Common two-phase titanium alloys mainly contain α phase and β phase, isoaxial α phase titanium alloys have good strength but slightly poor fracture toughness characteristics, and titanium alloys with lamellar structure have good toughness advantages, but the strength and shape of the isoaxial structure is slightly worse. The combination of mechanical properties of equiaxial structure and lamellar structure through chemical composition adjustment and corresponding forging process is the goal pursued in the industry.
In the composition of titanium alloy, different chemical elements have effects on the composition, proportion and size morphology of titanium alloy α phase and β phase, so the mechanical behavior of titanium alloy with different chemical composition is very different. Al element is the most widely added alloying element in titanium alloy, belonging to the displacement α-phase stable element, which has a solid solution strengthening effect on the alloy, and can form α2 phase with Ti in the alloy aging treatment to further strengthen the α phase. The elements Mo, V, Cr and Fe belong to the β phase stability of substitution type, in which Mo and V belong to β isomorphic elements, while Cr and Fe belong to β eutectic elements. The stable β phase can be obtained at room temperature by adding a certain amount of β phase stable element, and the α precipitated in the β phase during the subsequent aging process has obvious strengthening effect on the alloy. Zr and Sn elements belong to the substitution type neutral elements, which have a certain effect on the high temperature mechanical properties of titanium alloys.
The objective is to provide a titanium alloy with high strength and high toughness matching and its preparation process. Compared with the most widely used Ti-6Al-4V alloy in the chemical composition range, the fracture toughness value of the new titanium alloy is equivalent to that of the material under the condition of significantly improving the tensile strength, and has excellent strength and toughness matching; At the same time, by adopting the special die forging process for the titanium alloy, the difficult problem of forging is solved.
It is suitable for high strength and high toughness titanium alloy forging forming and heat treatment process, by coordinating the forging deformation of β single-phase zone and α+β two-phase zone to ensure the forming of forging, the solid solution treatment of forging is integrated into the forging process of α+β two-phase zone, reducing the solid solution treatment of a single two-phase zone, in addition, the designed forging heat treatment process has aging and stress relief treatment. The forging forming and heat treatment process designed by the invention is not only applicable to the alloy involved in the invention, but also solves the forging and forming problems of other high-strength titanium alloy forgings, and is different from the existing conventional titanium alloy forging production process.
