Since entering the 21st century, my country's aerospace industry has achieved unprecedented development, all of which rely on efficient airframe structure, strong engine, strong landing gear, advanced systems, etc., and the main components that form the basis of all these parts and components It is an aviation metal material.
The following editor will lead you to understand the application of metal materials in the aerospace field. Products in the aerospace field are expensive, and even small weight reductions can have a huge impact on the total cost, so the lightweighting of materials is critical in the aerospace field. Alloy materials such as aluminum alloys, magnesium alloys, titanium alloys and nickel-molybdenum-tungsten alloys are widely used in aircraft and aerospace fields due to their low density, high service life, excellent corrosion resistance and high temperature resistance and other comprehensive properties.
Among them, aluminum alloy materials account for about 50%--70% of aircraft materials, and magnesium alloy materials account for about 5%--10% of aircraft materials. In modern aircraft, the proportion of titanium alloys is increasing, while nickel-tungsten-molybdenum alloys account for more and more. are used in aircraft engines.
Aluminum alloy
Aluminum (face-centered cubic structure) is a light metal with low density (ρ=2.7g/cm3), about 1/3 of iron, low melting point (660°C), and high plasticity (δ: 32~40% , ψ: 70~90%), easy to process, can be made into various profiles, plates, good corrosion resistance; but the strength of pure aluminum is very low, the annealed state σb value is about 8kgf/mm2, so it is not suitable for structural materials. Through long-term production practice and scientific experiments, people gradually strengthen aluminum by adding alloying elements and applying heat treatment, which results in a series of aluminum alloys.
Aluminum alloy has low density, high strength, close to or surpasses high-quality steel, good plasticity, can be processed into various profiles, has excellent electrical conductivity, thermal conductivity and corrosion resistance, and is widely used in machinery manufacturing, transportation machinery, power machinery And in the aviation industry, the fuselage, skin, compressor, etc. of the aircraft are often made of aluminum alloys to reduce their own weight. Using aluminum alloy to replace the welding of steel plate material, the structural weight can be reduced by more than 50%.
magnesium alloy
It is the lightest metal among practical metals. The specific gravity of magnesium is about 2/3 of that of aluminum and 1/4 of that of iron. The specific gravity is about 2.1--2.3, and the melting point is about 300 degrees. It has high strength and high rigidity. Mainly used to manufacture non-load-bearing components and shells. For example, various valve housings, oil pump housings, etc.
Magnesium alloys are alloys composed of magnesium-based and other elements. Its characteristics are: low density (about 1.8g/cm3 magnesium alloy), high specific strength, large specific elastic modulus, good heat dissipation, good shock absorption, higher impact load capacity than aluminum alloy, and corrosion resistance to organic substances and alkalis. Okay. The main alloying elements are aluminum, zinc, manganese, cerium, thorium and a small amount of zirconium or cadmium. At present, the most widely used is magnesium-aluminum alloy, followed by magnesium-manganese alloy and magnesium-zinc-zirconium alloy. Mainly used in aviation, aerospace, transportation, chemical, rocket and other industrial sectors to manufacture low-load parts.
Magnesium alloys are prone to oxidation and corrosion in humid air, so the surface of the part needs to be chemically treated or painted before it can be used. Magnesium alloy has high anti-vibration ability, can absorb large energy when subjected to impact load, and has good heat absorption performance, so it is an ideal material for manufacturing aircraft hubs. Magnesium alloys are very stable in gasoline, kerosene and lubricating oil, and are suitable for the manufacture of engine gear casings, oil pumps and oil pipes. They are also used to manufacture rocker arms, flaps, Moving parts such as hatches and rudder surfaces.
Titanium alloy
Titanium is also a light metal with a specific gravity of about 4.5, which is heavier than aluminum, but has high strength, high temperature resistance, and a melting point of more than 1660 degrees. Most of the turbine shafts, turbine discs, nozzles, etc. are made of titanium alloy materials.
Titanium is an important structural metal developed in the 1950s. Titanium alloys are widely used in various fields due to their high strength, good corrosion resistance and high heat resistance. Many countries in the world have recognized the importance of titanium alloy materials, and have successively carried out research and development on them, and have been put into practical applications. In the 1950s and 1960s, it was mainly to develop high-temperature titanium alloys for aero-engines and structural titanium alloys for airframes. In the 1970s, a number of corrosion-resistant titanium alloys were developed. Since the 1980s, corrosion-resistant titanium alloys and high-strength titanium alloys have been further developed. The development of titanium alloys is mainly used to make aircraft engines and compressor parts, followed by structural parts of rockets, missiles and high-speed aircraft.
Nickel Molybdenum Tungsten Alloy
It is an ideal material for making engines. The temperature of the aircraft engine is as high as more than 2000 degrees, the general material is not enough, only the nickel-tungsten-molybdenum alloy can do it.
High strength steel
High-strength steels are commonly used in structural parts that require high stiffness, high specific strength, high fatigue life, and good moderate temperature strength, corrosion resistance, and a range of other parameters. No matter in the production of semi-finished products or in the construction of complex structural parts, especially in the production of welded structural parts with welding as the final process, steel is an irreplaceable material.
For a long time, the most used steel in the aircraft industry is medium alloyed high-strength steel with a strength level of 1600-1850MPa and a fracture toughness of about 77.5-91MPa per square meter. At present, under the condition of maintaining the same fracture toughness index, the minimum strength level of steel has been increased to 1950Mpa. We have also developed a new type of economical alloyed high-crack-resistant, high-strength welded structural steel, and developed a high-reliability structural steel with a strength performance level of 2100-2200Mpa; the high-strength corrosion-resistant steel has a strength level similar to that of medium-alloy structural steel, and is reliable The performance parameters greatly exceed those of medium alloy structural steel.
With the application of polymer materials in aircraft materials, the performance of aircraft is getting better and better. In the aviation industry, corrosion and anti-corrosion are important issues, but the general metal anti-corrosion effect is very poor. Because the corrosion resistance of polymer materials in acid, alkali and salt media is better than that of metals and other alloy materials, it is used in in the manufacture of aircraft. In addition, polymer materials have the advantages of low density and high strength, which are of great significance for reducing the weight of the aircraft itself and reducing energy consumption.