AZ31B镁合金TIG焊焊接裂纹的产生及其特征分析

在厚度为8.0 mm 的AZ31B 镁合金板材上分别进行钨极氩弧焊 TIG 自熔焊和斜 Y 型坡口添丝焊焊接裂纹试验,研究焊接裂纹的产生原因和扩展特征,分析镁合金材料的裂纹敏感性。试验结果表明,在自拘束条件下,自熔焊焊缝区焊后立即产生焊接热裂纹,斜 Y 型坡口添丝焊焊缝区在焊接电流为170 A 和180 A 的情况下出现焊接热裂纹。自熔焊焊接热裂纹是沿晶扩展,添丝焊焊接热裂纹是沿晶与穿晶的混合扩展,裂纹在扩展过程中都存在分叉裂纹。未出现裂纹的焊接试件放置48 h 后仍然没有观察到任何形式的延迟裂纹。

Analysis of the formation and characteristics of the TIG welding cracks for the AZ31B magnesium alloy

Cracking test of the tungsten inert gas welding(TIG),autogenous welding and the Y-groove filler wire welding were carried out on the thickness of 8.0 mm of the AZ31B magnesium alloy.The forming reason and extending characteristics of the welding cracks were investigated,and the sensitivity of cracks in the magnesium alloys was analyzed.The results of the experiment showed that after autogenous welding,the hot cracks in the welding line zone were immediately discovered in the condition of self-constrain.The hot cracks when welding currents were 170 A and 180 A were immediately found after the Y- groove filler wire welding cracking test.The welding hot crack of the autogenous welding was intercrystalline extending,and that of filler wire welding was intercrystalline and transcrystalline mixed extending.There were branches during both of their extending.Any forms of delayed cracks were not discovered in other welding testing plates after deposited for 48 hours.