Effect of Hot and Cold Compression Deformation on the Slip and Twinning Behavior of Ti–5Mo–4Fe Alloy

In metastable β titanium with a BCC structure, slip mainly occurs due to the high stacking fault energy that enables free dislocation motion. Deformations at room temperature generate a higher strain energy than that at high temperatures; as the thermal energy at room temperature is not sufficient to relieve it, deformation mechanisms such as twinning and stress-induced martensite are activated, which complement and promote slip. However, compared to the {332} twin, the {112} twin is less likely to be activated as it requires a higher critical shear stress for formation. In this study, the slip and twinning activated during hot and cold deformations are analyzed with respect to grains that recrystallize during hot deformations and possess specific orientations. During multipass hot rolling, the grains were aligned in orientations favorable for slip activation, and the {110} slip system was activated within the grains with the {100}[110] orientation. In addition, a cold compression test was conducted, and the compressive stress and strain values were measured. Subsequently, the {112} twin was activated in grains with a {111}[110] orientation. An analysis of the deformation mechanisms under each temperature conditions revealed that the previously described mechanisms are favorably activated in grains with the [100] orientation.