Build a strong "heart" for "Eagle"-a list of my country's superalloy applications in aeroengines
- Time of issue:2019-11-11
(Summary description)On November 11, the Chinese People's Liberation Army Air Force celebrated its 70th anniversary. For 70 years, under the Party’s strong leadership, the People’s Air Force has played a vital role in safeguarding national sovereignty, security, and development interests, and has established immortal merits.
- Categories:Industry News
- Time of issue:2019-11-11 11:05
On November 11, the Chinese People's Liberation Army Air Force celebrated its 70th anniversary. For 70 years, under the Party’s strong leadership, the People’s Air Force has played a vital role in safeguarding national sovereignty, security, and development interests, and has established immortal merits.
Over the past 70 years, the iron and steel industry has made outstanding contributions to the construction and development of the modern air force, creating a series of "air fist" and "blue sky weapon". Today, the editor will introduce you to the high-temperature alloy steel used in aeroengines. It is it that has created a strong "heart" for the Air Force "Eagle"!
After 70 years of development in the new China's aviation industry, my country has evolved from the initial imitation of Soviet fighters to fully independent design and manufacturing capabilities. From the imitation of MiG's J-5, J-6, J-7, etc., to the J-8's independent innovation, to the J-10's skyrocketing as a "competitive aircraft", to the J-20's emergence In one fell swoop, Chinese fighters caught up with foreign military aircraft. Over the past 70 years, my country's metallurgical industry has made an indelible contribution to the development of fighter aircraft and the growth of the People's Air Force, and has provided key material support for the creation of a powerful "heart" for aeroplane engines of all generations of fighter aircraft in my country.
The picture shows the Jiuzhai aero engine.
Overview of R&D and production of high-temperature alloys for aviation in my country
As a kind of irreplaceable key metal material for military and civil gas turbine engine hot-end components, superalloys currently account for more than 50% of the amount used in advanced aeroengines. The performance level of the engine depends to a great extent on the performance level of high-temperature alloy materials, so high-temperature materials have the reputation of "advanced engine cornerstone". Without the high-temperature alloy developed by the metallurgical industry, there can be no high-speed development, high efficiency, safe and reliable aviation industry, and it is impossible to achieve the leap from medium to high thrust of China's aero engine, from turbojet engine to turbofan engine. Leapfrogging, from the second generation engine to the fourth generation engine.
High-temperature alloys are developed on the basis of nickel-based corrosion-resistant alloys, but the driving force behind their development is the traction required by the development of aviation jet engines. China's aero engine was launched in 1955, and the simplest nickel-based superalloy GH3030 was trial-produced in 1956. Around 1958, in order to meet the needs of the development of the aviation industry, China began to develop its own high-temperature alloys, such as GH4033, GH4037, GH4049 and K417 and other alloys. Since the 1960s, China has developed more than 100 high-temperature alloy grades, some of which have reached the level of similar foreign alloys, such as blade alloys K417, K417G, K403, DZ404, DZ422, DZ417G, DZ4125, DZ4125L, IC6 (JG4006 ), DD403, DD402, DD407, DD406, etc., alloys for turbine disks GH2901, GH4133B, GH4169, GH4720, GH4065, FGH4097, etc., alloys for combustion chambers GH1140, GH4099, GH1015, GH3230, etc. and alloys for ring parts GH2903, GH2907, GH2909 . In short, my country's high-temperature alloys have basically formed a system and research and production base with Chinese characteristics. Various high-temperature alloys used in aviation and other industrial sectors can be produced and supplied in China.
At present, China has built a production base of deformed high-temperature alloy materials mainly composed of Fushun Special Steel, Baowu Special Metallurgy (formerly No. 5 Steel Plant) and Panchang Special. The annual production capacity is over 20,000 tons. It can produce forgings, Bars, plates, wires, belts, rings, pipes; formed a high-temperature alloy research and development and multi-variety small batch production base mainly composed of steel research Gaona, Beijing Institute of Aeronautical Materials, Metal Institute of Chinese Academy of Sciences, with a large number of well-known experts, scholars, Experienced engineering technicians and workers.
Since high-temperature alloys are the key materials for aero-engines, the chemical composition and mechanical properties of high-temperature alloys are disclosed internationally, and the production process is strictly confidential and blocked. Over the past few decades, China has relied on self-reliance and independent innovation to overcome various difficulties and take the path of its own characteristics in light of national conditions. It has formed a high-temperature alloy R&D system with industry-university-research integration, Chinese characteristics, and independent innovation capabilities, which meets advanced aviation engines. The demand for hot-end key components has made a tremendous contribution to the development of China's aviation industry.
It is our consistent policy to combine originality and tracking, to innovate in tracking, and to take our own characteristic research path in light of national conditions. Through decades of development, China has achieved a number of scientific achievements that have reached the international level. Originally innovated a number of alloys. Typical high-temperature alloys are GH4133B, GH3128, GH4586, K13, GH4761, etc.; production process technology innovation has trace element modification And micro-alloying technology, high alloying superalloy thermal processing technology, sleeve forging technology, purification and low segregation special melting technology, extra large turbine disk production technology, etc.
With the maturity of vacuum metallurgy technology and the improvement of alloying design level, a large number of new processes have been adopted, "integration of design, process and materials", the establishment and application of mathematical models and simulations of metallurgical processing, China's high-temperature alloy system has tended to mature. The only domestic high-temperature alloy academic institution is set up in the Chinese Metal Society High-temperature Alloy Academic Committee. In April 2018, China Steel Research Technology Group, Steel Research Gaona, and more than 60 enterprises and institutions in the United Nations mainly engaged in R&D, production and application of high-temperature alloys established the China High-temperature Alloy Industry Technology Innovation Strategic Alliance to promote the high-temperature alloys. The coordinated innovation of the industrial chain has realized the high-quality development of China's high-temperature alloy industry and better served China's aviation industry.
The picture shows the turbofan-B (Taihang B) engine.
Application of superalloys in my country's aircraft engines
At present, high-temperature alloys are mainly used in the four hot end parts of aero engines: fuel chamber, turbine guide blades, turbine working blades and turbine disks, in addition to casings, ring parts and tail nozzle regulators, turbine shafts, support rings , Shell, various bolts and other components. In high-performance aircraft engines, high-temperature alloys are also used for the disks and rotor blades at the rear of the compressor. Due to the complexity of the aero engine structure, the temperature and stress of each part are quite different, and the requirements and selection of materials are also different.
High temperature alloy for turbine disk. There are more than 10 kinds of deformed superalloys for engine turbine disks in production and research in my country. Deformed superalloys for turbine disks can be divided into two categories: the first category is iron-based superalloys, typically GH2036, GH2132, GH2901, etc., the operating temperature is below 650 ℃; the second category is nickel-based superalloys, typical : GH4169 is suitable for working below 650 ℃, GH4133, GH4133B and GH4698 are suitable for working in the range of 700 ℃ ~ 750 ℃, GH4500, GH4710, GH4720, GH4742, GH4079 are suitable for working below 800 ℃. The comprehensive performance of the FGH4097 superalloy powder turbine disk developed in my country has also fully reached the level of the Russian EP741NP powder disk.
Among the above alloys, GH2132 alloy is the earliest developed iron-based superalloy. In addition to being used as a turbine disk, it can also be rolled into profiles for the production of other high-temperature parts for aircraft engines. GH4133B alloy is a domestic alloy developed by micro-alloying on the basis of GH4033 alloy. It is currently the best and most widely used high-temperature alloy. It is used on more than 10 engines and has produced dozens of turbines. plate. GH4169 alloy is mainly used to make discs, blades, shafts, fasteners, etc., and has broad application prospects in the aviation industry. The Taihang engine uses a variety of GH4169 alloy discs. Among them, the high-quality high-strength GH4169 alloy high-pressure turbine discs produced by the advanced DA process are the largest and highest-performance GH4169 turbine discs produced so far in China. Since the Tenth Five-Year Plan period, with the technological transformation of smelting equipment and blanking equipment by steel mills, my country has produced high-quality GH4169 alloy vacuum consumable ingots with a diameter of 660 mm. At present, domestic steel mills can smelt high-quality GH4169 alloy, which has brought my country's high-temperature alloy smelting level to a higher level. With the successful application of GH4169 alloy in various types of helicopters, fighter jets and rocket engines, the market demand for this variety is increasing, and the quality requirements are constantly improving. Therefore, the production cost of GH4169 alloy is reduced and its international Competitiveness and product quality in the market are the directions for future research and efforts.
High-temperature alloy for turbine guide blades. Early engines had lower front turbine temperatures and simpler guide vane structures. The two deformed superalloys GH4033 and GH3128 can meet the requirements of the engine. However, with the development of the engine, the temperature in front of the engine turbine increases, the structure of the guide vane becomes complicated (such as cooling), and the working temperature of the required material also increases. The blade material has gone through the development process from the general deformed alloy to the traditional casting equiaxed superalloy and oriented eutectic, single crystal superalloy. After achieving the breakthrough of investment casting technology, casting superalloy has become the leading material of the guide blade.
China has developed more than 20 kinds of cast superalloys, and made turbine guide blades by investment casting process, including solid blades, hollow blades and directional solidification hollow blades of complex cooling systems, which basically meets the requirements of China’s active and research engines demand. Among nearly 20 kinds of equiaxed crystal casting superalloys, K403 alloy is the most widely used. K403 alloy is used in the manufacture of more than 20 different types of domestic engine guide vane blades. The use temperature is in the range of 900 ℃ ~ 1000 ℃. It has achieved good results and has achieved mass production. Alloys such as K418B, K406C for turboshaft engines have achieved good results in the manufacture of integral turbine guides. K438 alloy is the alloy with the best corrosion resistance. Some gas turbine engines use it as a guide vane. The application of directional solidification alloy has further increased the engine inlet temperature.
High temperature alloy for turbine working blades. The engine turbine working blades produced in early China generally use deformed superalloys, of which the most used are GH4037 (6 blades are manufactured on 5 engines) and GH4049 (9 blades are manufactured on 9 engines) nickel-based deformed high temperature The alloy can work stably for a long time at a temperature of 750℃~950℃; the GH4105, GH4080A, GH4720, GH4133, GH4220, GH4710 alloys are used less, and they have only made 1-2 blades on one engine.
As the engine thrust-to-weight ratio (power-to-weight ratio) increases, the turbine inlet temperature of the engine also increases, and the design department requires the use of turbine working blades with higher temperature capacity, thus starting to use high alloying and higher heat strength. Cast superalloy replaces deformed superalloy. Therefore, in the development of new machines and modification of old models, casting high-temperature alloys are used to make turbine working blades. For example, in the WP7 series engine, using the K417 alloy casting nine-hole hollow turbine blade to replace the GH4049 alloy forged solid blade, for the first time in China, the scientific research task of casting instead of forging was completed, which increased the turbine inlet temperature of the WP7 series engine by 100°C, greatly Improves the performance of the engine. The subsequent application of directional solidification alloys and first- and second-generation single crystal alloys has further increased the inlet temperature of advanced engines.
High temperature alloy for combustion chamber. The first superalloy GH3030 used in my country's combustion chamber was developed in 1956. Under the guidance of the demand of the former Soviet Union model engines, it has been successfully developed and put into use in the late 1950s and 1960s, such as GH3030, GH3039, GH3044, GH4033 and GH1140. These alloys basically meet the requirements of the original Soviet model engine.
In the 1960s, my country also developed some alloys with higher temperature or strength, such as GH3128, GH4099, GH1015, GH1016 and so on. In the late 1970s and after the 1980s, China introduced the WS9, WZ6 and WZ8 successively, and developed the FWP14 and WZ9 engines. GH5188, GH5605, GH3230, GH4648, MGH2756 and other superalloys, its performance has fully reached the level of similar superalloys in Britain, the United States and other countries.
The traditional Ni-based, Fe-based and Co-based high-temperature alloy sheets are limited by the nature (melting point) of the alloy, and have almost reached their limit service temperature, making it difficult to develop further. Therefore, since the 1980s, no high-temperature alloys or high-temperature materials for combustion chambers have been used in my country since the 1980s. In order to further develop high-temperature materials for combustion chambers, it is necessary to study a completely new material matrix and material technology. As the temperature of the combustion chamber increases, in addition to the use of some existing materials, high temperature alloys with a temperature resistance of more than 1000°C and high-efficiency cooling stave heating barrier coatings and short annular and floating wall structures must be used to ensure their reliable use. .
At present, China has begun to develop and trial-produce MGH4756 alloy for use in high-aero-engine flame tubes, afterburners, tail nozzle linings, flame stabilizers, fuel injection rods for confluence casings, etc., with operating temperatures above 1100°C And nitriding strengthened superalloy.
The picture shows the AEF3500 new turbofan engine, which is currently the engine with the largest domestic thrust.
Development trend and application prospect of superalloy
With the development of aero-engines, the temperature of the turbine inlet of the engine increases, and the temperature-bearing capacity of the material required to make the turbine hot end is getting higher and higher. At present, the amount of high-temperature alloys accounts for more than 50% of the total weight of gas turbines. In the future, the proportion of high-performance alloys such as directional solidified columnar crystals and single-crystal high-temperature alloys, powder metallurgy high-temperature alloys will increase.
Specifically, the future development trend of high-temperature alloys is to use Re, Ru, and Ir as alloying elements to maximize the high-temperature creep strength and develop third- and fourth-generation single crystal alloys; with a certain amount of Hf and Y Alloy oxidation resistance and process performance; more widely used directional solidification and single crystal turbine blade and guide blade castings; improving the purity of the turbine disk alloy in order to minimize the inherent internal defects of the turbine disk alloy; more widely used isothermal forging to make the turbine The disk has a uniform grain structure; the pre-alloyed powder is more widely used to produce turbine disk alloys; the hot isostatic pressing process is more widely used to reduce the looseness of the cast turbine blades and the structure is denser; the composite components are more widely developed and applied This kind of combined component is to connect two or more parts together by precision casting or diffusion connection method to form an integral component.
However, the melting point of the high-temperature alloy is lower than 1400°C, and it is difficult to use it at 1200°C or higher, so it is also facing new challenges. Intermetallic compounds, carbon-carbon and metal matrix composites, refractory metals and ceramics will be the main competitive materials. However, such materials have low plasticity and difficult to form and weld, which is a big problem in the world. Although high-temperature alloys face powerful challenges with new materials, the emergence of new processes and the development of new technologies in my country provide conditions for the development of new high-temperature alloys, improving the temperature and reliability of alloys, and reducing costs. In the next few decades, superalloys will still be the dominant material for future aero engines, and they still have strong vitality and bright prospects at present and in the future.
Aeroengine has become one of the important symbols to measure a country's scientific and technological level, military strength and comprehensive national strength. In the new era, we will continue to carry forward traditions, learn advanced foreign technologies, shorten the gap with foreign countries, take the path of independent innovation of Chinese-made high-temperature alloys, boldly explore, strengthen basic research and cutting-edge technology research, strengthen original innovation, integrated innovation and import digestion and absorption Re-innovate, continue to enhance innovation capabilities, and stimulate innovation vitality; the majority of science and technology workers in the metallurgical industry will under the leadership of the Party Central Committee with Comrade Xi Jinping at the core, do not forget the original intention, keep in mind the mission, and make new contributions to the research and production of high-temperature alloys, continue Make new and greater contributions to the development of high thrust-to-weight aeroengines
(China Metallurgical News China Steel News Network / Reporter Luo Zhonghe / Reprinted from China Metallurgical News WeChat public account)
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