Hot tensile deformation behaviors of TA32 titanium alloy based on back-propagation neural networks and three-dimensional thermal processing maps

Abstract

The hot deformation behavior of TA32 titanium alloy in the temperature range of 650–850 °C and strain rate range of 0.0001–0.1 s−1 was studied by isothermal hot tensile tests conducted on an electronic universal testing machine equipped with an environmental chamber. The effects of temperature and strain rate on the flow stress of TA32 were investigated. Moreover, a back-propagation artificial neural network (BP-ANN) model was developed to predict the flow stress at elevated temperatures and three-dimensional (3-d) thermal processing maps. The results show that the three-layer BP-ANN model can precisely predict the flow stress as the correlation coefficient reaches 0.99365 and the mean relative error is 1.15621%. The 3-d thermal processing maps demonstrate that the lower strain rate, higher temperature, and larger strain lead to higher power dissipation efficiency and better formability. And it shows a flow instability tendency at lower temperatures and higher strain rates. Based on the 3-d thermal processing maps and microstructure analysis, the optimized temperature range and strain rate range for TA32 hot forming were 770–830 °C and 0.0001–0.00015 s−1.