AZ31B镁合金TIG/MIG焊焊接接头的腐蚀研究

Corrosion performance of AZ31B magnesium alloy joints welded by TIG welding and MIG welding

对AZ31B镁合金的TIG焊和MIG焊接头进行酸洗的腐蚀研究,分析腐蚀后接头各区域的表面状况及腐蚀原因,利用金相图和XRD对TIG焊和MIG焊接头的腐蚀差异进行探讨。结果表明:较大电流焊接的接头经酸洗处理后,表面较为平整且均匀,腐蚀产物相对较少,晶界具有一定连续性;晶粒细小、晶界处分布大量析出相,导致焊接接头腐蚀严重,是MIG焊与TIG焊接头酸洗腐蚀差异的主要原因。

In this paper,the corrosion porperties in acid pickling solution were studied for the joints of AZ31 B magnesium alloy welded by TIG welding and MIG welding,respectively,and the surface feature and the cause of corrosion were analyzed for each part of the joints,then the corrosion difference between the joints welded by TIG welding and MIG welding were simply discussed based on metallographic examination and XRD method. The results show that the surface of the joint welded under the condition of larger current is relatively smooth and uniform,with less the corrosion products,and the grain boundary still maintained a certain continuity. Fine grain size and large amount of precipitated phase distributed at the grain boundary would lead to severe corrosion of the welded joint,which is the main reason for the corrosion difference between the MIG welding and the TIG welding joints treated by acid pickling solution.