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通过激光焊接方法对7449铝合金进行焊接,并对焊接接头整体进行焊后固溶处理。运用光学显微镜(OM)、扫描电镜(SEM)、显微维氏硬度计、疲劳试验机等方法对固溶处理前后的焊接接头进行显微组织观察以及宏观力学性能表征。结果表明,7449铝合金激光焊接接头在固溶处理之后,其接头组织分布更加均匀,晶粒尺寸略有增大,第二相粒子明显减少;拉伸时,固溶处理前后焊接接头的断裂位置均在焊缝和熔合线附近;固溶处理前后焊接接头的抗拉强度分别为268.4 MPa和425.6 MPa,焊接接头的平均显微硬度分别为111.2 HV20和141.8 HV20;经固溶处理后,焊接接头的断裂方式由固溶处理前的沿晶断裂变为韧性断裂。
The 7449 aluminum alloy is welded by the laser welding method, and the post-weld solution treatment is performed on the welded joint as a whole. The microstructure and mechanical properties of the welded joint before and after solution treatment were observed by optical microscope (OM), scanning electron microscope (SEM), micro Vickers hardness tester and fatigue tester. The results show that the joint microstructure of 7449 aluminum alloy after laser treatment is more uniform and the grain size increases slightly and the second phase particles decrease obviously. When tensile, the fracture location of the welded joints before and after solution treatment The tensile strength of the welded joints before and after the solution treatment were 268.4 MPa and 425.6 MPa respectively, and the average microhardness of the welded joints was 111.2 HV20 and 141.8 HV20, respectively. After solution treatment, the welded joints The fracture mode changes from intergranular fracture before solution treatment to ductile fracture.