Magnesium alloys for aerospace applications -- wrought magnesium alloys

Magnesium alloy has a good damping function and a high capacity to absorb shock and vibration, so it is suitable for manufacturing parts to withstand shock load and vibration. In addition to structural applications, magnesium alloys have many non-structural applications.

MB8 is a magnesium - manganese series non - heat treatment strengthened wrought magnesium alloy. The process plasticity of the alloy is lower than that of the medium-strength MB2, MB3 and MB8 alloys, so the varieties produced are limited to extruded products, forgings and die forgings. The alloy can be processed into plate, bar, profile and complex shape forgings, die forgings, made of parts can be under 150C for a long time and under 200C for a short time.

Mg-zn-zr series alloys are available in three grades, MB15, MB22 and MB25. MB15 and MB25 belong to high strength magnesium alloys. The room temperature mechanical function is better than MB8, can be made into complex shape forgings and die forgings, used in the manufacture of aircraft internal components, doors, panels and missile skin, etc., can work for a long time below 150C, short time below 200C. Can work under 150C for long time and under 200C for short time. A small amount of cerium (mass fraction 0.15%~0.35%) is added to the alloy to refine the grain and improve the mechanical function, and the strength of the alloy is about 40MPa better than that of MB1. Let's take a look at magnesium alloys used in aviation and aerospace

The corrosion resistance of magnesium alloy in Marine weather environment is poor, so its application in aviation products is limited. Tensile performance of MB25 at room temperature is better than that of MB15 alloy. Magnesium in nickel alloy and copper alloy smelting as deoxidizer and desulfurizer, in the iron and steel industry as desulfurizer and nodular cast iron spherodizing agent, in the smelting of beryllium, titanium, hafnium and uranium as reducing agent. Welding function is good, argon arc welding resistance welding can be used. The alloy has poor plasticity at room temperature and good plasticity at high temperature, so the pressure working procedure of the alloy must be carried out in the heated state.

Mg-mn series alloy FOR aviation and aerospace, MB8 contains a small amount of rare earth cerium (mass fraction is 0.15%~0.35%), is not heat treatment strengthened alloy, has a high corrosion resistance, no stress erosion tendency, good welding function, can be made into various specifications of the shape of semi-finished products (plate, bar, mold and forgings), For the manufacture of aircraft skins, panels and gasoline, oil system parts, can work below 200 C for a long time and below 250C for a short time. The alloy can be manufactured into a wide variety of deformed semi-finished products, which can be used in aircraft skins and panels, as well as parts for gasoline and oil systems. According to the experimental data announced in the American Aerospace Structure Metal Manual, the corrosion resistance of AZ91E magnesium alloy is close to that of A357 forged aluminum alloy which is widely used in the aviation of European and American countries, which will be of great significance for the expansion of the application of magnesium alloy in aviation. The manufactured parts can work for a long time below 200C and for a short time below 250C. Similarly, Russia has also developed high purity wrought magnesium alloys which have been successfully applied in aviation products. MB15, MB25 alloy cutting function is good, welding function is poor. Therefore, aircraft, especially missiles, satellites and space shuttles are widely used in various wrought magnesium alloys. The alloy has good machinability and weldability, and is prone to stress erosion cracking, and is larger than MB2 alloy.

Magnesium alloy is the lightest metal structure material, its density is 1.75~1.85g/cm2. It can reduce the structural weight in aviation and aerospace vehicles, and reduce the inertia force for high-speed running parts. The alloy has poor process plasticity at room temperature and good process plasticity at high temperature, so the forming of the parts should be carried out under the state of heating, and the alloy machining function is good. In addition, it can also be used to make fireworks.

Magnesium alloys are divided into deformation alloys and forged alloys. The alloy is mainly processed into plate and used as the skin, wall panel and internal parts of aircraft, such as aircraft tail fin and cabin door. It can be used for short time operation of aerospace structure parts below 300C.

MB25 is mg-Zn-Zr-Yttrium series high strength wrought magnesium alloy, usually without heat treatment, used in hot extrusion or hot forging state, mainly used for processing extrusion products and die forgings, tensile strength, yield strength, high temperature and potential strength are better than the high strength magnesium alloy MB15 at room temperature

MB22 is a magnesium - yttrium-zn-zirconium series thermal strong deformation magnesium alloy, mainly made of sheet, its tensile strength at room temperature is slightly higher than MB3 alloy, high temperature yield strength, high temperature instantaneous strength and compressive yield strength is significantly better than other magnesium alloys (such as MB3, MB8). The strength and elastic modulus of magnesium alloy are lower than that of steel and aluminum alloy, but the specific strength and specific stiffness are higher. In the construction of the same weight, the use of magnesium alloy can make the member get higher stiffness. Magnesium alloy can be used as battery and battery material; Magnesium can be used as an alloying element in aluminum, zinc, lead, and other non-ferrous alloys. AZ91D suitable for die casting and AZ91E high purity magnesium alloy suitable for sand mold, metal mold and solution die forging were developed. Magnesium alloy has excellent cutting function, which is beneficial to the machining of parts. The alloy has good machinability and welding ability, small stress erosion tendency and good corrosion resistance. This kind of alloy is used to manufacture aircraft girder, rocker arm of control system, bearing and other mechanical components, which can work for a long time below 125C. The alloy has high corrosion resistance and no stress erosion tendency. The alloy can be recommended for short - term service up to 300C aviation structural parts. Foreign research and application of magnesium alloys has been committed to improving the corrosion resistance of magnesium alloys, mainly by improving the purity of magnesium alloys. For AZ91 magnesium alloys which are widely used in aviation in the United States, the purity of the alloy is improved to minimize the content of heavy metal impurities in the alloy, such as copper, nickel and iron. The stress erosion tendency of MB2 is smaller than that of MB3.

MB2 is a magnesium - aluminum - zinc series non - heat treatment strengthened wrought magnesium alloy. It can be used for parts working below 125C, such as aircraft boom, operating system parts, aviation hub, etc. About 600kg of wrought magnesium alloy was used in the launch rocket of the degerminet spacecraft. 675kg of wrought magnesium alloy was used in the giscaverlier satellite; The 1m diameter "verger" rocket case is made of magnesium alloy extrusion pipe; It is also used extensively in tactical aircraft missile cabins, aileron skins, panels, stiffeners, rudder surfaces, and bulkheads, decoy torpedo hulls, and in radar and satellite tacs

The plasticity, toughness and corrosion resistance of the alloy are similar to those of MB15.

MB15 is a high strength wrought magnesium alloy of magnesium-zn-zirconium series which can be strengthened by heat treatment.

MB3 is a non-heat-treated reinforced wrought magnesium alloy of magnesium-aluminum-zinc series. The strength of this alloy at room temperature is higher than THAT of MB2 alloy, but the process plasticity is poor at room temperature and good at high temperature. Therefore, the forming of parts should be carried out under the state of heating. For example, each B-36 heavy bomber uses 4,086 kg of magnesium alloy sheet. The wing of jet fighter lockheed F-80 is also made of magnesium alloy, which reduces the number of structural parts from 47,758 to 16,050. The Talon supersonic trainer has 11% of its fuselage made of magnesium (360lb of sheet, 280lb of castings and a small amount of extruder, sheet and pipe); The b-52 used 3,600 lb of magnesium alloy (199 extrusions, 19 forgings, 542 sand castings, and 380lb of sheet); The Falon Gar-1 air-to-air missile is made of 90% magnesium alloy. The body is made of 0.04m AZ31B-H24 plate rolled, longitudinally welded, and then deep drawn. As a new structural material in the aerospace industry, it can replace the medium strength aluminum alloy for the mechanical components of aircraft. Because the alloy welding function is poor, not recommended for welding parts.

Magnesium alloys for aerospace applications -- wrought magnesium alloys

. Good cutting and welding function, easy to argon arc welding resistance welding. MB22 is a magnesium-zn-zirconium alloy containing high yttria (mass fraction 2.9%~3.5%), mainly made of thick plate, its room temperature strength is slightly higher than MB3 alloy, room temperature tensile yield strength and compressive yield strength, high temperature instantaneous strength is significantly better than other magnesium alloys (such as MB2, MB3, MB8), the alloy has good forming and welding function. No stress erosion tendency. The alloy is usually used in the artificial aging state after hot forming. Its room temperature strength and yield strength are better than other magnesium alloys, and its cutting function is good, but the welding function is poor.

Magnesium-aluminum-zinc alloys, including MB2 and MB3, are non-heat-treatable alloys. The alloy has good forming and welding function and no stress erosion tendency. Because magnesium and its alloys have high electronegative properties, they can be used as sacrificial anode materials to prevent erosion of other metals and protect important metal components from erosion and destruction.

Compared with wrought magnesium alloy, wrought magnesium alloy is finer in structure, more average in composition and denser in interior. Therefore, wrought magnesium alloy has the advantages of high strength and high elongation than wrought magnesium alloy, and is lighter than wrought aluminum alloy under the premise of satisfying the same work. Because the process plasticity is lower than that of medium strength MB2, MB3 and MB8 alloys, the varieties produced are limited to extruded products, forgings and die forgings.