TY - JOUR A1 - Schröder, Jakob A1 - Evans, Alexander A1 - Luzin, V. A1 - Abreu Faria, G. A1 - Degener, Sebastian A1 - Polatidis, E. A1 - Čapek, J. A1 - Kromm, Arne A1 - Dovzhenko, G. A1 - Bruno, Giovanni T1 - Texture-based residual stress analysis of laser powder bed fused Inconel 718 parts N2 - Although layer-based additive manufacturing methods such as laser powder bed fusion (PBF-LB) offer an immense geometrical freedom in design, they are typically subject to a build-up of internal stress (i.e. thermal stress) during manufacturing. As a consequence, significant residual stress (RS) is retained in the final part as a footprint of these internal stresses. Furthermore, localized melting and solidification inherently induce columnar-type grain growth accompanied by crystallographic texture. Although diffraction-based methods are commonly used to determine the RS distribution in PBF-LB parts, such features pose metrological challenges in their application. In theory, preferred grain orientation invalidates the hypothesis of isotropic material behavior underlying the common methods to determine RS. In this work, more refined methods are employed to determine RS in PBF-LB/M/IN718 prisms, based on crystallographic texture data. In fact, the employment of direction-dependent elastic constants (i.e. stress factors) for the calculation of RS results in insignificant differences from conventional approaches based on the hypothesis of isotropic mechanical properties. It can be concluded that this result is directly linked to the fact that the {311} lattice planes typically used for RS analysis in nickel-based alloys have high multiplicity and less strong texture intensities compared with other lattice planes. It is also found that the length of the laser scan vectors determines the surface RS distribution in prisms prior to their removal from the baseplate. On removal from the baseplate the surface RS considerably relaxes and/or redistributes; a combination of the geometry and the scanning strategy dictates the sub-surface RS distribution. KW - Additive manufacturing KW - Electron backscattered diffraction KW - Principal stress KW - Residual stress PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-578331 DO - https://doi.org/10.1107/S1600576723004855 SN - 1600-5767 VL - 56 IS - Pt 4 SP - 1076 EP - 1090 AN - OPUS4-57833 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wandtke, Karsten ED - Becker, Amadeus ED - Schröpfer, Dirk ED - Kromm, Arne ED - Kannengießer, Thomas ED - Scharf-Wildenhain, R. ED - Hälsig, A. ED - Hensel, J. T1 - Residual Stress Evolution during Slot Milling for Repair Welding and Wire Arc Additive Manufacturing of High-Strength Steel Components N2 - High-strength steels offer potential for weight optimization due to reduced wall thicknesses in modern constructions. Additive manufacturing processes such as Wire Arc Additive Manufacturing (WAAM) enable the resource-efficient production of structures. In the case of defects occurring in weld seams orWAAM components due to unstable process conditions, the economical solution is local gouging or machining and repair welding. It is important to understand the effects of machining steps on the multiaxial stress state in conjunction with the design-related shrinkage restraints. Research into how welding and slot milling of welds andWAAM structures affects residual stresses is still lacking. For this reason, component-related investigations with high-strength steels with yield strengths ≥790 MPa are carried out in our research. In-situ digital image correlation (DIC) and ex-situ X-ray diffraction (XRD) were used to analyze the stresses and strains induced on specimens during and after milling. The systematic analyses revealed a significant interaction of the stiffness and microstructure of the specimens with the initial residual stresses induced by welding. Subsequent repair welds can result in significantly higher residual stresses. KW - High strength steels KW - Additive manufacturing KW - Residual stress KW - Repair welding KW - Ditigtal image correlation PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-593515 DO - https://doi.org/10.3390/met14010082 VL - 14 IS - 1 SP - 1 EP - 11 PB - MDPI CY - Basel AN - OPUS4-59351 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Santi, Alberto A1 - Schröder, Jakob A1 - Serrano-Munoz, Itziar A1 - Bayat, Mohamad A1 - Hattel, Jesper Henri T1 - Exploring the Flash Heating method in additive manufacturing for residual stress prediction: A comparative study with diffraction results from X-ray and neutron techniques N2 - Residual stress (RS) control is crucial for ensuring the performance and reliability of components produced through laser-based powder bed fusion (PBF-LB) additive manufacturing (AM). This study evaluates the Flash Heating (FH) method as an efficient approach for RS prediction, comparing its outcomes with multiple experimental techniques, including X-ray diffraction, neutron diffraction, and layer removal methods. These experimental assessments are conducted in different regions of the component, both before and after detachment from the baseplate. The study validates the FH method and analyzes key numerical parameters, such as meta-layer height, contact time, and time-stepping strategies. Results indicate that FH effectively predicts bulk RS distributions but shows discrepancies in surface stress estimations, likely due to unaccounted factors like surface roughness. Additionally, implementing experimentally derived material properties from as-built AM samples significantly enhances model accuracy compared to conventional material datasets. These findings underscore the potential of FH for efficient RS prediction in PBF-LB while identifying areas for further improvement. Refinements should focus on incorporating anisotropic, temperature-dependent material behavior derived from as-built AM samples and surface roughness effects. This work advances the understanding of key factors necessary for accurate and computationally efficient RS prediction, supporting the optimization of AM processes. KW - Finete element method KW - Inconel 718 KW - Metal additive manufacturing KW - Residual stress KW - Thermomechanics PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-639533 DO - https://doi.org/10.1080/01495739.2025.2541862 SN - 0149-5739 SP - 1 EP - 24 PB - Taylor & Francis AN - OPUS4-63953 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 - Evans, Alexander A1 - Schröder, Jakob A1 - Pirling, T. A1 - Ulbricht, Alexander A1 - Suárez Ocaño, Patricia A1 - Bruno, Giovanni T1 - Resolving the Subsurface Residual Stress Maximum in Laser Powder Bed-Fused 316L Stainless Steel by Diffraction-Based Analysis N2 - Laser powder bed fusion (PBF-LB/M) is a metal additive manufacturing process. Due to the complex nature of the layer-wise, repeated heating and cooling cycles, it tends to generate high-magnitude residual stresses. If not correctly understood and mitigated through in- or post-process approaches, these residual stresses can be detrimental as they are often tensile at the surface. However, determining the magnitude and location of peak tensile residual stresses is not trivial as they are often located subsurface. This work focuses on determining the magnitude and location of these deleterious tensile residual stresses in a PBF-LB/316L specimen. Two diffraction-based Methods are used to reveal the relationship between the residual stresses and the underlying microstructure. On the one hand, high spatial resolution Neutron diffraction is used to determine triaxial stresses from the bulk to a depth of 0.15 mm. On the other hand, laboratory X-ray diffraction coupled with electrolytical layer removal allows the biaxial residual stress depth profile to be probed from the surface to a depth of about 0.6 mm. The results show a good agreement between the two methods. The peak residual stress is shown to be 500 MPa, which appears as a plateau between 0.08 and 0.35 mm in depth. KW - Residual stress KW - Diffraction KW - Laser Powder Bed Fusion KW - 316L KW - Additive manufacturing KW - Microstructure KW - AGIL PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-652138 DO - https://doi.org/10.1007/s11837-025-07719-y SN - 1543-1851 VL - 77 IS - 12 SP - 9726 EP - 9737 PB - Springer Nature AN - OPUS4-65213 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fardan, Ahmed A1 - Fazi, Andrea A1 - Schröder, Jakob A1 - Mishurova, Tatiana A1 - Deckers, Tobias A1 - Bruno, Giovanni A1 - Thuvander, Matthias A1 - Markström, Andreas A1 - Brodin, Hakan A1 - Hryha, Eduard T1 - Microstructure tailoring for crack mitigation in CM247LC manufactured by powder bed fusion – Laser beam N2 - Tailored microstructures in powder bed fusion – laser beam (PBF-LB) can aid in crack mitigation of non-weldable Ni-base superalloys such as CM247LC. This study explores the effect of a range of stripe widths from 5 mm down to 0.2 mm to control solidification cracking, microstructure, and residual stress in CM247LC manufactured by PBF-LB. The decrease in melt pool depth with the reduction in stripe width from 5 to 0.2 mm promoted the < 100 > crystallographic texture along the build direction. The crack density measurements indicated that there is an increase from 0.62 mm/mm2 (5 mm) to 1.71 mm/mm2 (1 mm) followed by a decrease to 0.33 mm/mm2 (0.2 mm). Atom probe tomography investigations at high-angle grain boundaries revealed that there is higher Hf segregation in 0.2 mm stripe width when compared to 5 mm. This indicates that the cracking behavior is likely influenced by the grain boundary segregation which in turn is dependent on melt pool shape/size and mushy zone length indicated by accompanying simulations. Residual stress, measured by X-ray diffraction, decreased from 842 MPa (5 mm) to 690 MPa (1 mm), followed by an abnormal rise to 842 MPa (0.7 mm) and 875 MPa (0.5 mm). This residual stress behavior is likely associated with the cracks acting as a stress relief mechanism. However, the 0.2 mm stripe width exhibited the lowest stress of 647 MPa, suggesting a different mechanism for stress relief, possibly due to re-melting. These findings highlight the critical role of stripe width as a scan strategy in PBF-LB processing of crack-susceptible alloys. KW - Additive manufacturing KW - Residual stress KW - Scanning strategy KW - Non-weldable superalloy KW - Solidification cracking PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-624606 DO - https://doi.org/10.1016/j.addma.2025.104672 SN - 2214-7810 VL - 99 SP - 1 EP - 14 PB - Elsevier B.V. AN - OPUS4-62460 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Malladi, Sri Bala Aditya A1 - Mishurova, Tatiana A1 - Anilkumar, Vishnu A1 - Mehta, Bharat A1 - Evans, Alexander A1 - Surreddi, Kumar Babu T1 - Reducing plastic anisotropy through stress induced martensitic transformation in an additively manufactured metastable medium entropy alloy N2 - Powder bed fusion laser beam (PBF-LB) is particularly effective for fabricating compositionally complex alloys such as high-entropy alloys (HEAs) or medium-entropy alloys (MEAs). Fabricating non-equiatomic metastable MEAs using PBF-LB can lead to the formation of unique microstructures that enhance the mechanical performance of these alloys. Nevertheless, plastic anisotropy in materials prepared by additive manufacturing routes including PBF-LB remains to be a technical challenge. This work presents the fabrication of a metastable non-equiatomic Co45Cr25(FeNi)30 MEA using PBF-LB. As-printed samples exhibited the formation of nano-scaled ε-martensite (HCP) phase along with the FCC phase. The HCP phase exhibited Shoji-Nishiyama orientation relationship with the FCC phase. High energy synchrotron X-ray diffraction (HEXRD) and electron backscatter diffraction (EBSD) in-situ tensile testing were employed to investigate the influence of the HCP phase on the alloy's deformation behavior. The presence of the HCP phase initiates stress-induced martensitic transformation well below the macroscopic yield strength. This transformation led to the non-linear stress and strain response for the FCC phase. Further straining resulted in significant load partitioning, with the HCP phase taking the majority of the load as it formed, significantly strain hardening the alloy and reducing the plastic anisotropy induced by texture in the as-printed material. KW - Neutron Diffraction KW - X-ray computed tomography KW - Mechanical Properties KW - Additive Manufacturing KW - Residual stress PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630588 DO - https://doi.org/10.1016/j.msea.2025.148308 SN - 1873-4936 VL - 933 SP - 1 EP - 10 PB - Elsevier B.V. AN - OPUS4-63058 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gunnerek, R. A1 - Soundarapandiyan, G. A1 - Mishurova, T. A1 - Schröder, J. A1 - Bruno, Giovanni A1 - Boykin, J. A1 - Diaz, A. A1 - Klement, U. A1 - Hryha, E.ON T1 - Chemical mechanical polishing of powder bed fusion – laser beam processed 316 L stainless steel N2 - Additive manufacturing via powder bed fusion – laser beam (PBF-LB) enables the fabrication of complex geometries but suffers from inherently rough surfaces and surface tensile residual stresses, both of which can compromise structural integrity, particularly under fatigue loading. To address these limitations, this study investigates chemical mechanical polishing (CMP) as a surface finishing method for improving surface quality and modifying the residual stress state in PBF-LB 316 L stainless steel. The work uniquely examines how scan rotation (0◦ vs. 67◦ rotation) and contour parameters influence CMP effectiveness in material removal, surface smoothing, and subsurface stress redistribution. With a targeted material removal of 110 μm, CMP reduced surface roughness (Sa) by up to 94 %, achieving values as low as 0.7 μm. Microstructural analysis revealed no grain refinement but identified a thin, plastically deformed surface layer. This plastic deformation resulted in the transformation of tensile surface stresses (340 MPa) into beneficial compressive stresses (􀀀 400 MPa), as confirmed by synchrotron X-ray diffraction, which also showed a shift toward isotropic strain distribution. Further, these findings demonstrate that the initial scan strategy influences CMP performance and that CMP can enhance both surface integrity and mechanical reliability without altering the underlying microstructure. This study advances the understanding of how process induced microstructure and surface features affect CMP outcomes, enabling more informed design of post-processing strategies for improved surface integrity and mechanical performance in additively manufactured metals. KW - Residual stress KW - Additive manufacturing KW - Chemical mechanical polishing KW - As-built microstructure KW - Surface roughness KW - Surface finishing KW - Material removal PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-640522 DO - https://doi.org/10.1016/j.jmatprotec.2025.119055 SN - 0924-0136/ VL - 345 SP - 1 EP - 12 PB - Elsevier B.V. AN - OPUS4-64052 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dixneit, J. A1 - Gibmeier, J. A1 - Kromm, Arne A1 - Schubnell, J. A1 - Lang, F. A1 - Loebich, F. A1 - Carl, E.-R. A1 - Ya, W. T1 - Residual stress distribution of a large component manufactured by AM-DED-Arc from high-strength weld filler material X90 N2 - Currently, DED-Arc manufactured components are not covered by design guidelines, and design factors such as residual stress factors are not defined for such components. This hinders industrial use, especially for components with a remaining surface waviness required by industry. For the first time the stress state of a high-strength, low-alloy, large-scale DED-Arc component was characterised in the as-built state and after cutting off the component from the substrate plate. Complementary methods of residual stress analyses were applied to gain a holistic insight into the residual stress distributions of a thick-walled part. In the as-built state, direction-dependent and position-dependent tensile residual stresses were found for the component at the level of the yield strength of the part. The additive manufacturing strategy continuous spiral deposition has no significant influence on the residual stresses in bead threshold area compared to the residual stresses of the remaining component. For this case, bead threshold is no structural imperfection. By removing the part from the substrate plate, the residual stresses are significantly redistributed. Tensile residual stresses are then present at a moderate level. Compressive residual stresses were determined in the volume of the deposited material. The general consideration of ‘‘high’’ tensile residual stresses in such thick-walled components is rather conservative. Therefore, design guidelines should take the manufacturing condition into account. KW - AM-DED-Arc KW - Residual stress KW - High strength steel PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655239 DO - https://doi.org/10.1177/03093247251406876 SN - 2041-3130 SP - 1 EP - 18 PB - SAGE AN - OPUS4-65523 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -