高速列车6N01侧墙激光复合焊接头软化行为分析

采用激光-电弧复合焊工艺焊接高速列车侧墙6N01铝合金型材,并对焊接接头的软化行为进行分析. 通过拉伸试验、显微硬度测试、微观金相试验和拉伸断口SEM试验,系统分析激光-电弧复合焊焊接接头软化行为,并与目前生产中应用的MIG焊接头的性能进行对比. 结果表明,采用复合焊,焊接接头强度均较MIG焊接头的强度提升10%以上,HAZ的软化区较MIG焊的减小了40%～60%;激光复合焊接头金相组织晶粒更细小,第二相质点数量多而且弥散细小,MIG焊热影响区晶粒长大倾向较大,强化相质点数量少并且尺寸较大. 采用激光-电弧复合焊方法对高速列车车体的侧墙所发生的焊接接头软化有较大的改善.

Investigation on softening of welded joint of side walls of high speed train of 6N01 aluminum alloy

In this paper, the softening of welded joint of 6N01 Al alloy of the side wall of high speed train welded with laser-MIG hybrid welding was investigated. The strength, hardness, microstructure of welded joint, fracture of tensile specimen, and chemical composition of weld metal were systematically investigated by means of tensile test, hardness test, metallographic test, and SEM test. All of them were compared with the MIG welding. The result showed that the strength of hybrid welding has increased by 10% compared with that of MIG welding, and decreased by 40% to 60%, but has more and fine major strengthening phase in the weld metal. So the welded joint softening of high-speed train body side wall can be improved greatly by using laser-arc hybrid welding.