Evolutions of the microstructures and mechanical properties of TC18 titanium alloy processed by hot-rolling in β single-phase region

Abstract

In this study, hot rolling treatment followed by water quenching was conducted on a TC18 titanium alloy in β single-phase region with varying reductions. Experimental evidences from X-ray diffraction and transmission electron microscopy indicate the formation of α phase, induced by sufficient stress and assisted by ω phase. In addition, the existence of α'' phase and diffuse streaks were also observed during the hot working processing. Furthermore, dynamic recrystallization (DRX) including continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) was proved to exist in the hot rolling process. During the whole DRX process, with increasing the deformation degree, recrystallized grains nucleated preferentially at high-energy areas such as grain boundaries and shear bands, then accumulated and grew until achieving a complete recrystallization state. It should be noted that DDRX mainly occurred at the grain boundaries, while CDRX grains nucleated within the shear bands. The elongation gradually decreased and tensile strength gradually increased with the increment of the deformation degree.

Keywords

• TC18 alloy
• Hot rolling
• Dynamic recrystallization
• Phase transformation
• Deformation mechanism