Acceleration of globularization during interrupted compression of a two-phase titanium alloy

To characterize the plastic deformation behavior and globularization in multistage primary hot working, isothermally interrupted compression was carried out for a TA15 titanium alloy with initial colony structure at temperature of 900 °C and strain rate of 0.1 s⁻¹. Through-process microstructural developments were examined by Electron Backscattered Diffraction (EBSD) and Scanning Electron Microscope (SEM). The globularization efficiency was analyzed via the evolution of intra-α boundaries, α/β interfaces and α grain size. The analyses show that the globularization efficiency is greatly enhanced by short time holding after a true strain of 0.73. The acceleration in globularization is associated with the formation of transverse intra-α boundaries across the α lamellae, the loss of α/β interfacial coherency, the change in deformation mode and the improvement of deformation homogeneity. Thus, the globularization efficiency increases with interrupted strain, holding time and loading pass. The results can be used to optimize the primary hot working of titanium alloys.