双脉冲对7A52铝合金MIG焊接质量的影响

摘要

采用了直流双脉冲MIG和直流单脉冲MIG的焊接方式,针对6 mm厚度的7A52铝合金,分别进行了对接试验,对两者焊缝外观成型,接头力学性能,显微组织进行了分析研究.结果表明,采用双脉冲的焊缝外观成型鱼鳞纹更加均匀清晰;拉伸强度达到230 MPa,比单脉冲高28 MPa;焊缝区最低显微维氏硬度为68.9 HV,比单脉冲高11.6 HV.焊缝区显微组织主要是白色的α相和弥散分布的析出相Al3 Mg2,以及少量絮状分布的镁锌强化相组成,铝镁共晶物以及镁锌强化相在一定程度上提高了焊缝的力学性能.%ln this paper, the DC double pulse MIG welding and the DC single pulse MIG welding are used to weld 6mm-thick 7A52 aluminum alloy. The appearance, mechanical properties and microstructure of the weld are compared and analysed. The results show that the double pulse MIG welding can be used to obtain a better performance with distinct Fish-scale pattern. The tensile strength is 230 MPa, 28 MPa higher than the single pulse MIG welding. The lowest HV hardness of the bead section is 68.9HV, 11.6HV higher than the single pulse MIG welding. The main microstructure of the bead section is whiteαphase and dispersed precip-itates Al3 Mg2 , and some flocculent Mg-Zn strengthening phase, which can enhance the mechanical properties of the weld joint.