【摘要】 对压铸AZ91D镁合金进行GTAW焊接,采用扫描电子显微镜观察焊缝气孔的形貌、类型及分布特征,研究气孔的形成机制,讨论热输入对焊缝气孔的影响。结果表明,自熔焊焊缝气孔问题严重,微小气孔主要集中分布在焊缝近表皮和熔合线附近,宏观气孔主要分布在焊缝中部区域。随热输入的增大,最大宏观气孔尺寸及气孔率均增大。添加填充材料,能够明显降低焊缝气孔率,减小气孔尺寸,但不能彻底消除焊缝气孔。更多还原

【Abstract】 The welding joint of AZ91 D alloy was prepared by GTAW, and the microstructures, types and distribution characteristics of the pore were observed by scanning electron microscopy. The formation mechanism of the pore was explained and the effects of heat input on the pore were discussed. The results show that the microstructures are mainly distributed in the weld near the surface and the weld line, and the macroscopic pores are mainly distributed in the middle of the weld. With the increase of heat input, the size of the maximum macropore and the porosity will increase. Adding filler materials can obviously reduce the porosity of welding, reduce the size of macro pores, but it can’t completely eliminate the welding pores.更多还原