焊接热输入对高强铝合金接头组织和性能的影响

Effect of heat input on microstructure and mechanical properties of the high strength aluminum alloy welds

采用MIG焊接工艺对2519高强铝合金进行焊接,研究了焊接热输入对焊缝组织、力学性能以及断裂特征的影响。结果表明,随着焊接热输入的增加,焊缝中心二次枝晶间距随之增加,焊缝中心溶质元素的含量随之减少,时效后焊缝中心析出的θ′相数量随之减少而尺寸随之增加,且晶界共晶组织由不连续短棒状弥散分布转变成长条状连续网络状分布,导致其断裂类型由穿晶断裂转化为沿晶断裂。接头的抗拉强度也随着焊接热输入的增加明显降低,时效后小热输入下接头的强度提升幅度更大。

2519 high strength aluminum alloy was welded with metal inert-gas welding process,and the effect of heat input on the microstructure,mechanical properties and fracture characters of the welds were studied.Results indicate that with the increase of the heat input,the second dendrite arm spacing increase and the content of solute in dendrite core decrease.After aging,the number of θ' phase decrease,but its size increase.And the morphology of the eutectic phase changes from low rod type to long band network type with the increase of heat input,which causes the fracture type from trasngrannular to intergrannular.The tensile strength reduces greatly with the increase of heat input,and the improvement of tensile strength is greater under low heat input condition after aging treatment.