Prediction Model for C-Warping Defect of Steel Strip in Continuous Annealing Process of Hot-Dip Galvanizing

C-warping of steel strip in the continuous annealing process (CAP) of a hot-dip galvanizing unit (HGU) increases the risk of strip defects and uneven coating, leading to reduced product quality. Considering the technological process and equipment characteristics of CAP, the formation mechanism of the C-warping defect was analysed in detail using plastoelasticity theory. Based on this analysis, a mechanical model of C-warping was derived, and the strip element method was applied to establish a C-warping prediction model. An optimization recursion method was then employed to address the difficulty of forecasting C-warping defects. Finally, a workflow for C-warping prediction was formulated and implemented in industrial practice. The proposed model was applied to predict the strip shape for five typical strip specifications in different stages of the continuous annealing furnace (CAF) on Lines 108 and 208. The results show that the deviation between predicted and measured strip shape values at the unit outlet satisfies product precision requirements. The model enables real-time prediction of strip shape in each CAF process stage and provides theoretical guidance for subsequent process parameter optimization, demonstrating strong potential for practical application.