以0.7 mm厚汽车用DX54+Z镀锌钢板为研究对象,基于正交试验设计不同焊接工艺的三层钢板点焊试验,并对熔核尺寸、拉剪强度等指标进行检验。结果表明:焊接时间对熔核尺寸的影响最大,焊接电流和电极压力相对较小;随焊接电流的增加,熔核直径先减小后增加;随焊接时间的延长,熔核直径呈线性增加;随电极压力的提高,熔核直径逐渐减小。焊接时间对拉剪强度的影响最大,其次是焊接电流,电极压力影响最小;随焊接电流的增加,拉剪强度先减小后增加;随焊接时间的延长,拉剪强度呈线性增加;随电极压力的提高,拉剪强度几乎不变。综合考虑熔核直径和拉剪强度指标,优化的焊接工艺参数:焊接电流为11 kA,焊接时间为260 ms,电极压力为1.5 kN。 Taking the DX54 + Z galvanized steel for automotive 0.7 mm thick as the research object, the three-layer steel spot welding experiment with different welding processes was designed based on the orthogonal test. The nugget size, tensile shear strength and other indexes were tested. The results show that the welding time has the biggest influence on the size of nugget, and the welding current and electrode pressure are relatively small. With the increase of welding current, the diameter of nugget first decreases and then increases. With the increase of welding time, the diameter of nugget increases linearly. With the increase of electrode pressure, the diameter of nugget decreases gradually. The welding time has the greatest influence on the tensile strength, followed by the welding current, and the electrode pressure has the least effect. With the increase of the welding current, the tensile strength first decreases and then increases. With the extension of the welding time, the tensile strength increases linearly. Increased pressure, tensile shear strength almost unchanged. Considering nugget diameter and tensile strength, the optimized welding parameters are as follows: the welding current is 11 kA, the welding time is 260 ms and the electrode pressure is 1.5 kN.