应变强化对S31603不锈钢母材与焊接接头应力腐蚀敏感性的影响

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

采用室温单轴拉伸对S31603不锈钢母材与焊接接头进行了不同应变量的应变强化处理。通过磁性检测、金相检验、硬度测试研究了应变强化对S31603不锈钢组织与力学性能的影响;通过在5%氯化钠溶液中的慢应变速率试验研究了不同应变量下S31603不锈钢母材与焊接接头应力腐蚀敏感性的变化规律。结果表明:经应变强化后,S31603不锈钢母材中产生了极其微量的形变马氏体,焊接接头处组织无明显变化,仍然为柱状奥氏体+蠕虫状δ铁素体双相组织;随着应变量的增加,母材与焊接接头处的显微硬度均有不同程度增大,同时应力腐蚀敏感性也均有小幅增加,但是始终处于较低水平,断口呈现出韧性断裂形貌,无明显的应力腐蚀倾向性。

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 microhardness 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.