材料科学
焊接
极限抗拉强度
微观结构
拉伸试验
复合材料
冶金
接头(建筑物)
合金
扫描电子显微镜
晶间断裂
穿晶断裂
晶间腐蚀
结构工程
工程类
作者
Cong Fan,Shanglei Yang,Chenfeng Duan,Minqi Zhu,Yishan Bai
标识
DOI:10.1007/s11771-022-4954-4
摘要
In this paper, 3 mm 6061 aluminum alloy sheets were welded by laser MIG hybrid welding. Based on the experiment, the best welding parameters were determined to ensure the penetration welding. The detailed microstructure, tensile and fatigue fracture morphology and surface fatigue damage of the welded joints were analyzed by optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results show that there are two main kinds of precipitates, one is the long Si rich precipitates at the grain boundaries, the other is the intragranular Cu rich precipitates. The tensile test results show that the tensile strength of the joint is 224 MPa, which is only 70.2% of the base metal. Through the analysis of tensile fracture, there are great differences in the formation of tensile dimple. In the tensile-tensile fatigue test with a stress rate of 0.1, the conditional fatigue limits of base metal and welded joint are 101.9 MPa and 54.4 MPa, respectively. By comparing the fatigue fracture of the welded joints under different stress amplitudes, it was found that the main factor leading to the fracture of the joint is porosity. Through further analysis of the pore defects, it was found that there are transgranular and intergranular propagation ways of microcracks in the pores, and the mixed propagation way was also found.
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