2A12铝合金TIG焊接接头显微组织及性能

Microstructure and Properties of TIG Welded Joint of 2A12 Aluminum Alloy

采用ER4043焊丝对2A12铝合金进行钨极惰性气体保护焊(TIG焊),通过显微组织观察(OM和SEM)、拉伸性能及硬度检测,对焊接接头显微组织及性能进行了研究。结果表明:2A12焊接接头热影响区晶粒大小不一。焊缝区显微组织为典型的铸态枝晶,呈现网状分布特征,枝晶组织的生长具有方向性。焊接接头抗拉强度平均值为281.3MPa,为母材的67.9%。母材断口呈韧窝型延性断裂,焊缝断口呈脆韧型混合断裂。焊缝中心硬度较低,其值为86 HB。热影响区是焊接件的最薄弱环节,硬度最低,仅为82 HB。275℃×12 h热处理对2A12焊接件的硬度影响很小。

Tungsten inert gas welding(TIG welding)of 2A12 aluminum alloy was carried out by using ER4043 welding wire.The microstructure and properties were studied by microstructure observation,tensile and hardness test.The results shows that the grain size of the heat affected zone of 2A12 welded joint is different.The microstructure of the weld zone is typical as cast dendritic structure,which shows network distribution characteristic,and the growth of dendrite structure is directional.The average tensile strength of welded joint is 281 MPa,which is 67.9%of base metal.The fracture of the base metal is dimple ductile fracture,and the fracture of the weld is brittle and tough mixed fracture.The hardness of weld center is lower,the value reaches 86 HB.The HAZ is the weakest zone,the hardness is the lowest,the value is only 82 HB.The effect of 275℃×12 h heat treatment on the hardness is negligible.