Compression Deformation Mechanism and Constitutive Equation of Ti-Mo Steel in the Mushy Zone

The deformation mechanism and constitutive equation of Ti-Mo steel in the mushy zone were investigated through high-temperature compression deformation. Nonlinear fitting and polynomial fitting were used to build a precise constitutive model. The law of microstructure evolution was also researched. During the deformation of Ti-Mo steel in the mushy zone, the liquid phase was squeezed to the edge, and macro separation between the solid and liquid occurred after deformation. The extent of dynamic crystallization in Ti-Mo steel increased with increasing strain rate, which is quite different from the dynamic recrystallization occurring during deformation in the solid region. The critical condition for dynamic recrystallization decreased and the grain refinement degree increased due to the return temperature effect of the liquid between solid particles. The prediction accuracy of the modified Fields-Backofen (FB) model with a liquid-phase adjustment factor was compared with that of the Arrhenius model with a liquid-phase adjustment factor. The results showed that the modified FB model had low prediction accuracy. The Arrhenius model with a liquid-phase adjustment factor was revised according to different strain rates. The revised model had higher prediction accuracy and was suitable for describing the metal rheology in the mushy zone of Ti-Mo steel, with accuracy of approximately 90 pct.