Establishment of Constitutive Equation of Hot Deformation of Ti-6Al-4V-0.1B alloy with Widmannstätten structure

Abstract In order to study the hot deformation behavior of the Ti-6Al-4V-0.1B alloy with Widmannstätten structure and obtain its constitutive equation,the Ti-6Al-4V-0.1B alloy cylindrical specimens with size of Φ8 × 12mm were prepared for the hot compression test on the Gleeble-1500 simulation machine,the deformation temperature from 850 to 980°Cand strain rates of 0.01 to 1s-1.The true stress-strain data and curves were obtained from the hot compression test.The results show that the true stress-strain curves of Ti-6Al-4V-0.1B alloy with Widmannstätten structure have the characteristics of flow stress softening and the flow stress is sensitive to temperature and strain rate.At the same temperature, flow stress increase with the strain rate.At the same strain rate, flow stress decrease with the temperature.Through regression analysis of true stress and strain data by Arrhenius hyperbolic sine function, the activation energy Q is calculated, 890.49kJ/mol.Under the range of the experimental deformation temperatures and strain rates, the constitutive equation is σ=11.36ln{(Z/e 88.47 ) 1/4.4107 +[(Z/ e88.47 ) 2/4.4107 +1] 1/2 }.