Modeling The Process Of Dynamic Recrystallization Of Pure Copper And Nickel Using Two-dimensional Cellular Automata

The final microstructure of hot deformation products is one important factor of which decides their properties. Therefore, the microstructural evolution of materials during the hot deformation process with dynamic recrystallization(DRX) is a concerned problem all the time. On the base of the metallurgical principles of the hot deformation process, this paper coupled variations of dislocation density, the nucleation rate and the growth rate of recrystallization grains(R-grains) with the strain rate, temperature, and built up a modified two-dimensional Cellular Automata(CA) model for dynamic recrystallization. The influences of temperature, strain rate, strain, and deformation time on a series of processes such as dynamic recovery, nucleation, and the growth of R-grains were considered. The microstructural evolution of pure copper and nickel during DRX under different hot deformation parameters was simulated. The simulated results were analyzed and compared with the former experimental results. Several main conclusions were given as follows:(1)The microstructural evolution of pure copper and pure nickel during DRX under different hot deformation parameters was simulated, and the simulated microstructure morphology of DRX accords with the characteristic of typical DRX microstructure.(2)R-grains get finer under higher strain rates or lower temperatures after enough strain, meanwhile the velocity of the dynamic recrystallization is also smaller. The characteristic of recrystallization kinetics curves calculated shows very well with that of the measured curves.(3)The simulated stress-strain curves agree well with the experimental ones, and their characteristic shows accordance with the phenomenon observed by the experiment. With the temperature rising and the strain rate dropping, the flow stress curves change from single-peak to multi-peak curves, and the peak stress and the steady state stress also decrease.(4)The influence of the initial grain sizes on the feature of the DRX flow stress curves is simulated. The results show that multi-peak flow stress curves are produced more easily for initially finer grained materials.(5)The mean size of any R-grain and steady-state grain could be calculated at any time. The calculated results of the mean size of steady-state grains show reasonable agreement with the experimental results under different conditions. It could provide a basis for the prediction and control of the microstructure during the hot deformation process in the future.