Effects of hot deformation parameters on flow stress and establishment of constitutive relationship system of BT20 titanium alloy
(1.黑龙江省哈尔滨市哈尔滨工业大学材料科学与工程学院2.School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China)
Abstract: The hot compression experiments were performed to investigate the effects of hot deformation parameters on the flow stress of BT20(Ti-6Al-2Zr-1Mo-1V) titanium alloy. The results show that the flow stress decreases with the increment of deformation temperature and increases with the growth of strain rate. The peak stress moves toward the direction of strain reducing and the strain rate sensitivity increases with the rising deformation temperature. There is obvious deformation heating created during hot deformation under relatively higher strain rate and lower deformation temperature. The improved back propagation(BP) neural network with 3-20-16-1 architecture has been employed to establish the prediction model of flow stress using deformation degree, deformation temperature and strain rate as input variables. The predicted values obtained by BP network agree well with the measured values, the relative error is within 6.5% for the sample data and not bigger than 9% for the non-sample data, which indicates that the ANNs adopted can predict the flow stress of BT20 alloy effectively and can be used as constitutive relationship system applied to FEM simulation of plastic deformation.
Key words: BT20 titanium alloy； hot deformation parameters； flow stress； constitutive relationship； BP network