Improving Flatness of Hot-Rolled Titanium Coil Using Residual Stress Characterization

Flatness defects in hot-rolled coils are primarily caused by non-uniform plastic deformation introduced during continuous processing. Each stage of the coil production line can contribute to such deformation. In the absence of effective analytical tools, issues like the C-bow defect have traditionally been addressed through empirical, trial-and-error methods. This study presents a method for identifying the fundamental mechanism responsible for the C-bow defect by employing residual stress measurement and analysis techniques. As the distribution of residual stress reflects the cumulative plastic deformation induced throughout the production process, the slitting method was adopted to obtain through-thickness stress profiles. Analysis of the residual stress characteristics enabled identification of the dominant deformation mechanisms. Based on these findings, a high-speed cooling strategy is proposed to improve material strength and minimize coiling induced deformation. The implementation of this approach demonstrates notable improvements in sheet flatness.