2219铝合金VPTIG焊接接头的断裂韧性

摘要

对2219铝合金变极性钨极惰性气体保护(VPTIG)焊接接头进行了拉伸、冲击和三点弯曲试验,对比研究了接头与母材的拉伸性能、冲击性能、断裂韧性及裂纹扩展行为.结果表明:焊接接头的抗拉强度为266~282 MPa,强度系数为0.6,接头强度远低于母材的;焊缝的冲击功为7~8 J,热影响区的冲击功为6~11 J,均高于母材的;当裂纹扩展量在0.14~0.35 mm时,焊缝裂纹尖端张开位移(CTOD)为0.056~0.124 mm,CTOD随裂纹扩展而增大;焊缝金属表现出比母材更好的断裂韧性,焊缝断口为弹塑性断裂,裂纹扩展区呈韧窝形貌,韧窝内存在第二相质点,使裂纹失稳扩展所消耗的能量增大.%The tension,impact and three-point bending tests were conducted on the variable polarity tangent inert gas (VPTIG)welded joint of 2219 Al alloy.Then the tensile property,impact property,fracture toughness and crack propagation process of the joint and base metal were studied and compared.The results show that the tensile strength of the welded joint was between 266 MPa and 282 MPa,which was higher than that of the base metal,and the tensile strength coefficient reached 0.6.The impact energy of the weld and heat affected zone was 7-8 J and 6-11 J,respectively,which were higher than that of the base metal.The crack tip open displacements (CTOD)in the weld were 0.056-0.124 mm with the crack extending of 0.14-0.35 mm.CTOD increased with the extension of cracks.The weld metal exhibited higher fracture toughness than the base metal.The fracture surface of the weld showed an elastic-plastic fracture feature.The crack propagation area showed dimple morphology.Some second phase particles existed in the dimples,resulting in the increase of the unstable propagation energy of the cracks.