6005铝合金搭接接头组织及疲劳性能研究

采用熔化极惰性气体保护(MIG)焊对6005铝合金进行搭接焊接试验.对焊接接头进行微观组织观察和显微硬度测试,结果显示,熔合区出现联生结晶特点,焊缝中心以等轴晶为主,热影响区(HAZ)晶粒发生严重粗化,焊缝区的维氏硬度(HV)为64.5,母材区为89.6,接头出现明显软化区.在疲劳性能测试中焊接接头疲劳强度只有母材的2...

Study on Microstructure and Fatigue Properties of 6005 Aluminum Alloy Lap Joint

Metal inert-gas (MIG) welding was used to conduct lap welding experiments on 6005 aluminum alloy. The microstructure and microhardness of the welded joint were observed. The results show that the intergrowth crystal appears in the fusion zone, the equiaxed crystal is dominant in the weld center, and the grain coarsening has occurred in the heat affected zone (HAZ). The Vickers hardness (HV) of the weld zone is 64.5, and that of the base metal zone is 89.6, and the joint appears obvious softening zone. The fatigue strength of the welded joint is only 21.41% of the base material in the fatigue performance test, and the fatigue fracture of the welded joint is a mixed fracture of ductile fracture and dissociative fracture. By analyzing the mechanism of fatigue crack propagation, it is concluded that the crack propagates in a “Z” shape along the 45° direction under the condition of crack tip passivation and loading stress cycle.