Multiresponse Optimization of Mechanical Properties and Formability of Hot Rolled Microalloyed Steels

In this study, a 2³ factorial design analysis was conducted to screen the significant factors influencing the mechanical properties and formability of Nb-microalloyed steel sheets in hot-rolling process and for optimizing these factors to predict maximum yield strength (YS), ultimate tensile strength (UTS), elongation (El), and dome height (DH), simultaneously. For this purpose, two levels for the major hot-rolling process parameters of roughing temperature (RT), finishing temperature (FT), and coiling temperature (CT) were chosen; eight experiments for each response were conducted. From the analysis of variance, the most important parameters affecting the YS, UTS, El, and DH were determined, and satisfactory prediction regression models were derived. It was observed that optimal condition of factors for the best combination of response variables was obtained at 1150 °C of RT, 836 °C of FT, and 604 °C of CT. Findings of this research show that the obtained predicted values were close to the experimental values indicating suitability of the models.