Fatigue strength of PBF‐LB/M and wrought 316L stainless steel: effect of post‐treatment and cyclic mean stress
Moritz Braun, Eduard Mayer, Igor Kryukov, Christian Wolf, Stefan Böhm, Aliakbar Taghipour, Rachael Elizabeth Wu, Sören Ehlers, Shahram Sheikhi
Abstract
Abstract Additive manufacturing (AM) enables the cost‐effective production of complex components, many of which are traditionally manufactured using costly subtractive processes. During laser‐based powder bed fusion of metals (PBF‐LB/M), internal pores and rough surfaces are typically inevitable, reducing fatigue and corrosion resistance compared to traditional processes. Additionally, large defects often occur near to or at surfaces. Thus, this study investigates the effect of hybrid additive and subtractive manufacturing on the fatigue strength of AISI 316L. To this goal, different post‐treatment routes are compared with wrought material. Additionally, computed tomography is used to determine the necessary machining depth of the surface layer. In this study, heat treatment and machining are both found to significantly increase fatigue strength (17% and 87%). Finally, the mean stress sensitivity M of as‐built PBF‐LB/M and wrought material is found to be highly affected by the assessed number of cycles to failure and residual stresses in PBF‐LB/M material.