Yield surface simulation for partially recrystallized aluminum polycrystals on the basis of spatially discrete data

The paper presents simulations of the yield surface evolution of plasticall y deformed aluminum polycrystals during recrystallization. The yield surfac es are calculated using a viscoplastic Taylor-Bishop-Hill strain rate polyc rystal homogenization method. The input data for the yield surface calculat ions are the crystal orientations, their volume fractions, and their shear stresses, While the crystal orientations determine the kinematic portion of the yield surface the threshold shear stress of each individual orientatio n determines the kinetic portion of the yield surface. The input data for t he homogenization calculations are generated through a spatially discrete s imulation, where crystal deformation and primary static partial recrystalli zation are simulated by coupling a viscoplastic crystal plasticity finite e lement model with a cellular automaton. The crystal plasticity finite eleme nt model accounts for crystallographic slip and for crystal rotation during plastic deformation using space and time as independent variables and the crystal orientation and the accumulated slip as dependent variables. The ce llular automaton uses a switching rule which is formulated as a probabilist ic analogue of Turnbull's rate equation for the motion of grain boundaries. The actual decision about a switching event is made using a simple-samplin g Monte Carlo step. The automaton uses space and time as independent variab les and the crystal orientation and a stored energy measure as dependent va riables. The kinetics produced by the switching algorithm are scaled throug h grain boundary mobility and driving force data. The crystallographic text ure and the orientation-dependent resistance to shear are for each interpol ation point extracted after each time step during recrystallization. The da ta serve as input for the calculation of discrete yield surfaces, (C) 2000 Elsevier Science B.V. All rights reserved.