22MnB5和QStE550TM的异种钢接头碳迁移现象分析  

Analysis of carbon migration phenomenon in dissimilar steel joints of 22MnB5 and QStE550TM

作　　者：张朋彦 张明 周磊磊 梁恩荣 朱志刚 ZHANG Pengyan;ZHANG Ming;ZHOU Leilei;LIANG Enrong;ZHU Zhigang(School of Metallurgical Engineering,Anhui University of Technology,Maanshan 243032,Anhui,China;Panzhihua Iron and Steel Research Institute Co.,Ltd.,Pangang Group,Panzhihua 617000,Sichuan,China;Construction Branch,Engineering Technology Co.,Ltd.,Pangang Group,Panzhihua 617000,Sichuan,China)

机构地区：[1]安徽工业大学冶金工程学院,安徽马鞍山243032 [2]攀钢集团攀枝花钢铁研究院有限公司,四川攀枝花617000 [3]攀钢集团工程技术有限公司修建分公司,四川攀枝花617000

出　　处：《钢铁》2024年第10期86-95,共10页Iron and Steel

基　　金：国家自然科学基金资助项目(52274375);安徽省重点研发计划资助项目(202104a05020020)。

摘　　要：碳迁移一直是异种钢焊接所需要关注的重点问题,同时碳元素的迁移会导致焊接接头出现力学性能不均匀的情况。通过探究22MnB5和QStE550TM这2种低合金高强钢焊接后的碳迁移现象,为22MnB5和QStE550TM的异种钢焊接应用到实际汽车制造中提供理论支持。试验选用H08Mn2Si焊丝,采用钨极氩弧焊(TIG)对QStE550TM钢与22MnB5钢进行连接,并且利用光学显微镜(OM)、扫描电镜(SEM)、电子背散射衍射分析(EBSD)以及电子探针(EPMA)等表征方法研究异种钢接头碳迁移程度以及显微组织,利用万能试验机分析碳迁移现象是否对该异种钢接头的整体力学性能产生明显的影响。结果显示,焊接接头的焊缝区域及两侧热影响区主要由贝氏体组成,其中焊缝区域以大角度晶界为主,并且晶粒大小较为均匀。焊缝区域与热影响区的主要组成相为铁素体,也出现了(Fe,Ni)的第二相析出。22MnB5侧熔合界面存在C元素的偏聚,其增碳层厚度约为70μm,增碳层的显微组成除了板条贝氏体,还观察到了羽毛状贝氏体与针状铁素体。接头的拉伸性能与弯曲性能良好,拉伸试样的断裂形式均为韧性断裂,位置为QStE550TM侧,弯曲试样经过面弯与背弯试验以后仍然完好并且均未出现裂纹。综合上述分析结果可知,此异种钢接头的碳迁移现象并未明显影响到整体力学性能,而且此接头不需在高温高压等极限环境下服役,因此,使用H08Mn2Si焊丝可以得到符合实际生产应用的异种钢接头。Carbon migration has always been a key issue in the welding of dissimilar steels,and the migration of carbon elements will lead to uneven mechanical properties of welded joints.The carbon migration phenomenon of 22MnB5 and QStE550TM low alloy high strength steels after welding is investigated,which provides theoretical support for the application of dissimilar steel welding of 22MnB5 and QStE550TM in actual automobile manufacturing.H08Mn2Si welding wire was used to weld QStE550TM steel and 22MnB5 steel by argon tungsten arc welding(TIG).Optical microscope(OM),scanning electron microscope(SEM),electron backscattering diffraction(EBSD)and electron probe analysis(EPMA)were used to study the carbon migration degree and microstructure of dissimilar steel joints,and universal testing machine was used to analyze whether the carbon migration phenomenon had obvious influence on the overall mechanical properties of the dissimilar steel joints.The results show that the weld area and the heat affected zone on both sides of the welded joint are mainly composed of bainite,and the weld area is dominated by large angle grain boundaries,and the grain size is relatively uniform.Ferrite is the main component phase in the weld zone and heat affected zone,and the second phase(Fe,Ni)is also precipitated.C element segregation exists at the fusion interface of 22MnB5,and the thickness of carburization layer is about 70μm.Besides lath bainite,feathery bainite and acicular ferrite are also observed in the carburization layer.The tensile and bending properties of the joints are good.The fracture mode of the tensile specimens is ductile fracture at QStE550TM side.The bending specimens are still intact and no cracks appear after face bending and back bending tests.Based on the above analysis results,it can be seen that the carbon migration phenomenon of this dissimilar steel joint does not obviously affect the overall mechanical properties.Combined with the fact that this joint does not serve in extreme environments such as high temperature

关 键 词：异种钢 碳迁移 夹杂物 力学性能 显微组织 贝氏体 

分 类 号：TG457.11[金属学及工艺—焊接]