• Severe plastic deformation via HPT and ECAP effectively refines grain size to sub-micrometer levels in Ti-6Al-4V, leading to a significant increase in yield strength and ultimate tensile strength.
• The processed alloy exhibits a bimodal grain size distribution, which contributes to a favorable combination of strength and ductility.
• The study provides a comprehensive comparison of HPT and ECAP, showing that HPT yields finer grains and higher strength at lower processing temperatures.
• The enhanced mechanical properties make SPD-processed titanium alloys promising for high-performance applications in aerospace and biomedical engineering.