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采用自动MIG焊焊接6005A-T6铝合金。使用高频疲劳试验机对焊接接头的疲劳性能进行测试,绘制了S-N曲线,测定其疲劳极限,并对接头的疲劳断口和显微组织进行了分析,研究疲劳断裂的原因。结果表明:6005A铝合金接头的高周疲劳极限应力为105 MPa,S-N曲线拟合公式为δ_(max)=16167N_f~(-0.383);高应力状态的疲劳断口与静态拉伸断口相似,疲劳裂纹萌发区存在缺陷,在疲劳裂纹扩展区未发现呈放射性的扩展辉纹;低应力状态的断口疲劳也萌发于缺陷处,但存在大量扩展辉纹。焊缝组织较为均匀,但是热影响区的粗晶区和焊缝区晶界聚集的第二相对疲劳性能不利。
Using automatic MIG welding 6005A-T6 aluminum alloy. The fatigue performance of the welded joint was tested by using a high-frequency fatigue tester. The S-N curve was drawn and its fatigue limit was measured. The fatigue fracture and microstructure of the joint were analyzed to investigate the cause of fatigue fracture. The results show that the high-cycle fatigue limit stress of 6005A aluminum alloy joint is 105 MPa and the SN curve fitting formula is δ max = 16167N_f ~ (-0.383). The fatigue fracture of high stress state is similar to static tensile fracture, and the fatigue crack There are some defects in the germination area, and no radiating exfoliation pattern is found in the fatigue crack growth area. The fracture fatigue in the low stress state also germinates in the defect, but there are a lot of extended fringes. The weld microstructure is more uniform, but the second relative fatigue performance of the coarse grain zone and the grain boundary of the weld zone in the heat affected zone is unfavorable.