Effect of Ultrasound on Heterogeneous Nucleation in TIG Welding of Al–Li Alloy

Abstract

The effect of ultrasound on heterogeneous nucleation in a tungsten inert gas (TIG) weld pool of 2195 Al-Li alloy has been investigated by a series of experiments. An ultrasonic vibration was imposed on the surface of base material before turning off the welding arc during the TIG welding implemented at a fixed point. The results suggest that ultrasound could promote heterogeneous nucleation in the TIG weld pool of 2195 Al-Li alloy. The grain around the fusion zone is changed from a column grain to an equiaxed grain after applying the ultrasonic treatment. To study the influencing mechanism of ultrasound on heterogeneous nucleation, further investigations were implemented where the welding arc was turned off after turning off the ultrasonic power. The results show that the equiaxed grain around the fusion zone disappeared gradually with an increase in heat input after turning off the ultrasonic power. It suggests that ultrasound could promote the heterogeneous nucleation particle to nucleate in advance before turning off the welding arc and the crystal nucleus could again be melted with an increase in heat input after turning off the ultrasonic power. Moreover, the effects of the welding current and ultrasonic amplitude on heterogeneous nucleation in the weld pool of 2195 Al-Li alloy were also investigated. Possible influencing mechanism of the welding current and ultrasonic amplitude on heterogeneous nucleation was discussed.

Effect of welding speed on microstructure and corrosion resistance of Al–Li alloy weld joint

“…The nonbranched equiaxed crystal regions that formed after welding had poor corrosion resistance. Chen et al introduced ultrasonic waves during the Al–Li alloy process. The results show that heterogeneous nucleation in the tungsten inert gas welding (TIG) weld pool was promoted by the addition of ultrasonic waves.…”

Mitigation of Porosity and Residual Stress on Carbody Aluminum Alloy Vibration Welding: A Systematic Literature Review

“…According to [52] that the melting temperature under these conditions increases, which will result in an increase in undercooling and an increase in nucleation. The increase in melting temperature, according to [50], [53] follows Equation (1).…”

Auxiliary energy-assisted arc welding processes and their modelling, sensing and control

“…Figure 13 demonstrates three ways to apply the ultrasound into the arc welding process. The first one is to exert the ultrasound on the workpiece surface and the ultrasonic energy propagates into the weld pool via the base material [63][64][65][66]. The second way is to apply ultrasound on the filler-wire/probe, which are in contact with the weld pool, so that ultrasound is directly introduced into the weld pool [67,68].…”