Defect-controlled fatigue mechanisms of LPBF 316L stainless steel: a mini-review

Laser powder bed fusion (LPBF) enables rapid fabrication of 316L stainless steel (SS 316L) with complex structures, but its rapid solidification and layer-by-layer deposition inevitably induce defects, such as pores and lack of fusion (LOF), severely restricting fatigue performance. This mechanics-focused mini-review summarizes recent research on the fatigue performance of SS 316L, focusing on the interaction mechanism between defect characteristics and the principal normal stress. The effects of build orientation and processing parameters on defect features are discussed, and the mechanisms by which defects influence fatigue under low-cycle fatigue (LCF), high-cycle fatigue (HCF), and various loading modes (tension, bending, and torsion) are compared. Furthermore, this review discusses the mechanisms and limitations of different post-processing methods, including heat treatment (HT), hot isostatic pressing (HIP), and surface treatments.