AZ31B镁合金/镀锌钢板电阻点焊接头形成机理

针对2.0 mm厚的AZ31B镁合金以及1.0 mm厚的SPHC镀锌钢板，采用KDWJ-17型三相次级整流电阻焊机进行焊接试验，通过光学金相、扫描电镜等方法分析接头各区域的组织结构和成分分布.提出了镁锌低熔点化合物挤压机制，分析了Zn元素在镁合金和镀锌钢板电阻点焊中的作用.结果表明，Zn与Mg元素形成的低熔点化合物MgZn₂在电极压力的作用下能填满由于焊接变形引起的间隙，使反应界面密封，促进Fe，Al元素在界面发生处扩散，Fe与Al元素在界面处发生反应生成Fe₂Al₅化合物，从而形成高强度的镁合金与镀锌钢板的电阻点焊接头.

Joint formation mechanism of AZ31B magnesium alloy and SPHC galvanized steel by resistance spot

2.0 mm thick AZ31B magnesium alloy and 1.0 mm thick SPHC galvanized steel were welded by KDWJ-17 three-phase secondary rectification resistance welding machine for welding test, and analyzed organizational structure and distribution of composition of the joints. A low-melting extrusion mechanism of compound about zinc and magnesium was proposed. The function of Zn in magnesium alloy and galvanized steel by resistance spot welding were analyzed. Zn and Mg can form low melting compounds.They can fill the gap due to welding deformation to make the reaction interface sealed. They assist the diffusion of Fe and Al at the interface. Fe and Al at the interface occurs Fe₂Al₅ compound. It forms high-strength welding joints of magnesium alloy and galvanized steel by resistance spot.