Study on formation of surface and microstructure of stainless steel part produced by selective laser melting

Abstract

In order to further develop selective laser melting (SLM) technology, the formation of surface and microstructure of 316 stainless steel SLM parts was studied using optical microscopy and SEM, differential thermal analysis and thermal gravity analysis methods. Some effects such as heat transmission, energy distribution and rapid cooling and solidification during SLM process on the formation of surface and microstructure were mainly discussed. The results indicated that the surface morphology was affected by viscosity and fluidity of steel melts, which were governed by laser energy, heat transmission history and material properties, while porosity was influenced by surface morphology of each intermediate layer and the cooling rates of steel melts, which were determined by laser energy, heat transmission conditions and laser scanning history. The microstructures of 316 stainless steel SLM part were irregular non-equilibrium ones that converted to normal austenite after being heated at 627°C h^–1.