Q345R/316L复合板埋弧焊接头组织及耐蚀性研究

Investigation on microstructure and corrosion resistance of submerged arc welded joint of Q345R/316L composite plate

采用埋弧焊(SAW)焊接方法分别焊接2种厚度的Q345R/316L不锈钢复合板,得到2种复合板焊接接头,通过金相、成分分析、晶间腐蚀试验和电化学测试等方法研究了复合板焊接接头不同焊道的组织及耐蚀性。结果表明,厚规格复合板不锈钢盖面焊接了5道次,焊接接头不锈钢各焊道主要为奥氏体组织,无晶间腐蚀倾向;薄规格复合板不锈钢盖面焊接了2道次,不锈钢焊缝组织为奥氏体/马氏体双相组织,出现晶间腐蚀开裂现象;焊缝自腐蚀电位受Cr含量控制,适量的马氏体相表面也能形成稳定的钝化膜,且在腐蚀过程中优先溶解,起到阴极保护的作用。

The submerged arc welding method was used to weld two Q345 R/316 L stainless steel composite plates with different thickness specifications to obtain two composite plate welded joints.The microstructure and the corrosive behavior of the different weld passes of each welded joint ’s cover plate were studied by metallographic analysis,com position analysis, intergranular corrosion test and electrochemical test.The results showed that the stainless steel cover of the thick specification clad plate was welded in 5 passes, and the welded joints were mainly austenite structure without intergranular corrosion tendency.The stainless steel cover of the thin specification clad plate was welded 2 passes, and the weld structure was austenite and martensite dual-phase structure, with intergranular corrosion cracking.Self-corrosion potential was controlled by the content of element Cr.Appropriate amount of martensite phase could form a stable passive film, which could play the role of cathodic protection because of the preferential dissolution of martensite phase in the process of corrosion.