Stress-induced martensite transformation and mechanical properties of fine-grained Ti-10V-2Fe-3Al alloy fabricated by friction stir processing

Abstract

Ti-10 V-2Fe-3Al, as the metastable β-type titanium alloy, has several applications in the aerospace industry due to its good mechanical properties. However, the study of stress-induced martensitic transformation behavior and corresponding mechanical properties in its small-sized grains (<20 μm) needs to be further clarified. This study investigates the relationship between grain size, stress-induced martensitic transformation, and mechanical properties of Ti-10 V-2Fe-3Al after friction stir processing. When the spindle speed increased from 200 rpm-100 mm/min to 350 rpm-100 mm/min, the grain size grew from 7.53 μm to 13.06 μm, and the martensite triggering stress decreased from 287 MPa to 111 MPa. The phase boundaries formed by α" and β, as well as the grain boundaries formed by α" and α", enhanced the plasticity of Ti-10 V-2Fe-3Al. The Crussard-Jaoul analysis method was used to investigate the effect of stress-induced martensitic transformation on Ti-10 V-2Fe-3Al, it was found that the martensitic transformation leads to dynamic softening. The formation of α" martensite results in an increased work hardening rate.