α+β Titanium Alloy

The (α+β) titanium alloys obtained by adding monthly stabilizing elements to titanium, and most of them also add a stabilizing element, have good plasticity, are easy to be forged, calendered and stamped, and can be strengthened by quenching and aging. Strength can be increased by 50%- 100% after heat treatment TC4 is a typical ((α+β) titanium alloy, composition Ti-6A1-4V, after quenching and aging treatment, the microstructure is bulk a + β + needle a. Which needle a is precipitated from the β-phase in the aging process. As TC4 has high strength, good plasticity, stable organization at 40000, high creep strength, good toughness at low temperatures, and good resistance to seawater stress corrosion and resistance to hot salt stress corrosion, it is suitable for the manufacture of parts that work for a long time under 4000C, engine parts that require a certain degree of high-temperature strength, as well as rockets and missiles that are used in low temperatures, such as liquid nitrogen fuel tank parts.

Cast titanium alloy has good tensile strength and fracture toughness, endurance strength and creep strength close to the deformation of the alloy, but the plasticity and fatigue strength is lower. Table 15-2 lists the grades and use of cast titanium alloys in major international countries.
China's titanium casting began in 1964, when the Beijing Institute of Aeronautical Materials took the lead in carrying out research on titanium melting and casting technology, followed by the Northwest Nonferrous Metals Processing Plant installed 150kg of titanium melting equipment. At present, there are mainly 10 domestic scientific research and production units in the development and production of titanium and its alloy castings.
Domestic casting of titanium is still the main modeling process of machining graphite type and pounding graphite type, and precision casting process is not widely used, and foreign casting level still has a certain gap.