Influence of Cold Work on Sensitization Kinetics and Evaluation of Degree of Sensitization in Type 316LN Stainless Steels

Abstract

The sensitization behavior of Type 316LN stainless steel (SS) with varying nitrogen content (0.07 wt% and 0.22 wt%) in 0% to 25% cold worked (CW) as well as in the as-received condition was evaluated. Time-temperature-sensitization diagrams were established for the cold worked Type 316LN SS (nitrogen content: 0.07 wt% and 0.22 wt%), using ASTM A262 Practice-E test. The time required for sensitization (ts) was found to decrease and critical cooling rates (CCR) increased up to 10% CW in the alloy with 0.07 wt% N. At higher CW, ts increased and CCR decreased. Similarly, ts decreased and CCR increased up to 15% CW in the alloy with 0.22 wt% N and at higher CW, ts increased and CCR decreased. To understand the sensitization behavior of Type 316LN SS with varying nitrogen content during thermal aging at 923 K for various durations, nondestructive electrochemical techniques like double loop electrochemical potentiokinetic reactivation (DL-EPR) technique and electrochemical reactivation technique (ERT) were adopt...