TY - CONF A1 - Schröder, Jakob T1 - Peculiarities of the determination of residual stress in additively manufactured materials N2 - The determination of residual stress in additively manufactured materials is a challenge, even after decades from the establishment of the basics of residual stress analysis. This is due to the peculiar microstructure of such materials. In fact, researchers have discovered that conventional methods for the determination of RS in materials do not properly work for AM materials. In this tutorial, the basics of RS analysis will be explained, together with the basics of AM manufacturing techniques. The microstructure of the peculiar materials (AM) dealt with here will be elucidated. Successively, the necessary modifications to the conventional approaches to RS analysis will be explained and case studies will be displayed, for the attendant to touch with hands the peculiarities of the approaches. Finally, a few experimental and theoretical tips will be given on dos and don’ts for a correct determination of RS in AM materials. T2 - 11th European Conference on Residual Stresses CY - Prague, Czech Republic DA - 03.06.2024 KW - Additive Manufacturing KW - Laser Powder Bed Fusion KW - Residual Stress KW - Diffraction PY - 2024 AN - OPUS4-60428 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröder, Jakob T1 - The heat treatment of L-PBF Inconel 718: A manyfold problem N2 - The interest to additively manufacture Nickel-based superalloys has substantially grown within the past decade both academically and industrially. More specifically, additive manufacturing processes such as laser powder bed fusion (LPBF) offer the ability to produce dense parts within a single manufacturing step. In fact, the exceptional freedom in design associated with the layer-based nature of the processes is of particular interest for the complex shapes typically required in turbine applications. In certain cases, the overall part performance can be achieved by tailoring the microstructure and the crystallographic texture to the specific application. However, these advantages must be paid at a price: the large local temperature gradients associated with the rapid melting and solidification produce parts that inherently contain large residual stress in the as-manufactured state. In addition, the presence of pores in the final part may further affect the in-service part failure. As among Nickel-based alloys Inconel 718 exhibits excellent weldability, this alloy has been widely studied in open research in the domain of LPBF. However, significant microsegregation of the heavier alloying elements such as Niobium and Molybdenum accompanied by dislocation entanglements may preclude the application of conventional heat treatment schedules. Therefore, different post processing heat treatments are required for laser powder bed fused Inconel 718 as compared to conventional variants of the same alloy. In this study, we investigated two different heat treatment routes for LPBF Inconel 718. In a first routine, the samples were stress relieved and subsequently subjected to hot isostatic pressing (HIP) followed by a solution heat treatment and a two-step age (referred to as FHT). In a second routine, the samples were subjected to a single-step direct age post stress relieving heat treatment (referred to DA). We investigated the consequences of such heat treatment schedules on the microstructure, texture, and mechanical behavior. We show that by applying a DA heat treatment the typical columnar microstructure possessing a crystallographic texture is retained, while an equiaxed untextured microstructure prevails in case of an FHT heat treatment. We further evaluate how these heat treatments affect the mechanical behaviour on the macroscopic and microscopic scale. T2 - 4th European Symposium on Superalloys and their Applications EuroSuperalloys 2022 CY - Bamberg, Germany DA - 18.09.2022 KW - Electron Backscatter Diffraction KW - Additive Manufacturing KW - Laser Powder Bed Fusion KW - Mechanical Behavior KW - Heat Treatment KW - X-Ray Diffraction PY - 2022 AN - OPUS4-55811 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sprengel, Maximilian T1 - Heat treatment induced residual stress relaxation in additively manufactured L-PBF 316L stainless steel N2 - Residual stress relaxation as a function of heat treatment strategies in laser based powder bed fused 316l samples. T2 - Eleventh Joint BER II and BESSY II User Meeting CY - Berlin, Germany DA - 04.12.2019 KW - Additive Manufacturing KW - Residual Stress KW - Neutron Diffraction KW - 316L PY - 2019 AN - OPUS4-49851 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - In-Situ Compression CT on Additively Manufactured in 625 Lattice Structures N2 - The porosity and the surface roughness are recently discussed problems for SLM parts. The influence of SLM process parameters on porosity is well studied for different materials. Nevertheless, the build angle (i.e. the angle between part orientation and build plate) needs to be understood as an additional SLM process parameter, as it has been shown, that the microstructure and hence the mechanical performance of various materials depend on the build angle. The inherent build angle of each strut as a part of a lattice structure is the motivation to investigate the influence of the build angle on the porosity and roughness on round-shaped (1 mm diameter) struts by means of CT. Conventional Coordinate Measuring Machine (CMM) has the limitation towards small and round shaped samples. The need for Computed Tomography (CT) regarding investigations of SLM parts will increase because no other non-destructive technique allows the assessment of complex geometries with inner laying surfaces. We used CT to assess the pores and the strut surface. Seven struts out of the nickel alloy Inconel 625 with build angles from 30° to 90° were studied. It was found that the number of pores is smaller, and the size of pores is larger for the 90° strut. In case of 30° strut, the number of pores is increased towards down-skin side, additionally, this strut orientation showed to have the largest number of attached powder particles. The elongated pores exist exclusively near the strut surface. While the roughness at the down-skin surface is highly depending of the biud angle, the roughness at the up-skin surface is the same for all struts. The mechanisms of pore and surface roughness formation is not mainly driven by gravity. T2 - ISAM Konferenz 2019 CY - Dresden, Germany DA - 29.01.2019 KW - Computed Tomography KW - Additive Manufacturing KW - Metals KW - Microstructure PY - 2019 AN - OPUS4-47327 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kromm, Arne T1 - Residual stress formation in selective laser melted parts of alloy 718 N2 - Additive Manufacturing (AM) through the Selective Laser Melting (SLM) route offers ample scope for producing geometrically complex parts compared to the conventional subtractive manufacturing strategies. Nevertheless, the residual stresses which develop during the fabrication can limit application of the SLM components by reducing the load bearing capacity and by inducing unwanted distortion, depending on the boundary conditions specified during manufacturing. The present study aims at characterizing the residual stress states in the SLM parts using different diffraction methods. The material used is the nickel based superalloy Inconel 718. Microstructure as well as the surface and bulk residual stresses were characterized. For the residual stress analysis, X-ray, synchrotron and neutron diffraction methods were used. The measurements were performed at BAM, at the EDDI beamline of -BESSY II synchrotron- and the E3 line -BER II neutron reactor- of the Helmholtz-Zentrum für Materialien und Energie (HZB) Berlin. The results reveal significant differences in the residual stress states for the different characterization techniques employed, which indicates a dependence of the residual state on the penetration depth in the sample. For the surface residual stresses, longitudinal and transverse stress components from both X-ray and synchrotron agree well and the obtained values were around the yield strength of the material. Furthermore, synchrotron mapping disclosed gradients along the width and length of the sample for the longitudinal and transverse stress components. On the other hand, lower residual stresses were found in the bulk of the material measured using neutron diffraction. The longitudinal component was tensile and decreased towards the boundary of the sample. In contrast, the normal component was nearly constant and compressive in nature. The transversal component was almost negligible. The results indicate that a stress re-distribution takes place during the deposition of the consecutive layers. Further investigations are planned to study the phenomenon in detail. T2 - Forschungsseminar OvGU Magdeburg CY - Magdeburg, Germany DA - 15.11.2018 KW - Additive Manufacturing KW - Selective Laser Melting KW - Residual Stresses PY - 2018 AN - OPUS4-46876 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - Characterization of Additive Manufacturing Materials at BAM N2 - The combination of tomographic, microstructural data with other experimental techniques and with modeling is paramount, if we want to extract the maximum amount of information on material and component properties. In particular, quantitative image analysis, statistical approaches, direct discretization of tomographic reconstructions represent concrete possibilities to extend the power of the tomographic 3D representation to insights into the material and component performance. This logic thread equally holds for industrial and academic research and valorizes expensive experiments such as those carried out at synchrotron sources, which cannot be daily repeated. I will show a few examples of possible use of X-ray tomographic data for quantitative assessment of damage evolution and microstructural properties, as well as for non-destructive testing. Examples of micro-structured inhomogeneous materials will be given, such as Composites, Ceramics, Concrete, and Additively manufactured parts. I will also show how X-ray refraction computed tomography (CT) can be highly complementary to classic absorption CT, being sensitive to internal interfaces. Additionally, I will show how Neutron Diffraction, which is extremely well suited to the study of internal stresses, both residual and under external load, can well be coupled to the microstructural framework gained by CT, allowing understanding the microstructure-property relationships in materials. Finally, I will show that BAM is very active in standardization and certification, including production of Reference Materials and Methods. T2 - Skoltech Determination of the microscopic residual stress CY - Moscow, Russia DA - 20.11.2019 KW - Additive Manufacturing KW - Computed Tomography KW - Neutron Diffraction KW - X-ray refraction techniques KW - Composites PY - 2019 AN - OPUS4-49929 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bhadeliya, Ashok T1 - High Temperature Fatigue Crack Growth in Nickel-Based Alloys Refurbished by Additive Manufacturing and Brazing 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, PA, USA DA - 08.09.2024 KW - Fatigue crack growth KW - Bi-material structure KW - Nickel-based alloys KW - Additive Manufacturing KW - Brazing PY - 2024 AN - OPUS4-61047 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Madia, Mauro T1 - Towards the Use of Representative Specimens for the Qualification of Additively Manufactured Parts N2 - The understanding of the process-structure-property-performance relationship is the key challenge for the qualification of safety-relevant parts made of additively manufactured metallic materials. The complexity of the manufacturing process and the number of influencing parameters affect the properties of test coupons and parts even fabricated in the same batch. This poses the problem of using reliable witness specimens for part qualification. This work presents a new approach which aims at the fabrication of test coupons tailored to the specific microstructure and fatigue properties of a component. The first step consisted in the evaluation of the temperature field by means of process monitoring during the production of parts. The results were used to tailor finite element models which were then used to design witness specimens representative of the thermal history in the component. Finally, the fatigue properties of designed specimens were compared to coupons machined out of the component. T2 - TMS2024 – 153rd Annual Meeting & Exhibition CY - Orlando, FL, USA DA - 03.03.2024 KW - Additive Manufacturing KW - Process simulation KW - Thermal history KW - Structural integrity KW - Damage tolerance PY - 2024 AN - OPUS4-65072 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ferrari, Bruno T1 - Microstructural evolution of PBF-LB/M Inconel 718 during solution-aging heat treatments - an in-situ x-ray diffraction study N2 - Inconel 718 (IN718) is a traditional age-hardenable nickel-based alloy that has been increasingly processed by additive manufacturing (AM) in recent years. In the as-solidified condition, IN718 exhibits chemical segregation and the undesired Laves phase, requiring a solution annealing (SA) prior to aging. The material produced by AM does not respond to the established thermal routines in the same way as conventionally produced IN718, and there is still no consensus on which routine yields optimal results. This work aims to provide a fundamental understanding of the heat treatment (HT) response by continuously monitoring the microstructural evolution during SA via time-resolved synchrotron x-ray diffraction, complemented by ex-situ scanning electron microscopy (SEM). The samples were produced by laser powder bed fusion to a geometry of 10x20x90 mm³, from which Ø1x5 mm³ cylindric specimens were extracted. Two different scanning strategies – incremental 67° rotations, Rot, and alternating 0°/67° tracks, Alt – were used, leading to two different as-built conditions. 1-hour SAs were carried out in the beamline ID22 of the ESRF at 50 KeV. Two SA temperatures, SA1 = 1020 °C, and SA2 = 1080 °C were tested for each scanning strategy. Data were processed using the software PDIndexer. In the as-built state, all samples showed typical subgrain columnar cell structures with predominant Nb/Mo segregation and Laves phase at the cell walls, as seen by SEM. The Alt scan induced higher intensity on the Laves peaks than the Rot scan, suggesting a greater content of Laves. Chemical homogenization in the SA was largely achieved during the heating ramp (Fig. 1). SA2 eliminated the Laves peaks just before reaching 1080 °C, and mitigated differences between Rot and Alt samples. On the other hand, SA1 induced the precipitation of the generally detrimental δ phase, also observed by SEM. Furthermore, the Rot scan showed higher δ peak intensities than the Alt scan, indicating a higher content of δ in the latter. No signs of recrystallization were observed in any of the investigated SAs. T2 - FEMS EUROMAT 2023 CY - Frankfurt a. M., Germany DA - 03.09.2023 KW - Additive Manufacturing KW - X-Ray Diffraction KW - Inconel 718 KW - Heat Treatments KW - Microstructure PY - 2023 AN - OPUS4-58392 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chaurasia, Prashant Kumar A1 - Cagtay, Fabry A1 - Andreas, Pittner A1 - Rethmeier, Michael T1 - Automated in situ monitoring and analysis of process signatures and build profiles during wire arc directed energy deposition N2 - Wire arc directed energy deposition (DED-Arc) is an emerging metal additive manufacturing process to build near-net shaped metallic parts in a layer-by-layer with minimal material wastage. Automated in situ monitoring and fast-responsive analyses of process signatures and deposit profiles during DED-Arc are in ever demand to print dimensionally consistent parts and reduce post-deposition machining. A comprehensive experimental investigation is presented here involving real-time synchronous measurement of arc current, voltage, and the deposit profile using a novel multi-sensor monitoring framework integrated with the DED-Arc set-up. The recorded current–voltage transients are used to estimate the time-averaged arc power, and energy input in real time for an insight of the influence of wire feed rate and printing travel speed on the deposit characteristics. A unique attempt is made to represent the geometric profiles of the single-track deposits in a generalized mathematical form corresponding to a segmented ellipse, which has exhibited the minimum root-mean-square error of 0.03 mm. The dimensional inconsistency of multi-track deposits is evaluated quantitatively in terms of waviness using build profile monitoring and automated estimation, which is found to increase with an increase in step-over ratio and energy input. For the multi-track mild steel deposits, the suitable range of step-over ratio for the minimum surface waviness is observed to lie between 0.6 and 0.65. Collectively, the proposed framework of synchronized process monitoring and real-time analysis provides a pathway to achieve dimensionally consistent and defect-free parts, and highlights the potential for closed-loop control systems for a wider industrial application of DED-Arc. T2 - IIW Annual Assembly 2025 CY - Genova, Italy DA - 23.06.2025 KW - Additive Manufacturing KW - Arc welding KW - Real-time monitoring and control KW - Dimensional inconsistency KW - DED-arc PY - 2025 AN - OPUS4-65231 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waske, Anja T1 - A unique authenticator for additively manufactured parts derived from their microstructure N2 - Components produced using additive manufacturing can be marked for unique identification and secure authentication [1,2]. Serial numbers and machine-readable codes can be used to identify the component, and link digital product-related data (i.e., a digital product passport) to the actual components. The most prevailing solution consists of local process manipulation, such as printing a quick response (QR) code [3] or a set of blind holes on the surface of the internal cavity of hollow components. However, local manipulation of components may alter the properties, and external tagging features can be altered or even removed by post-processing treatments. This work therefore aims to provide a new methodology for identification, authentication, and traceability of additively manufactured (AM) components using microstructural features that are unique to each part. X-ray computed tomography (XCT) was employed to image the microstructural features of AlSi10Mg parts. Based on size and geometry, the most prominent features were selected to create a unique digital authenticator. We implemented a framework in Python using open-access modules that can successfully create a digital object authenticator using the segmented microstructure information from XCT. The authenticator is stored as a QR code, along with the 3D information of the selected features. T2 - MRS Spring Meeting Seattle CY - Seattle, WA, USA DA - 07.04.2025 KW - Additive Manufacturing KW - Fingerprint KW - Non-destructive testing PY - 2025 AN - OPUS4-65199 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Witte, Julien T1 - The Impact of Ultrasonic-Assisted Milling and Alloying Elements on the Surface Integrity of Additively Manufactured Iron Aluminides N2 - The increasing focus on energy and resource efficiency has driven the implementation of additive manufacturing (AM) of high-performance materials, particularly in lightweight constructions with optimization of material efficiency. Iron aluminides (FeAl) hold great potential due to their low density, excellent corrosion and wear resistance, high-temperature stability, and vast availability. However, the inherent heterogeneity and anisotropy of FeAl-AM structures pose significant challenges, especially regarding hardness and brittleness. These material characteristics complicate the mostly necessary post-processing via mechanical finish machining, often resulting in elevated cutting forces, accelerated tool wear, and suboptimal surface integrity. Ultrasonic-assisted milling (USAM), a hybrid machining process, offers significant advantages over conventional milling (CM), including the reduction of cutting forces and tool wear. Notably, USAM has been demonstrated to decrease surface defect density and mitigate tensile residual stresses, while potentially inducing beneficial compressive residual stresses within the depth profile of the component’s surface. These effects can significantly enhance crack propagation resistance, improve corrosion behavior, and extend the fatigue life of components in safety-relevant applications. The present study investigates the effects of additional alloying elements such as molybdenum, nickel, titanium and Vanadium in FeAl as well as milling parameters, including cutting speed vc and feed rate fz, on the surface integrity with special regard to residual stress formations. T2 - BMDK der OvGU Magdeburg CY - Magdeburg, Germany DA - 10.12.2025 KW - Additive Manufacturing KW - Wear Protection KW - Ultrasonic-assisted Milling KW - Iron-aluminides KW - MPEA KW - Surface Integrity KW - Residual Stresses PY - 2025 AN - OPUS4-65234 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Quosdorf, Heike T1 - Digital object identifier for additively manufactured parts as software package N2 - A method to uniquely identify samples without printed or handwritten labels is an advantage not just for additively manufactured parts. To kickstart industry use cases, it is also important to provide a ready-made implementation kit. Following an open-science and open-source software approach Germanys Federal Institute for Materials Research and Testing (BAM) seeks to promote digital solutions of ongoing research projects. With this software package a novel method based on microstructural features as identifiers – DOI4AM (digital object identifier for additively manufactured parts) – will be explained alongside its implementation as open-source Python software package. The digital object identifier (DOI) links product data clearly and forgery-proof with real components. Its implementation helps to identify and securely authenticate additively manufactured components during its product life cycle by using characteristic microstructure features - just like a fingerprint. To calculate the DOI fingerprint, a few preprocessing steps need to be performed to detect the uniquely distributed microstructure features that occur during the 3D printing process. A go-through guide shows the preprocessing steps that include CT image capturing, feature segmentation, and data distribution with CSV files. While all steps can be followed along in a Jupyter notebook, the software package includes an application for creating and checking of previously created fingerprints, as well, as a containerized API (application programming interface) service for implementation in existing software platforms or workflows. While data visualization is crucial to understanding the methodology and an essential tool to check for data correctness, an implementation in an industry use case needs to be slim and resource efficient. Therefor the software’s API can be used as an independent service. The project's industry partner proofs its first successful implementation in their digital product passport web solution PASS-X. T2 - AI MSE 2025 CY - Bochum, Germany DA - 18.11.2025 KW - Authentication KW - Unique identification KW - Digital object identifier KW - Additive Manufacturing KW - Non-destructive testing KW - Open Source Software KW - Digital fingerprint KW - X-ray Computed Tomography KW - Open Science PY - 2025 AN - OPUS4-65293 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mohr, Gunther T1 - R&D insights into sustainable additive manufacturing for high-temperature applications (HTA) N2 - Im Rahmen des AM Forums Berlin 2026 wird durch diesen Vortrag ein Einblick in FuE-Aktivitäten der BAM auf dem Gebiet der additiven Fertigung für Hochtemperaturanwendungen gegeben. Es werden dabei insbesondere Aspekte der nachhaltigen Verwendung von Pulverausgangswerkstoff und der Einfluss von Sauerstoff im Pulverwerkstoff auf die Degradation resultierender mechanischer Eigenschaften von Probekörpern beleuchtet. Die präsentierten Arbeiten sind im Rahmen des Pro FIT Projektes HTA2.0 entstanden. T2 - 10. AM Forum 2026 CY - Berlin, Germany DA - 10.03.2026 KW - Additive Manufacturing KW - Sustainability KW - Powder recycling KW - Powder degradation PY - 2026 AN - OPUS4-65725 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -