Evaluation of Thermal Breakage in Bimetallic Work Roll Considering Heat Treated Residual Stress Combined with Thermal Stress during Hot Rolling

Abstract

Bimetallic rolls are widely used in steel rolling industry because of their excellent hardness, wear resistance, and high temperature properties. Heat treated residual stresses consist of compressive stress in the shell and tensile stress in the core are produced in the bimetallic roll during heat treatment. In the subsequent hot rolling process, severe thermal stresses are caused by heating-cooling thermal cycles at the roll surface. The combination of heat treated residual stresses and thermal stresses will cause a complex stress field in work roll during hot rolling process. The high combined tensile stress at the roll center may cause thermal breakage, once the tensile stress exceeds the material strength. Consequently, it is necessary to investigate the combined stresses to improve roll service life during hot rolling process. In this paper, the combined stresses in the work roll during hot rolling are investigated based on the FEM simulation, considering the heat treated residual stress after tempering process and thermal stress generated during hot rolling. In addition, the thermal breakage of work roll is evaluated in breakdown of water cooling systems and rolling incidents.

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

“…Generally, a 3D model of the work roll is justified for the thermo-mechanical analysis of hot rolling, while it also needs multiplied computational effort and time. Therefore, a 2D model in the circumferential plane was applied for temperature evaluation of the work roll during hot rolling [12,19]. As shown in Figure 1d, a mesh refinement was imposed near the surface along both the circumferential and radial directions to capture the great thermal gradient there.…”

“…Although the residual stress in work rolls has been investigated, these studies were limited to investigating quenching or tempering, while the thermal stress during hot rolling was not taken into account [17,18]. In our previous studies, the simulation of thermal stress and residual stress were performed on the basis of a simplified thermo-elastic model [19]. In fact, the compressive thermal stress is high enough to cause yielding with plastic deformation in the bite region, and tensile yield stress may develop if the roll surface is cooled sufficiently in the cooling region.…”

Fatigue Failure Analysis for Bimetallic Work Roll in Hot Strip Mills

“…Rolling technology is developing and advancing further although seemingly mature. [ 1–13 ] Figure 1 shows the rolling roll in roughing stands of hot rolling stand mills. By replacing the conventional single‐material rolls, bimetallic work rolls are developed through improving wear resistance and heat crack resistance.…”

Remote Cooling of Rolls in Hot Rolling; Applicability to Other Processes

“…Papers [7,8] study thermal stresses in bimetallic rolls. Advanced technology of production and heat treatment of these rolls allow to prepare favorable distribution of residual stresses.…”