The martensitic transformation during deformation of titanium alloys with metastable ? phase

Abstract

1. It was established by x-ray analysis that metastable β and α" phases can transform during plastic deformation. 2. The large difference between the ultimate and yield strengths observed in titanium alloys quenched to metastable β phase decreases greatly with increasing degrees of cold plastic deformation. This limits the use of the high plasticity of quenched α+β titanium alloys. 3. The region was determined in which β phase is mechanically unstable in binary titanium alloys with Mo, V, Nb, Ta, Fe, and Cr (alloys containing up to 20%Mo, 20%V, 50%Ta, 4%Fe, or 12%Cr). 4. The addition of aluminum substantially increases the tendency of metastable β phase to transform during deformation. The addition of eutectoid-forming elements (Fe, Cr, Mn) to alloys containing elements isomorphous with β titanium (Mo and V) with composition close to the critical composition inhibits the martensitic transformation during deformation. 5. Lowering the temperature from room temperature to −196° negligibly reduces the tendency of metastable β phase to transform during deformation.