TY - JOUR A1 - Schröder, Nina A1 - Uhlig, Marvin A1 - Kromm, Arne A1 - Schröpfer, Dirk A1 - Höfer, Kevin A1 - Hensel, Jonas A1 - Kannengießer, Thomas T1 - Challenges in the evaluation of the weldability of old mild steels for future use N2 - For reasons of sustainability and cost efficiency, there is an increasing trend in the steel-processing industry to retrofit existing structures, avoiding costly shutdowns or dismantling. Although welding is a cost-effective joining method, it is rarely applied to old steels, whereas riveted or bolted connections are often uneconomical. Repair and refurbishment frequently require the replacement of damaged material or the creation of dissimilar old–new steel joints. Due to the varied manufacturing processes of historical steels, not all twentieth-century steels are inherently weldable, making an initial assessment of weldability essential. In this study, a historical non-deoxidized mild steel (produced by Siemens–Martin processing) originating from the construction of the Berlin Radio Tower (erected in 1926) was investigated using dilatometry to analyze its welding behavior. A database of welding CCT diagrams and HAZ simulations was established to support practice-oriented welding experiments, providing key insights into their weld-metallurgical behavior and weldability. Furthermore, initial welding trials were conducted, and the local residual stress states in dissimilar old–new steel joints were determined. These foundational investigations are critical for the development of innovative, load-adapted welding concepts for the repair and refurbishment of existing old-steel infrastructure in Germany. KW - Old mild steels KW - Repair welding KW - Weldability KW - Thermo-physical simulation KW - CCT diagrams PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-654784 DO - https://doi.org/10.1007/s40194-026-02366-6 SN - 1878-6669 SP - 1 EP - 14 PB - Springer nature AN - OPUS4-65478 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scharf-Wildenhain, R. A1 - Engelking, Lorenz A1 - Hälsig, A. A1 - Schröpfer, Dirk A1 - Kannengießer, Thomas A1 - Hensel, J. T1 - Influence of build‑up height on residual stresses in additive repair and modification using DED‑Arc with high‑strength filler metals N2 - Directed energy deposition (DED)-Arc is suitable for the hybrid additive manufacturing, modification and repair of large metal components with high deposition rates. Residual stresses and distortion are of central importance when characterizing the manufactured components and the sensitive transition area between additive manufactured (AM) component and semifinished product. Residual stresses caused by the thermal cycles during the manufacturing process can impair the mechanical properties of the manufactured parts and can lead to component failure, especially for high-strength steels. Therefore, understanding and controlling residual stresses, when combining different base and feedstock materials, is critical to improve the quality and efficiency of the hybrid DED-Arc process. This article deals with the influence of the build-up height on the residual stress distribution of additively manufactured components with a selected base and feedstock material from commercial high-strength steels. Using a robot-assisted DED-system and a controlled short arc, AM welding experiments were carried out with close to the application parameters at working temperature (200 °C) and heat input (650 kJ/m). Five hybrid AM specimens (AM wall on upright structural steel plate) were produced using a one bead per layer strategy and selected AM-wall heights between 15 and 300 mm. The influence of the AM build height on the longitudinal residual stress in the whole hybrid AM specimen (in welding direction) was analyzed and discussed. All experiments exhibit comparable stress distributions in the area of the substrate plate up to the heat-affected zone (HAZ) and the transition zone, regardless of the building height. The height significantly influences the residual stress distribution of the deposited AM-component. Tensile residual stresses with a maximum range between 300and 400 MPa were always found in the last approx. 18 component layers (upper 40 mm). This is due to restraint of the shrinking of the top layers by the layers below. The lower layers show homogeneous residual stress distributions characterized by low compressive stresses due to the process-related tempering during the deposition of each layer on top of each other. As a result, the significant difference between the various AM build-up heights of the hybrid AM specimens is the extent (or height) of this tempered zone with low compressive stresses. These correlations contribute to the understanding of residual stress development with increasing structure height or ratio of component heights of substrate semi-finished product and AM component in hybrid additive manufacturing. T2 - 78th IIW Annual Assembly and International Conference CY - Genoa, Italy DA - 22.06.2025 KW - DED-Arc KW - Residual stress KW - Heat control PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-656793 DO - https://doi.org/10.1007/s40194-026-02417-y SN - 1878-6669 SP - 1 EP - 12 PB - Spriner AN - OPUS4-65679 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liepold, Philipp A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - A Force Based Determination of Hot Cracking Susceptibility N2 - Two high-strength, low-alloy Gas Metal Arc Welding (GMAW) wires were evaluated for their susceptibility to Solidification Cracking (SC) using a modified version of the Transverse Motion Weldability (TMW) test. In theoriginal TMW test, the Transverse Displacement Speed (TDS) is varied iteratively, and crack lengths are measured in each iteration. The modified version eliminates the need for multiple runs by continuously reducing the TDS over a single run. Rather than emphasizing crack lengths, this method assesses the reaction force to the TDS, thereby determining a Critical TDS (CTDS). This critical point directly correlates with the cessation of SC growth. CTDS values were measured under a range of welding parameters, thereby demonstrating the influence of Welding speed and arc energy (U × I/welding speed) on SC susceptibility for the tested filler metals. The CTDS data obtained from this testing method have the potential to provide valuable insights for practical applications in the field. KW - Force based KW - Neural Network KW - TRS PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-640140 DO - https://doi.org/10.5781/JWJ.2025.43.4.10 SN - 2466-2100 VL - 43 IS - 4 SP - 447 EP - 457 AN - OPUS4-64014 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Willeke, Maraike A1 - Giese, Marcel A1 - Lorenz, Swenja A1 - Treutler, Kai A1 - Schröpfer, Dirk A1 - Wesling, Volker A1 - Kannengießer, Thomas T1 - Effect of alloy modification on the wear protection coatings made of Ni- and Co-based materials and surface machinability via ultrasonic milling process N2 - AbstractWear-resistant coatings are required for highly efficient and economical steel components in equipment, process, and power plant engineering to withstand high corrosive, tribological, thermal, and mechanical stresses. Co-alloys are used as wear-resistant coatings for steel components, tailored to the specific application. The substitutability of Co alloys with Ni-based wear protection systems, in addition to price and supply uncertainties, is facilitated by the combination of innovative welding and machining processes such as ultrasonic-assisted milling. The aim of the study is to improve the machinability of two different hard-facing alloys while maintaining the same wear protection potential. Therefore, the wear-resistant alloys NiMoCrSi (Colmonoy C56) and CoMnCrSi (Tribaloy T400) were modified by the alloying additions Nb, Hf, and Ti and then applied to a carbon-manganese steel S355 using the plasma transfer arc (PTA) welding process. The influence of the alloying additions on the microstructure as KW - Wear resistance KW - Co-based alloy KW - Ni-based alloy KW - PTA welding process KW - Ultrasonic assisted milling process PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623931 DO - https://doi.org/10.1007/s00170-024-14955-0 SN - 0268-3768 SP - 1 EP - 17 PB - Springer Science and Business Media LLC AN - OPUS4-62393 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liepold, Philipp A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - Transvarestraint testing of high-strength steel filler metal N2 - High-strength steel welds are typically not known to be susceptible to Solidification Cracking (SC). However, modern light-weight constructions may force welding in highly restrained conditions, which are known to increase the probability of Solidification Crack (SC) emergence. In this article, the Modified Varestraint-Transvarestraint (MVT) test was used to evaluate the hot cracking susceptibility of welds made from high-strength, low-alloyed filler material. The materials tested include solid wires and a metal-cored wire. All wires are typically used in the Gas Metal Arc Welding (GMAW) process. Susceptibility to SC was measured over a wide range of welding parameters and bending speeds. Results show little affinity of the tested materials to SC. However, crack length increases in most cases with arc energy ( U ∙ I∕welding speed ) and welding speed. The length of the longest crack in one test specimen follows a similar trend until high welding speeds, where stagnation of crack length with changing arc energy was observed. KW - MVT KW - Varestraint KW - Transvarestraint KW - Solidification cracking KW - High-strength steel PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630084 DO - https://doi.org/10.1007/s40194-025-02042-1 SN - 1878-6669 VL - 2025 SP - 1 EP - 12 PB - Springer CY - Berlin ; Heidelberg AN - OPUS4-63008 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rhode, Michael A1 - Czeskleba, Denis A1 - Fleißner-Rieger, H. A1 - Nietzke, Jonathan A1 - Kannengießer, Thomas T1 - Combined heating rate and restraint condition effect on stress relief cracking during PWHT of thick-walled Cr–Mo-V steel SAW joints N2 - Creep-resistant steels such as 13CrMoV9-10 are utilized in the manufacture of thick-walled pressure vessels and are typically joined by submerged arc welding (SAW). However, these materials are susceptible to stress relief cracking (SRC) if the required post weld heat treatment (PWHT) is not applied correctly. Existing PWHT guidelines, encompassing heating rate and dwell (or holding) time at a given temperature, are derived from a synthesis of empirical knowledge and typically free-shrinkage weld experiments to assess the susceptibility to SRC. Therefore, this study discusses the combined effect of the PWHT heating rate under free-shrinkage compared to restrained shrinkage. Welding experiments were conducted (using plates with a thickness of 25 mm) for both shrinkage conditions for a variety of heating rates and maximum temperatures. In-situ acoustic emission analysis was used to locate propagating SRCs during PWHT. Hardness measurements, mechanical property characterization (Charpy impact strength), and microstructure correlation were used to evaluate the SRC susceptibility. The results suggested that the influence of heating rate could not be directly related to SRC formation and that the initial weld microstructure prior to PWHT was more relevant in terms of very high hardness in the coarse grain heat affected zone, especially that of the last beads in the top layer of the welding sequence. This was seen in the form of random, unexpected SRC occurrence in only one specimen at a heating rate commonly used in welding practice (approximately 100 K/h). In this context, the additional effect of an external shrinkage restraint on SRC must be considered in the form of increasing mechanical loads during welding, which are typically not within the scope of welding practice. To mitigate the probability of SRC during PWHT, it is imperative to reduce the welding heat input and to restrict the structural shrinkage restraint of the weld joint. KW - Component test KW - Stress relief cracking KW - PWHT KW - Creep-resistant steel PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-631439 DO - https://doi.org/10.1007/s40194-025-02062-x SN - 1878-6669 SP - 1 EP - 17 PB - Springer Nature AN - OPUS4-63143 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liepold, Philipp A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - Investigation of restraint intensity influence on solidification cracking of high-strength filler materials in fillet welds via CTS testing N2 - In addition to chemical composition, metallurgy, and welding parameters, the intensity of restraint is one of the key variables influencing solidification cracking (SC). Due to their high strength-to-density ratio, many modern lightweight steel constructions increasingly rely on high-strength steel. Given the theoretical framework of solidification cracking theory, tests tend to focus on the effects of strain rate. Externally restrained tests have provided valuable insights into solidification crack susceptibility. In practice, most welded structures are self-restrained; therefore, self-restraint tests more accurately reflect real-world applications. By varying the plate thickness in controlled thermal severity (CTS) tests conducted on S1100 QL, it was possible to adjust the intensity of restraint on fillet welds at a high level. Testing was performed using four different filler wires for gas metal arc welding (GMAW), including three solid wires and one metal-cored wire. Additionally, two sets of welding parameters were evaluated. High arc energy (U × I/welding speed) and increased welding speed were found to be more prone to solidification cracking compared to the parameter set with lower arc energy and welding speed. The results indicate a correlation between increasing restraint severity and a higher incidence of solidification cracking. KW - CTS KW - Controlled thermal severity KW - High-strength steel KW - GMAW KW - Restraint PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-631315 UR - 1878-6669 DO - https://doi.org/10.1007/s40194-025-02046-x SP - 1 EP - 13 PB - Springer AN - OPUS4-63131 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scharf-Wildenhain, R. A1 - Engelking, Lorenz A1 - Hälsig, A. A1 - Schröpfer, Dirk A1 - Kannengießer, Thomas A1 - Hensel, J. T1 - Effect of heat control on mechanical properties and residual stresses at the transition zone of component and substrate in hybrid DED‑arc manufacturing N2 - In hybrid additive manufacturing, components or semi-finished products manufactured by conventional primary forming are enhanced or modified by additive manufactured structures. However, systematic investigations focusing on the critical transition area between the specific properties of the substrate (like high-strength) and the additively manufactured component, made of specific filler material, are still lacking. The focus of the present study was to determine the influence of heat control on the Δt8/5 cooling time, the distortion, the mechanical properties, and the residual stresses in the transition area of hybrid-additive components. This contributed to the knowledge regarding the safe avoidance of cold cracking, excessive distortion, a reduction in yield stress, and the implementation of hybrid DED-arc manufacturing. The heat control was varied by means of heat input and working temperature such that the Δt8/5 cooling times corresponded to the recommended processing range. The heat input has a greater influence on the cooling time in the transition area than the working temperature. Working temperature and the total energy applied per layer have a significant effect on component distortion. The lowest working temperature of 100 °C in combination with the highest total energy per layer leads to significantly greater distortion compared to manufacturing with a high working temperature of 300 °C and low total energy per layer. In addition, the longitudinal residual compressive stresses in the sensitive transition area are reduced from − 500 MPa to approx. − 200 MPa by adjusting the working temperature from 100 to 300 °C. Such complex interactions must be clarified comprehensively to provide users with easily applicable processing recommendations and standard specifications for an economical hybrid additive manufacturing of components made, for example, of high-strength steels in the transition area. T2 - IIW Annual Assembly and International Conference CY - Rhodes Island, Greece DA - 07.07.2024 KW - Hybrid additive manufacturing KW - DED-arc KW - Heat control KW - High-strength metals KW - Residual stress PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630415 DO - https://doi.org/10.1007/s40194-025-02036-z SN - 1878-6669 SP - 1 EP - 15 PB - Springer AN - OPUS4-63041 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröder, Nina A1 - Rhode, Michael A1 - Kannengießer, Thomas A1 - Kromm, Arne A1 - Kadoke, Daniel A1 - Kruse, Julius T1 - Effect of Ti microalloying on the local strain behavior of cross-weld tensile samples determined by digital image correlation N2 - High-strength low-alloyed (HSLA) steels with yield strength / proof stress ≥ 600 MPa are the basis of modern light-weight steel constructions. Indeed, the economic and ecological benefits strongly depend on their processability in terms of welding. In this context, the use of highly productive welding processes and suitable welding consumables is of vital interest and requires a fundamental understanding of the microstructural changes in the HSLA steel and especially the heat-affected zone (HAZ) of the welded joint. Microalloying elements, such as Ti or Nb, are essential to achieve the desired mechanical properties. To analyse the weldability, three-layer welds were performed using gas metal arc welding (GMAW) and critical microstructures, such as areas of the HAZ that exhibit significant softening or hardening, were identified. The effect of the softened HAZ region on failure was evaluated using cross-weld tensile specimens. Digital image correlation (DIC) was used for in-situ monitoring of the development and accumulation of the local strains in different HAZ regions during tensile testing. Using a specially designed mirror system, the local strains of the microstructure zones on the top and bottom of the weld were recorded simultaneously. In addition, the analysis of the local deformation helps to understand the effects of the softened HAZ on the global strain, the reduction in area, the fracture position, and the overall fracture behavior. KW - High-strength structural steel KW - Microalloying influences KW - HAZ-softening KW - Digital Image Correlation KW - Constraint effect KW - Thermodynamic simulation PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-643558 DO - https://doi.org/10.1007/s40194-025-02185-1 SP - 1 EP - 17 PB - Springer Nature AN - OPUS4-64355 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Graebner, Maraike A1 - Giese, Marcel A1 - Lorenz, Svenja A1 - Treutler, Kai A1 - Schröpfer, Dirk A1 - Wesling, Volker A1 - Kannengießer, Thomas T1 - Wear resistance of modified NiMoCrSi claddings in relation to the resulting surface machinability via ultrasonic-assisted milling N2 - In the field of plastics processing, extruder screws are subjected to significant wear stresses. The extruder screw is the main wear component in those production machines and is usually coated with intermetallic wear protection alloys composed of Ni-based alloys, specifically Colmonoy C56 PTA (NiMoCrSi). There is a growing demand for providing an economic machinability of these alloys to achieve defined contours with a sufficient surface integrity. Recent investigations exhibit promising results applying ultrasonic milling for such hard-to-cut materials. The Colmonoy C56 is modified by various alloying additions Ti, Nb, Mo, Hf, and Al, and then cladded on a steel S355 via Plasma Transferred Arc process. The effect of alloying additions on the microstructure is analyzed regarding their resistance to abrasive and adhesive wear. With Miller test ASTM G75 the influence of alloying elements on resistance to abrasive wear for two abrasive materials is investigated (high-grade corundum F220 and quartz powder). The wear loss is not increased for additions of Nb and Ti compared to the base material C56. Modifications with Hf or Al reduces the resistance to abrasive wear and significantly increases material loss. The extruder screw is also subject to adhesive wear, which can be quantified by means of the pin-roll test. It is demonstrated that the addition of Hf, for example, contributes to a reduction in wear loss. Aim of the investigations is to find suitable modifications for the wear claddings of C56 for a sufficient machineability, without compemising the wear resistant. The machinability is considerably affected by the alloy additions, and is determined using ultrasonic-assisted milling. The addition of hafnium reduces machinability, i.e. significantly increases cutting forces. The incorporation of Nb exhibits a significant reduction of cutting forces, and results in reduced tool wear and an enhanced of surface integrity (roughness, density of defects, residual stresses). KW - Colmonoy C56 KW - PTA welding KW - Adhesive wear KW - Abrasive wear KW - Ultrasonic-assisted milling process KW - Surface integrity KW - Service life and efficiency KW - Substitution of critical raw materials PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-651530 DO - https://doi.org/10.1016/j.wear.2025.205830 SN - 0043-1648 VL - 571 SP - 1 EP - 10 PB - Elsevier B.V. AN - OPUS4-65153 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kromm, Arne A1 - Thomas, Maximilian A1 - Kannengießer, Thomas A1 - Gibmeier, Jens T1 - On the interpretation of Varestraint and Transvarestraint hot cracking test results N2 - The Varestraint test and its variant Transvarestraint are one of the most widely used techniques for evaluating a material solidification cracking sensitivity during welding. The result of such tests is a crack length which is proportional to the material’s cracking susceptibility. Nevertheless, the welding and load parameters can unintentionally influence the crack length, which in some cases can distort the material evaluation. An approach is described as to how these effects can be assessed with the aid of a digital crack analysis. The crack lengths are compared position-dependently with their possible propagation due to the weld pool movement during continuous loading. The index derived from this can be used by the operator to evaluate his test parameters. In addition, a comparison of the results of different Varestraint setups is made possible. Alongside experimental results, a numerical sensitivity analysis is presented on how individual welding and loading parameters can affect the crack lengths. KW - Varestraint test KW - Solidification cracking KW - Weldability PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595089 DO - https://doi.org/10.1007/s40194-024-01706-8 SN - 0043-2288 SP - 1 EP - 13 PB - Springer Science and Business Media LLC AN - OPUS4-59508 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Quackatz, Lukas A1 - Griesche, Axel A1 - Nietzke, Jonathan A1 - Kannengießer, Thomas T1 - In situ measurement of hydrogen concentration in steel using laser‑induced breakdown spectroscopy (LIBS) N2 - The ISO 3690 standard “Determination of hydrogen content in arc weld metal” requires a thermal activation of the diffusible hydrogen in a piece of weld metal for the subsequent ex situ concentration measurement by carrier gas hot extraction CGHE or thermal desorption spectroscopy (TCD). Laser-induced breakdown spectroscopy (LIBS) offers a time and spatially resolved, almost non-destructive, in situ measurement of hydrogen at surfaces without sample preparation. We measured hydrogen in steels, which were charged either electrochemically or by high-pressure hydrogen gas, and compared the results. Further, the feasibility of quantitative hydrogen line scan measurements with LIBS was demonstrated by measuring hydrogen at water jet cut surfaces. The hydrogen concentrations measured with the help of LIBS were compared with CGHE measurements. It was observed that hydrogen can be reliably measured with LIBS for concentrations larger than 2 wt.-ppm. The maximum hydrogen concentration achieved using electrochemical charging was 85.1 ppm. The results show that LIBS is a promising technique for time- and spatially resolved measurements of hydrogen in steels. T2 - IIW Annual Assembly 2023 CY - Singapore KW - LIBS KW - Hydrogen measurement KW - Welding KW - Stainless steel KW - Diffusible hydrogen PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-593664 DO - https://doi.org/10.1007/s40194-023-01677-2 SP - 1 EP - 9 PB - Springer AN - OPUS4-59366 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröpfer, Dirk A1 - Witte, Julien A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - Stresses in repair welding of high-strength steels—part 1: restraint and cold cracking risk N2 - AbstractThe sustainable and resource-efficient production of wind energy plants requires the use of modern high-strength fine-grain structural steels. This applies to both foundation and erection structures, like mobile or ship cranes. During the assembly of steel structures, unacceptable defects can occasionally be found in the weld area. In most cases, the economical solution would be local thermal gouging of the affected areas and re-welding. Due to the high shrinkage restraint of the joint groove in the overall structure, the superposition of global and local welding-induced stresses may lead to crack formation and component failure, particularly in interaction with the degradation of the microstructure and mechanical properties of high-strength steels during the repair process. However, manufacturers hardly have any information about these issues and there is a lack of recommendations and guidelines to take these safety-relevant aspects into account in adequate repair concepts. The aim of this research is to derive recommendations for repair concepts appropriate to the stresses and materials involved providing a basis for standards and guidelines to avoid cold cracking, damage and expensive reworking especially for high-strength steels. Part 1 of this study involves systematic investigations of influences of shrinkage restraint during repair welding of two high-strength steels S500MLO for offshore application and S960QL for mobile crane structures. The quantification of the shrinkage restraint of repair weld joints was achieved by means of experimental and numerical restraint intensity analysis. In welding experiments with self-restrained slot specimens, restraint intensity and introduction of hydrogen via the welding arc using anti spatter spray were varied systematically to analyse the effect on welding result, residual stresses and cold cracking. It could be shown that increasing restraint intensities result in significantly higher transverse residual stress levels. In the case of hydrogen introduction S500MLO showed no cold cracking independent of the restraint conditions. However, S960QL was found to be considerably cold cracking sensitive if hydrogen is introduced. With increasing restraint intensity length and number of cold cracks increases significantly. Part 2 [1] of this study is focussed on microstructure and residual stresses due to gouging and stress optimization via adequate heat control parameters in repair welding. KW - Metals and Alloys KW - Mechanical Engineering KW - Mechanics of Materials PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595212 DO - https://doi.org/10.1007/s40194-024-01691-y SN - 0043-2288 SP - 1 EP - 13 PB - Springer Science and Business Media LLC AN - OPUS4-59521 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröder, Nina A1 - Rhode, Michael A1 - Kannengießer, Thomas T1 - Influence of microalloying on precipitation behavior and notch impact toughness of welded high‑strength structural steels N2 - Microalloying elements such as Nb and Ti are essential to increase the strength of quenched and tempered high-strength low alloy (HSLA) structural steels with nominal yield strength ≥ 690 MPa and their welded joints. Standards such as EN 10025–6 only specify limits or ranges for chemical composition, which leads to variations in specific compositions between steel manufacturers. These standards do not address the mechanical properties of the material, and even small variations in alloy content can significantly affect these properties. This makes it difficult to predict the weldability and integrity of welded joints, with potential problems such as softening or excessive hardening of the heat-affected zone (HAZ). To understand these metallurgical effects, previous studies have investigated different microalloying routes with varying Ti and Nb contents using test alloys. The high-strength quenched and tempered fine-grained structural steel S690QL is the basic grade regarding chemical composition and heat treatment. To evaluate weldability, three-layer welds were made using high-performance MAG welding. HAZ formation was investigated, and critical microstructural areas were identified, focusing on phase transformations during cooling and metallurgical precipitation behavior. Isothermal thermodynamic calculations for different precipitations were also carried out. Mechanical properties, especially Charpy notch impact toughness, were evaluated to understand the influence of different microalloys on the microstructure of the HAZ and mechanical properties. KW - High-strength structural steel KW - Gas metal arc welding KW - HAZ-softening KW - Notch impact toughness KW - Microalloying influences KW - Thermodynamic simulation PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608548 DO - https://doi.org/10.1007/s40194-024-01827-0 SN - 0043-2288 SP - 1 EP - 13 PB - Springer AN - OPUS4-60854 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Quackatz, Lukas A1 - Westin, Elin Marianne A1 - Griesche, Axel A1 - Kromm, Arne A1 - Kannengießer, Thomas A1 - Treutler, Kai A1 - Wesling, Volker A1 - Wessman, Sten T1 - Assessing ferrite content in duplex stainless weld metal: WRC ‘92 predictions vs. practical measurements N2 - AbstractThe weldability of stainless steels is largely controlled by the chemical composition, and alloys with ferritic or ferritic-austenitic solidification show the highest resistance to hot cracking. As the resulting phase balance also affects the final properties, it may be beneficial to both foresee and measure the weld metal ferrite content. The WRC ‘92 constitution diagram is currently the most accurate prediction tool available, but it does not take the cooling rate into consideration and the precision may be less accurate for stainless steels with high ferrite numbers (FNs). This study aims to assess the reliability of the WRC ‘92 diagram for weld metals with FN  50. The chemical composition was altered through gas tungsten arc welding (GTAW) of UNS S32205 with ER347 filler wire that had been coated using physical vapor deposition (PVD) with either niobium (Nb), copper (Cu), nickel (Ni), manganese (Mn), carbon (C), or silicon (Si). The actual ferrite content was evaluated using image analysis, FeriteScope and X-ray diffraction (XRD). While predictions from the WRC ‘92 diagram were deemed acceptable for Ni, Si, and Mn, notable deviations were observed for Nb, Cu, and C. The FeriteScope exhibited a consistent trend with image analysis, albeit with slightly higher FN values, wider scatter, and the conversion factor from FN to vol% is open for discussion. The lowest accuracy and largest spread were obtained using non-contact XRD, rendering it unsuitable for ferrite measurements of welds. These findings underscore the need for improved prediction tools and appropriate measurement methods for assessing ferrite content in duplex weld metals. KW - Duplex stainless steel KW - Welding KW - Phase balance KW - Microscopy KW - Microstructure PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-618777 DO - https://doi.org/10.1007/s40194-024-01878-3 SN - 1878-6669 VL - 69 IS - 1 SP - 31 EP - 45 PB - Springer CY - Berlin AN - OPUS4-61877 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Quackatz, Lukas A1 - Westin, Elin Marianne A1 - Griesche, Axel A1 - Kromm, Arne A1 - Kannengießer, Thomas A1 - Treutler, Kai A1 - Wesling, Volker A1 - Wessman, Sten T1 - Assessing ferrite content in duplex stainless weld metal: WRC ‘92 predictions vs. practical measurements N2 - AbstractThe weldability of stainless steels is largely controlled by the chemical composition, and alloys with ferritic or ferritic-austenitic solidification show the highest resistance to hot cracking. As the resulting phase balance also affects the final properties, it may be beneficial to both foresee and measure the weld metal ferrite content. The WRC ‘92 constitution diagram is currently the most accurate prediction tool available, but it does not take the cooling rate into consideration and the precision may be less accurate for stainless steels with high ferrite numbers (FNs). This study aims to assess the reliability of the WRC ‘92 diagram for weld metals with FN  50. The chemical composition was altered through gas tungsten arc welding (GTAW) of UNS S32205 with ER347 filler wire that had been coated using physical vapor deposition (PVD) with either niobium (Nb), copper (Cu), nickel (Ni), manganese (Mn), carbon (C), or silicon (Si). The actual ferrite content was evaluated using image analysis, FeriteScope and X-ray diffraction (XRD). While predictions from the WRC ‘92 diagram were deemed acceptable for Ni, Si, and Mn, notable deviations were observed for Nb, Cu, and C. The FeriteScope exhibited a consistent trend with image analysis, albeit with slightly higher FN values, wider scatter, and the conversion factor from FN to vol% is open for discussion. The lowest accuracy and largest spread were obtained using non-contact XRD, rendering it unsuitable for ferrite measurements of welds. These findings underscore the need for improved prediction tools and appropriate measurement methods for assessing ferrite content in duplex weld metals. KW - Duplex stainless steel KW - Phase fraction prediction KW - WRC diagram PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623682 DO - https://doi.org/10.1007/s40194-024-01878-3 VL - 69 SP - 31 EP - 45 PB - Springer Science and Business Media LLC AN - OPUS4-62368 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Giese, Marcel A1 - Gräbner, Maraike A1 - Schröpfer, Dirk A1 - Treutler, Kai A1 - Lorenz, Svenja A1 - Kannengießer, Thomas A1 - Wesling, Volker T1 - Alloy modification and ultrasonic-assisted milling of wear-resistant alloys with defined surfaces N2 - The reduction of CO2 emissions is closely linked to the development of highly efficient and economical steel components in plant and process engineering. To withstand the high combined corrosive, tribological, thermal, and mechanical stresses, wear-resistant coatings tailored to the application and steel grade are used. In addition to the increasing demand to substitute conventional cobalt alloys with nickel alloys, there is also a growing need for defined or functional surfaces of high integrity. Due to high tool wear, milling operations required to produce the complex geometries of the components are often not economically feasible for SMEs. By means of alloy modification of the filler metals for nickel-based plasma build-up welded wear-resistant coatings and by the use of innovative ultrasonic-assisted milling processes more favourable machinability shall be achieved without reducing the wear protection potential. In this paper, the influence of the microstructure and precipitation morphology adjusted by means of alloy modification on the machinability is investigated. This is done based on a wear protection alloy NiCrMoSiFeB (trade name: Colmonoy 56 PTA) typically used for screw machines, which substitutes conventional CoCr alloys (Stellite). Metallurgical investigations and in-situ measurements of occurring process forces and temperatures at the tool cutting edge during milling as well as subsequent investigations of tool wear and surface integrity allow a detailed analysis and correlation between microstructural properties and machinability. For the cast samples, a clear change in the microstructure and hardness can be seen through the addition of Al, Ti, or Nb. These differences lead to an improvement in the machining process for Nb. Al and Ti cause long-needled or star-shaped precipitations and hardness increases, which lead to higher cutting forces and increased tool wear. KW - Cladding KW - Wear resistant alloys KW - Alloy modification KW - Post-processing KW - Ultrasonic assisted milling KW - Renewable energy PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-622918 DO - https://doi.org/10.1007/s40194-024-01786-6 SN - 1878-6669 VL - 68 SP - 2567 EP - 2575 PB - Springer Science and Business Media LLC CY - Berlin ; Heidelberg AN - OPUS4-62291 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Czeskleba, Denis A1 - Nietzke, Jonathan A1 - Rhode, Michael A1 - Kannengießer, Thomas T1 - Investigation of stress relief crack susceptibility of CrMoV steels coarse grain HAZ via simulation of uniaxial stress conditions during PWHT N2 - Creep-resistant steels such as the 13CrMoV9-10, used in the construction of thick-walled pressure vessels, are most commonly submerged arc welded (SAW). These steels can develop stress relief cracks (SRC) if the mandatory post weld heat treatment (PWHT) is performed improperly. Current PWHT parameters, such as heating rate and holding time at a specific holding temperature, are based on both empirical experience and conventional free shrinking welding experiments to characterize the SRC-susceptibility of the weld. These cannot adequately depict the higher residual stresses caused by the structurally induced stiffness of the surrounding construction. This study discusses the development of a repeatable, precise, and time-efficient methodology to study the effects of different stress levels and heating rates on the SRC susceptibility of the coarse grain heat-affected zone (CGHAZ). For that purpose, samples were thermically treated to simulate a coarse grain heat-affected zone (CGHAZ) and subsequently exposed to representative levels of stress during the heating phase of a PWHT. The recorded stress and heating rate–dependent strains were mathematically analyzed via curve tracing/calculus to identify interdependent effects. This procedure facilitates the measurement of material characteristics such as carbide growth on grain boundaries at the µm-scale via an integrated value over the entire sample volume. The first and second derivatives show a slight, precipitate-dependent, increase in hardness of the sample, depending on the heating rate and applied stress. This new methodology generates an improved assessment of the SRC susceptibility of SAW microstructures of creep-resistant CrMoV steels. KW - Submerged arc welding KW - Creep-resistant steel KW - Stress relief cracking KW - Component-like test KW - Post weld heat treatment PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-576007 DO - https://doi.org/10.1007/s40194-023-01539-x SN - 0043-2288 SP - 1 EP - 9 PB - Springer Nature CY - Basel (CH) AN - OPUS4-57600 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eissel, A. A1 - Engelking, Lorenz A1 - Gustus, R. A1 - Treutler, K. A1 - Wesling, V. A1 - Schröpfer, Dirk A1 - Kannengießer, Thomas T1 - Alloy modification for additive manufactured Ni alloy components—part I: effect on microstructure and hardness of Invar alloy N2 - Alloy 36 (1.3912), also known as “Invar,” is an alloy with 36% nickel. The alloy has a remarkably low thermal expansion coefficient in certain temperature ranges. This peculiarity is called the invar effect, which was discovered in 1896 by the Swiss physicist Charles Édouard Guillaume. Therefore, it is used in applications in which dimensional stability is critical, such as molding tools for composite materials in aerospace, automotive applications, or liquified natural gas (LNG) cargo tanks. Moreover, increasingly complex structures and the optimization of resource efficiency also require additive manufacturing steps for the production or repair of components. Additively manufactured components have a heterogeneous microstructure and anisotropic mechanical properties. In addition, the manufactured components require subsequent machining surface finishing, like finish milling, to achieve their final contour. Nickel iron alloys are difficult to machine. Additionally, inhomogeneous microstructure may lead to unstable cutting forces and conditions. In part I of this investigation, the initial alloy 36 is modified with the elements Ti, Zr, and Hf up to a maximum of 0.33 wt.-%. The influence of the modification elements on the microstructure as well as on the hardness of the AM components is examined. Furthermore, one modification is applied to metal arc welding process and investigated. Part II focuses on the effect of the alloy modifications on machinability as well as on the surface integrity of plasma-transferred-arc-welded (PTA) and finish milled invar components. T2 - 75th IIW Annual Assembly CY - Tokyo, Japan DA - 17.07.2022 KW - Alloy modification KW - Alloy 36 KW - Plasma-transferred arc welding PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-571777 DO - https://doi.org/10.1007/s40194-023-01510-w SN - 0043-2288 SP - 1 EP - 9 PB - Springer CY - Heidelberg AN - OPUS4-57177 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Engelking, Lorenz A1 - Eissel, A. A1 - Schröpfer, Dirk A1 - Treutler, K. A1 - Kannengießer, Thomas A1 - Wesling, V. T1 - Optimisation of surface residual stresses using ultrasonic‑assisted milling for wire‑arc additive manufactured Ni alloy components N2 - Nickel alloys are cost intensive materials and generally classified as difficult-to-cut material. However, machining of these materials is needed especially in case of alloy 36 (1.3912), which is commonly used in mould construction for the production of fibre-reinforced composites. With regard to repair, modification and manufacturing of such components, additive manufacturing offers significant economic advantages. Nevertheless, subsequent machining steps are needed to achieve the final component contour and defined surface conditions. Dependent on the material and machining process conditions, detrimental tensile residual stresses may be the result on the machined surface, having negative impact on the component performance and safety. In this investigation, machining experiments were carried out on wire arc additive manufactured components made of alloy 36, varying the cutting speed and the feed rate. In addition, the conventional milling process (CM) was compared with a modern, hybrid machining process, the ultrasonic-assisted milling (US). The cutting forces and the surface-near residual stresses were analysed using X-ray diffraction. A significant improvement of the machinability as well as the surface integrity by using the ultrasonic assistance was observed, especially at low cutting speeds. The CM induced mainly tensile residual stresses, the US mainly compressive residual stresses. KW - Surface integrity KW - Ultrasonic-assisted milling KW - Additive manufacturing KW - Ni alloy KW - Alloy 36 PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-575246 DO - https://doi.org/10.1007/s00170-023-11326-z SN - 1433-3015 VL - 126 IS - 9 SP - 4191 EP - 4198 PB - Springer Nature AN - OPUS4-57524 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -