搅拌摩擦焊和熔化极气体保护焊6082铝合金疲劳性能分析
Comparison of fatigue property of 6082 aluminum alloy joint by friction stir welding and metal inert-gas welding
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摘要: 对10 mm厚6082-T6铝合金进行搅拌摩擦焊(FSW)和熔化极气体保护焊(MIG焊)焊接,利用疲劳性能试验机、光学显微镜、扫描电子显微镜等手段对6082铝合金FSW和MIG焊接头的疲劳力学性能、微观组织、裂纹扩展特征、疲劳断口进行了分析. 结果表明,在疲劳寿命为2×106周次时,6082铝合金母材及其FSW和MIG焊接头的名义应力分别为126.3,110.2,84.2 MPa;在高应力水平下(Δσ=160 MPa),FSW接头疲劳寿命明显大于MIG焊接头、与母材的疲劳寿命相当. MIG焊疲劳断口均位于焊趾处,焊缝内的气孔缺陷为其主要裂纹源;FSW疲劳断口大多发生在轴肩边缘. 接头的微观断口具有准解理特征,断口中存在疲劳条纹和韧窝.Abstract: The fatigue behavior of friction stir welded (FSW) joint and metal inert-gas welded (MIG) joint of 6082-T6 aluminum alloys of 10 mm in thickness were studied by fatigue test. The microstructure of joints and fatigue crack propagation were investigated by optical microscopy and scanning electron microscopy. The results demonstrated that under cycle times of 2×106, the fatigue strength of base metal (BM), FSW joint and MIG joint are 126.3, 110.2 and 84.2 MPa, respectively. Moreover, under high stress level (σ=160 MPa), FSW joint fatigue life is significantly greater than that of MIG welded joints, and equivalent of that of the base metal. MIG joint fatigue fracture occurs at the weld toe, and the porosity defects is the main crack initiation. Most of FSW fatigue fracture appears on the shoulder edges. The micro-fracture appearance has the characteristic of quasi-cleavage pattern, and fatigue striation and dimple appear on fatigue fracture appearance.
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Keywords:
- 6082 aluminum alloy /
- friction stir welding /
- MIG welding /
- fatigue property
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