Evolution and mechanism analysis of bending direction of steel plates during asynchronous rolling

Existing research conclusions on the correlation between asynchronous rolling process parameters and plate bending behavior are contradictory, and the underlying bending mechanism remains unclear. Taking 08Al steel plate as the research object, this paper systematically investigates the influence law and mechanism of rolling parameters on the bending behavior of steel plates during asynchronous rolling by combining finite element simulation and rolling experiments. A rolling model was established based on ABAQUS software, and the formation mechanisms of plate bending and bending reversal were revealed by analyzing stress evolution and the distribution characteristics of strain rate bands. The results show that X-shaped equivalent plastic strain rate bands distribute in the deformation zone. The number of strain rate bands is positively correlated with the reduction rate and negatively correlated with the initial plate thickness. Asynchronous rolling drives the migration of neutral points on the upper and lower surfaces of the plate and forms a cross shear zone. To balance the moment generated by the cross shear zone, the staggered distribution of rolling pressure on the upper and lower surfaces produces a reverse moment to stabilize the rolling process, which causes an asymmetric distribution of strain rate bands at the roll exit and further induces plate bending. The bending direction is closely related to the number of strain rate bands in the forward slip zone. When only one X-shaped strain rate band exists in the forward slip zone, the steel plate bends toward the fast roll dominated by the asynchronous effect. At a small speed ratio, the number of strain rate bands in the forward slip zone increases with the rise of reduction rate or the decrease of initial plate thickness. In this case, the asynchronous effect is weakened and only affects the distribution of strain rate bands near the neutral point. The newly added strain rate bands before the exit undergo dynamic adjustment, making the steel plate bend toward the slow roll. With the continuous increase of speed ratio, the asynchronous effect is enhanced, and the bending direction of the steel plate reverses toward the fast roll. This study provides a theoretical basis and practical guidance for the plate shape control in asynchronous rolling.