Evaluation of the type and amplitude of the flatness defect of a hot-rolled steel strip produced on a continuous mill

This work presents a brief overview of approaches to evaluate the flatness of hot-rolled strips and regulatory documents for rolled products. The requirements for the flatness of steel sheets based on different national standards are presented. A method for estimating the amplitude of the flatness defect is proposed, which considers the nonuniformity of reductions across the width of the strip, arcuate shape of the nonplanar section, strip thickness, and elastic and strength properties of the strip material. The uneven temperature distribution of the sheet along its width is also considered, which can also result in the loss of a flat shape when cooling the rolled product. The verification of the newly proposed method for evaluating the type and amplitude of nonflatness, based on experimental data, demonstrated the reliability of the proposed approach.