Corrosion behavior of underwater laser deposition remanufactured nuclear steel 316LN stainless steel at a pressure of 0.3 MPa

Abstract

The current study focuses on investigating the corrosion behavior of 316LN nuclear steel that has been repaired with the underwater laser directed metal deposition (UDMD) technique at a simulated water depth of 30 m and with in-air laser directed metal deposition (in-air DMD). The findings highlight a refined grain size, higher dislocation density, more oxide inclusions, and M₇C₃ in the samples repaired by UDMD in comparison to the samples repaired by in-air DMD. Moreover, all samples developed a passive film comprising Cr₂O₃, Fe₂O₃, and MoO₃ on their surface in 3.5 wt% NaCl solution. The corrosion and pitting behavior of the UDMD samples differed from those of the in-air DMD samples due to variations in grain size, oxide inclusions, carbide, and dislocation density. The UDMD samples exhibited better corrosion resistance compared to the in-air DMD samples.