振动CO_2气体保护焊缝残余应力和接头显微组织分析

Residual stress and microscopic structure in a welded seam using vibrating CO_2 arc welding method

采用振动CO_2气体保护焊对轻型汽车驱动桥壳进行了焊接。对被焊接工件在常规CO_2气体保护焊、常规CO_2气体保护焊后振动时效处理及不同激振频率下振动CO_2气体保护焊三种工艺进行了对比,并就不同条件下的焊缝残余应力、焊接接头显微组织作了分析。结果表明,采用适当振动参数,在较大振幅时,振动CO_2气保焊接能有效减小焊接变形,降低焊接残余应力,最大主动应力降低幅度达到41.74%。熔合区和过度区变窄,焊缝和热影响区晶粒明显细化,由柱状晶转变为等轴晶,魏氏组织减少甚至消失。

To improve welding characteristics of CO2 arc welding, sedan split case and sleeve of a car were welded with conventional CO2 arc welding, conventional CO2 arc welding combined with vibration aging and vibrating CO2 arc welding processes. A welded seam residual stress and microscopic structure at various welding conditions were also investigated. The experimental results indicated that the vibrating CO2 arc welding can reduce welding deformation and residual stress in cases of proper vibration parameters, resonance frequency and higher vibration amplitude. The highest Von Mises stress decreased by 41.74%. The weld bond zone and transition zone of the vibrating CO2 are welding become more narrower compared with those of the conventional CO2 arc welding. The crystalline grain in the welded seam and the heat affect zone （HAZ） became smaller. The microscopic structure changed from columnar grain to equiaxed grain,and the widmanstatten structure decreased even disappeared increasingly.