7055喷射成形高强铝合金激光焊接头组织及性能

Microstructures and mechanical properties of laser welded joint of spray formed 7055 high strength aluminum alloy

采用激光焊接对2 mm厚喷射成形的7055-T76511铝合金进行焊接试验。通过显微硬度和拉伸试验测试焊接接头的力学性能,通过光学显微镜（OM）、扫描电镜（SEM）、背散射电子衍射技术（EBSD）以及X射线衍射（XRD）分析焊接接头的微观组织。结果表明,7055铝合金激光焊接头无明显的软化区,焊缝显微硬度最低,约为130-140 HV,接头的抗拉强度372 MPa,伸长率4.1%。焊缝组织有明显的三个区（热影响区、熔合区和焊缝区）。热影响区组织是产生了部分再结晶的等轴晶粒;熔合区由于非均匀形核形成了等轴非枝晶区（non-dendritic equiaxed grain zone,EQZ）,晶粒尺寸3-8μm;焊缝区靠近熔合线为柱状枝晶,中心为胞状枝晶。

Laser welding was employed in the welding experiment of spray formed 7055-T76511 aluminum alloy plate with thickness of 2 ram.The mechanical properties of the welded joint were tested by microhardness test and tensile test.In addition,the microstructure of the welded joint were analyzed by OM,SEM, EBSD and XRD.The results show that the welded joint hasn＇t obvious soften zone,and the microhardness of the weld zone is the lowest,which is about 130-140 HV. The welded joint consist of three zones （the heat affected zone,the fusion zone and the weld zone）. The heat affected zone is characterized by equiaxed recrystallized grains,due to heterogeneous nucleation of the fusion zone formed non-dendritic equiaxed grain zone（EQZ） and an average grain size of 3-8 μm,weld area near the fusion line is columnar dendrite,and the center is cellular dendrite.