Internal state variable models for microstructure in high temperature deformation of titanium alloys

There exists an interaction between microstructural evolution and deformation behavior in high temperature deformation of titanium alloys. And the microstructure of titanium alloys is very sensitive to the process parameters of plastic deformation process. In this paper, on the basis of plastic deformation mechanism of metals and alloys, a microstructural model including dislocation density rate equation and grain growth rate equation is established with the dislocation density rate being an internal state variable. Applying the model to the high temperature deformation process of Ti60 titanium alloy, the average relative errors of grain sizes between the experiments and the predictions are 9.47% for sampled data, and 13.01% for non-sampled data. Supported by the National Natural Science Foundation of China (Grant No. 50475144), the NPU Foundation for Research (Grant No. NPU-FFR-006), and the National Basic Research Program of China (“973”) (Grant No. G20000672)