Influence of Roll Cooling Water Composition on Surface Degradation

Work roll cooling is one of the most important actuators to control roll degradation in a hot rolling mill. Besides pressure and flow rate, the influence of cooling water composition is of high importance to avoid excessive work roll degradation. However, this actuator is very often underestimated in most of the hot strip mills worldwide.

The development of a lab equipment simulating work roll degradation enabled us to compare the impact of rolling parameters on work roll degradation. This contribution gives an overview of the influence of several elements present in the water used in direct roll cooling (e.g. chlorides, sulphates, bactericide, phosphates) on work roll surface degradation.

Apart from lab analyses, on-site examinations of worn work rolls enable us to determine degradation mechanisms and to highlight the main influencing parameters. The link between strip surface defects and work roll degradation has highlighted the corrosivity of cooling water as a main contributing factor in several cases. This contribution illustrates those cases.