The flow behavior and microstructure evolution during (alpha plus beta) deformation of beta wrought TA15 titanium alloy

摘要

The hot compressions in (alpha + beta) region were conducted on beta wrought TA15 titanium alloy, so as to investigate the effect of beta working on the flow behavior and dynamic globularization of lamellar microstructure. The results indicated that initial beta grain size had no significant influence on flow stress. The dynamic globularization rate of alpha laths in smaller beta grains was higher due to the difference in lamellar length. beta predeformation would decrease the flow stress of (alpha + beta) deformation. Most of a laths in the microstructure after beta predeformation were short with a geometric orientation vertical to beta grain boundary and rotated together during compression, which would promote the formation of alpha/alpha substructures, thus highly enhanced the dynamic globularization rate of alpha laths. While beta heat treated microstructure had long alpha lamellae with a random orientation, which tended to become kinked first and then break up into short ones, resulting in the delay of dynamic globularization. In addition, prior beta deformation changed the initial a phase texture and dynamic globularization rate would be affected by strain path. When the compressive direction in (alpha + beta) region was vertical to that of beta predeformation, the globularized fraction of alpha lamellae was apparently high. (C) 2016 Elsevier Ltd. All rights reserved.