Fatigue Life and Surface Quality of Laser Powder Bed Fusion Manufactured 316L Parts by Laser Heat Treatment

Abstract

Laser heat treatment (LHT) with two sets of energy inputs was applied to laser powder bed fusion (LPBF) manufactured 316L parts and its effects were studied in this research. LHT processed structures were compared to the as built material in terms of microstructural analysis, hardness measurements and mechanical testing, surface roughness and fatigue life. The results show that the LHT can be used to enhance the material properties of LPBF manufactured 316L parts in several ways. With the higher energy density, the surface roughness could be nearly halved while the fatigue strength was simultaneously doubled with no meaningful recorded loss in hardness or ultimate tensile strength. Microstructural evolution at the surface due to the LHT resulted in a mixture of coarse columnar dendrite and cellular grain structure. According to the findings of this work, LHT appears as an attractive tool for enhancing the properties of LBPF 316L.