【摘要】 对压铸AZ91D镁合金进行TIG自熔焊接,研究焊接电流对压铸镁合金气孔的影响,探讨焊缝中不同区域的气孔形貌特点及形成机理。结果表明:焊接气孔主要集中在焊缝近表面和熔合线附近;焊接接头的凸起面积、熔化区面积以及气孔率均随着焊接电流的增大而增加。在焊缝近表面主要是氢致气孔,其H主要来自母材;在焊缝中心,气泡受向上的流体力和浮力作用,气孔问题并不严重;在半熔化区,气泡受阻碍其上浮运动的流体力作用,且液态金属黏度较大,气泡很难上浮逸出到熔池表面,从而滞留在半熔化区成为大气孔。更多还原

【Abstract】 The plates of die casting AZ91D magnesium alloy were autogenously welded by tungsten inert gas welding(TIG)processing.The effect of welding currents on porosity was investigated.The characteristic and formation mechanism of pores in different zones in the weld were also analyzed.The results indicate that pores are mainly present in the subsurface and near the fusion line in the weld.The area of convexity,melting and porosity all increase with the increasing welding currents.Pores in the subsurface are induced by hydrogen,which results mainly from the base metal.And pores in the center of weld,influenced by the fluid force and buoyancy,are not a serious problem.However,pores in the partially melted zone have few chances to float out of the molten pool,because of the effect of fluid force and the high viscosity of molten metal,which results in a great number of large pores in the partially melted zone.更多还原