Dynamic recrystallization behavior and numerical simulation in β phase of BT25 titanium alloy

Abstract:

The single-pass isothermal compression test of BT25 titanium alloy was carried out by Gleeble-3500 thermal simulation machine. Najafizadeh-Jonas model of working hardening rate and Cingara-McQueen model of flow stress were used to study the critical conditions of dynamic recrystallization under the conditions of deformation temperature 1040 ~ 1100 ℃, strain rate 0.001 ~ 1 s_^-1 and maximum height reduction of 60%. The true stress-true strain curve were analyzed, and the critical strain model was established. At the same time, JMAK dynamic recrystallization kinetic equation was constructed by calculating material parameters and linear regression method. A numerical simulation model was developed to simulate the dynamic recrystallization behavior of BT25 titanium alloy during thermal deformation. The results show: The flow stress is sensitive to the strain rate and deformation temperature. High temperature and low strain rate are favorable for DRX. The prediction error of the finite element model for predicting DRX volume fraction is less than 10%. The results show that the model has a good prediction ability and provides an effective tool for predicting plastic deformation and microstructure in industrial production.

Key words:BT25 titanium alloy; critical strain model; DRX dynamic equation; DRX volume fraction; numerical simulation