Development of flow stress model for hot deformation of Ti-47%Al alloy

The hot deformation behavior of a gamma-TiAl based alloy (Ti-47%Al, mole fraction) was investigated by isothermal compression tests performed at elevated temperature of 900-1 200 degrees C and strain rate of 0.001-0.02 s(-1). The effect of temperature, strain rate and strain on the flow stress of the alloy was evaluated. The higher the deformation temperature and the lower the strain rate, the smaller the deformation resistance. The stress exponent, n, and the apparent activation energy, Q, were determined as 2.6 and 321.2 kJ/mol by the sine hyperbolic law, respectively. Based on the experimental results by the orthogonal method, a flow stress model for hot deformation was established by stepwise regression analysis. Then the effectiveness of the flow stress model was confirmed by other experimental data different from those experimental data used to establish the model. And it was proved that the flow stress model can well predict the mechanical behavior and flow stress of the alloy during hot deformation.