The application of titanium alloy in aviation industry is divided into aircraft structure titanium alloy and engine structure titanium alloy. In aerospace, titanium alloy is mainly used as the structure and container material for rockets, missiles and spacecraft. The use temperature of aircraft structure titanium alloy is generally below 350℃, which requires high specific strength, good toughness, excellent anti-fatigue performance, good welding performance, etc. Titanium alloy for engine is required to have high specific strength, good thermal stability, oxidation resistance, creep resistance and other properties. Apart from the performance requirements of titanium alloy for aviation, space vehicles also need to be able to withstand high temperature and radiation.
The main parts of aircraft titanium alloy structure are landing gear parts, frames, beams, fuselage skin, heat shield and so on. Russia's il-76 USES a high-strength BT22 titanium alloy to make key components such as landing gear and load bearing beams. The main landing gear transmission beam material of Boeing 747 is ti-6al-4v, the forging is 6.20 meters long, 0.95 meters wide and weighs 1,545 kilograms. High strength and high toughness ti-62222s titanium alloy is used in key parts of the horizontal stabilizer shaft of c-17 aircraft. The rear fuselage area of the f-22 aircraft engine and the heat shield at the tail of the aircraft are designed with titanium alloy thin-walled structure, which has good temperature resistance.
In terms of aeroengine, titanium alloy materials are used in compressor disc, blade, drum, high pressure compressor rotor, compressor casing, etc. About 30% of the structural weight of modern turbine engines is made of titanium alloy, which reduces the quality of compressor blades and fan blades, and prolongs the service life and inspection interval of components. The leading edge and tip of the fan blades of the Boeing 747-8genx engine are protected by titanium alloy sleeves, which have been replaced only three times during their 10-year service life.
Titanium alloy forgings for aviation use need to go through the processes of ingot casting, billet making, die forging and machining to obtain the required material structure and properties. According to hb5024-1989, the outside diameter of large forging should not be less than 500mm. With the development of aircraft and engines, the quality requirements of aviation forgings are higher and higher, the size is larger and the shape is more and more complex. Aircraft structural parts are complicated in shape, and the material utilization rate is generally less than 10%. The four large main load bearing frame materials of the f-22 aircraft are ti-6al-4v ELI, and the projection area of the die forgings is 4.06 ~ 5.67 square meters. In recent years, China's aviation titanium alloy professional forging equipment has been greatly improved, now has been able to produce 5 square meters of titanium alloy overall forging.
The spacecraft works under extreme conditions such as ultra-high temperature, ultra-low temperature, high vacuum, high stress and strong corrosion. In addition to excellent structural design technology, it also relies on excellent properties and functions of materials. Titanium alloy has been used in the manufacture of fuel storage tank, rocket engine housing, rocket nozzle conduit, satellite housing and so on.
