点焊电极压力对2A21铝合金微观组织中柱状晶和等轴细晶的影响

Spot welding electrode pressure's effect on columnar grain and equiaxed fine grain of the 2A21 aluminum alloy

研究不同焊接电极压力对酸洗和未酸洗的2A21铝合金试样的拉剪强度和点焊接头微观组织的影响。结果表明,经过酸洗的试样焊后无表面裂纹,而未酸洗的试样焊后焊点质量较差,存在表面裂纹;焊接压力0.24MPa、焊接时间110ms、焊接电流18kA时,焊点成形状况最佳,且熔核直径随电极压力的增大而减小,此时,柱状晶及大量的等轴细晶弥散分布,拉剪屈服强度最大。

The study was conducted on the effects of the spot welding electrode on the tensile shear strength and the spot welded joints＇ microstructure of 2A21 aluminum alloy samples with or without pickling. The results show that： There was no crack on the surface of welded samples which were pickled, and the poor welding quality appeared on the surface of welding joints which were not pickled; With the welding pressure, welding time and welding current of 0.24MPa, ll0ms and 18KA, respectively,, the conditions of joints formation were optimal, the diameter of the nugget increased as the electrode pressure decreased, and the columnar grains and plenty of equiaxed fine grains were dispersed resulting in maximum tensile shear yield strength.