The influence of energy density on the low cycle fatigue behaviour of laser powder bed fused stainless steel 316L

Abstract

Laser powder bed fusion (LPBF) is an additive manufacturing (AM) process capable of single-step fabrication of intricate and complex structures. However, there are multiple engineering challenges associated with the introduction of AM based parts into functional industrial applications due to the lack of understanding of the role that process parameters have on the structural integrity of additively manufactured (AM) components and the subsequent effect this has on the mechanical behaviour of such materials when subjected to cyclic loading conditions. The present work will investigate the low cycle fatigue (LCF) behaviour of LPBF stainless steel 316L components manufactured with different process parameters sets and how this effects the material built in different orientations and the resulting impact this has on the material’s resistance to cyclic deformation. The LCF results are supported by microstructural, fractographic and advanced surface profilometry assessments to investigate the key parameters that control the resulting fatigue performance across three different build orientations. Finally, the generated mechanical data has also been interpreted through empirical fatigue lifing models, and the various data sets have been successfully correlated to enable an estimation of longer fatigue lives.