On thermal stress and fatigue life evaluation in work rolls of hot rolling mill

Abstract

The paper proposes an approach for thermal stress evaluation and fatigue life assessment of work rolls in hot rolling mills. Temperature and thermal stress distributions are calculated with a simplified finite element approach, based on a plane model of work roll loaded on its boundary by rotating thermal actions for a typical hot rolling configuration. A transient of one hour is simulated and the calculated temperature field is next applied as thermal loading in elastic–plastic mechanical simulation, to get thermal stresses and elastic–plastic strains in work roll. Calculated cyclic stresses and strains are finally used to estimate work roll service life, based on Universal Slopes equation that is modified to account for the multiaxial stress state. A comparison of results by three multiaxial fatigue criteria is provided. The obtained results show that, according to such multiaxial criteria, stress multiaxiality would have a great effect on fatigue life, despite it is generally neglected in approaches usually adopted in literature.