Aviation titanium alloys are mainly used in aircraft structural parts, aero-engine structural parts and aviation fasteners.
The operating temperature of titanium alloys for aircraft structures is generally below 350 °C, and it is required to have high specific strength, good toughness, excellent fatigue resistance, good welding process performance, etc. The main application parts are landing gear components, frames, beams, Fuselage skins, heat shields, etc.
Titanium alloys for engines are required to have high specific strength, good thermal stability, good oxidation resistance and creep resistance. The main application fields are compressor discs, blades, drums, high-pressure compressor rotors, and compressor casings.
Titanium alloys for aviation fasteners are required to have good processability, non-magnetic, corrosion resistance, etc., mainly including titanium alloy rivets, titanium alloy bolts, etc.
Aircraft fuselage structural parts: the amount of titanium alloys continues to increase
Application of titanium alloy for fuselage structural parts: used for important structural parts such as wings, landing gear and tail
Titanium alloy has excellent properties such as low density, high specific strength, corrosion resistance, high temperature resistance, non-magnetic, weldable, wide operating temperature range (-269℃-600℃), and can be used for various parts forming, welding and machining. , which was soon widely used in the aviation field.
In the early 1950s, military aircraft began to use industrial pure titanium to manufacture less stressed structural parts such as heat shields, tail covers, and speedbrakes of the rear fuselage.
In the 1960s, titanium alloys were further applied to major stress-bearing structural parts such as aircraft flap slide rails, load-bearing bulkheads, mid-wing box beams, and landing gear beams.
Taking the American F14 fighter jet as an example, titanium alloys account for 26% of the structural weight of the F14 fighter jet. Components made of titanium include wing structures, landing gear components, tail structures, as well as small fasteners, springs and hydraulic pipes.
The use of titanium alloy as the body material has many advantages:
1) Substituting steel and nickel-based superalloys can greatly reduce aircraft quality;
2) It can meet the strength requirements of aircraft. Compared with aluminum alloys, titanium alloys with a mass of about 60% can achieve the same strength.
3) Good corrosion resistance, titanium alloy does not need surface anti-corrosion coating or coating.
4) Good electrochemical compatibility with polymer composites.
5) Meet the strength requirements in the limited space
Titanium alloy material for fuselage structural parts: Ti-64 is the most widely used and is developing towards better processing performance
At present, the titanium alloy materials used in the aviation field mainly include TC4 (US Ti-64 alloy), TC18, TC21, TA15, TB6 (US Ti-1023 alloy) and so on.
Ti-64 titanium alloy is the earliest and most classic titanium alloy, and it is designed to operate at temperatures up to 350°C. Ti-64 not only has high temperature resistance, but also has very good plastic workability, and is widely used in the aerospace field.
TC18 has greater hardenability and is suitable for the manufacture of large forgings. Russia has developed Ti-55531 titanium alloy on the basis of TC18 alloy according to the needs of civil aircraft such as Boeing and Airbus. Ti-55531 is stronger, with superior hardenability and a wider processing window, and has been used on parts such as A380 aircraft pylons and landing gear struts.
In terms of cast titanium alloys, the most widely used and most used cast titanium alloy in the aviation field is ZTC4 titanium alloy. Among the titanium alloy castings developed and produced in my country, the amount of ZTC4 and ZTA15 alloys accounts for 80%.
In addition, the commonly used cast titanium alloys in China are ZTC3 and ZTC6. ZTC3, ZTC6 and ZTA15 are titanium alloys and high-strength cast titanium alloys developed by BJHC Aerospace Materials Technology Corporation according to the development needs of China's aviation industry, or high-temperature casting titanium alloys play an important role.
Aeroengine Structural Parts: Mainly used for aircraft cold end components, and the application range of new titanium alloy performance improvement has been continuously expanded
Titanium alloys are mainly used in aircraft cooling end components, and the proportion of the usage continues to increase
The use of titanium alloys is the key to improving the thrust-to-weight ratio of aviation engines. The thrust-to-weight ratio is an important performance indicator of aero-engines. The thrust-to-weight ratio of the earliest aeroengines was 2~3, and the thrust-to-weight ratio of the fourth-generation aeroengines exceeded 10.
Titanium has good high temperature resistance, creep resistance and oxidation resistance at 300~650℃, and it is light in weight and high in specific strength. Tweet weight ratio.
Titanium alloys are generally used for rotating parts such as fans, high-pressure compressor discs, and blades of aero-engines, and stationary parts such as combustion chambers and tail nozzles.
In foreign advanced aero-engines, the amount of titanium alloys has accounted for 25% to 40% of the total engine mass. The amount of titanium alloys used in the third-generation aviation engine F100 has reached 25%, and the amount of titanium alloys used in the fourth-generation aviation engine F119 has reached 40%.
Titanium alloys are also used for fans, compressor discs, blades and other components. Taking the V2500 aero-engine as an example, the titanium alloy content reaches 31%, and the titanium alloy parts are mainly concentrated in the front of the engine and the position where the external working temperature is low. Alloy parts are used less. Titanium alloy parts are used in casings, rotor hubs, rotor blades, stator blades, bearing supports, pipes, brackets and many other parts.
Aerospace titanium alloys have high performance requirements, and the new titanium alloys further expand the scope of application
The application of titanium alloys in aero-engines requires good instantaneous strength, heat resistance, durable strength, high temperature creep resistance and organizational stability in a higher temperature range. α-type, near-α-type and α+β-type titanium alloys have good comprehensive properties in medium and high temperature environments, and are widely used in aero-engines.
Titanium alloys used in active aero-engines mainly include TC4, TC11, TC17 and TA11, etc., which are used for blades, discs, casings and other parts that work in the low temperature section of engine fans and compressors.
TC4 has good plastic workability, and TC17 is a two-phase titanium alloy with high strength, high toughness and high hardenability. Due to its low operating temperature, it is widely used in the manufacture of low-temperature components such as aero-engine fan blades and compressor discs.
TC25 titanium alloy is a heat-strength titanium alloy (Russian brand BT25) developed by the former Soviet Union. The alloy contains high melting point elements such as molybdenum and tungsten. It has good thermal strength and heat resistance. , mainly used in the manufacture of aero-engine high-pressure compressor discs.
With the urgent demand for high-performance titanium alloys in advanced aerospace, 600 ℃ high-temperature titanium alloys, flame-retardant titanium alloys, TiAl and SiCf/Ti composite materials have become the focus of the development of new high-temperature titanium alloys.
600℃ high temperature titanium alloy is suitable for high-pressure compressor overall blisk, casing, etc. with a working temperature of 500℃-600℃; flame-retardant titanium alloy is suitable for high-pressure compressor casing, blades, etc.; TiAl alloy is suitable for working temperature of 700℃ ℃-850℃ high-pressure compressor blades, turbine blades, etc.; SiCf/Ti titanium-based composite materials are suitable for high-pressure compressor integral blade rings.
TA29 titanium alloy still has good creep resistance at 620℃, when other properties meet the design requirements, it can be extended to about 620℃ for long-term use. In addition, TA29 titanium alloy can still maintain high tensile strength at 750℃-800℃, can be used in this temperature range for a short time, and is used in the body components of hypersonic missiles, rockets, aircraft, aerospace aircraft and other equipment, Skins, and high temperature parts of the engine used. TA29 titanium alloy has been manufactured from 3t-type industrial ingot smelting, Φ300mm large-sized bar preparation, large-sized blisk forging preparation to blisk parts machining, inspection and surface treatment.
TB12 and TF550 are flame-retardant titanium alloys, and flame-retardant titanium alloys are one of the development directions of new titanium alloys in China. On the rotating parts of aero-engines, due to the tendency of titanium alloy to be flammable, titanium alloy parts are added with anti-titanium fire coating or flame-retardant titanium alloy is used on the surface of titanium alloy parts. The Alloy-C (Ti-35V-15Cr) developed by P&W is highly stable. The flame-retardant beta titanium alloy has been used in the F-22 fighter jet's F119 engine with compressor baffles, superchargers and nozzles. Domestically, based on the composition of the American Alloy-C alloy, TB12, which can be used for a long time at 500 °C, and TF550, which can be used for a long time at 550 °C, have been developed.
TiAl alloy has both metal and ceramic properties. At 600℃-800℃, the specific strength of TiAl alloy is better than that of conventional titanium alloy, and it has good creep resistance, oxidation resistance and other properties. The 6th and 7th stage blades of the GEnx engine low-pressure turbine developed by GE for Boeing 787 use cast TiAl alloy blades instead of nickel-based superalloy blades, achieving a weight reduction of 72.5kg.
In 2014, Mecachrome signed a TiAl alloy supply agreement with French company Snecma. Mecachrome will supply CFM with TiAl alloy low-pressure turbine rotor blades for the manufacture of LEAP series engines.