Flow behavior and microstructure evolution during double-hit compression of Ti-5.6Al-4.8Sn-2Zr-1Mo-0.35Si-0.7Nd titanium alloy

In this paper double-hit compression processes are utilized to study the effects of cooling rate from beta region to alpha+beta region and deformation amount on the microstructures of near-alpha titanium alloys containing two different contents of carbon. It is found that during double-hit compression, the flow stress of first step in the beta region is comparable to that of the single-pass deformation, and that after second compression in the alpha+beta region is obviously higher than that in single-pass compression. The higher cooling rate and larger deformation amount in the alpha+beta region resulted in recrystallization and globularization of alpha platelets for both alloys because of inhibition of beta phase dynamic recovery caused by dislocation annihilation. Under the same conditions the amount of globularized alpha was much higher in the 0.3% C alloy than that in the 0.06% C alloy, which can be ascribed in carbide dissolution in solid solution as an alpha stabilizer during deformation in alpha+beta region and accelerated globularization of the alpha platelets. (c) 2012 Elsevier B.V. All rights reserved.