基于Fe-Cr-Ni基钎料的SUS444/SUS304接头钎焊工艺及组织与性能  

Brazing process,microstructure and properties of SUS444/SUS304 joints based on Fe-Cr-Ni based brazing filler metal

作　　者：李朋成 陆青松 王凯 韩琦 王雷刚[1] Li Pengcheng;Lu Qingsong;Wang Kai;Han Qi;Wang Leigang(Jiangsu University,Zhenjiang 212013,Jiangsu,China;Zhejiang Yinlun Machinery Co.,Ltd.,Taizhou 317200,Zhejiang,China)

机构地区：[1]江苏大学,江苏镇江212013 [2]浙江银轮机械股份有限公司,浙江台州317200

出　　处：《焊接》2023年第12期23-31,共9页Welding & Joining

摘　　要：采用新型Fe-Cr-Ni基钎焊材料对SUS444/SUS304异种不锈钢进行真空钎焊,研究了搭接接头的扩散连接机制,探究了钎焊温度、搭接间隙参数对显微组织和室温抗剪强度的影响规律,最后分析了T形接头在酸性介质中不同时间的浸泡腐蚀行为。结果表明,在钎焊过程中,钎料在SUS444母材侧扩散作用较为明显,存在较宽的元素扩散区,钎缝主要由两侧界面区先凝固Fe(Cr,Ni,Si)固溶体、钎缝中心区(Fe,Cr,Ni)_(3)P金属间化合物及Fe(Cr,Ni,Si)固溶体形成的类似共晶组织构成;钎料对钎焊温度较为敏感,温度过高,易产生虚焊孔穴,导致抗剪强度下降明显;钎料对搭接间隙敏感性较小,可满足大间隙钎焊要求。在钎焊温度1125℃、搭接间隙35μm条件下,抗剪强度最大达到177.3 MPa。T形接头腐蚀优先发生在钎角共晶组织中的Fe(Cr,Ni,Si)固溶体,浸泡腐蚀288 h后,溶液侵蚀至钎角界面区,并蚀穿先凝固固溶体,对母材进行电偶腐蚀。A new Fe-Cr-Ni based brazing filler metal was used for vacuum brazing of SUS444/SUS304 dissimilar stainless steels.Diffusion bonding mechanism of lap joints was researched,and effects of brazing temperature and lap gap on microstructure and room temperature shear strength were investigated.Finally,immersion corrosion behavior of T-joints in acid medium for different periods of time was analyzed.The experiment showed that during brazing process,diffusion effect of brazing filler metal on SUS444 base metal side was more obvious,and there existed a wider element diffusion zone.Brazing seam was mainly composed of pre-solidified Fe(Cr,Ni,Si)solid solution in the interface zone on both sides and eutectic microstructure formed by(Fe,Cr,Ni)_(3)P intermetallic compound and Fe(Cr,Ni,Si)solid solution in the center of brazing seam.Brazing filler metal was sensitive to brazing temperature.If the temperature was too high,it was easy to produce false brazing holes,resulting in a significant decrease of shear strength.Brazing filler metal was less sensitive to lap gap and could meet requirements of brazing with large gap.The maximum shear strength reached 177.3 MPa under conditions of brazing temperature of 1125℃and lap gap of 35μm.Corrosion of T-joints preferentially occurred in Fe(Cr,Ni,Si)solid solution of eutectic structure at brazing corner.After immersion for 288 h,corrosion solution eroded to interface area of brazing corner and passed through pre-solidified solid solution to make galvanic corrosion of base metal.

关 键 词：真空钎焊 Fe-Cr-Ni基钎料 SUS444不锈钢 抗剪强度 钎焊工艺 

分 类 号：TG454[金属学及工艺—焊接]