King, Andrew A1 - Henry, Laura A1 - Bruno, Giovanni T1 - Understanding the hot isostatic pressing efectiveness of laser powder bed fusion Ti‑6Al‑4V by in‑situ X‑ray imaging and difraction experiments JF - Scientific reports N2 - In the present study, in-situ observation of Hot Isostatic Pressure (HIP) procedure of laser powder bed fusion manufactured Ti-6Al-4V parts was performed to quantitatively estimate the densifcation rate of the material and the infuence of the defect initial size and shape on such rate. The observations were performed in-situ using the Ultrafast Tomography Paris-Edinburgh Cell and the combination of fast phase-contrast synchrotron X-ray tomography and energy dispersive difraction. With this strategy, we could quantify how the efectiveness of HIP depends on the characteristics of a defect. Smaller defects showed a higher densifcation rate, while the defect shape did not have signifcant efect on such rate. KW - Additive manufacturing KW - Laser powder bed fusion KW - X-ray computed tomography KW - Hot isostatic pressing PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-587702 DO - https://doi.org/10.1038/s41598-023-45258-1 SN - 2045-2322 VL - 13 IS - 1 SP - 1 EP - 11 AN - OPUS4-58770 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana T1 - In-situ hot isostatic pressing combined with x-ray imaging and diffraction of laser powder bed fusion ti-6al-4v N2 - Hot Isostatic Pressing (HIP) is often introduced to tackle the porosity issue in additively manufactured (AM) materials. For instance, HIP post-processing is recommended to improve fatigue resistance of Laser powder bed fusion (PBF-LB) manufactured parts [1, 2]. Even though HIP cannot completely remove porosity, it significantly decreases the defect population and its average size below the critical threshold value leading to early crack initiation. In the present study, in-situ investigation of HIP procedure of PBF-LB Ti-6Al-4V parts was carried out to gain further insights into the densification mechanism occurring during HIP. The in-situ observations at high pressure and high temperature are uniquely possible at the PSICHE beamline of the Soleil synchrotron (France), thanks to the Ultrafast Tomography on a Paris-Edinburgh Cell (UToPEC) and the combination of the fast phase-contrast tomography and energy-dispersive diffraction [3, 4]. A detailed methodology was developed to ensure that the correct pressure and temperature were maintained during the experiments. The results allowed an estimation of the global dentification rate during HIP of PBF-LB Ti-Al-4V material, as well as a detailed quantitative characterization of the influence of pore size and shape on the densification process, thereby understanding the effectiveness of HIP process on different pore categories. After 20 mins, 75% of porosity can be considered as closed or has size below the resolution of the XCT reconstruction. We also observed that the smallest defects showed higher densification rate, while the defect shape did not have significant effect on such rate. The current development of in-situ HIP experiment allows experimental quantification and validation of the simulation work. Ultimately it paves the road to tailoring the HIP procedure for different materials depending on the porosity and microstructure. T2 - AAMS 2023 CY - Madrid, Spain DA - 26.09.23 KW - Additive manufacturing KW - HIP KW - X-ray computed tomography PY - 2023 AN - OPUS4-58482 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -