Additively manufactured structures reveal a poor surface quality and a high number of process‐induced defects in the surface‐near area, leading to a significant reduction of the fatigue strength. As laser‐based powder bed fusion (PBF‐LB) processes are used to produce topologically optimized lightweight structures with complex geometries, which cannot be fully machined, the influence of the process‐induced surface on the fatigue behavior needs to be analyzed. For this, also the interrelation of the surface‐induced notch effects with the surrounding material volume must be considered. As thermal treatments can also be applied to filigree components with complex geometries, in the presented work the influence of different heat treatments, i.e., stress relief annealing (SR) and artificial aging (T6), on the material properties, especially the defect tolerance, of AlSi10Mg manufactured via PBF‐LB is analyzed. Both heat treatments lead to a dissolution of the cellular Si‐rich network, resulting in decreased hardness and tensile strength, but higher fatigue strength. The increased fatigue strength results from a reduction of the process‐induced residual stresses, but mainly a strongly improved defect tolerance. Consequently, to evaluate the fatigue strength of additively manufactured materials, besides the materials strength and the process‐induced defects, also the defect tolerance must be considered.

Due to the high potential of shot peening to improve the surface quality of additively manufactured components, in this work, the influence on surface morphology and, thus, the surface topography and selected properties of the surface and subsurface regions of additively manufactured parts is analysed. For this, cubic specimens made of stainless steel 316L and AlSi10Mg were manufactured via powder bed fusion laser beam metal (PBF-LB/M), and subsequently, their “as-built” surfaces were shot peened. Shot peening was conducted with stainless steel or ceramic beads using pressures of 3 and 5 bar. The resulting morphologies were analysed regarding topography, microstructure and mechanical properties (hardness and cyclic deformation behaviour) in the subsurface region and the residual stresses. The results demonstrate a strong plastic deformation due to shot peening, resulting in a decreased surface roughness as well as an increased hardness and compressive residual stresses near the surface. These effects were generally more pronounced after using higher peening pressure and/or ceramic beads. Note that two sets of PBF-LB/M parameters were used to produce the AlSi10Mg specimens. The investigation of these specimens reveals an interrelation between the parameters used in shot peening and PBF-LB/M on the resulting surface morphology.

Non-destructive evaluation (NDE) is highly relevant to assessing micro- and macrostructural changes in ferritic and ferritic/martensitic steels subjected to high temperature loading. These materials are widely used in energy generation, where they undergo extreme thermal and mechanical loads. This study examines the feasibility of micromagnetic NDE techniques, i.e., micromagnetic measurements, supported by machine learning methods, to identify and characterize the micro- and macrostructural changes caused by the mechanical loading at high temperatures of power plant steels, i.e., ferritic/martensitic P91 and the high chromium ferritic steel HiperFer-17Cr2. While the P91 did not show any systematic changes in micromagnetic measurements, which generally correlate with the evolution of the microstructure and the mechanical properties, for the HiperFer-17Cr2, pronounced changes in the micromagnetic properties were observed. In correlation with the evolution of the hardness and cyclic deformation behavior, which are both mainly attributed to Laves phase precipitation, the micromagnetic measurements significantly changed depending on the temperature, number of load cycles and load amplitude applied. Thus, these NDE methods can be used for early diagnosis and preventive maintenance strategies for HiperFer-17Cr2, potentially extending the lifespan of the components and mitigating safety risks.