Constitutive relationship of Ti600 alloy for hot deformation

The hot deformation behavior of Ti600 alloy at deformation temperatures ranging from 25 to 800 ℃ and strain rates of 10^-4 and 10^-3 s^-1 was studied by isothermal compression on a WDW-300 electronic universal testing machine. GW-1200A controller and high-temperature furnace were used to provide an accurate temperature control and measurement during testing. The true stress-true strain curves of Ti600 alloy were obtained. The results show that the flow stress of Ti600 alloy does not change obviously with the increasing of strain rate at lower temperatures (25 and 300 ℃), while it increases with the increasing of strain rate at higher temperatures (600 and 800 ℃), and the flow stress decreases with the increasing of temperature at the same strain rate. Based on the experimental results of true stress-true strain curves of Ti600 alloy at different temperatures, a modified Inoue Katsuro constitutive model was established to explore the flow stress of Ti600 alloy at elevated temperatures. A good agreement between the model predictions and the experimental results is derived, which verifies the reliability of the model. The fracture mode of Ti600 alloy at room temperature after the quasi-static compression was analyzed using scanning electron microscopy (SEM) and results show that the alloy is mainly of brittle fracture with some ductile fracture in the local region of the fracture surface.