TY - CONF A1 - Evans, Alexander T1 - Residual Stresses in Additive Manufacturing (L-PBF) N2 - Metal Additive manufacturing (AM) technologies such as Laser Powder Bed Fusion (LPBF) enable the fabrication of complex structures, giving rise to potential improvements in component and manufacturing efficiency. However, the processes are typically characterized by the generation of high magnitude residual stress (RS) which can have detrimental consequences for subsequent applications. Therefore, the characterization of these RS fields and the understanding of their formation and mitigation through optimized processing is crucial for the wider uptake of the technology. Due to the potential complex nature and high value of components manufactured by LPBF, it is important to have suitable characterisation methods which can determine the spatial variations of RS in a non-destructive manner. Neutron diffraction is considered to be the best suited for these requirements. However, the microstructures developed in the complex thermal cycles experience in the production can pose challenges to the ND method for RS analysis. The BAM has conducted significant research over the past years to overcome these obstacles, enabling higher confidence in the RS determined in LPBF materials by neutron diffraction. This contribution will overview some of these advancements made recently at European neutron sources including on Stress-Spec at FRM2/MLZ. T2 - MLZ User Meeting 2021 CY - Online meeting DA - 07.12.2021 KW - Residual stress KW - Additive manufacturing KW - Diffraction KW - AGIL KW - Manufact PY - 2021 AN - OPUS4-54044 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hejazi, Bardia A1 - Compart, Amaya A1 - Fritsch, Tobias A1 - Wagner, Ruben A1 - Weidner, Anja A1 - Biermann, Horst A1 - Benz, Christopher A1 - Sander, Manuela A1 - Bruno, Giovanni T1 - Fatigue Crack Segmentation and Characterization of Additively Manufactured Ti‐6Al‐4V Using X‐Ray Computed Tomography N2 - X‐ray computed tomography (XCT) is extremely useful for the non‐destructive analysis of additively manufactured (AM) components. AM components often show manufacturing defects such as lack‐of‐fusion (LoF), which are detrimental to the fatigue life of components. To better understand how cracks initiate and propagate from internal defects, we fabricated Ti‐6Al‐4V samples with an internal cavity using electron beam powder bed fusion. The samples were tested in high‐cycle and very high‐cycle fatigue regimes. XCT was used to locate crack initiation sites and to determine characteristic properties of cracks and defects with the aid of deep learning segmentation. LoF defects exposed to the outer surface of the samples after machining were found to be as detrimental to fatigue life as the internal artificial defects. This work can benefit industries that utilize the AM of high‐strength, lightweight alloys, in the design and manufacturing of components to improve part reliability and fatigue life. KW - Additive manufacturing KW - Deep learning KW - Ttitanium alloy KW - Very high-cycle fatigue KW - X-ray computed tomography PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-615107 DO - https://doi.org/10.1111/ffe.14489 SP - 1 EP - 13 PB - Wiley AN - OPUS4-61510 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Voloskov, Boris A1 - Mishurova, Tatiana A1 - Evlashin, Stanislav A1 - Firsov, Denis A1 - Bruno, Giovanni A1 - Sergeichev, Ivan T1 - Influence of scanning strategy and hatch distance on porosity and mechanical characteristics of 316L stainless steel produced by laser powder bed fusion N2 - The effect of scanning strategies and hatch distances on the porosity and mechanical properties of 316L stainless steel produced by laser powder bed fusion (PBF-LB) is studied. Two scanning strategies were analyzed along with three hatch distances (50 μm, 80 μm, and 110 μm). Using X-ray computed tomography (XCT), the study revealed different defect distributions: 90° alternating hatch scanning strategy resulted in a higher number of lack of fusion defects, while the chessboard strategy produced smaller, more uniformly distributed gas pores. The optimal hatch distance of 80 μm was found to minimize porosity and maximize tensile strength for both strategies. Mechanical testing supported these findings, showing that specimens printed with an 80 μm hatch distance exhibited better mechanical characteristics. This study highlights the critical role of scanning parameters in the quality and reliability of additively manufactured parts. KW - X-ray computed tomography KW - Additive manufacturing KW - Porosity PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-621164 DO - https://doi.org/10.1016/j.prostr.2024.11.045 SN - 2452-3216 VL - 65 SP - 302 EP - 309 PB - Elsevier B.V. AN - OPUS4-62116 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 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 - CONF A1 - Kang, M. T1 - Influence of mica particle content in composites for high voltage applications produced by additive manufacturing and mold casting N2 - The insulation system of high voltage electrical devices like generators and electrical motors has to withstand thermal, electrical, ambient and mechanical influences (TEAM) during operation. Especially the dielectric properties have to satisfy the requirements also under elevated temperatures and extreme environments. To provide this high quality, the conventional fabrication process uses partly manually applied insulation tapes combined with a cost-intensive and under safety concerns at least problematic vacuum pressure impregnation step (VPI). In order to reduce process costs by increasing the degree of automation and avoiding the VPI process, additively manufactured (AM) insulations were studied. This study focuses on the fabrication of ceramic/polymer compounds via AM technique. The AM technology used a rotating screw extrusion print head with air pressure to supply the paste. Plate-like samples with dimensions of 55 mm x 55 mm x1mm thickness were produced. This work focuses on the homogeneously high viscous paste with 12.5 to 50 volume % ratio of filler particles. Three types of mica powders as ceramic filler materials with different particle sizes from micro to mm scale were evaluated. The controlled volume % ratio of particles affects the paste viscosity which enables stacking of paste layers with a viscosity close to clay pastes. The mixed pastes were cured by heating and UV light to increase mechanical properties. A TG/DTA was performed, and electrical properties were investigated. First experiments with respect to the dielectric properties such as volume resistance, permittivity and dielectric strength revealed promising results and the possibility to use AM techniques for the fabrication of high voltage insulations for electrical machines. T2 - MaterialsWeek 2021 CY - Online meeting DA - 07.09.2021 KW - HV-Insulation KW - Polymer-Ceramic-Composite KW - Additive manufacturing PY - 2021 AN - OPUS4-54368 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bhadeliya, Ashok A1 - Rehmer, Birgit A1 - Fedelich, Bernard A1 - Jokisch, Torsten A1 - Skrotzki, Birgit A1 - Olbricht, Jürgen T1 - High Temperature Fatigue Crack Growth in Nickel-Based Alloys Refurbished by Additive Manufacturing N2 - Hybrid additive manufacturing plays a crucial role in the restoration of gas turbine blades, where, e.g., the damaged blade tip is reconstructed by the additive manufacturing process on the existing blade made of a parent nickel-based alloy. However, inherent process-related defects in additively manufactured material, along with the interface created between the additively manufactured and the cast base material, impact the fatigue crack growth behavior in bi-material components. This study investigates the fatigue crack growth behavior in bi-material specimens of nickel-based alloys, specifically, additively manufactured STAL15 and cast alloy 247DS. The tests were conducted at 950 °C with stress ratios of 0.1 and −1. Metallographic and fractographic investigations were carried out to understand crack growth mechanisms. The results revealed significant retardation in crack growth at the interface. This study highlights the potential contributions of residual stresses and microstructural differences to the observed crack growth retardation phenomenon, along with the conclusion from an earlier study on the effect of yield strength mismatch on crack growth behavior at a perpendicular interface in bi-material specimens. T2 - Superalloys 2024 Conference CY - Champion, Pennsylvania, USA DA - 08.09.2024 KW - Fatigue crack growth KW - Bi-material structure KW - Additive manufacturing KW - Nickel-based alloys PY - 2024 SN - 978-3-031-63937-1 DO - https://doi.org/10.1007/978-3-031-63937-1_92 SN - 2367-1181 SN - 2367-1696 VL - 15th SP - 994 EP - 1001 PB - Springer CY - Cham AN - OPUS4-60907 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ávila Calderón, Luis T1 - Creep and fracture behavior of conventionally and additively manufactured stainless steel 316L N2 - A critical task within the frame of establishing process-structure-property-performance relationships in additive manufacturing (AM) of metals is producing reliable and well-documented material behavior’s data and knowledge regarding the structure-property correlation, including the role of defects. After all, it represents the basis for developing more targeted process optimizations and more reliable predictions of performance in the future. Within this context, this contribution aims to close the actual gap of limited historical data and knowledge concerning the creep behavior of the widely used austenitic stainless steel 316L, manufactured by Laser-Powder-Bed-Fusion (L-PBF). To address this objective, specimens from conventional hot-rolled and AM material were tested under application-relevant conditions according to existing standards for conventional material, and microstructurally characterized before and after failure. The test specimens were machined from single blocks from the AM material. The blocks were manufactured using a standard scan and build-up strategy and were subsequently heat-treated. The creep behavior is described and comparatively assessed based on the creep lifetime and selected creep curves and characteristic values. The effect of defects and microstructure on the material’s behavior is analyzed based on destructive and non-destructive evaluations on selected specimens. The AM material shows shorter creep lives, reaches the secondary creep stage much faster and at a lower strain, and features lower creep ductility compared to its conventional counterpart. The creep damage behavior of the AM material is more microstructure than defect controlled and is characterized by the formation and accumulation of single intergranular damage along the whole volume. Critical features identified are the grain morphology and the grain-boundary as well as the dislocation’s density. Micro-computed tomography (µCT) proves to be an alternative to metallography to analyze the creep damage. T2 - ASTM International Conference on Additive Manufacturing 2020 CY - Online meeting DA - 16.11.2020 KW - 316L KW - Creep behavior KW - Laser powder bed fusion KW - Additive manufacturing KW - Microstructure PY - 2020 AN - OPUS4-51823 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Suárez Ocaño, Patricia A1 - Ávila Calderón, Luis A1 - Agudo Jácome, Leonardo A1 - Rehmer, Birgit A1 - Mohr, Gunther A1 - Evans, Alexander A1 - Skrotzki, Birgit T1 - Effect of 700–900 °C heat treatments and room and high temperature tensile deformation on the microstructure of laser powder bed fused 316L stainless steel N2 - The effect of post-processing heat treatments on the hierarchical microstructure evolution and mechanical strength of the austenitic stainless steel 316L produced by laser powder bed fusion has been investigated. Heat treatments between 700 and 900 ◦C and 0.5 to 3 h, were applied to samples treated at 450 ◦C for 4 h. The results showed a stable microstructure at all studied temperatures and times in terms of grain size, morphology, aspect ratio, density of low-angle grain boundaries, and texture. However, temperature and time promoted the diffusion of segregated elements together with a reduction in dislocation density and disappearance of the cellular structure. This was associated with a reduction in hardness and tensile proof strength at both room and high temperature. In addition, microstructural characterization coupled with thermodynamic CALPHAD-based equilibrium calculations showed that the formation of carbides and intermetallic phases was already visible after annealing at 800 ◦C for 3 hours, although these intermetallics did not affect the tensile properties at this level. Analysis of the microstructure evolution after tensile deformation showed differences in the deformation mechanisms at room and high temperature, with twinning and martensitic transformation occurring at room temperature, the latter not widely reported for additively manufactured 316L. Finally, comparisons with similar materials produced under comparable conditions showed differences in the tensile properties, attributed to differences in chemical composition and the associated presence of stacking faults in the undeformed state. KW - Additive manufacturing KW - 316L stainless steel KW - Heat treatments KW - Tensile properties KW - Microstructure PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-632471 DO - https://doi.org/10.1016/j.msea.2025.148469 SN - 0921-5093 VL - 939 SP - 1 EP - 24 PB - Elsevier CY - Amsterdam AN - OPUS4-63247 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ávila Calderón, Luis T1 - Assessing the low cycle fatigue behaviour of additively manufactured Ti-6Al-4V: Challenges and first results N2 - The understanding of process-microstructure-property-performance (PMPP) relationships in additive manufacturing (AM) of metals is highly necessary to achieve wide-spread industrial application and replace conventionally manufactured parts, especially regarding safety-relevant applications. To achieve this understanding, reliable data and knowledge regarding material’s microstructure-property relationships (e.g. the role of defects) is needed, since it represents the base for future more targeted process optimizations and more reliable calculations of performance. However, producing reliable material data and assessing the AM material behaviour is not an easy task: big challenges are e.g. the actual lack of standard testing methods for AM materials and the occasional difficulties in finding one-to-one comparable material data for the conventional counterpart. This work aims to contribute to end this lack of reliable material data and knowledge for the low cycle fatigue behaviour of the most used titanium alloy in aerospace applications (Ti-6Al-4V). For this purpose, two sets of test specimens were investigated. The first set was manufactured from cylindrical rods produced by an optimized DED-L process and the second was manufactured from a hot formed round bar. The test specimens were cyclically loaded until failure in the low-cycle-fatigue (LCF) regime. The tests were carried out according to ISO 12106 between 0.3 to 1.0 % axial strain amplitude from room temperature up to 400°C. The LCF behaviour is described and compared between materials and with literature values based on cyclic deformation curves and strain-based fatigue life curves. Besides, the parameters of Manson-Coffin-Basquin relationship were calculated. The microstructures (initial and after failure) and fracture surfaces were comparative characterized. Thereby, the focus lied on understanding the role of grain morphology and defects on the failure mechanisms and fatigue lifetimes. For this latter characterization, optical microscopy (OM), scanning electron microscopy (SEM) and micro computed tomography (µCT) were used. T2 - 4th International Symposium on Fatigue Design and Material Defects CY - Online meeting DA - 26.05.2020 KW - Ti-6Al-4V KW - Additive manufacturing KW - Low cycle fatigue KW - Micro computed tomography KW - Microstructure PY - 2020 AN - OPUS4-50893 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 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 - JOUR A1 - Cabo Rios, Alberto A1 - Mishurova, Tatiana A1 - Cordova, Laura A1 - Persson, Mats A1 - Bruno, Giovanni A1 - Olevsky, Eugene A1 - Hryha, Eduard T1 - Ex-situ characterization and simulation of density fluctuations evolution during sintering of binder jetted 316L N2 - Efficient density evolution during sintering of the as-printed component is vital to reach full densification and required properties of binder jet (BJT) components. However, due to the high porosity and brittle nature of the green compact, analysis of the microstructure development during sintering is very difficult, resulting in lack of understanding of the densification process. Density development from green state (57 ± 1.6 %) up to full density (99 ± 0.3 %) was characterized by high-resolution synchrotron X-Ray computed tomography (SXCT) on BJT 316L samples from ex-situ interrupted sintering tests. Periodicity of density fluctuations along the building direction was revealed for the first time and was related to the layer thickness of ~ 42 μm during printing that decreased down to ~ 33 μm during sintering. Sintering simulations, utilizing a continuum sintering model developed for BJT, allowed to replicate the density evolution during sintering with a mean error of 2 % and its fluctuation evolution from green (1.66 %) to sintered (0.56 %) state. Additionally, simulation of extreme particle size segregation (1 μm to 130 μm) suggested that non-optimized printing could lead to undesirable density fluctuation amplitude rapid increase (~10 %) during sintering. This might trigger the nucleation of defects (e.g., layer delamination, cracking, or excessive residual porosity) during the sintering process. KW - Additive manufacturing KW - Synchrotron X-ray CT KW - Binder Jetting KW - Sintering KW - FEM Simulation PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594389 DO - https://doi.org/10.1016/j.matdes.2024.112690 SN - 0264-1275 VL - 238 SP - 1 EP - 18 PB - Elsevier AN - OPUS4-59438 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 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 - Evans, Alexander T1 - Residual Stresses in Additive Manufacturing (L-PBF) N2 - Additive manufacturing (AM) technologies are experiencing an exceedingly rapid growth, driven by their potential through layer wise deposition for transformational improvements of engineering design, leading to efficiency and performance improvements. Laser Powder Bed Fusion (LPBF) is an Additive Manufacturing (AM) method which permits the fabrication of complex structures that cannot otherwise be produced via conventional subtractive manufacturing methods. Nevertheless, the rapid cooling rates associated with this process results in the formation of significant and complex residual stress (RS) fields. A large body of both experimental and simulation research has been dedicated in recent years to the control and mitigation of RS in AM. In order to validate simulations with the end goal of being able to model the residual stress state in AM components and to devise strategies for their reduction during manufacturing, experimental methods need to be able to accurately determine 3D residual stresses fields in complex geometries. Several destructive and non-destructive methods can be used to analyze the RS state, the choice of which depends on the geometry and the information required. Diffraction-based methods using penetrating neutron and synchrotron X-rays at large scale facilities offer the possibility to non-destructively spatially resolve both surface and bulk residual stresses in complex components and track their changes following applied thermal or mechanical loads. This presentation will overview the success stories of using large scale facilities by the BAM for the characterization of residual stresses in additively manufactured metallic alloys. In particular, the study of the influence of process parameters on the residual stress state and the relaxation of these stresses through heat treatment will be presented. However there remains challenges to overcome particularly of the hypotheses underlying the experimental determination of residual stresses, which will be discussed. T2 - 10th International Conference on Mechanical Stress Evaluation by Neutron and Synchrotron Radiation – MECASENS 2021 CY - Prague, Czech Republic DA - 25.11.2021 KW - Residual stress KW - Additive manufacturing KW - Diffraction KW - L-PBF KW - AGIL PY - 2021 AN - OPUS4-54105 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Evans, Alexander T1 - Residual stresses Analysis in Additively Manufactured alloys using neutron diffraction (L-PBF) N2 - An overview of recent progress at BAM of residual stress analysis in additively manufactured, in particular Laser Powder Bed Fusion of metallics materials, using neutron diffraction will be presented. This will cover important topics of the stress-free reference, the diffraction elastic moduli and principal stress determination. T2 - AWT-Fachausschuss 13 "Eigenspannungen" CY - Berlin, Germany DA - 28.03.2023 KW - AGIL KW - Residual stress KW - Additive manufacturing KW - Laser Powder Bed Fusion KW - Diffraction PY - 2023 AN - OPUS4-59177 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Suarez Ocano, Patricia T1 - Exploring the impact of heat treatment on room and high temperature strength of 316L stainless steel fabricated by PBF-LB N2 - Laser Powder Bed Fusion (PBF-LB/M) enables the fabrication of 316L stainless steel components with superior strength and intricate geometries. The alloy PBF-LB/M/316L features a fully austenitic microstructure with hierarchical characteristics— such as fine dislocation structures, segregated elements, low-angle grain boundaries, and nano-dispersed silicates—that enhance strength and ductility. Additionally, it includes metallurgical defects and residual stresses. Apart from process control, heat treatments (HTs) are used to tailor the microstructure for specific loading conditions. This study investigate the effects of post-processing HTs on the hierarchical microstructure and tensile properties of PBF-LB/M/316L at room and high temperature. The heat treatments, ranging from 400 °C to 900 °C for 1 to 4 hours, focus on sub-recrystallization temperatures to preserve the microstructural hierarchy. The HTs applied had minimal impact on the grain shape, size, or texture of PBF-LB/M/316L. However, significant modifications occurred in the solidification cellular substructure after HTs at 800 °C and 900 °C, when compared to a heat-treated condition at 450 °C. HTs at 800 °C notably decreased dislocation density and enlarged cellular structures, though they remained partially intact. After 1 hour at 900 °C, the cellular substructure dissipated, correlating with a further reduction in dislocation density. These microstructural changes resulted in a decreased yield strength and increased work hardening capacity at both room and high temperature, highlighting the critical link between HT parameters, microstructural evolution, and mechanical performance. T2 - The 20th International Conference on Strength of Materials (ICSMA 20) CY - Kyoto, Japan DA - 02.06.2025 KW - Additive manufacturing KW - 316L stainless steel KW - Heat treatments KW - Tensile properties KW - Microstructure PY - 2025 AN - OPUS4-63914 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Suárez Ocano, Patricia T1 - Effect of heat treatment on the hierarchical microstructure and properties of 316L stainless steel produced by Laser Powder Bed Fusion (PBF-LB/M). N2 - Laser Powder Bed Fusion (PBF-LB/M) of AISI 316L stainless steel has gained popularity due to its exceptional capacity to produce complex geometries and hierarchical microstructures, which can increase the yield strength while maintaining good ductility. Nevertheless, owing to high thermal gradients encountered during the process, the as printed 316L stainless steel often exhibit microstructural heterogeneities and residual stresses, which can limit its performance in demanding environments. Hence, employing heat treatments which balance the reduction of residual stresses while retaining improved static strength may be beneficial in various scenarios and applications. This study investigates the impact of post-processing heat treatments on the microstructure of 316L stainless steel manufactured via PBF-LB/M, along with its correlation with micro-hardness properties. To this end, 6 different heat treatments, i.e., 450 °C for 4h, 700 °C for 1h, 700 °C for 3h, 800 °C for 1h, 800 °C for 3h, and 900 °C for 1h, were applied to different specimens and Vickers hardness measurements (HV1) were performed in all states. At 800 °C, although the cellular structure appears to be retained, there is an observable increase in cellular size. However, while treatments exceeding 900 °C indicate no significant grain growth compared to other conditions, the cellular structure is entirely dissolved, which leads to a reduced Vickers hardness. The effect of the heat treatments on other microstructural features such as grain size and morphology, melt pool boundaries (MPB), crystallographic texture, chemical segregation, dispersoids and phase stability are also discussed in the present work T2 - 4th Symposium on Materials and Additive Manufacturing CY - Berlin, Germany DA - 12.06.2024 KW - Additive manufacturing KW - Heat treatment KW - Microstructure PY - 2024 AN - OPUS4-60304 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Rehmer, Birgit A1 - Bayram, Faruk A1 - Ávila Calderón, Luis A1 - Mohr, Gunther A1 - Skrotzki, Birgit T1 - BAM reference data: Temperature-dependent Young's and shear modulus data for additively and conventionally manufactured variants of austenitic stainless steel AISI 316L N2 - The elastic properties (Young's modulus, shear modulus) of austenitic stainless steel AISI 316L were investigated between room temperature and 900 °C in an additively manufactured variant (laser powder bed fusion, PBF‑LB/M) and from a conventional process route (hot rolled sheet). The moduli were determined using the dynamic resonance method. The data set includes information on processing parameters, heat treatments, grain size, specimen dimensions and weight, Young’s and shear modulus as well as their measurement uncertainty. The dataset was generated in an accredited testing lab using calibrated measuring equipment. The calibrations meet the requirements of the test procedure and are metrologically traceable. The dataset was audited as BAM reference data. KW - Elastic modulus KW - Young's modulus KW - Shear modulus KW - Additive manufacturing KW - AISI 316L PY - 2023 DO - https://doi.org/10.5281/zenodo.7813835 PB - Zenodo CY - Geneva AN - OPUS4-57288 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -