Modeling the Stress State of a Steel Strip with a Roller Leveling Machine under Cyclic Alternating Deformations

Abstract

The final stage in the production of hot rolled steel is leveling on roller levelers under cyclic alternating deformation. When laser cuts a sheet, it may bend due to the release of residual stresses that are unevenly distributed over the volume. The majority of roller leveler models for calculating the process under cyclic alternating deformation does not provide an adequate assessment and prediction of residual stresses in a steel sheet. On the basis of finite element analysis, formation of residual stresses due to roller leveling of hot rolled strip is disclosed. The implementation of a leveling process model was performed in SIMULIA Abaqus. Models are verified by comparing forces under the rollers. We have experimentally confirmed the convergence of the simulation results with the measurements of the strip flatness obtained after sheets plasma cutting. It was found that after leveling, tensile longitudinal residual stresses remain on the upper surface of the sheet, compressive ones remain on the lower surface, stresses are zero in the middle in thickness, and the stress values are opposite in sign in the remaining parts of the section. It was established that the same parameters of the leveling process of different strength categories lead to different deviations of stresses. An increase in yield strength of the strip leads to an increase in the deviation of residual stresses along the strip thickness. The proposed method of simulation of roller leveling process should be used to study the stress-strain state of hot-rolled steel and to design improved strip leveling setting modes with minimal residual stress deviations.