ABSTRACT
During normal service in the mill (i.e., no accidental events), roll life is determined by proper consumption during rolling, which also establishes the campaign length. In many cases, damages to the surface roll lead to xes in the roll change to avoid quality problems on the rolled strip. A large amount of roll consumption is due to regrinding wear not always optimized with respect to real surface damaging of the roll. The complex tribological situations encountered by the work rolls are
Surface fatigue (thermal and mechanical) • Normal and tangential stress needed for rolling • Hertzian stress developing during contact with the • back-up roll Stress corrosion phenomena due to cooling and • lubrication system
In all stands of the mill, work rolls must guarantee suf cient hot strength. The dominant mode of roll wear is the abrasion, which assumes more and more weight moving from roughing to nishing stands. The scale of the rolled steel is the main cause of the abrasion of the roll surface; the abrasion effect of this scale depends strongly on rolling parameters, and a general discussion does not cover speci c mill (and/ or stand) situations. The level of damage due to thermal fatigue establishes not only the surface aspect of the roll, but also the weight of abrasion phenomena concerning roll material loss. Existing theories also involve adhesive wear mechanisms, where the roll surface plastically deformed, but there is a lack of consensus. So the HSS-speci c microstructure with its mechanical properties is of great importance, because it can limit surface damage with only positive consequences for reducing roll consumption. The correlation between microstructural features and rolling stresses is still actual valid matter for discussion because, in many cases, laboratory test results are not con rmed during mill trials. What are the reasons? Many times, there isn’t the goodwill to clarify thoroughly the situation concerning roll consumption, and then confusion reigns supreme.
