中文摘要：

采用电阻点焊作为热源,进行AZ31镁合金与Q235钢的直接连接。通过扫描电镜、金相显微镜以及万能实验机分析与测试镁-钢点焊接头的微观组织、界面特性以及拉剪性能。研究表明,虽然镁和铁之间几乎不能互溶和形成金属间化合物,但氧和铝元素在镁合金-钢直接电阻点焊中起决定性作用,在镁-钢界面某些区域促进了以镁、铝、氧以及铁元素组成的复杂元素扩散层的形成,而镁、钢之间物理性能的巨大差异在一定程度上限制了界面反应的均匀性,接头拉剪强度约为40 MPa。

英文摘要：

AZ31 magnesium alloy and Q235 mild steel were joined using resistance spot welding. The microstructure, interface characteristics and mechanical properties were examined by scanning electron microscope,,netallurgical microscope and the universal testing machine. Studies show that magnesium and iron are nearly zero solubility ,but the oxygen and aluminum elements play a decisive role in the direct joining of tire magnesium alloy and steel,which promotes the formation of a complex diffusion layer composed of magnesium,aluminum,oxygen and iron elements at some regions of Mg-steel interface. The great difference between Mg and steel in their melting physical properties limits the uniformity of the interfacial reaction ,and tensile shear strength of joint is about 40 MPa.