超声频脉冲电信号耦合前后铝合金TIG堆焊接头特点

电弧堆焊作为一种低成本高效率的焊接方法在材料表面修复领域具有广阔的应用前景，文中将超声频脉冲电信号与低频交流TIG焊接电信号耦合，将超声能量引入TIG堆焊过程，改善铝合金TIG堆焊质量. 对超声频脉冲电信号耦合前后5083铝合金TIG堆焊焊缝成形、组织及硬度进行对比. 结果表明，随超声电源输出电压的增大，焊缝成形向熔宽减小、余高增大的趋势变化. 超声作用后，晶粒尺寸发生了一定变化，但晶粒形态无明显变化. 熔合区的晶粒细化最显著；焊缝区及热影响区的晶粒细化不明显，相反，随超声电源输出电压的增大，晶粒明显粗化. 熔合区及热影响区的第二相分布呈聚集现象. 超声作用对晶粒内部Mg元素的分布影响较大，增大超声电源输出电压，Mg元素在晶界处的偏析减弱. 硬度测试结果表明，超声频脉冲电信号耦合后焊缝硬度增大.

Characteristics of TIG overlaying welded joints of aluminum alloy before and after implementing ultrasonic frequency pulse electric signal

As a low-cost and high-efficiency welding method, arc overlaying welding has a broad application prospect in the field of material surface repair. In this study, ultrasonic energy is introduced into the TIG overlaying process to improve the welding quality of aluminum alloy by coupling the ultrasonic frequency pulse electrical signal with the low-frequency AC TIG welding electrical signal. The weld formation, microstructure, and hardness of overlaying welded joints of 5083 aluminum alloy were compared before and after implementing an ultrasonic pulse electrical signal. The results show that the weld formation changes towards the trend of decreased fusion wide and increased surplus height with the increase of the output voltage of the ultrasonic power. The grain size changs to some extent, but the grain morphology changs little after implementing the ultrasonic treatment. Grain refinement is the most significant in the fusion zone, but it is not obvious in the weld zone and the heat-affected zone. On the contrary, grain coarsening is obvious with the increase of the output voltage of the ultrasonic power. The distribution of the second phase in the fusion zone and the heat-affected zone shows an aggregation phenomenon. The ultrasonic effect has a great influence on the distribution of Mg element inside the grain. The segregation degree of Mg element at the grain boundary could be weakened by increasing the output voltage of the ultrasonic power. The hardness test results show that the weld hardness increases after coupling the ultrasonic frequency pulse electrical signal.