Work roll surface profile design and optimization for hot-core heavy reduction rolling process

Abstract

Hot-core Heavy Reduction Rolling (HHR2) is an innovative technology designed for eliminating center defects of blooms, which provides heavy reduction to blooms with two-high mill after solidification at the end of the strand. This works mainly focus on design and optimization of work roll profile that apply specifically to HHR2 process to obtain the best effect on shrinkage closing. Firstly, hot rolling experiment and corresponding finite element calculation were carried out. Based on the experiment and FEM results, the void closure model was established to describe the behavior of shrinkage closing. Secondly, this model was used in analyzing the effects of different roll profiles on void closure during HHR2 process. The result shows that the convex profile and box groove profile had better effects than flat profile and parabolic profile, which can provide greater value of effective strain and smaller value of stress triaxiality respectively. Finally, a new roll profile for HHR2 was designed by combining both geometrical features of convex profile and box groove profile. The rational value scope of convex width coefficient θ and convex height coefficient γ were optimized to achieve a better effect on eliminating shrinkage cavities.