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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40 kHz,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%.
The ultra-rapid transformation composite super-frequency pulsed square wave TIG arc welding process was used to weld 2219-T87 high strength aluminum alloy, and the changes of the microstructure and joint tensile properties of the weld were analyzed.The results showed that the 2219-T87 aluminum alloy composite The microstructures and properties of the ultra-audio pulsed current changing polar welding joints changed significantly. The microstructure of the weld zone was obviously refined. The transition from coarse columnar grains to fine equiaxed grains showed that the joint tensile strength and elongation at break were significantly increased . The fracture of the joint changes from the main feature of brittle fracture to the mixed fracture mode of “ductile + brittleness.” Within a certain range, the higher the pulse current frequency is, the smaller the pulse duty cycle is, the more obvious the effect is. When the current frequency is 40 kHz and the pulse current duty cycle is 20%, the tensile strength and elongation at break of the joint reach 70% and 58% of the base metal, respectively.