Microstructure and Mechanical Response of Commercially Pure Titanium VT1-0 After Short-Term Hot Deformation

Short-term (1–2 s) hot bulk plastic deformation of commercially pure titanium VT1-0 was studied at 25, 500, 600 and 700 °C without post-deformation annealing. Optical metallography, XRD line-profile analysis and Vickers micro-hardness testing were used to characterize the as-deformed structural state. The α-Ti single-phase structure was retained across the entire temperature range. Both microhardness and grain size evolved non-monotonically: hardness ranged from 161.7 ± 11.2 HV at 600 °C to 184.5 ± 10.8 HV at 700 °C, while grain size varied between 21.5 and 24.9 μm against 36.5 μm in the initial material. Such non-monotonic hardness evolution with deformation temperature is consistent with the interplay between deformation strengthening and thermally activated softening reported for CP-Ti processed under other conditions. The fitted FWHM of the α-Ti (101) reflection ranged from 0.463° to 0.738° in the deformed specimens, compared with 0.24° in the as-received reference. Size-related and strain-related broadening were not separated, precluding a unique interpretation of these differences in terms of coherent-domain size or defect structure. Hardness evolution cannot be attributed to grain refinement alone. Thermally activated restoration processes may contribute to the observed differences; however, the present measurements do not establish the underlying mechanisms. Among the investigated specimens, the specimen processed at 700 °C exhibited the highest mean microhardness. This observation does not establish an optimal processing temperature or an optimum across other material properties.