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Title

THERMO-MECHANICAL MODELING OF THE HOT ROLLING PROCESS: WORK-ROLL COOLING OPTIMIZATION AND WORK-ROLL DEGRADATION MECHANISMS MASTERING

Authorship

FALL, Thierno

FALL, Thierno

1 Articles, Downloaded 637 Times

DOI

10.5151/9785-9785-32381

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Abstract

The rolls are the first source of cost in a hot strip mill. To get a strip with good quality, a proper wear resistance and a resistance to surface degradation is needed. In the hot rolling process, the work-rolls undergo two types of fatigue solicitations. The most damaging one is the thermal fatigue. To reduce the industrial use cost (mainly roll price) and to have a good strip surface quality, we must master its degradation. The work-roll cooling can have a strong effect too. Therefore, a suitable and mastered work-roll cooling can avoid or delayed the roll degradation. To assess the work-roll lifetime or to optimize its efficiency, different ways of modelling are available. Currently, most of the thermo-mechanical models used are based on 1D thermal transient hypothesis. That kind of model allows us to predict the effects of design constraints on the cooling efficiency. For instance, different technical assistances are done to help mills to implement an anti-peeling system also knowns as skin-cooling, to study the effect of an addition or removal of cooling nozzles, to build parametric studies on the effect of each cooling headers etc. Nevertheless, that kind of model is too conservative and not adequate to determine a thermal fatigue criterion based on multiaxial solicitations as it is the case for the work-rolls. Consequently, a 3D model based on FEM (finite elements method) of the work-roll in the finishing mills is currently under development to have a better insight of the thermal field distribution within the work-roll. Afterwards, a mechanical analysis will be done to understand how thermal and mechanical stresses are created inside the work-roll. This study will help us to deepen our knowledge on work-roll cooling and work-roll degradation that can bring more reactivity to tackle plant's issues.

Keywords

Hot rolling, work-roll cooling, work-roll degradation, thermal fatigue