热输入对镁合金对焊接头微观组织和力学性能的影响

摘要

The effects of heat input on the microstructures and mechanical properties of tungsten inert gas (TIG) butt-welded AZ31/MB3 dissimilar Mg alloys joint were investigated by microstructural observations, microhardness testing and tensile testing. The results reveal that with the increase of heat input, the width of welding seam increases obviously and the grains both in the fusion zone and the heat affected zone coarsen during TIG welding process. The tensile strength of butt-welded joint increases with the increase of heat input and the maximum joining strength of 242 MPa is obtained with welding current of 90 A. However, lots of welding pores occur with the further increase of heat input, which results in the decrease of joining strength. It is experimentally demonstrated that robust joint can be obtained by TIG welding process.%通过观察微观结构、硬度检测和力学性能检测,研究热输入对AZ31/MB3镁合金钨极氩弧焊接头微观组织和力学性能的影响.实验结果表明:随着热输入的增加,焊缝宽度明显增加,同时接头熔焊区和热影响区的晶粒也出现粗化.镁合金对焊接头的力学性能也随热输入的增加而增强,当焊接电流为90 A时,焊件达到最高连接强度242 MPa.然而当焊接电流过大时,焊接孔洞出现,导致接头连接强度下降.综上所述,可以通过钨极氩弧焊工艺获得可靠的镁合金接头.