Effect of Nitrogen on the Precipitation and Pitting Corrosion Susceptibility of High Nitrogen 316SS Weld

Abstract The present study aimed to understand the effect of nitrogen on the carbide precipitation and its influence on pitting corrosion of shielded metal arc welded high nitrogen 316SS weld. Nitrogen addition to weld reduces Cr availability sites in ferrite and enhances Cr in nearby austenite. Although higher carbon and continuous ferrite with ferritic austenitic mode exist, the changes in the degree of sensitisation were avoided at all the stages, and marginal changes in pitting potential ( E pit ) at 898 K/100 h and 998 K/24 h were observed. Nitrogen addition to weld further reduced the number of stable pits in ferrite and austenite, and the protectiveness of passive film was affected by nitrogen in ferrite and austenite, which affected pit propagation. This results in stable pits in ferrite and austenite, which affects pit propagation during thermal ageing.