Deformation characteristics of Ti-6Al-4V alloy under isothermal forging conditions

An investigation was undertaken to determine the influence of forge temperature, ram rate, and starting microstructure on the deformation characteristics of isothermally forged Ti-6A1-4V alloy. Both yielding and finish forge pressures were measured in the practical range of forge temperatures and ram rates. With the absence of die-chilling, the results obtained can be quantitatively related to the hot deformation properties. The yielding and finish forge pressures and the stress-strain relationship are strongly de-pendent on forge temperature, ram rate, and initial microstructure. Although the forge pressures do not vary significantly with strain, an apparent yield-drop was observed, particularly in the Β preforms. On the basis of the above experimental findings and the activation analysis, the rate-controlling deformation process under isothermal forgings is discussed with respect to the dynamic softening. Additional observation was made on dynamic recrystallization in the temperature range of 1500‡F (1089 K) to 1650‡F (1172 K). Structural features and tensile properties of isothermally forged material are also pre-sented.