Thermomechanical characterization of β-stabilized Ti-45Al-7Nb-0.4W-0.15B alloy

The correlation between hot deformation parameters and the workability of beta-stabilized Ti-45Al-7Nb -0.4W-0.15B (at.%) alloy was studied in the temperature range 1000-1200 degrees C and the strain rate range 0.001-1 s(-1). Deformation mechanisms were characterized by detailed analyses of the deformation behavior and microstructural observations. The results indicate that the deformation and recrystallization occurred preferentially in the grain boundary beta phases because its good high temperature deformability enhances grain boundary sliding and migration, and thus improves the workability. Decomposition of the beta phase to alpha(2) and gamma phases partly accommodates the stress concentration and is thus beneficial in hot deformation. Appropriate deformation processing parameters were suggested based on the processing map, and were successfully applied in the quasi-isothermal canned forging of industrial-scale billets. (C) 2011 Elsevier Ltd. All rights reserved.