基于非对称电极的镁/钛电阻点焊接头的组织与性能

2024,45(10):202-210.Microstructure and properties of Mg/Ti joint welded by resistance spot welding with asymmetric electrodes

采用非对称电极对2 mm厚的AZ31B镁合金和TA2钛板进行了电阻点焊,研究了焊接电流和焊接时间对接头熔核直径和抗剪载荷的影响,分析了接头焊接区的微观组织。结果表明:随焊接电流的增大和焊接时间的延长,AZ31B/Ti接头的熔核直径增大,抗剪载荷呈先增大后稍微减小的变化趋势;当焊接时间为180 ms、焊接电流为16 kA和电极压力为3 kN时,接头的抗剪载荷最大,约为5.9 kN;在镁合金侧熔核内的靠近界面处形成了富Al的层状物,其内部形成了较多的结晶裂纹。基于非对称电极电阻点焊的AZ31B/Ti接头的形成过程是熔钎焊过程,熔核内靠近界面处的富Al层是制约接头性能的主要因素。

Resistance spot welding was carried out on 2 mm thick AZ31B magnesium alloy and TA2 titanium plate using asymmetric electrodes.The effects of welding current and welding time on weld nugget diameter and tensile shear load of the joint were studied,and microstructure of the joint welding zone was analyzed.The results show that with the increase of welding current and welding time,the nugget diameter of the AZ31B/Ti joint increases,and the tensile shear load shows a trend of first increasing and then slightly decreasing.When the welding time is 180 ms,the welding current is 16 kA and the electrode pressure is 3 kN,the maximum tensile shear load of the joint is about 5.9 kN.An Al-rich layer is formed near the interface in the nugget at the magnesium alloy side,and many crystalline cracks are formed inside this layer.The formation process of the AZ31B/Ti joint welded by resistance spot welding with asymmetric electrodes is a fusion brazing process,and the Al-rich layer near the interface in the nugget is the main factor restricting the performance of the joint.