Method of fast, effective ultrasonic degassing by forced cooling

Abstract

The method of combining ultrasonic treatment (UST) and forced cooling at the bottom of ingots can effectively decrease the gas content in the interior of the ingots. If an appropriate UST is used, the gas content of ingots decreases to 0·02 × 10–5 m3 kg–1, which is lower than the value of industrial production standard of 0·1 × 10–5 m3 kg–1, and the degassing efficiency is higher than 97%. Otherwise, the method of combining UST and forced cooling at the bottom of ingots not only influences the effectiveness of ultrasonic ingot refinement, but also, with the increase in UST duration, improves rapidly the equiaxed grain occupancy in ingots, and even the occupancy reaches 100%. The ultrasonic degassing effect is due to the release of hydrogen in the bifilms which expand and rise gradually; in the end, they burst on the melt surface, achieving the effect of degassing.