Abstract:A near β-type Ti-5.5V-4Mo-2.2Cr-Fe-3.6Al alloy was designed based on the multi-alloying principle of critical compo-sition, combined with parameters, such as electron concentration, molybdenum equivalent and Bo-Md, that can influence the stability of β phase. The homogenized alloy was subjected to solid solution, intermediate annealing during the rolling process, and aging treatment. The microstructure and mechanical properties of the alloy were analyzed by optical microscope, scanning electron microscope, X-ray diffractometer, electron backscattered diffraction and transmission electron microscope, as well as room-temperature tensile properties. The results show that martensitic transformation occurs in the alloy during rolling. The grain size of the alloy after intermediate annealing is only 38 μm, because the martensite is a hindrance to grain boundary migration. Grain refinement endows the annealed alloy with a good match of strength and plasticity, a yield strength of 1050 MPa and an elongation of 15%. A large number of α phases are precipitated in the microstructure of the rolled alloy after aging treatment, which further improves the properties of the alloy: the strength of the alloy exceeds 1500 MPa and the elongation is 5%.