A DATA-DRIVEN APPROACH TO THE SELECTION OF SUSTAINABLE EMULSIONS FOR COLD-ROLLED STEEL PRODUCTION

The use of emulsions in the cold rolling process significantly reduces rolling forces, increases material reduction, and enables the production of thinner final steel products. This enhances the stability and surface quality of the processed material. However, annealing these cold-rolled coils often leads to sustainability challenges due to the formation of surface defects such as soot. These defects are influenced by factors including uneven emulsion application, inadequate surface preparation, and the specific physicochemical properties of the emulsion itself. This study investigates the root causes of soot-related defects in annealed steel coils processed with emulsions, highlighting the necessity of mitigating these issues to ensure sustainable and environmentally friendly production. To achieve this, optimal physicochemical parameters for lubricating and cooling fluids were determined, supporting waste minimization and resource efficiency. A novel testing methodology was introduced to evaluate the tendency of emulsions to produce soot under actual annealing conditions. This process involved applying concentrated emulsions to test samples, annealing them alongside coils in identical furnace conditions, and assessing the soot formation visually. The study analysed 54 emulsions, employing regression models to establish relationships between soot formation and parameters such as density at 20 °C, kinematic viscosity at 50 °C, and saponification number. Advanced mathematical techniques, including regression analysis and correlation evaluation, were utilized to quantify these relationships, ensuring robust conclusions. A significant correlation was identified between the pH of a 3% water-based emulsion and these properties. The Pareto analysis was applied to prioritize the influence of emulsion properties on soot formation, enabling the identification of the most impactful factors for optimization. As a result, 27 sustainable emulsions were recommended for implementation at PJSC "ZAPORIZHSTAL," contributing to lower rejection rates due to surface defects and promoting sustainable practices in rolled steel manufacturing.