【摘要】 采用熔化极惰性气体保护电弧焊方法（MIG）实现镁合金和低碳钢的连接,并研究焊接热循环特点和镁-钢对接接头的显微组织及力学性能。研究结果表明,在焊接过程中,接头的温度场分布是不均匀的。镁合金焊缝金属为细小的等轴晶结构。在镁/钢界面存在主要由AlFe、AlF₃和Mg（Fe,Al）₂O₄相组成的过渡层,这一过渡层是镁-钢接头的最薄弱环节。焊接线能量和焊缝Al含量对镁-钢接头的抗拉强度具有明显的影响。焊接线能量由1680J/cm增至2093J/cm,接头强度明显增加,这主要归因于镁/钢界面反应。增加焊缝Al含量至6.20%,镁-钢接头强度可达192 MPa,为AZ31镁合金母材强度的80%。因此,选择合适的焊接线能量和焊缝Al含量有利于改善镁-钢接头的抗拉强度。更多还原

【Abstract】 The joining of Mg alloy to steel was realized by metal inert-gas arc welding,and the weld thermal cycle characteristics and Mg-steel joints were investigated.The results show that the temperature distribution in the joints is uneven.Mg alloy welds present a fine equiaxed grain structure.There exists a transition layer consisting mainly of AlFe,AlFe3 and Mg（Fe,Al）₂O₄ phases at Mg/steel interface,and it is the weakest link in Mg-steel joints.The welding heat input and weld Al content have the significant effect on the joint strength.The joint strength increases with increasing the heat input from 1680 J/cm to 2093 J/cm,due to promoting Mg/steel interface reaction.When weld Al content is increased to 6.20%,the joint strength reaches 192 MPa,80%of Mg alloy base metal strength.It is favorable to select the suitable welding heat input and weld Al content for improving joint strength.更多还原