Constitutive equation and processing map for hot compressed as-cast Ti-43Al-4Nb-1.4W-0.6B alloy
(1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
2. School of Aeronautics and Astronautics, Central South University, Changsha 410083, China)
2. School of Aeronautics and Astronautics, Central South University, Changsha 410083, China)
Abstract: High temperature compressive deformation behaviors of as-cast Ti-43Al-4Nb-1.4W-0.6B alloy was investigated at temperatures ranging from 1323 K to 1473 K, and strain rates from 0.001 s-1 to 1 s-1. The results indicated that the true stress—true strain curves show a dynamic flow softening behavior. The flow curves after the friction and the temperature compensations were employed to develop constitutive equations. The effects of temperature and the strain rate on the deformation behavior were represented by Zener-Holloman exponential equation. The influence of strain was incorporated in the constitutive analysis by considering the effect of the strain on material constants by a five-order polynomial. A revised model was proposed to describe the relationships among the flow stress, strain rate and temperature and the predicted flow stress curves were in good agreement with experimental results. Appropriate deformation processing parameters were suggested based on the processing map which was constructed from friction and temperature corrected flow curves, determined as 1343 K, 0.02 s-1 and were successfully applied in the canned forging of billets to simulate industrial work condition.
Key words: TiAl alloy; flow stress; hot deformation; constitutive equation; processing map