Fatigue Failure Analysis for Bimetallic Work Roll in Hot Strip Mills

In hot rolling of steels, bimetallic rolls consisting of high-speed steel and ductile casting iron are extensively used because of their excellent hardness and wear resistance although the fatigue failure study is not available. To extend the roll life service, herein, a 3D finite element method is applied to investigate the residual stress and the rolling stress of the bimetallic work roll in the four-high rolling mill. The residual stress is analyzed by considering preheating, quenching, and tempering. Using the results as an initial condition, the rolling stress analysis is carried out consecutively. Then, the fatigue failure risk is discussed focusing on several critical points subjected to the largest stress amplitude inside of the work roll. The accuracy of the simple superposition method is also discussed to evaluate the risk conveniently.