Mechanism of lateral metal flow on residual stress distribution during hot strip rolling

Abstract

During hot strip rolling, the lateral metal flow can change the longitudinal residual stress to reduce the risk of buckling deformation of the strip. The mechanism of lateral metal flow on residual stress was studied by combining a residual stress model with experimentation. A buckling risk coefficient was proposed to quantify the risk of buckling deformation. The calculated results show that the lateral metal flow has a self-correcting effect on the residual stress caused by the change in unit crown, this is, metals preferentially flow towards the direction helping reduce the maximum residual compressive stress. Changes in width and thickness of the strip induce a large difference in the attenuation of the maximum residual compressive stress even if the unit crown has the same change. For instance, under a large reduction rate the mode of residual stress may change from the edge-waves to the W-waves mode. A novel rolling experiment was developed, in which the grid method was employed to capture the tiny metal flow along the width. The measured lateral metal flow law is consistent with the description of the self-correcting effect of the lateral metal flow.