摘要
铝合金具有密度低、比强度高、耐蚀性强和成型性好等优点,已经成为高速列车车体轻量化制造的主要材料。激光-MIG复合焊接热输入低、焊接速度快、工艺稳定性高,是高速列车铝合金车体低变形、高效率、高质量焊接的理想技术。针对高速列车用6 mm厚6082-T6铝合金开展激光-MIG复合焊接工艺特性研究,系统研究复合焊接工艺参数对焊缝成形及内部气孔缺陷的影响规律,分析接头的组织特征、硬度分布及力学性能。研究结果表明:在获得全熔透接头条件下,激光功率在较大的变化范围内均可获得无气孔缺陷的焊缝;MIG电流显著影响气孔缺陷的分布位置,当MIG电流大于150 A时气孔缺陷主要分布在焊缝的熔合线附近;气孔缺陷的含量及尺寸随着焊接速度的增加而显著增加;热源间距为3 mm左右、保护气流量小于25 L·min;时均有利于降低气孔缺陷含量。焊缝组织由等轴晶区、柱状晶区、半熔化区和过时效区组成,电弧作用区的半熔化区和过时效区宽度均大于激光作用区。接头热影响区存在两处明显的软化区域,分别位于熔合线附近和远离熔合线2~4 mm的区域。接头的平均抗拉强度为255.1 MPa,达母材的82.3%,试件断裂于热影响区,断裂扩展路径基本与熔合线一致,整体呈现韧性断裂特征。
Due to its superior properties,such as low density,high specific strength,excellent corrosion resistance,and good formability,aluminum alloy has become the main material for the light-weight manufacturing of high-speed train body.With the characteristics of low heat input,high welding speed,and high process stability,laser-MIG hybrid welding is a promising joining technology for the high-speed train aluminum alloy body with the features of low deformation,high efficiency,and high quality.In the present work,the welding characteristics of laser-MIG hybrid welding for 6 mm thickness 6082-T6 aluminum alloy was studied.The effects of welding parameters on the weld formation and porosity defects were investigated.The microstructure features,micro-hardness distribution,and mechanical properties were also researched.The results indicated that the full-penetration weld could be performed free of porosity in a wide range of laser power.The MIG current arc significantly affected the porosity positions,and the porosity mainly existed near the fusion line of when the MIG current greater than 150 A.The content and size of the porosity both increased as the welding speed increasing.It was beneficial for the reduction of the porosity rate when the heat source distance was around 3 mm,or the gas flow rate less than 25 L·min;.The weld microstructure has consisted of the equiaxial crystal zone,columnar crystal zone,partly melted zone,and over-aging zone.The widths of the partly melted zone and over-aging zone in the arc affected zone were larger than that in the laser affected zone.There were two obvious softening areas in the heat affected area,which were located near the fusion line and 2—4 mm away from the fusion line.The average tensile strength of the joint was 255.1 MPa,which could reach up to 82.3%of the base material.The fracture occurred in the heat-affected zone,and the fracture propagation path was basically parallel with the fusion line.The fracture appearance of the laser-MIG hybrid welded joints belonged to the ductile fracture.
作者
李巧艳
赵昕
辛志彬
赵函
杨志斌
Li Qiaoyan;Zhao Xin;Xin Zhibin;Zhao Han;Yang Zhibin(CRRC Daliati Co.,Ltd.,Dalian,Liaoning 116022,China;School of Mechanical Engineering,Dalian University of Science ami Technology,Dalian,Liaoning 116052,China;School of Materials Science and Engineering,Dalian Jiaotong University,Dalian,Liaoning 116028,China)
出处
《应用激光》
CSCD
北大核心
2021年第6期1168-1177,共10页
Applied Laser
基金
辽宁省教育厅科学研究青年项目(JDL2020026)
辽宁省教育厅青年科技人才“育苗”项目(L2019008)
大连市高层次人才创新支持计划(2017RQ023)。
关键词
铝合金
激光-MIG复合焊
气孔缺陷
组织特征
力学性能
aluminum alloy
laser-MIG hybrid welding
porosity defects
microstructure
mechanical property
作者简介
李巧艳(1980-),女,硕士,高级工程师。研究方向:城市轨道车辆制造工艺等。E-mail:lqy.2005@163.com;通信作者:赵昕(1987-),女,硕士,副教授。研究方向:激光焊接及其数值模拟等。E-mail:zhaoxin881@126.com。
