Influence of Prior Deformation on the Sensitization Kinetics of Nitrogen Alloyed 316L Stainless Steels

This paper presents the influence of prior deformation on the sensitization kinetics of nitrogen-alloyed 316L stainless steels. Systematic investigations were carried out for two varieties of 316L SS containing (i) 0.025% C and 0.14% N; (ii) 0.033% C and 0.11% N. Using ASTM standard A262 Practice A and E tests, time-temperature-sensitization diagrams were constructed for as-received as well as 5-25% cold-worked materials. Using these TTS diagrams, critical cooling rates (CCR) above which there is no risk of sensitization were calculated. TTS diagrams established for these two stainless steels will be useful for avoiding time-temperature combinations that may result in sensitization and susceptibility to IGC. These CCR obtained can be used to optimize heating rates/cooling rates to be followed which will not lead to sensitization during solution annealing, stress-relieving, and dimensional stabilization of critical components for fast breeder reactors.