MODELING DISTRIBUTION OF MICROSTRUCTURE DURING HOT-ROLLING OF STAINLESS-STEEL

Two models have been combined to calculate the mechanics and metallurgy of hot rolling processes. An Eulerian finite element model is used to predict the temperature, strain rate, and strain distribution within the roll bite during steady state hot flat rolling. A finite difference model is used to calculate the temperature distribution, and the evolution of microstructure between passes resulting from recrystallisation. This combined model predicts that the kinetics of static recrystallisation varies systematically through the thickness of the stock. Experimental rolling trials on type 316L stainless steel have been followed by annealing treatments and metallographic studies to establish the form and extent of the through thickness microstructural gradients that develop in rolled slabs. The results of these trials reveal that the gradients exist in the general form predicted by the model, but are much smaller. The discrepancy appears to result from the use of equivalent strains to describe recrystallisation kinetics, when the sign of redundant shears changes during a rolling pass.