Corrosion behavior of 316L austenitic steel processed by selective laser melting, hot-isostatic pressing, and casting

This study investigated the corrosion behavior of grade 316L austenitic steel processed by casting, hot isostatic pressing (HIP), selective laser melting (SLM), and SLM+HIP. Electrochemical results showed that the SLM-densified specimen exhibited poorer corrosion resistance than specimens processed by casting and hot isostatic pressing in solution-annealed condition. Microstructural investigations revealed that the SLM-densified specimen had a fine-grained microstructure but comparatively higher porosity, which negatively influenced corrosion resistance. Additional HIP treatment further worsened corrosion resistance. The HIP process does not significantly reduce porosity compared to the SLM process, which can be attributed to the argon atmosphere used when manufacturing the SLM samples. Nevertheless, it was possible to reduce the crack density via HIP treatment and the formerly lamellar oxides underwent spheroidization.