316L/X65双金属复合管管端根焊工艺研究

Research on Root Welding Process of 316L/X65 Double-metal Composite Pipe End

316L不锈钢/X65双金属复合管在衬管管端钨极氩弧焊根焊时,采用不添加焊丝自熔焊和添加镍基合金焊丝两种焊接工艺,试验对比发现,不添加焊丝自熔焊后,管端自熔区域硬度较高,超过相应的技术要求;而添加镍基合金焊丝后,管端焊区硬度正常。对焊区化学成分、维氏硬度、显微组织及微区成分进行了分析。结果表明,采用不添加焊丝自熔焊,自熔区的Fe含量偏高,Cr,Ni和Mo含量偏低,冷却后形成的马氏体组织是导致自熔区硬度偏高的主要原因;采用镍基合金Inconel625焊丝进行钨极氩弧根焊后,焊区以焊丝成分为主,显微组织为奥氏体与铁素体,使该区域硬度降低到相应的技术要求。

It adopted two kinds of welding process, self-fusible welding without adding welding wire and adding nickel-based alloy welding wire, during tungsten argon arc welding root welding on liner pipe end of 316L stainless steel/X65 double-metal pipe. By comparing test, the results indicated that after self-fusible welding without adding welding wire, the hardness of pipe end self-fusion area is higher, exceeding corresponding technical requirements; However, after adding nickel-based alloy wire, the welding zone hardness is normal. The chemical composition, Viekers hardness, microstructure and micro area composition were analyzed, the results showed that adopting self-fusion welding without adding welding wire, the content of Fe is higher, the content of Cr, Ni and Mo are lower, and martensitic structure formed after cooling is the main reason leading to the high hardness in self-fusion area. After adopting nickel-based alloy Incone1625 welding wire to conduct TIG root welding, welding wire is mainly composition in fusion area ,mierostructure composite of austenite and ferrite ,so the hardness of this area is reduced to the corresponding technical requirements.