铜铝异种金属激光焊接焊缝成形和组织

Weld formation and microstructure of Cu-Al dissimilar metals by laser welding

用IPG YLS-1500型光纤激光器对TU1镀镍无氧铜和6061铝合金进行激光搭接焊试验,探究焊缝成型及显微组织,通过扫描电子显微镜(SEM)和能谱仪(EDS)观察并分析接头的组织形貌。结果表明:接头成型良好,铜铝充分融合,焊缝横截面处有明显的铝向铜侧扩散。铝侧熔合线到焊缝中心,先形成珊瑚状的亚共晶组织Al_(2)Cu+Al Cu,而后是平行排列的板条状Al_(2)Cu和块状Al Cu,最后为紧密排列的块状Al Cu和Al_(4)Cu_(9)。由于熔池溶液的流动,熔池中出现了不规则的"T"形晶粒。接头的剪切力达铜母材拉伸力的43.0%,为脆性断裂,接头内生成的Al_(2)Cu和Al_(3)Cu_(4)金属化合物是导致裂纹扩展的主要原因。

IPG YLS-1500 fiber laser was used to weld TU1 nickel-plated oxygen-free copper and 6061 aluminum alloy by laser lap welding.The weld formation and microstructure were investigated.The microstructure of the joint was observed and analyzed by scanning electron microscopy(SEM)and energy dispersive spectrometer(EDS).The results show that the welded joint is well formed.The aluminum phenomenon intruding into copper occurrs in the cross section of the weld seam.The aluminum side fusion line is fused to the weld center,and the coral-like hypoeutectic structure Al_(2)Cu+Al Cu is formed first,then the parallel arranged slatted Al_(2)Cu and massive Al Cu are formed,and finally the close arranged massive Al Cu and Al_(4)Cu_(9)precipitate.Due to the flow of molten pool solution,irregular"T"shaped grains appear in the molten pool.The shear force of the joint is 43.0%of the tensile force of the copper base metal,and the fracture type is brittle fracture.The main cause of crack propagation is the formation of Al_(2)Cu and Al_(2)Cu;metal compounds in the welded joint.