Ultrasonic Grain Refining of Continuous Cast Aluminum: Microstructure and Properties

Abstract

Southwire Company located in Carrollton, Georgia U.S.A. has developed ultrasonic grain refining technology to be used on the Southwire Continuous Rod (SCR) process. Grain refining of aluminum occurs when the crystal size of the solid phases is reduced using chemical, physical, or mechanical means. The ultrasonic grain refining process uses power ultrasound to give rise to non-linear effects such as cavitation, acoustic streaming, and radiation pressure. These non-linear effects are then used to nucleate new grains and break up dendrites during the solidification process of an alloy. The first section of this paper discusses the mechanism of grain formation and refinement using acoustic irradiation. Then the results from the lab trials will be presented. Following this, the benefits of ultrasonic grain refining will be reviewed. Finally the test data from initial scale-up of the ultrasonic grain refining technology at the Southwire Kentucky Plant will be summarized and discussed.