Microstructures and mechanical properties of metal inert-gas arc welded Mg-steel dissimilar joints  

镁-钢异种金属MIG焊接头的显微组织与力学性能（英文）

作　　者：汪晓勇[1] 孙大千[1] 殷世强[1] 刘东阳[1] 

机构地区：[1]吉林大学材料科学与工程学院汽车材料教育部重点实验室,长春130025

出　　处：《Transactions of Nonferrous Metals Society of China》2015年第8期2533-2542,共10页中国有色金属学报（英文版）

摘　　要：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.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、AlF_3和Mg(Fe,Al)_2O_4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。

关 键 词：AZ31B Mg alloy Q235 steel metal inert-gas arc welding dissimilar metal joining 

分 类 号：TG407[金属学及工艺—焊接]