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铝合金激光-多股绞合焊丝MIG复合焊接头组织与性能分析

Microstructure and performance analysis of laser-MIG hybrid welding joints of aluminum alloy with multi-stranded wire

  • 摘要: 选用1 × 3结构的ER5356铝合金多股绞合焊丝,进行5A06铝合金激光-多股绞合焊丝MIG复合焊对接试验,通过金相、扫描电镜、电子背散射衍射、拉伸和硬度测试等方法对20 mm厚焊接接头的微观组织和力学性能相关性进行分析. 结果表明,铝合金激光-多股绞合焊丝MIG复合焊工艺性较好,焊缝主要由α(Al)基体和弥散分布的Al3Mg2第二相组成,焊缝中心区以等轴晶为主,晶粒的平均尺寸为34.83 μm;热影响区晶粒细小,存在回复再结晶,晶粒的平均尺寸为10.21 μm. 焊接接头硬度在75 ~ 90 HV之间,其中熔合区硬度值最低,为母材硬度值的84.6 %;焊接接头平均抗拉强度292 MPa,为母材抗拉强度的84 %,拉伸试件断口断裂位置为熔合区附近,呈现出韧性断裂特征.

     

    Abstract: The butt welding experiment of 5A06 aluminum alloy laser multi-strand MIG hybrid welding was carried out by 1 × 3 structure ER5356 aluminum alloy multi-strand wire. The mechanical properties and microstructures of 20 mm thick welded joints were studied by scanning electron microscopy, EBSD analysis, tensile and hardness tests. The results showed that the laser multi-strand MIG hybrid welding presented good process performance. The weld was mainly composed of α (Al) matrix and dispersedly distributed Al3Mg2 second phases. The center zone of the weld was mainly equiaxed grains, with the average grain size of 34.83 μm. The grain in the heat affected zone was fine, with the average grain size of 10.21 μm, and there existed recovery and recrystallization. The hardness of the welded joint was between 75 and 90 HV, and that of the fusion zone was the lowest, which was 84.6% of the base metal. The average tensile strength of the welded joint was 291 MPa, which was 84.2% of that of the base metal. The fracture position of the tensile specimen was near the fusion zone, and the fracture showed ductile fracture characteristic.

     

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