Aero-engine material development (marketing department of Shanghai HY Industry Co., Ltd)
This paper introduces in detail the development and application of aero-engine materials, including key metal materials such as superalloys, titanium alloys, and steel, and ceramic matrix composites. The research and development status, research and development subjects and market demand prospects of China’s aero-engine materials are briefly described. Each aero-engine material has its own application parts and staged research and development results. In addition, this paper also objectively expounds the problems existing in the research and development, production and application of aero-engine materials in China and the gap with foreign countries, and analyzes the reasons for the problems and the direction of future efforts.
1 Materials used for key equipment in application fields
1.1 Overall situation of aero-engine materials
Aero-engine is an indispensable power system for cutting-edge weapon equipment and civil aircraft. It is known as “the jewel in the industrial crown”. Its development level embodies a country’s industrial base and technological level, and is one of the symbols of comprehensive national strength. At present, the world aviation engine industry has formed a highly monopolized situation dominated by companies such as GE, PW in the United States, RR in the United Kingdom, and SNECMA in France. After more than 60 years of development, especially since 2006, China’s aero-engine industry has initially formed the production of second-generation engines represented by turbojet series and the production of third-generation engines represented by turbofan series, a new generation of advanced military The general pattern of research and development of aero-engines and domestic large aircraft engines has greatly improved the development and production support capabilities of weapons and equipment, and has made great contributions to the development of the national defense industry and the civil aviation industry.
Aero-engine materials are an important material basis for the aero-engine industry. After decades of development, the localization and autonomy of some key materials have made great progress. Through the support of various scientific and technological projects, such departments have started independent innovation research that is synchronized with the world. Some new materials have promoted the smooth development of China’s aero-engines and made special contributions to national defense construction and national economic development. Driven by the design, development and production needs of new advanced power models, a series of high-quality Superalloy, titanium alloy, steel and other key metal materials and ceramic matrix composite materials have been developed and produced.
1.2 Application of Aero-Engine Materials
Advanced aero-engines are developing in the direction of high pre-turbine temperature, high thrust-to-weight ratio, long life and low fuel consumption. In addition to advanced design technology, the improvement of engine performance is strongly dependent on the development of advanced materials and manufacturing technology. The key and important parts of the engine are There is an urgent need for advanced materials such as superalloys, titanium alloys, thermal barrier coatings and ceramic matrix composites with high temperature resistance, high specific strength and oxidation resistance. 80% of the total weight of the aircraft engine.
Superalloys refer to high-temperature metal materials based on iron, nickel, and cobalt elements that can work for a long time at high temperatures above 600 °C and under certain stress conditions. Fatigue resistance, fracture toughness and other comprehensive properties are mainly used for aero-engine turbine blades, turbine discs, turbine shafts, turbine casings, compressor blades, compressor discs, compressor casings, annular parts, various fasteners, various Such components as pipelines have become irreplaceable key materials for aero-engine hot-end components, and are known as “the cornerstone of advanced engines”. Superalloys can be divided into iron-based superalloys, nickel-based superalloys and cobalt-based superalloys according to the types of matrix elements; according to alloy strengthening methods, they can be divided into solid solution strengthened superalloys and precipitation strengthened superalloys; according to material forming methods, they can be divided into For deformed superalloys, cast superalloys and powder metallurgy superalloys.
Titanium alloys can be divided into traditional titanium alloys and Ti-Al intermetallic materials (TiAl, Ti3Al and Ti2AlNb alloys), of which traditional titanium alloys are mainly used to manufacture aero-engine fan and compressor blades, discs, drums and casings These parts require materials with high specific strength, high temperature creep resistance, fatigue strength, permanent strength and organizational stability under high temperature working conditions (350-600 ° C). After decades of development, the maximum working temperature of solid solution strengthened titanium alloys has been increased from 350°C to 600°C. In the temperature range of 650-850 °C, ordered strengthened Ti-Al intermetallic compounds will be used. These alloys have high specific strength, specific stiffness, high creep resistance, excellent oxidation resistance and flame retardant properties, in addition to Low-density features help to reduce the overall weight of the engine. It is the main light-weight and high-temperature resistant material for structural parts used in aero-engine applications above 600 °C. It can be used to prepare high-pressure compressor blades, discs, casings and low-pressure turbine blades. Parts.
Aero-engine high-performance thermal barriers and protective coatings improve the corrosion resistance, high temperature oxidation resistance and wear resistance of hot-end components, which can effectively prolong the service life of components and are an important guarantee material for improving the performance of aero-engines. Thermal barrier coating materials can be divided into YSZ thermal barrier coating (use temperature 1170°C, coating thermal barrier temperature 50-100°C), rare earth composite oxide new thermal barrier coating (use temperature 1200-1300°C, coating heat Barrier temperature 150-200℃), rare earth magnesium-based hexaaluminate new thermal barrier coating (use temperature 1350℃, coating thermal barrier temperature 200-250℃).
Due to its remarkable temperature resistance and excellent comprehensive performance, ceramic matrix composites meet the urgent need for a substantial increase in the temperature bearing capacity of materials brought about by the performance improvement of advanced aero-engines. verify. The international key development of ultra-high temperature ceramics and their composite materials are: 1200-1400 ℃ grade SiCf/SiC ceramic matrix composite materials, 1400-1650 ℃ grade SiCf/SiBCN series ceramic matrix composite materials. In the future, the application potential of ceramic matrix composites in the field of aero-engines is huge.
High-temperature alloys and titanium alloys have become irreplaceable key materials for the hot-end components of military and civilian gas turbine engines, mainly used for key hot-end components, such as high and low pressure turbine disks, high and low pressure turbine working blades and guide vanes, pen tooth disks, Compressor disc, turbine shaft, combustion chamber, casing, etc. These hot-end components have been working under harsh conditions of high temperature, high pressure, hot corrosion, oxidation and high stress for a long time, so they put forward strict requirements on their metallurgical quality and preparation process.
1.3 Research and development status of aero-engine materials
After more than 60 years of development, China has basically formed a major force in the basic research of aero-engine materials, material development, material production material application research and material application, breaking through the key technologies of key material development and application, and basically solving the urgent problems in the field of aero-engine At the same time, the main unit of the key material industry has basically been formed, and good progress has been made in the industrialization of key technologies and equipment, realizing the transformation of the aero-engine material industry from scratch.
The basic research of aero-engine materials is mainly conducted by Beijing University of Science and Technology, Shanghai Jiaotong University, Central South University, Northwestern Polytechnical University, Northeastern University, Beihang University, National University of Defense Technology, Harbin Institute of Technology, Donghua University and other universities;
Materials are developed by China Aviation Development Beijing Institute of Aeronautical Materials, Beijing Steel Research Gaona Technology Co., Ltd., Institute of Metal Research, Chinese Academy of Sciences, Northwest Institute of Nonferrous Metals, Institute of Chemistry, Chinese Academy of Sciences, Aviation Industry Beijing Institute of Aviation Manufacturing Technology, Chinese Academy of Sciences Changchun Institute of Applied Chemistry as the main body;
Material application research is dominated by China Aviation Development Beijing Institute of Aeronautical Materials; in terms of material production, Fushun Special Steel Co., Ltd., Baowu Special Metallurgy Co., Ltd., Pangang Group Jiangyou Great Wall Special Steel Co., Ltd., Baoji Titanium Industry Co., Ltd. Co., Ltd. and Western Superconducting Materials Technology Co., Ltd. are the main production bases.
Driven by the application market, some private enterprises in China have also developed high-quality superalloy and titanium alloy materials. Typical private enterprises include Jiangsu Longda Superalloy Aviation Materials Co., Ltd., Jiangsu Tunan Alloy Co., Ltd., and Jiangsu Yonghan Special Alloy Technology Co., Ltd., Shanghai HY Industry Co., Ltd, etc., but the actual application amount is generally small; the material applications are China Aviation Development Shenyang Liming Aviation Engine Co., Ltd., China Aviation Development Xi’an Aviation Engine Co., Ltd., China Aviation Development South Industry Co., Ltd., China Aviation Development Chengdu Engine Co., Ltd., China Aviation Development Guizhou Liyang Aero Engine Co., Ltd., etc.
2 Problems existing in the application of materials in the field of aero-engine
At present, China has formed a major force in the research and application of aero-engine materials, breaking through a series of key technologies in material research and application research, and basically solving the problem of aero-engine research and development needs; Good progress has been made in chemical key technologies and equipment, and the transformation of key materials from scratch has been realized. However, compared with the aero-engine powerhouses such as the United States, the United Kingdom, and Russia, the industrial scale and level of China’s aero-engine materials are relatively small. At present, the main problems of aero-engine materials are as follows:
1) High-temperature alloys and titanium alloys are mainly imitations. There are few alloys with independent intellectual property rights, and independent material systems have not been formed. The ability of independent innovation needs to be strengthened urgently. Due to history and many reasons, China’s superalloys and titanium alloys are mainly based on the tracking and imitation mode, and the independent innovation ability is insufficient, and it is difficult to meet the needs of weapons and equipment to match and lead the development. China has imitated more than 100 grades of superalloys from the United Kingdom, the United States, Russia and other countries. That is to say, in so many application fields, they are basically imitation alloys, and no independent material system has been formed. In terms of single crystal superalloys, although independent research and development Four generations of alloys have been produced, but many foreign alloys are still imitated due to the imitation requirements of aero-engines; in terms of powder superalloys, the first and second generation powder superalloys are all imitated from abroad. Since China is mainly based on imitation alloys and has not formed an independent material system, it is urgent to improve the ability of independent innovation. Titanium alloys are mainly imitated from American and Russian materials, forming a variety of alloy series used in the range of 300-600 °C.
2) The basic research in the field of aero-engine materials is insufficient, the research and development units are too scattered, and there are too many materials of the same level, resulting in low technological maturity of most materials, especially deformed superalloy materials, poor batch stability, high prices, and many materials rely on imports.
In the field of aero-engines, the research and production units of key engine materials, especially deformed superalloy materials, have not carried out systematic research and development work in accordance with the whole process of material development, resulting in low material technology maturity, poor batch stability, high prices, and a large number of grades of alloys relying on Imports, such as deformed superalloy GH4169 large-sized bar used in the aero-engine field, the price in China is about 350 yuan/kg, and the price of the corresponding foreign brand IN718 alloy is only 200 yuan/kg, so more than 70% of this alloy in China relies on imports; cold-drawn bars , wire, strip, pipe also mainly rely on imports.
3) The application research of aero-engine materials is seriously insufficient, and the connection between production and application is insufficient. On the one hand, the traction and assessment of the material development process and batch production stability are seriously insufficient; Even lacking, the design and use data and typical parts assessment tests are seriously insufficient, the stability of the batch production of parts in the aviation factory is poor, and the performance of the parts cannot meet the service requirements. There is a phenomenon that “there are materials that will not be used or not used well, and the problem will be attributed to the material”.
4) China’s market capacity is limited, and there are too many brands and specifications used, resulting in insufficient demand traction and difficulty in forming an industry. The annual demand for deformed superalloys for aviation is about 10,000 tons, but there are nearly 80 grades; the annual demand for cast superalloys does not exceed 5,000 tons; the annual demand for powder superalloys does not exceed 1,000 tons; the demand for titanium alloys is less than 4,000 tons. In addition, it is expected that domestic civil aviation engines will be difficult to achieve mass production in the next 10 years, and it is difficult to greatly increase the total amount of superalloy and titanium alloy materials required for aviation.
5) Some cutting-edge materials and cutting-edge technologies in China have not yet been applied in engineering. In the aspect of deformed superalloys, 750 ℃ plate alloys have been applied abroad, and the triple purification melting process of superalloys has been maturely applied abroad in the 1990s, and currently only a few enterprises in China can apply them; foreign ceramics Matrix composite materials have been tested and verified, but China is still in the research and development stage, and there are various technical routes; foreign cast alloy blades have been applied, while China is still in the research and development stage.
6) The phenomenon of “few, missing and scattered” data in the production and application of aero-engine materials is more serious. The recorded content of the original data is very small, the data background information is incomplete, and the traceability is poor. It is difficult to form the accumulation of data resources and cannot meet the requirements of engine design. The rapid and timely application of material data makes it difficult to ensure data traceability.
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