2205双相不锈钢与Q235A异种金属焊接接头的组织与性能

Microstructure and mechanical properties of dissimilar metal welded joint between 2205 duplex stainless steel and Q235A carbon steel

采用钨极氩弧焊(GTAW)打底,焊条电弧焊(SMAW)填充和盖面的焊接方法,分别以ER2209焊丝和E2209焊条作为填充材料对2205双相不锈钢和Q235A异种金属的焊接进行了研究。对获得接头进行拉伸强度和显微硬度测试,发现拉伸试样断裂位于强度相对较低的Q235A母材一侧,在接头区域Q235A母材与焊缝金属交界面处的硬度值较高;金相组织观察显示,在接头的Q235A与焊缝金属侧分别存在脱碳层与增碳层,这是由于焊接过程中碳元素发生迁移的结果;利用扫描电镜观察接头断口形貌,接头呈明显的韧性断裂;对接头焊缝金属区进行X射线衍射相结构组成测定,未发现焊缝金属区中存在有害相析出,表明获得接头的质量良好,完全能够满足实际工程结构的使用要求。

The welding of dissimilar metal between 2205 duplex stainless steel and Q235A carbon steel was carried out. The backing welding was performed by tungsten inert gas arc welding (GTAW) with welding wire ER2209 and the filling and cosmetic welding was performed by shielded metal arc welding (SMAW) with electrode E2209. The tensile strength and microhardness of the welded joint are tested, respectively, and results show that the fracture of joint tensile specimen occurs at the side of Q235A base metal whose strength is relatively lower. Compared to the other region of welded joint, the microhardness is higher at the interface between Q235A and weld metal. The analysis of microstructure of joint indicates that the carbon-enriched layer and decarburized layer appear close to the fusion line at the side of Q235A base metal because of the migration of carbon element during welding. The morphology of tensile fracture of was analyzed by scanning electron microscope (SEM), and the joint presents obvious characteristics of ductile fracture. The XRD analysis shows that no deleterious precipitation phases are found in the weld metal. Consequently, the quality of dissimilar metal welded joint is good, which can meet the application requirements of engineering