铝合金与镁合金的夹锡电阻点焊

Resistance Spot Welding between Al Alloy and MgAloV with An Insert of Tin

采用电阻点焊对铝合金A6061与镁合金AZ31B进行了焊接,并针对异种金属焊接特点,在两者焊接过程中添加锡金属层以调控接头性能。利用扫描电镜及拉伸机等设备对所得接头的组织、性能进行观察、检测。研究了电阻点焊三大工艺参数(焊接电流、时间及电极压力)对A6061/Sn/AZ31B接头中熔核的形貌及接头力学性能的影响。结果表明:镁合金侧的熔核边界区域生成了Al_(12)Mg_(17)柱状晶反应层(约10μm),铝合金侧的熔核边界区域生成了Al_(3)Mg_(2)和(Al)的共晶组织层(约3.5μm);随以上工艺参数的增大,A6061/Sn/AZ31B接头的抗剪载荷均先增大,达到最大值然后减小;且当焊接电流为30 kA、焊接时间为20 cyc、电极压力为2.1 kN时接头的抗剪载荷达到最大,约4.6 kN。

Aluminum alloy A6061 and magnesium alloy AZ31B were welded using resistance spot welding.According to the characteristics of dissimilar metal welding,tin metal layer was added during the welding process to control the joint performance.The microstructure of the joint was observed by scanning electron microscope and the properties were tested by the tensile machine.The effects of three main process parameters(welding current,time and electrode pressure)on the morphology of nuggets and mechanical properties of A6061/Sn/AZ31B joints were studied.The results show that Al_(12)Mg_(17) columnar crystal layer(about 10μm)is formed at the nugget boundary area of magnesium alloy,and Al_(3)Mg_(2) and eutectic structure layer of Al(about 3.5μm)are formed at the nugget boundary area of aluminum alloy.With the increase of the three parameters,the shear load of A6061/Sn/AZ31B joint increases firstly,then reaches the maximum value,and then decreases.When the welding current is 30 kA,the welding time is 20 cyc,and the electrode pressure is 2.1 kN,the shear load of the joint reaches the maximum of about 4.6 kN.