High-intensity ultrasound can effectively improve the grain structure and element distribution uniformity of industrial large-scale Al alloy ingots. In this paper

ultrasonic-assisted casting of 2219 Al alloy ingots (Ф630 mm×4500 mm) was carried out to compare the microstructure differences between the two ingots. The results indicate that the core of the conventional ingot is predominantly composed of coarse dendrites. After ultrasonic treatment

the α-Al grains in the ingot are refined

with refinement rates of 27.7%

31.4%

and 24.2% at the edge

R/2

and core positions

respectively. The area fractions of the coarse Al

2

Cu eutectic phase are

15.18%

8.42%

and 5.3%

respectively

which represent relative reductions of 21.1%

31.6%

and 30.4% compared to the ingot without ultrasonic treatment. The tensile strength

yield strength

and elongation of the ultrasonically treated ingot are significantly improved compared to those of the untreated ingot. Specifically

the tensile strength at the center

R/2

and edge positions is relatively increased by 18.2%

24.2%

and 11.1%

respectively. This study validates that ultrasonic cavitation and acoustic streaming promoting heterogeneous nucleation are the dominant mechanisms for modifying Al alloy melts

and by establishing a quantitative relationship with the undercooling required for nucleation

it provides a precise basis for process control in industrial applications of this mechanism.