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 β region to α+β region and deformation amount on the microstructures of near-α titanium alloys containing two different contents of carbon. It is found that during double-hit compression, the flow stress of first step in the β region is comparable to that of the single-pass deformation, and that after second compression in the α+β region is obviously higher than that in single-pass compression. The higher cooling rate and larger deformation amount in the α+β region resulted in recrystallization and globularization of α platelets for both alloys because of inhibition of β phase dynamic recovery caused by dislocation annihilation. Under the same conditions the amount of globularized α 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 α stabilizer during deformation in α+β region and accelerated globularization of the α platelets.