Analysis of Residual Stresses and Metallurgical Phase Changes in Centrifugally Cast Bi-Metal Grinding Rolls

Abstract

A mathematical model was developed for computing the metallurgical phase transformations and residual stresses in centrifugal casting of bi-metal grinding rolls used for coal pulverizing. The model considers variation of thermo-mechanical properties of material with temperature, effects of phase changes and metallurgical phase transformations. Rolls idealized as having infinite cylindrical geometry and the actual finite conical geometry are analysed for cases of air and water jet cooling of the centrifuging die. As expected an increase in the martensitic fraction is obtained on the grinding surface due to water jet cooling. The study indicates that the large size rolls analysed herein have higher martensitic fraction as compared to small size roll. Simplified analysis model is developed for usage in parametric studies involving various sizes for initial sizing of the rolls.