Influence of Hot Rolling on Formability of Nb-Microalloyed Steel: An Experimental Design Study

The present paper presents an effective and economical approach for the evaluation of the consequences of essential uncertainties on formability. Its aim is to validate the use of factorial experimental design to determine the influence of hot rolling process parameters of roughing, finishing and coiling temperatures on the dome height and grain size of Nb-microalloyed steel sheets and optimizing these parameters to obtain maximum dome height and minimum grain size. For perceptual evaluation of formability, 2 levels for the above temperatures were chosen and 24 experiments for each response were conducted based on a two-level full factorial design. Also, from the analysis of variance, the most significant parameters which are efficient in hot rolling can be obtained. It is observed that increasing the coiling and finishing temperatures causes an increase of the dome height and decreasing the coiling and finishing temperature effectively causes more grain refinement of the microstructure. The present results highlight the advantage of applying experimental designs in the investigation of formability of Nb-microalloyed steels.