Metal Additive Manufacturing Conference - MAMC 2022

316L austenitic stainless steel is a commonly used alloy in a wide range of applications, including energy, petroleum, automotive, and medical industry. 316L has been a choice for combustion section components in steam and gas turbine engines. Owing to its low carbon content and extremely ductile austenitic matrix, 316L is one of the most commercially exploited steels for the laser powder bed fusion (L-PBF) process. Recently, the use of higher layer thicknesses aimed at increasing the productivity of the L-PBF process has been suggested and evaluated on an industrial scale. The as-built microstructure in 316L comprises a cellular/dendritic solidification structure with micro-segregation of alloying elements to the cell boundaries as a result of far from equilibrium, fast solidification. Therefore, in some applications a full homogenization of the microstructure by high temperature solution annealing treatments might be necessary. In the current work, the solution annealing response of L-PBF 316L, in particular, the effect of the layer thickness and energy input on the recovery, recrystallization and grain growth is studied. Scanning Electron Microscope (SEM) and Electron Back Scattered Diffraction (EBSD) results showed that higher normalized energy input during the L-PBF process increases the kinetics of the recrystallization during solution annealing. This is due to the increased number density of energetically preferential nucleation sites for the recrystallization process (i.e., high dislocation density, and low angle grain boundaries). As a result, at high energy inputs a lower annealing temperature was needed for the microstructural homogenization and formation of an equiaxed grain morphology