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采用激光焊接方法对2 mm厚喷射成形的7055铝合金进行了焊接实验。通过背散射电子衍射技术(EBSD)、扫描电镜(SEM)、能谱仪(EDS)、透射电镜(TEM)、显微硬度和室温拉伸试验等测试方法对焊接接头的微观组织和力学性能进行了分析。结果表明:7055铝合金激光焊接头热影响区无明显的软化,焊缝显微硬度最低,约为母材的77%,接头的抗拉强度和伸长率分别约为母材的61%和4.1%。热影响区观察到发生了再结晶的等轴晶粒,但晶内可观察到弥散的η’相;熔合线附近形成了晶粒取向随机分布的细小的等轴非枝晶区;焊缝区靠近熔合线为柱状枝晶,靠近焊缝中心为胞状枝晶,晶内无弥散强化相。综上所述,这些区域的微观组织特征揭示了焊接接头的不均匀性,其综合机械性能较母材有所下降,焊缝成为接头的最薄弱环节。
The laser welding method was used to weld the 2mm thick spray-formed 7055 aluminum alloy. The microstructure and mechanical properties of the welded joint were studied by backscattering electron diffraction (EBSD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), microhardness and room temperature tensile test Analysis. The results show that the heat affected zone of 7055 aluminum alloy laser welded joint has no obvious softening, and the microhardness of the weld is the lowest, about 77% of the base metal, the tensile strength and elongation of the joint are about 61% and 4.1% %. In the heat-affected zone, recrystallized equiaxed grains were observed, but the dispersed η ’phase was observed in the grain boundaries; small equiaxed nondendritic zones were randomly distributed around the weld line. The weld zone Close to the fusion line for the columnar dendrite, near the center of the weld cell dendrites, no dispersion within the enhanced phase. In summary, the microstructural characteristics of these regions reveal the inhomogeneity of weld joints, the decrease of their overall mechanical properties compared with that of the parent metal, and the weld joint becoming the weakest link.