Superalloy refers to a type of metal material based on iron, nickel, and cobalt that can work for a long time under a high temperature above 600 ℃ and a certain stress. Superalloys have high high temperature strength, good oxidation and corrosion resistance, good fatigue performance, fracture toughness and other comprehensive properties. The biggest characteristic of superalloys is not that their absolute melting point is very high, but that they still have good characteristics at high temperatures.
In a high-temperature environment, the material will accelerate degradation. During use, it is easy to cause unstable organization, deformation and crack growth under the action of temperature and stress, and oxidation and corrosion of the surface of the material. The high temperature resistance and resistance of high-temperature alloys Corrosion and other properties mainly depend on its chemical composition and organizational structure.
According to the matrix elements, superalloys can be divided into iron-based superalloys (accounting for 14.3%), nickel-based superalloys (accounting for 80%), cobalt-based superalloys (accounting for 5.7%)
Superalloy classification
Classification according to basic elements
Iron-based superalloy
Also known as heat-resistant alloy steel, heat-resistant alloy steel can be divided into martensite, austenite, pearlite, and ferritic heat-resistant steel according to its normalizing requirements. The operating temperature is low (600~850℃), and it is generally used for parts with low operating temperature in the engine, such as turbine discs, casings and shafts.
Nickel-based superalloy
The highest operating temperature (about 1000°C) is widely used in the manufacture of the hottest parts of aero jet engines and various industrial gas turbines, such as turbine blades, guide blades, turbines, etc.
Cobalt-based superalloy
The service temperature is about 950℃, with good castability and weldability. It is mainly used as guide vane material. The alloy is expensive due to less cobalt resources
Classification according to the preparation process
Wrought superalloy
The largest amount is required to prepare a high-temperature alloy master alloy first, and then process it into a material through cold and hot deformation methods such as forging, rolling, and extrusion. The degree of alloying and high-temperature strength are low.
Casting superalloy
The higher the service temperature and strength, the higher the degree of alloying. Under this circumstance, traditional hot forming is more difficult, and some parts are complicated in structure, requiring precision casting to make parts
Powder metallurgy superalloy
Using liquid metal atomization or high-energy ball milling machine powder, the crystal grains are fine, the composition and the structure are uniform, and the hot workability is significantly improved. The casting superalloys that are difficult to deform can be transformed into deformed superalloys by improving their thermoplasticity by the powder method.
Intermetallic Superalloy
Ti-Al intermetallic compound has low density, specific strength, high specific stiffness and excellent high temperature performance. It is the most ideal new high temperature structural material for aerospace flying chess.
Classification according to reinforcement method
Solid solution strengthened superalloy
It has excellent oxidation resistance, good plasticity and formability, and certain high temperature strength. It is mainly used for parts with higher ambient temperature but lower stress, such as combustion chambers and flame tubes.
Aging strengthened superalloy
It has high high temperature strength and creep strength as well as good overall performance. It is mainly used for parts with high load, high ambient temperature and medium temperature, such as turbine blades and turbine discs.
Oxide dispersion strengthened superalloy
Oxide particles are dispersed in the alloy, which has high thermal stability and can maintain high strength above 1000℃
Grain boundary strengthened superalloy
The addition of trace elements such as boron, cerium, zirconium and magnesium to the alloy improves the state of the grain boundary to improve the creep resistance of the alloy.
1. International
The development of high-temperature alloys is mainly carried out in Germany, Britain, the United States, Japan, Russia and other countries in the world. The international development system of superalloys presents a major feature. The applicable working temperature range of superalloys is getting higher and higher, from less than 800℃ in the early days to the current working temperature of 1700℃. With the continuous improvement of working temperature, it is new technology and new technology. The continuous iteration of the process, from deformed superalloys, casting superalloys to powder metallurgical superalloys, especially the promotion of directional solidification and other technologies has promoted the continuous improvement of aero-engine performance.
The United States is the most important country in the production of superalloys, with an annual production of about 50,000 tons, of which 60% is used for civilian use. In the military field, aero-engine manufacturers General Electric (GE) and Pratt-Wilani (PW) also produce superalloys; in the civilian field, US companies engaged in the R&D and production of superalloy materials include Special Metals Corporation and Cabot Company, Hannes-Stetter, etc.
The British International Nickel Corporation produced the world's first nickel-based metal superalloy. In addition, British Aero Engine Company Rolls-Royce also developed directional solidification alloys and single crystal alloys.
Major Japanese high-temperature alloy manufacturers are JFE Corporation, Nippon Steel, Ishikawajima Harima Heavy Industries and Kobe Steel. Japanese companies participate in the development of aeroengines, leading the world in single crystal alloys. Among them, NIMS and IHI used the fourth-generation Ni-based single crystal superalloy tms-138 to conduct high-temperature endurance tests for supersonic commercial airliners, and successfully reached 1,650 degrees of turbine input. The highest air temperature in the world.
General Electric Company/United States
The world's largest multinational company providing technology and service businesses. The aviation sector involves aero engines and control systems. In 2019, the revenue of this sector reached 229.3 billion yuan. General Electric is one of the world's three largest aero engine manufacturers. General Electric has mastered the second-generation single crystal blade RenN5, which is widely used in the aero engine field.
Pratt-Whitney Company/United States
One of the two largest aero engine manufacturing companies in the United States, and one of the world's leading manufacturers of aero gas turbine engines. Master the second-generation single crystal superalloy PWA1484. Revenue in 2019 reached 145.7 billion yuan.
Canon-Muskogon Corporation/United States
A well-known high-temperature alloy production company in the United States, and a global leader in investment casting alloys, produces equiaxial, directional solidification and single crystal nickel-based and cobalt-based alloys, as well as gas-melted cobalt alloys for smelting applications. It has a product line of single crystal and directionally solidified alloys, including CMSX-4 (high temperature single crystal superalloy) under the CM Alloy brand.
Westinghouse/United States
Major US electrical equipment manufacturers and nuclear reactor manufacturers' factories, most of the business is currently being acquired by Toshiba Corporation.
Hannes State Corporation/United States
Specializing in corrosion-resistant and high-temperature resistant aerospace alloys, chemical processing and industrial gas turbine industries, it was established in October 1912, with revenue of RMB 2.479 billion in the first three quarters of 2019 and net profit of RMB 25 million. Haynes products are used in almost all commercial aircraft parts today, as well as military aircraft parts used in the United States and its allies.
Cobalt Corporation (Cabot)/United States
Cabot Corporation is a global multinational company specializing in the production of special chemical products and special chemical materials. Its business scope includes carbon black, fumed silica, inkjet ink pigment paste, special metal materials, nano glue, plastic masterbatch and special drilling fluids. Cabot Corporation and its affiliates have production facilities and operations throughout the United States and approximately 20 other countries. Operating income in 2019 reached 23.602 billion yuan,
International Inco Alloy Company/United States
The world's first manufacturer to produce and develop malleable and machinable high-performance nickel alloys.
Martin-Marita Company/United States
A company whose main business is the wholesale and retail of high-performance nickel alloy materials.
Standard Pressed Steel Company/United States
Main AAR standard wheel wide flange profile-truck service-carbon steel; AAR standard wheel narrow flange profile-diesel locomotive; AAR standard truck rolling bearing axle (M-101)
Special Metals Corporation/United States
The world's leading inventor, developer and manufacturer of nickel alloys and cobalt alloys. Its product portfolio includes more than 100 alloy components, forged products and welding materials. The materials are widely used in petroleum exploration, aerospace, power generation, general industry and other fields .
Universe-Cyclops Steel Company, USA
A steel company located in Pittsburgh, Pennsylvania, was established in 1902 and was acquired by Alleghany Corporation in February 1987 for US$494 million. In the third quarter of 2019, operating income was RMB 1.329 billion, and net profit was RMB 29 million.
Hometech/United States
It is a division of Arconic, formerly Alcoa, an American company specializing in investment casting of superalloys, aluminum and titanium, mainly for jet aircraft and industrial gas turbine engine components. The company announced on February 8, 2019 that it would split into two separate businesses, one focusing on rolled products and the other focusing on engineered products. In November 2019, the company announced that its business focused on engineered products would be named Howmet Aerospace.
Rolls-Royce Company/UK
The famous British aero engine company, Europe's largest aero engine company. Directional solidification and single crystal alloys SRR99, SRR2000 and SRR2060 and other high-temperature alloys are mainly used in aero engine manufacturing.
International Nickel Corporation/United Kingdom
At present, the world's largest nickel supplier has always dominated the nickel market. Acquired by Vale Brazil in 2016
JFE Steel Corporation/Japan
It is the second largest steel group in the world, with multiple technologies representing the highest level of the world steel industry. In fiscal year 2018, its annual revenue was RMB 235.778 billion and net profit was RMB 9.952 billion. Tokyo-based JFE Steel has announced a partnership with China’s Baosteel Metal. The joint venture will start producing pre-mixed iron powder uniformly coated with copper and nickel alloys in 2018.
Nippon Steel & Sumikin Co., Ltd./Japan
Its crude steel output ranks first in Japan, and second only to Baosteel and ArcelorMittal in the world. It was formed by the merger of Nippon Steel and Sumitomo Metal in 2012. In fiscal year 2018, its annual revenue was 376.033 billion yuan and net profit was 15.288 billion yuan.
Kobe Steel/Japan
One of the largest steel companies in the world and the third largest steel conglomerate in Japan. In fiscal year 2019 (March 31, 2019-March 31, 2020), the company expects attributable net loss of 15 billion yen, operating loss of 5 billion yen; net sales of 1.89 trillion, a year-on-year decrease 4.2%.
Ishikawajima Harima Heavy Industries/Japan
The predecessor was the Ishikawajima Shipbuilding Institute, which was established on December 5, 1853. It has a history of more than 140 years. As early as the 1980s, Ishikawajima Harima Heavy Industries Co., Ltd. was involved in the research and development of aero engines. It has participated in the development of aero engines through Japan’s special international status. In recent years, it has participated in the research and development of Pratt & Whitney's gear turbofan engine with MTU of Germany. The Yokohama plant, which originally manufactured nuclear energy equipment, will focus on the production of aero engine parts.
2. China
China's superalloy has undergone the development process of imitation, imitation and creation combined with original creation, forming a unique superalloy system in China. There are more than 200 kinds of superalloys developed in China, and 177 of them were included in the national standard in 2005, forming the basis of the superalloy system. Before 1980, China's superalloys had formed its own basic system, which is now more complete and systematic.
Different from the international standards where manufacturers have formed their own systems, China's superalloys have formed a unified national standard, which builds a complete system in the order of alloy forming methods, matrix elements and strengthening methods. Among them, alloy forming methods include deformed superalloys, cast superalloys (including equiaxed crystal casting superalloys, directionally solidified columnar superalloys and single crystal superalloys), welding superalloy wires, powder metallurgy superalloys, and dispersion strengthened superalloys It is divided into high temperature materials with intermetallic compounds; under these different alloy series, it is divided into iron-based, nickel-based, cobalt-based and chromium-based alloys; under the same matrix, it is divided into solid solution strengthening and aging strengthening types.
The research and production of superalloys in China has experienced more than 60 years of development, and a relatively complete superalloy system has now been formed.
The field of superalloy materials has a high technical content. At present, there are only four countries with complete superalloy systems in the world, including the United States, Britain, Russia, and China. There are no more than 50 companies in the world that can produce superalloys for aerospace use. The field of superalloy materials not only requires high production technology, long-term capital investment, long certification time and customer stickiness are also one of the manifestations of the high threshold of the industry. Whether it is military or civilian products, the superalloy industry has strict audits, long time spans, time-consuming and laborious, and has built a natural barrier to entry for the industry. Half of superalloys are used in the aerospace field, especially military supplies. Due to the requirements of strategic security and confidentiality, the leading Chinese manufacturers of superalloy materials are expected to maintain their leading advantages.
At present, the number of high-temperature alloy enterprises in China is small, and the overall technical level still lags behind that of leading foreign companies. Especially in the high-end aerospace field, there is a large gap between the production capacity and actual demand of high-temperature alloys. According to our years of research in the field of superalloy materials, there are 12 superalloy materials head enterprises in China, and their theoretical capacity of superalloys totals about 20,000 tons. At present, 50% of the market demand for superalloys depends on imports. Taking into account the current China The gap between the effective production capacity and demand for superalloys is expected to be more dependent on imports.