Effect of heat treatment on corrosion behaviour of additively manufactured 316L stainless steel in high-temperature water

Post-manufacturing heat treatment (PMHT) effect on the corrosion behaviour of directed energy deposition (DED) 316L stainless steel was investigated in hydrogenated water at 325 °C. As-DEDed and residual stress relief PMHTed (850 °C/2 h) specimens exhibited similar corrosion resistance, showing thick and thin inner oxide layer on the Cr-depleted cell interior and Cr-rich cell boundary, respectively. Composition homogenization PMHTed (1150 °C/1 h) specimen showed the best corrosion resistance with the much thinner inner oxide layer. The enhanced corrosion resistance of the PMHTed DED 316L than wrought 316L could be related to the unique large grain in DED 316L.