Fatigue strength prediction through defects-based analysis of L-PBF 17-4 PH stainless steel

Abstract

Murakami’s approach has been used in the high cycle fatigue regime to relate the fatigue limit to the critical defect size and location in additively manufactured (AM) metallic materials. However, the applicability of this model has not yet been thoroughly examined for AM materials in the very high cycle fatigue (VHCF) regime. Therefore, this study investigates the possibility of relating the volumetric defect features to the fatigue strength of 17-4 precipitation hardened (PH) stainless steel (SS) manufactured via laser-powder bed fusion (L-PBF) additive manufacturing technology. The 17-4 PH SS specimens are manufactured using an EOS M290 L-PBF system, heat-treated, machined, polished, and tested in the VHCF regime using an ultrasonic fatigue testing system. Careful fractography has also been performed on all fractured specimens to determine the volumetric defects responsible for the crack initiation.