Effects of Strain Strengthening on Stress Corrosion Sensitivity of S31603 Stainless Steel Base Metal and Welded Joint

Strain strengthening treatment was carried out for S31603 stainless steel base metal and welded joint under different strain degrees by uniaxial tensile at room temperature. The effects of strain strengthening on the microstructure and mechanical properties of S31603 stainless steel were studied through magnetic checking, metallurgical analysis, hardness testing. By the slow strain rate test in 5% sodium chloride solution, the variation of stress corrosion susceptibility of S31603 stainless steel base metal and welded joint in different strain degrees was discussed. The results show that after strain strengthening process, S31603 stainless steel base metal produced a very small amount of strain-induced martensite. The microstructure of welded joint had no significant change, which was dual phase structure of columnar austenite and wormlike δ ferrite. With the increase of strain degree, the micro-hardness of base metal and welded joint increased at different levels, and stress corrosion susceptibility also had a small increase, but still at a low level. The fracture showed a ductile fracture morphology without obvious stress corrosion tendency.