Effect of Stress and Strain Path on Cavity Closure during Hot Working of an Alpha/Beta Titanium Alloy

Abstract

The effect of strain path and stress state on deformation and cavitation during hot working of Ti-6Al-4V was established via torsion-compression and reversed-torsion tests. Measurements of the cavity area fraction and the size of individual cavities revealed that the rate of cavity closure during the change in strain path following torsion is approximately twice as large in compression compared to reversed torsion. The observations were interpreted in the context of the effect of texture on local stress state and a micromechanical model for the consolidation of porous media. From an engineering standpoint, this work also indicated that the rate of cavity closure decreases with increasing deformation, thus suggesting that very large strains may be required to totally heal damage.