添加N_(2)保护对CMT-P复合电弧焊接头组织与性能的影响  

Influence of N_(2)protection on microstructure and properties of CMT-P composite arc welded joints

作　　者：路学成 韩玉茹 张志强 白玉洁[2] 张天刚[1] 郭志永 LU Xuecheng;HAN Yuru;ZHANG Zhiqiang;BAI Yujie;ZHANG Tiangang;GUO Zhiyong(Civil Aviation University of China,Tianjin,300300,China;Tianjin University,Tianjin,300350,China)

机构地区：[1]中国民航大学,天津300300 [2]天津大学,天津300350

出　　处：《焊接学报》2023年第4期63-70,I0007,共9页Transactions of The China Welding Institution

基　　金：国家自然科学基金资助项目(51905536);天津市自然科学基金资助项目(22JCYBJC01280);中央高校基本科研业务费项目中国民航大学专项资助项目(3122023039)。

摘　　要：以UNS S32750超级双相不锈钢为研究对象,采用冷金属过渡脉冲(cold metal transfer pulse,CMT-P)复合电弧焊接技术,运用光学显微镜、扫描电子显微镜、透射电子显微镜、X射线衍射仪和电子探针组织表征手段以及显微硬度和低温冲击韧性性能测试方法,对比研究了纯Ar和Ar+2%N_(2)气体保护对焊接接头的微观组织、硬度和低温韧性的影响规律.结果表明,与纯Ar保护气相比,添加2%N_(2)保护的焊接过程飞溅较少,焊缝平整笔直,鱼鳞纹更加细致紧密.此外,热影响区主要由过量的铁素体和少量的奥氏体组成,并伴随有害的Cr2N析出.因此,与CMT-P复合电弧焊接头的其它区域相比,热影响区的硬度较高和韧性较低.添加2%N_(2)气体保护增加了焊缝和热影响区奥氏体含量和N原子在铁素体与奥氏体内的固溶量,从而提高了接头各区域的低温韧性.Taking UNS S32750 super duplex stainless steel as research object,cold metal transfer pulse(CMT-P)composite arc welding technology was adopted.Using optical microscopy,scanning electron microscopy,transmission electron microscopy,X-ray diffraction,electron probe microstructure characterisation tools,microhardness,low temperature impact toughness properties test methods,this paper comparatively studied the influence mechanism of pure Ar and Ar+2%N_(2)as shielding gas on the microstructure,micro-hardness and low temperature toughness of welded joint.The result showed that compared with pure Ar in shielding gas,the welding process with 2%N_(2)protection has less spatter,the weld metal is flat,straight and the fish scale pattern is more detailed and tight.In addition,the heat affected zone(HAZ)is mainly composed of excess ferrite and a small amount of austenite,accompanied by some harmful precipitation of Cr2N.Therefore,compared with other areas of CMT-P composite arc welded joints,HAZ is with higher microhardness and lower toughness.The addition of 2%N_(2)increases the austenite content in the weld metal and HAZ,the solid solution amount of N atoms in the ferrite and austenite,thereby improves the low-temperature toughness of the welded joints.

关 键 词：冷金属过渡 超级双相不锈钢 微观组织 显微硬度 冲击韧性 

分 类 号：TG444[金属学及工艺—焊接]