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Application of titanium in foreign Aerojet engines
Aviation industry is the main field of titanium, and jet engine is an important part of the main field of titanium. According to the statistics of relevant parties in the United States, from 1959 to 1973, titanium used in jet engine manufacturing in the United States accounted for 37% - 50% of the total national consumption, while titanium used in small subsonic jet engines accounted for 1 / 3 of its total mass.
In aero-engine, medium temperature components made of titanium have higher fatigue strength, yield degree, creep strength and lower elastic modulus than steel, so it can reduce the stress under fatigue load. Titanium alloy has high corrosion resistance, which can greatly relieve the compression performance of jet engine. Increasing the boost ratio of the engine compressor and the gas temperature at the turbine inlet can improve the overall efficiency of the engine, so as to improve the engine thrust, improve the thrust weight ratio and reduce fuel consumption. The total pressure ratio of engine compressors in the United States and Britain has increased from 10-13 in the early 1960s to 20-27 in the 1970s, and is increasing year by year. The total pressure is expected to increase to 50. Without cooling technology, the temperature of turbine inlet of multipurpose fighter has already exceeded 1650 ℃.
Due to the harsh working conditions and the increase of the size of the engine, light alloy and stainless steel are difficult to be competent, so the dosage does not decrease. However, titanium alloy and superalloy have more and more advantages due to the decline of production cost, the continuous improvement of processing performance and the adoption of new technology, and their applications in the engine are increasing year by year. The materials of several major aircraft engines in the United States from 1950 to 1980 are shown in the table below.
The titanium used in jet engines produced by Pratt & Whitney company of the United States is 7% - 15% of the total mass, and that used in J73 jet engine of General Electric (GE) company is 6%. The rotor of j79 engine was originally grade 17 stainless steel and later changed to grade 11 titanium alloy, the titanium used in j79-8 engine is 20%, and that used in j79-3 engine is 4%.
The use of titanium in American aeroengines began in 1954. At that time, four titanium engines j57 were equipped for B52 bombers, with titanium materials of 7% - 15%. Industrial pure titanium was used for inlet gate and low-pressure gate, and Ti-6Al-4V alloy was used for blades, discs and disc diaphragms of low-pressure compressor. The titanium consumption of jt3d turbofan engine is 15%: the low-pressure compressor fan blade, blade diaphragm and fan valve are all Ti-6Al-4V, and the fan blade is 406mm long, more than 2 times longer than the compressor blade. Because these components are made of titanium alloy, the engine performance has been greatly improved.
The jt9d engine fan blade is 711 mm long, almost 10 times longer than the compressor blade. Military jt3d modified engine and tf33 engine use 2% titanium. The titanium consumption of jt9d turbofan engine accounts for 28% of its total mass, about 1.035t, and its 46 fan blades are made of Ti-6Al-4V alloy; The rotor of low-pressure compressor and 9 stages of 11 stage high-pressure compressor are made of Ti-6Al-4V, ti-8al-1mo-1v and ti-6al-2sn-4zr-2mo alloys. The latter alloy is a kind of superalloy with working temperature of 480 ℃ and dosage of 450kg. The stator blade adopts ti-5ai-2.5sn. The modified jt9f engine uses 4.5t titanium material, and the cost of titanium material accounts for 5% of the engine. The titanium material used in tf39 fan engine is up to 33%, which is equipped in C5a military transport machine and weighs about 3T. The compressor disc and blade are made of Ti-6Al-4V and ti-5ai-2.5sn. The compressor blank is forged, with the original weight of 312kg, which is reduced to 126kg by precision forging. The blade gross weight was originally 21.5kg, but only 5.7kg after forging.
The total weight of ge4 turbojet engine is about 5T and 10% titanium is used. The first four stages of hollow compressor are made of ti-6al-2sn-4zr-2mo alloy. It is a kind of high creep alloy. The working temperature can reach 500 ℃, which is 100 ℃ higher than that of Ti-6Al-4V alloy. Using titanium instead of steel to make some components of lift engine can improve the thrust weight ratio. For example, the thrust weight ratio of jr200 engine, whose compressor and turbine were originally made of steel and made of titanium alloy and heat-resistant aluminum alloy, increased from 10 to 16. Its first compressor blade, front axle, compressor disc, rear axle and disc of the turbocar are made of Japanese ks150 alloy (ti-5ai-2cr-1fe). The static blade of the compressor is made of Ti-6Al-4V alloy instead of Cr12 stainless steel, reducing the mass by 43%.
In Russia, the HK8 turbofan engine equipped with il-62 transport aircraft uses about 40% of its mass of titanium alloy, and the hk144 turbofan engine equipped with Tu-144 supersonic transport aircraft also uses a lot of titanium alloy.
The high pressure compressor drum of rb172 engine of British RR company (rolls – Royce) is made of titanium alloy imi685 (ti-6al-5zr-0.5mo-0.25si), which has high creep resistance, fracture toughness and excellent weldability.
V2500 engines used in Airbus A320 and McDonnell Douglas MD-90 civil aircraft are twin shaft turbofan jet engines with a mass of 2.2t, and titanium alloy structural parts account for 31%. They are jointly developed by the UK, the United States, Germany, Italy and Japan. The high-pressure compressor is manufactured by RR company, and its stages 3-6 are made of iml550 (ti-4al-4mo-2sn-0.5si) alloy with high creep resistance; Fans and low-pressure fans made in Japan mainly use Ti-6Al-4V alloy.