Residual Stress Differences between Uniform and Non-Uniform Heating Treatment of Bimetallic Roll: Effect of Creep Behavior on Residual Stress

Abstract

The work roll is one of the most important tools in the steel rolling industry. Work rolls are used under extremely severe conditions such as high temperature, high loading, and an aggressive atmosphere. To meet those demands, bimetallic rolls have recently been used to replace conventional single material rolls. Usually, a compressive residual stress is introduced to prevent surface cracking. However, a tensile residual stress at the center appears to balance the compressive residual stress. This center residual stress sometimes causes roll failure. In this paper, therefore, a simulation is performed using the finite element method (FEM) for the quenching process of the bimetallic roll by considering the creep behavior. Then the effect of pre-heating conditions is discussed. The results show that the maximum stress point for the tensile stress at the roll center for non-uniform heating is 24% less than that achieved with uniform heating, although the same compressive stresses appear at the surface. Then, using different work roll diameters, the center tensile residual stress for non-uniform heating is found to be smaller than the uniform heating. Also, it is found that the area ratios of the shell-core only have a small influence on the residual stress of the bimetallic roll for both heating treatments.

Fatigue Failure Analysis for Bimetallic Work Roll in Hot Strip Mills

“…Then, the rolling stress analysis is carried out. As the detail of the residual stress analysis is indicated in the previous paper, [ 30–33 ] this section mainly focuses on the method of rolling stress analysis. In this study, the fatigue of the work roll is focused as the fatigue failure of the backup roll hardly happens.…”

“…The direct constrain method is used for contact analysis between work roll and backup roll. In this study, the previous residual stress analysis [ 30–33 ] described in Appendix A is extended to rolling stress analysis. First, the same simulation is carried out using 3D modeling in Figure 4 instead of the axisymmetric FEM modelling used in the previous study.…”

“…In our recent studies, the residual stress was discussed by analyzing quenching and tempering as the appropriate compressive residual stress prevents thermal cracking at the roll surface. [ 30–33 ] In this article, therefore, after analyzing the residual stress, the rolling stress will be clarified by applying the rolling analysis where the work roll and the backup roll are subjected to the total rolling force as shown in Figure 1. [ 34,35 ] Then, the risk of internal fatigue fracture will be discussed by considering the fatigue of the roll material by focusing on some critical points empirically known.…”

Simulation of Thermal Stress and Fatigue Life Prediction of High Speed Steel Work Roll during Hot Rolling Considering the Initial Residual Stress

“…Since the temperature variation range (about 20-1100 • C) is very large for both heat treatment and hot rolling, temperature-dependent material properties were used for the simulation to ensure the accuracy of the FEM results. The test specimens were cut from HSS work roll after tempering and the material properties of HSS and DCI used in this study were measured experimentally at room temperature and 100-600 • C with an interval of 100 • C [20]. direction, a series of mesh sensitivity tests was conducted to investigate the accuracy of FEM model in terms of the maximum temperature at the roll surface and the computational time.…”

“…where C = 35 × 10 −6 is a general roughness term; k s is the thermal conduction of the strip; P r is the rolling pressure; and σ is the flow stress of strip calculated using the equation derived by Shida [20,25].…”