Roll-strip Interfacial Heat Fluxes in Twin-roll Casting of Low-carbon Steels and Their Effects on Strip Microstructure

Abstract

In twin-roll casting, interfacial heat transfer between the rolls and the solidifying metal can affect strip quality and limit productivity.
In the present work, interfacial heat fluxes between the roll and the solidifying metal were evaluated in a pilot twin-roll caster used in the production of strips of low-carbon steel. This evaluation was based on an inverse heat transfer analysis and on readings of thermocouples inserted at different positions of the roll sleeve of the IMI pilot scale TRC caster in Boucherville, Quebec.
Variations in transient roll-melt interfacial heat fluxes during contact of the freezing shells with the roll surfaces exhibited two patterns, one characterized by a simple peak, the other by a double peak in the heat flux versus time curves, depending on the casting conditions. Mechanisms explaining the two types of curve are advanced. Solidification and as-cast structures of strips produced in the pilot caster were also studied, and their characteristics analyzed in terms of fluid flow and heat transfer within the caster's sump.