Microstructure and mechanical properties of hybrid pulse VPTIG arc welding of high strength aluminum alloy
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摘要: 采用超快速变换复合超音频脉冲方波变极性TIG电弧焊接工艺进行2219-T87高强铝合金焊接,研究分析了焊缝显微组织和接头拉伸性能变化.结果表明,2219-T87铝合金复合超音频脉冲电流变极性焊接接头的组织和性能均发生显著变化,焊缝区显微组织明显细化,由粗大柱状晶向细小等轴晶转变,接头抗拉强度和断后伸长率显著提高.接头断口由脆性断裂主要特征转变为"韧性+脆性"的混合型断裂模式.在一定范围内,脉冲电流频率越高,脉冲占空比越小,作用效果越明显.复合超音频脉冲电流频率为40kHz,脉冲电流占空比为20%时,接头抗拉强度和断后伸长率分别达到母材金属的70%和58%.Abstract: The effect of ultrasonic pulse square wave current on 2219-T87 high strength aluminum alloy welds microstructure and mechanical properties was researched based on a novel ultrafast convert hybrid pulse variable polarity TIG arc welding technology. The experimental results show that the microstructure in the weld is predominantly columnar in the case of traditional variable polarity current. The grain structures in the weld zone become finer and more equiaxed with the effect of ultrasonic pulse current. Weld tensile strength and percentage elongation are obviously improved, respectively. Weld fracture type is changed from mostly brittle to the obvious mixture of dimple and brittle. The effect of hybrid pulse current is more effective with higher pulse frequency and lower pulse current duration in a certain range. The rates of weld tensile strength and percentage elongation to base metal are 70% and 58%, respectively, under a 40 kHz ultrasonic pulse current frequency and 20% pulse duty cycle.
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