添加变质剂的铝合金电阻点焊工艺及接头性能

Resistance Spot Welding Process and Joint Properties of Aluminum Alloy with Modifier Addition

为实现利用单相低功率电阻点焊机焊接铝合金,获得性能达标的接头,在传统铝合金电阻点焊工艺的基础上添加变质剂并对接头的组织性能进行分析。利用YR-155S型单相交流电阻点焊机对0.8 mm的6061铝合金进行焊接,在添加不同的变质剂的基础上通过撕裂试验优化焊接工艺,采用的变质剂主要有Ti、B、Ti-B混合粉末,分析不同变质剂对6061铝合金的点焊接头组织与力学性能的影响。结果表明:添加变质剂可有效提高铝合金搭接界面的接触电阻并增加熔核直径,三种变质剂均可细化熔核区晶粒并形成均匀细小的等轴晶,其中添加Ti-B混合粉末后,β-Mg2Si相沿晶界偏析减少,弥散分布于α-Al基体,此时接头抗剪力最大,为1.52 kN。

In order to achieve the welding of aluminum alloy by single-phase low-power resistance spot welding machine and obtain the joint with good performance,the modification agent was added on the basis of the aluminum alloy resistance spot welding process,and the microstructure and properties of the joint were analyzed.The 0.8 mm 6061 aluminum alloy was welded by YR-155S single-phase AC resistance spot welding machine.On the basis of adding different modifiers,the welding process was optimized by tearing test.The modifiers mainly include Ti,B and Ti-B mixed powder.The effects of different modifiers on the microstructure and mechanical properties of 6061 aluminum alloy joint spot welded were analyzed.The results show that the addition of modifier can effectively improve the contact resistance of the lap interface of aluminum alloy and increase the diameter of the nugget.All three modifiers can refine the grains in the nugget zone and form uniform and fine equiaxed grains.After adding Ti-B mixed powder,the segregation ofβ-Mg2Si phase along the grain boundary is reduced and dispersed in theα-Al matrix.On this way,the shear resistance of the joint is the largest,which is 1.52 kN.