Effect Of Grain Boundary On Stress Corrosion Of 316L In Cl^- And H₂S Environments

316L austenitic stainless steel is widely used in energy,chemical and other fields due to its excellent physical and chemical properties,but it faces severe intergranular stress corrosion cracking in some specific environments,such as Cl-,H2 S,and hydrogen challenge.This paper uses the grain boundary engineering method to improve the intergranular stress corrosion cracking of 316 L.Three samples with different grain boundary compositions were prepared by cold deformation-recrystallization annealing,and the special grain boundary content was calibrated using EBSD technology,which were 12.5%,43.1%,and 54.4% in order.The proportions of(50)3 and(50)9 were: 6.8%,21.7% and 17.9%.316 L austenitic stainless steel with different grain boundary components was subjected to a slow strain rate tensile test in air and Cl-/ H2 S environment and its fracture was analyzed by SEM.The results showed that at 90 ?,43.1% of the special grain boundaries The component 316 L has the largest section shrinkage rate and the lowest stress corrosion sensitivity.At 200 ?,the 316 L elongation loss of the three grain boundary components is almost the same,and all of them are brittle fracture along the grain.The microstructure of 316 L with three different grain boundary components was analyzed.The results show that the three kinds of 316 L grain boundary components obtained are all single austenite structures,and no residual martensite is found.The sample with 12.5% special grain boundary composition has the highest residual stress and the highest dislocation density,and the other two are relatively low.The 43.1% sample with special grain boundary composition has the largest Schmid factor,and the sliding system is the easiest to start.The results of the electrochemical hydrogen permeation experiment show that the effective diffusion coefficient of hydrogen in the 12.5% special grain boundary composition sample is the largest,while the other two are relatively low.The above results indicate that the preparation of high-component special grain boundaries through grain boundary engineering can reduce the effective diffusion coefficient of hydrogen and thus improve the stress corrosion cracking resistance of 316 L austenitic stainless steel in Cl-/ H2 S environment to a certain extent.