【摘要】 研究了单丝单脉冲、单丝复合脉冲和双丝TandemMIG焊对高强Al Cu合金焊缝组织及性能的影响。试验结果表明 ,单丝复合脉冲焊接时 ,峰值电流周期性变化引起的熔池液体强烈的搅拌作用 ,使熔池的温度梯度降低 ,固液界面前沿成分过冷区中的形核核心增加 ,促进了焊缝组织的细化 ,提高了焊缝的强度和塑性。双丝MIG焊高的热输入和快的焊接速度 ,使焊缝产生了粗大的等轴枝晶组织 ,并增加了晶界和枝晶间共晶相的数量 ,使焊缝的强度、硬度和塑性降低。更多还原

【Abstract】 The effects of single-wire unitary pulsed metal inert-gas(MIG), synergic pulsed MIG and double-wires tandem MIG welding processes on the microstructures and properties of high strength Al-Cu alloy welds were investigated. The results showed that the enhanced stirring action of the liquid metals in weld pool due to peak-current fluctuating periodically under single-wire synergic pulsed MIG welding decreased temperature gradients and increased heterogeneous nuclei within the region of constitutional supercooling just ahead of the solid-liquid interface. As a result, the microstructure of the weld was refined. The strength and ductility of the weld increased. The high heat inputs and rapid welding speed of double-wires MIG welding enhanced the formation of coarse equiaxed dendrites in the weld and increased the eutectic constituents at grain or dendrite boundaries. The strength, hardness and ductility of the weld decreased.更多还原