The effects of hot isostatic pressing (HIP) and solubilization heat treatment on the density, mechanical properties, and microstructure of austenitic stainless steel parts produced by selective laser melting (SLM)

Despite ongoing optimization, selective laser melting (SLM) technology still cannot guarantee the production of completely defect-free components. This work investigates hot isostatic pressing (HIP) in a nitrogen environment and solubilization heat treatment as methods for improving the quality of 316L stainless steel components produced by SLM. The characteristics of HIP-treated specimens are firstly correlated with the initial density of samples obtained with different SLM process parameters, showing that HIP is effective at eliminating pores in components with high initial density (above 99%) but not in those with low initial density (approximately 94%). Subsequently, the mechanical properties and microstructure of 316L stainless steel specimens produced by SLM are examined in the as-built state and after various post-process conditions including solubilization heat treatment and HIP at pressures from 50 to 2000 bar. The observed effects of post-processing on the porosity and microstructure of each specimen are consistent with hardness and tensile test results, with the benefits and limitations of HIP clarified for future implementation.