Effect of Grain Size on the Shear Banding Behavior of Ti-6Al-4V Alloy Under Quasi-Static Compression

Ti-6Al-4V alloys with average grain sizes of 0.3 to 1.5 μm were fabricated by high-energy ball milling (HEBM) and spark plasma sintering (SPS). Mechanical properties and deformation behaviors of sintered Ti-6Al-4V samples were investigated. The compressive yield strength increases while the ductility diminishes when the average grain size of Ti-6Al-4V decreases. Localization of plastic deformation occurs in all the fine-grained titanium alloys under quasi-static compression. Macro shear bands are observed in the deformed Ti-6Al-4V specimens with average grain size of 1.5 μm. When the grains are refined to ultrafine-grained regime, not only macro shear bands but also micro shear bands are generated in the deformed specimens. It is found that the spacing distance between macro shear bands increases once the micro shear bands are formed, indicating that the generation of profuse micro shear bands could suppress the nucleation of macro shear bands.