Solidification of a Steel Billet in the Mold of a Synchronized Rotary Type Continuous Caster

Abstract

A high speed continuous billet caster where casting speed matches the rolling speed has been developed. The mold of the caster consists of a copper wheel with a groove and an endless belt, both strongly cooled by water. There is almost no friction between the mold and a cast billet because of the mold moving simultaneously with a billet. In the course of development two studies were performed to establish the optimum casting and operating conditions. The first was to study the effects of casting conditions on the shell thickness in the mold. The second was on the heat transfer characteristics of the rotating wheel. The results are summarized as follows:
(1) The solid shell thickness of the belt side was smaller than that of the wheel side when the molten steel with large superheat was poured.
(2) Water modeling experiment revealed that flow with high velocity went downward along the belt side, while there was upward flow with low velocity along the wheel side.
(3) The allowable superheat was estimated to be 50°C by the casting experiments and computer calculation taking account of fluid flow.
(4) Good contact between a cast billet and the wheel was obtained by smooth nozzle stream, tension casting where the pinch rollers were driven at a slightly higher rate than the wheel and appropriate guide roller configuration.
(5) The solidification rate constant was 27mm/min^1/2, which was somewhat larger than that of an average conventional caster.
Based upon these results the belt wheel type continuous caster was put into practical use.