汽车大梁用BS700MC低碳微合金钢焊接接头的组织和力学性能  

Microstructure and Mechanical Properties of Welded Joint of BS700MC Low Carbon Micro-alloy Steel for Automobile Beam

作　　者：肖轶[1,2,3] 马敏莉[2] 周代义 钟庆东[1] 

机构地区：[1]上海大学上海市现代冶金与材料制备重点实验室,上海200072 [2]南通职业大学机械工程学院,南通226007 [3]南通市钢铁冶金过程控制工程技术研究中心,南通226002

出　　处：《机械工程材料》2014年第12期15-19,104,共6页Materials For Mechanical Engineering

基　　金：南通市应用研究计划项目(BK2013033;BK2014027);南通市产学研协同创新计划项目(BC2014010)

摘　　要：通过裂纹敏感性、显微硬度、弯曲、冲击、拉伸试验及组织观察,研究了汽车大梁用BS700MC低碳微合金钢焊接接头的显微组织和力学性能。结果表明：采用WH80-G焊丝焊接时,BS700MC钢具有较好的抗裂性,焊前不需要预热处理;焊接接头的焊缝组织为针状铁素体和极少量贝氏体与先共析铁素体;焊接接头具有良好的综合力学性能,焊缝硬度为380HV,与母材相当,接头底部硬度分布波动明显,热影响区存在软化现象,在-20~20℃范围内焊接接头具有良好的冲击韧性;接头的抗拉强度为815 MPa,为母材的97.1%,断裂于热影响区,拉伸断口为韧窝与解理台阶混合型断口。Microstructure and mechanical properties of welded joint of BS700 MC low carbon micro-alloy steel for automobile beam were investigated by testing cold crack sensitivity,micro-hardness,bending performance,impact property,tensile property and microstructure observation.The results show that the BS700 MC steel had good crack resistance,and didn′t need heat treatment before welding with WH80-G welding wires.The microstructure of the weld was acicular ferrite,very little bainite and proeutectoid ferrite.The welded joint had good comprehensive mechanical property.The hardness of weld was 380 HV,which was close to the base metal.But the hardness had obvious fluctuation at the bottom of welded joint,and softened phenomenon appeared in the HAZ.The welded joint had good impact toughness in the temperature range from-20℃to 20℃.The tensile strength of BS700 MC welded joint reached 815 MPa,which was 97.1% of the base metal,and fracture position located in the HAZ.Tensile fracture showed mixed type of dimples and cleavage steps.

关 键 词：汽车大梁 BS700MC低碳微合金钢 焊接接头 显微组织 力学性能 

分 类 号：TG444.1[金属学及工艺—焊接]