Flow Stress Prediction of Near-β Ti-55511 Alloy During Iso-thermal Compression Based on Corrected Arrhenius Model with Material Parameter Evolution and BP-ANN Model

Abstract:

To investigate the hot flow behavior of Ti-55511 alloy in near-β region, isothermal compression tests were conducted at the temperature of 973-1223 K and the strain rate of 0.001–1 s^-1 by Gleeble-3500 thermomechanical simulation equipment. The flow stress curves obtained from experiments were corrected, and the influence of friction and adiabatic temperature rise on flow stress was reduced. The corrected Arrhenius model with consideration of material parameter evolution and the back-propagation artificial neural network (BP-ANN) model were used for flow stress prediction of Ti alloys during hot deformation process, and the precision of these prediction models were evaluated by statistical analysis. The stress and strain data extended by the two prediction models were implanted into finite element to simulate the hot compression process. Results show that the flow stress of Ti-55511 alloy has a positive correlation with strain rate and a negative correlation with temperature. The alloy softening mechanism is primarily the recrystallization. Both the corrected Arrhenius model and BP-ANN model can describe the flow behavior of fluid, and the fitting accuracy of BP-ANN model is higher than that of corrected Arrhenius model in α+β region but lower than that of corrected Arrhenius model in β region.

Key words:constitutive model;Ti-55511 alloy;flow stress;corrected Arrhenius model;BP-ANN model