Analysis on Influencing Mechanism of Periodical Ultrasound on Formation of TIG Weld of Aluminum Alloys

Ultrasound could effectively affect the crystallizationbehavior of weld metal and the formation of TIG weld of aluminum alloy. In this work, the influence mechanism of ultrasound on the formation of TIG weld of Al-Li alloy was analyzed. The macro morphology of weld and the vibration of weld pool surface was investigated. The effect of ultrasound on the fluidity of weld pool was analyzed by finite element simulation. The results showed that the ultrasonic energy resulted in a periodical lifting on the top surface of TIG weld and a decrease in the weld width. The ultrasound could increase the periodical vibration amplitude on the top surface of weld pool. The formation mechanism of the periodical deformation of molten pool was analyzed. The ultrasound increased the velocity of fluid and made the melt flows change around the edge of weld pool. The embossment appearance was formed at the edge of weld pool after solidification. The ultrasonic energy periodically affected the fluidity of the molten metal and the crystallization of the weld so that the periodical embossments appeared on the top surface of TIG weld.