引入CMT-P复合焊接方法成功制备了成形质量优异的UNS S32750超级双相不锈钢焊接接头，选用金相显微镜、X射线衍射仪、扫描电镜、能谱仪及透射电镜等设备研究了接头不同区域的微观组织. 结果表明，焊缝、热影响区和母材组织呈现显著差异. 与母材和焊缝相比，热影响区内奥氏体含量最低(32.3%)，但焊接接头各微区的奥氏体含量均满足不低于30%的标准要求．由于焊接热循环过程中再加热的作用，焊根及热影响区中析出了尺度和形貌均不同的晶粒内γ2和晶粒边界γ2，而焊缝填充区没有γ2析出．此外，焊根和热影响区均析出了短棍状Cr2N，主要分布在铁素体晶粒内和晶粒边界，Cr2N析出致使相邻铁素体基体形成了明显的贫Cr区．
By introducing the CMT-P welding method, the welded joints of UNS S32750 super duplex stainless steel with excellent forming quality were successfully prepared. Metallographic microscope, X-ray diffractometer, scanning electron microscope, energy dispersive spectrometer and transmission electron microscope were used to study the microstructure of different regions of the joint. The results showed that the weld, heat-affected zone and base metal structure show significant differences. Compared with the base metal and the weld, the austenite content in the heat-affected zone is the lowest (32.3%), but the austenite content in each micro-zone of the welded joint meets the standard requirement of not less than 30%. Due to the effect of reheating during the welding thermal cycle, intra-grain γ2 and grain boundary γ2 with different scales and morphologies are precipitated in the weld root and heat-affected zone, but there is no γ2 precipitation in the weld filling zone. In addition, short rod-shaped Cr2N precipitated in the weld root and heat-affected zone, which is mainly distributed in the ferrite grains and grain boundaries. The precipitation of Cr2N caused the adjacent ferrite matrix to form an obvious Cr-poor zone.
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