Preprint for Impact of chemical composition on solidification microstructure and hardness of additively manufactured 316L steel

Laser-powder bed fusion (L-PBF) is an efficient and advanced manufacturing technology that utilizes a laser to melt and solidify metallic alloy powders, layer by layer, to form the desired object shape. Among numerous L-PBF processing parameters, four basic parameters are vital for the quality of the final product, namely laser power (P), scanning speed (v), layer thickness (t), and hatch spacing (h). Another essential parameter, usually not considered in abundant studies on L-PBF 316L stainless steel, is the chemical composition of the used powders. This study addresses the crucial importance of the chemical composition of the feedstock powder on the microstructural characteristics (shape and size of grains, grain boundary types, texture, solidification/dislocation cells, etc.) of SLM 316L stainless steels. Using various advanced microscopic techniques, it is demonstrated that even very slight variations in the chemical composition of powders from different producers, still within allowable ranges, manufactured using identical processing parameters and conditions, result in a change of solidification mode that significantly impacts the final microstructure and mechanical performance of L-PBF 316L stainless steel.