Deformation Behavior And Models At The High Temperature Deformation Of Ti-6.62Al-5.14Sn-1.82Zr Titanium Alloy

Plastic deformation is a complicated process. At the high temperature deformation, both deformation behavior and microstructure undergo a series of dynamic changes. The microstructure evolution not only influences the deformation process, but also determines the deformation behavior of materials significantly. Therefore, based on understanding of deformation mechanism, to establish accurately the microstructure and flow stress models, which reflects the influence of microstructure evolution on the flow stress, is a basis for realizing the coupled simulation of deformation behavior, heat transfer and microstructure evolution. And it is very important to reveal the deformation principle, optimize the process parameters, improve the quality and mechanical properties of workpiece, and develop the advanced plastic processes.Ti-6.62Al-5.14Sn-l.82Zr titanium alloy is a near alpha titanium alloy, which has good strength of high temperature and the thermostability, and the service temperature of Ti-6.62Al-5.14Sn-l.82Zr titanium alloy can reach at 600℃. Effects of the process parameters, including deformation .temperature, strain and strain rate, on the microstructure during high temperature deformation have been investigated by the isothermal compression and quantitative metallography. At the high temperature deformation process of Ti-6.62Al-5.14Sn-l.82Zr titanium alloy, the microstructure evolution model has been established in terms of the fuzzy-neural network theory. And the flow stress model has been proposed based on the microstructure model and the deformation mechanism of Ti-6.62Al-5.14Sn-l.82Zr titanium alloy. Integrating the present flow stress model into the FE code, a coupled simulation of deformation with heat transfer and microstructure has been carried out for upsetting of Ti-6.62Al-5.14Sn-1.82Zr titanium alloy. Effects of the process parameters on the equivalent stress field, the equivalent strain field, the temperature rise and the grain size during the upsetting process have been studied.Meanwhile, the models are verified through experimental results of Ti-6.62Al-5.14Sn-l.82Zr titanium alloy. The calculated results are in a good agreement with the experimental results. Thus, the present models have high prediction accuracy.