Modification of roll pass design of low pearlite, fine-grained sheet steel using numerical modeling and processing maps

The main objective of this pass design is to achieve fine-grained structure with high strength properties and good ductility for 2.0 mm thickness steel sheet on a six stand finishing mill. Numerical modeling is used to evaluate the different rolling parameters while processing maps are used to determine a workability 'window' in which dynamic recrystallization must occur. The existing rolling parameters would not lead to a dynamically recrystallized structure. The proposed technique retains the sequence of reduction in thickness at the working temperatures, while it diminishes the rotational speed of the first stand and consequently all the other stands. The first stand is proposed to rotate with 25 rpm at 7.2 s-1 rate of deformation. The final rotational roll speed would be 177 rpm at stand no. 6 with 83.4 s-1 rate of deformation at 850 oC. Rolling force and torque needed in the proposed technique are lower than those in the existing ones at most of the passes. The proposed technique saves energy as it reduces the power consumption. (author)