A Contribution to Scale Growth during Hot Rolling of Steel

Abstract

This work was carried out in context with the development of strip casting by the single‐belt process. In this new process the casting is directly connected with hot rolling which must be carried out at lower speed than in conventional hot rolling, to match the casting rate. It is of interest to theoretically study the effect of low rolling speed on operational parameters and materials behaviour, among them scale formation. In the present investigation it is demonstrated that, under the conditions of hot rolling, the oxidation of iron in air is governed by a mixed mechanism involving diffusion in the oxide and transport of molecular oxygen in the gaseous boundary layer. An algorithm has been formulated for the description of the deformation behaviour of the scale in the roll bite. Scale formation was computed for conventional finishing rolling with a seven stand mill and for in‐line hot rolling of strip produced by the single‐belt process. It is found that the final scale thickness in the single‐belt casting/in‐line hot rolling process is about twice that in conventional hot rolling, for the same strip thickness behind the last stand.