Microstructure Simulation Of Ti-55 High Temperature Titanium Alloy Based On Cellular Automata Method

Ti-55 titanium alloy is widely used in aviation aerospace, chemical industry, environmental protection, medical devices and other fields due to its corrosion-resistant, non-magnetic, good performance in high and low temperature, low damping and other unique features, including superconductivity, hydrogen storage,shape memory and biocompatible. However the grain size of material is difficult to control in the thermal deformation process result from its strong thermal sensitivity. The grain size depends on the the behavior of recrystallization during the thermal deformation process. So, studying the behavior of recrystallization and the evolution of microstructure for Ti-55 high temperature titanium alloy during hot deformation process are important to develop reasonable processing parameters and to control material properties.Carrying out hot compression tests on different conditions is commonly used in researching recrystallization behavior. But this method can not reflect grains growth and evolution of dynamic recrystallization in the real thermal deformation process. Algorithm structure of cellular automata is si mple and computationally efficient. However it can simulate the dynamic microstructure evolution of material and increasingly is favored by the majority of material researchers. In this paper, the main contents include the following sections:Isothermal hot compress test is carried out for Ti-55 titanium alloy on Gleeble3800 thermal-mechanical simulator. According to true stress- strain curve obtained experiment and microstructure analysis technique, thermodynamic behavior and dynamic recrystallization b ehavior of material can be researched and how does different deformation conditions influence dynamic recrystallization behavior of metal can be revealed.By learning the basic principles of Cellular Automata and relevant knowledge and understanding current situation, microstructure evolution simulation using cellular automata can be researched. Relevant model which can generate the initial grain structure can be established and the subsequent dynamic recrystallization process can be simulated in differen t conditions. Combined with theoretical knowledge of dynamic recrystallization, cellular automata models of dynamic recrystallization process is developed, including the dislocation density evolution model, recrystallization nucleation model and recrystallization grain growth kinetics model.Then the corresponding core computing program on MATLAB software is preparated.Using the above cellular automata model and putting experimental results obtained by isothermal compress deformation into procedure,then d ynamic recrystallization process at deformation temperature of 1050 ℃ and strain rate of 0.01 mm / s can be simulated. Comparing with real physical experiments, the correctness of the cellular automaton model is verified.Then simulating microstructure evolution of Ti-55 titanium alloy during hot deformation at different deformation temperature and different strain rate is used to analyze the impact of dynamic deformation parameter on recrystallization process.The results showed that: the model about generating initial structure and the model about simulating dynamic recrystallization established in this paper can accurately simulate recrystallization microstructure evolution for Ti-55 high temperature titanium alloy during thermal deformation process and simulate microstructure evolution in different deformation conditions.Variation of dynamic recrystallization obtained by simulation meet metallurgical test results very well.The model can simulate recrystallization microstructure for Ti-55 titanium alloy and forecast grain size of dynamic recrystallization during hot compress deformation.