2024-T4铝合金光纤激光填丝焊缝横截面分为钉头形和近X形2种典型形貌,对比分析了该2种形貌的焊缝成形与组织形态、显微硬度和接头拉伸性能的相关性.结果表明:近X形横截面的焊缝在焊接过程中更加平稳,焊接飞溅更少.焊缝区的组织特征为垂直于熔合线相对生长的柱状晶组织和焊缝中心的等轴晶组织.钉头形焊缝中心晶粒的二次枝晶较发达,逐渐形成等轴树枝晶,而近X形焊缝中心晶粒相对细小,呈现为等轴胞状晶.与钉头形横截面的接头相比,近X形横截面的接头焊缝区析出的强化相θ(Al2Cu)相对较多,平均显微硬度值略高,热影响区的软化现象逐渐减弱,接头强度和塑性略低.%Two typical cross-section of welds,including nail shape and near X shape,are obtained in the process of fiber laser welding 2024-T4 Al alloy with filler wire.The correlations of the two weld appearances and other elements (such as microstructure,microhardness,and joint's tensile properties) were analyzed.The results show that the weld with near X shape cross-section during the welding process is more stable than that with nail shape cross-section,and the welding spatter of the former is smaller than that of the latter.The microstructure of the weld zone is columnar grains and equiaxed grains,the columnar grains are formed near the fusion line and growing along the vertical direction of the fusion line,the equiaxed grains are distributed in the center of the weld zone.The secondary dendrite of the grains in the center of the weld with nail shape cross-section grows better,and gradually forms to equiaxed dendrite,while the grains size of the weld with near X shape cross-section is relatively finer,exhibiting equiaxed cellular grain.Compared with the joint with nail shape crosssection of the weld,the joint with near X shape cross-section of the weld have some different characteristics,the precipitation strengthening phase θ(Al2Cu) content in weld zone of the latter is more than that of the former,the average microhardness value of the weld zone of the latter is higher than that of the former,the softening phenomenon of heat affect zone (HAZ) of the latter is weaker than that of the former,and the joint's tensile strength and plasticity of the latter are lower than that of the former slightly.
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