Effect of Nitrogen on the Intergranular Stress Corrosion Cracking Resistance of 316LN Stainless Steel

Abstract

Here the effect of nitrogen on the intergranular stress corrosion cracking (SCC) resistance of sensitized Type 316LN stainless steel containing different amounts of nitrogen is reported. SCC studies were performed at 70% of yield strength. Double-loop electrochemical potentiokinetic reactivation technique was used to quantify degree of sensitization (DOS) that was correlated with SCC resistance. SCC time to failure increased from 220 h to 285 h with increasing nitrogen content from 0.07 wt% to 0.14 wt%, but decreased drastically to approximately 120 h at 0.22 wt% nitrogen (i.e., beyond N solubility limit), due to excessive precipitation of Cr23C6 and Cr2N and drastic reduction in the coincidence site lattice (CSL) boundary distribution from 48% to approximately 32%. Scanning electron microscope images showed mixed mode of failure.