Deformation mechanism and warping model of steel/aluminum thin strip composite rolling process

To address the issue of post-rolling warpage caused by differences in material properties during the composite rolling process of steel/aluminum thin strips, stress analysis was conducted at the entrance, middle, and exit sides of the rolling deformation zone for both steel and aluminum units. The unequal characteristics of the upper and lower contact arc lengths and the micromoment phenomenon, generated by the transfer of force between adjacent units on the aluminum side, were analyzed to explain the mechanical mechanism of warpage in the composite rolling process. A formula for calculating the contact arc length in the upper and lower rolling deformation zones was derived using the relationships among the contact arc length, rolling force, roll parameters, and strip parameters. On the basis of the deformation characteristics of steel and aluminum in the rolling deformation zone, the concepts of the inlet half-rolling zone, relative sliding zone, rolling composite zone, and outlet half-rolling zone were proposed. A quantitative model for characterizing warpage during the composite rolling of steel/aluminum composite thin strips was established. These results indicate that adjusting the diameters of the upper and lower work rolls is an effective method for controlling warpage defects and that warpage plays a dominant role in steel/aluminum thin strip composite rolling. Furthermore, finite element simulations of steel/aluminum composites rolled with different upper and lower roll diameters verified the deformation mechanism and influence of roll diameter differences on warpage defects.