Heat treatment effects on hydrogen embrittlement in 316L stainless steel produced by selective laser melting in high-pressure environment

The influence of heat treatment on the hydrogen embrittlement (HE) sensitivity of selective laser melted 316L stainless steel was investigated by tensile test and thermal desorption spectroscopy (TDS). The sample heat treated at 900 °C for 4 h showed the lowest HE sensitivity. The large volume of deformation twins increased the intersections between deformation twins and the melt-pool boundaries, resulting in HE of as-received sample. By reducing dislocation density, heat treatment suppressed hydrogen transport via mobile dislocations. Moreover, heat treatment suppressed the stress concentration by minimizing melt-pool boundary content. Therefore, the heat treatment optimized HE resistance through dual regulation of microstructure and hydrogen diffusion. • The cellular sub-grain boundary acted as HAGB during deformation. • Deformation twins intersect with melt-pool boundary, resulting in local high stress. • The HT900 4h sample showed no HE, due to the reduced stress concentration.