Rich Zinc Phase Formation Mechanism at the Surface of Continuously-Cast Brass Billets

This work is devoted to studying formation of a rich zinc phase at the surface of continuously-cast brass billets. It is shown that the effect almost always occurs during brass continuous casting. A study of rich zinc phase formation is performed for small section ingots prepared by continuous casting vertically upwards. Microstructural analysis is conducted for sections of ingots in zones of rich zinc phase formation and its composition is determined. A mechanism is proposed for the formation of this phase including zinc sublimation and condensation in the shrinkage gap followed by spreading zinc over the ingot surface and partial dissolution within it of basic composition alloy. Methods are analyzed and proposed for minimizing this phenomenon under brass ingot continuous casting conditions.