ã€China Aluminum Network】 Among the high-performance aluminum alloys, the high-strength and high-grade aluminum alloys are highly representative of the high mobility, high load, high pressure resistance, high fatigue resistance, high speed, and high reliability required for aerospace vehicles. Tough aluminum alloys, mainly including 2××× and 7××× series of IM conventional fused cast aluminum alloys, and PM powder metallurgy aluminum alloys, SF spray-molded aluminum alloys, aluminum matrix composites, and super Plastic aluminum alloy and so on. The main new alloys are: 2124, 2224, 2324, 2048, 2419, Д16, 1161, and 1163 in the 2××× series; 7149, 7249, 7175, 7475, 7075, 7150, 7055, and 7175 in the 7××× series. ,7010,7068,7090,7091,7064,CW67,B93пч,B95оч,B96ц-1,B96ц-3,01975,01970 and other aluminum alloys. Typical aluminum alloy extrusion materials for aerospace industry are: no coarse-grained rods, high-quality seamless pipes, complex sections of solid profiles and profiled seamless hollow profiles, profiled sections and tubes; large-scale integral panels, girders Profiles; large, medium and small special high-performance hollow section and solid sections for modern transportation. It is required to continuously improve the strength index while having a combination of good toughness, stress corrosion resistance, fatigue resistance, and fracture toughness. The main research methods and achievements for high-performance aluminum alloys are:
(1) Improve the research and development of traditional Al-Cu-Mg and Al-Zn-Mg-Cu alloys and the development of new extrusion materials. Adjust the content of major alloying elements in the alloy and the ratio of each component, add trace elements and Rare earth elements reduce Fe, Si and other impurities in the alloy and hydrogen, oxygen and other gases. Improve the purity of the alloy, thereby changing the properties and composition of various compounds in the alloy, and adopting special processing and heat treatment processes to produce different states such as T351, T7451, T851, T651, T7651, T7351, T7451, T77, T775, T791 and so on. High-performance aluminum alloy profiles, tubes and bars.
(2) New alloys using new alloying elements and extrusion materials 1 Al-Li alloys Al-Li alloys have low density, high elastic modulus and high strength. Currently developed Al-Li alloys are mainly Al-Li-Sc-Zr and Al-Li-Mg-Zr alloys. Al-Li-Sc-Cu-Zr-based alloys can be used to replace the 7×× super high-strength alloys. More typical aluminum alloys are 2090 and 8091 alloys. The goal of the development is to achieve the strength of the 7075-T6 aluminum alloy and the corrosion resistance of the 7075-T73 aluminum alloy. In 1996, Al-Li alloys used in helicopters in the United States reached about 20% of the weight of the body; after 2010, it is expected that more than 20% of the structures on large passenger aircrafts will use Al-Li alloys to make 2Al-Sc alloys. Sc belongs to rare earths The metal element has a low density and a high melting point because it can significantly increase the recrystallization temperature and the mechanical properties of the aluminum alloy, thus attracting great attention. In recent years, Russia and Germany have made great progress in the research of Al-Sc alloys and Al-Zn-Mg-Sc-Zr and Al-Mg-Sc alloys have been developed. The former is characterized by high strength, good plasticity, fatigue performance and good welding performance. It is a new high-strength, high-toughness weldable aluminum alloy. Its application areas are also mainly aviation and aerospace, and can also be applied to high-speed ships and high-speed trains.
3Al-Be alloy Be is also a rare-earth rare-earth metal. Al-(7.0-30)Be-(3-8)Mg alloys are in the two-phase region of the Al-Be-Mg ternary phase diagram. Be and solid solution Mg α (Al) phase composition, the alloy has a very good overall performance. Such as Al-7.0Be-3Mg alloy tensile strength of 650N/mm2, elongation greater than 10%, can be applied in the aviation industry. However, due to the complicated manufacturing process and Be toxic, its application is limited.
(3) Research and development of new ultra-high strength aluminum alloy materials using new preparation technology 1 Although ultra-high strength aluminum alloys currently produced by the PM method are expensive and have small product sizes, they can produce high-performance alloys that cannot be produced by the IM method. Foreign developed PM ultrahigh-strength aluminum alloys are 7090, 7091 and CW67 aluminum alloys, and their strengths are all above 700N/mm2. Their strength and SCC resistance are better than those of IM alloys, especially the fracture toughness of CW67 alloys. better. Now the United States can produce billets weighing up to 650 kg. The processed extrusions and die forgings have been applied to aircraft, missiles and spacecraft.
The 2SD spray deposition method (spray molding method) is a new type of rapid solidification technology, which is characterized by DC casting and PM powder metallurgy. Compared with the PM method, the SD method has a simple production process, low cost, low metal oxide content (only 1/3 to 1/7 of the PM method), and a large weight of the ingot (up to 1000 kg or more), and can be mass-produced. Compared with the IM method, the larger advantage is that it is possible to produce a highly alloyed aluminum alloy that cannot be produced by the IM method, and it is also possible to produce a particulate composite material. Even the production of ordinary alloys has the characteristics of extremely fine ingot grains and good comprehensive properties of the processed material. Therefore, using this method to develop and manufacture ultra-high-strength aluminum alloys with high performance has a very good prospect of development.
The study of aluminum matrix composites is in the ascendant. It is a composite material that has been studied more and more in metal matrix composites. The current development of aluminum-based composite materials mainly B / Al, BC / Al, SiC / Al, Al2O3 / Al and so on. The reinforcing agents added can be divided into particles, whiskers, short fibers and long fibers, of which the SiC/Al composite material is more promising because it does not need to coat the fibers with a diffusion layer and has a low cost. Aluminum matrix composites are characterized by low density, high specific strength and specific rigidity, high specific elastic modulus, good electrical and thermal conductivity, corrosion resistance, high temperature resistance, creep resistance and fatigue resistance. The 10m-long profiles and tubes made in the United States have been used in a variety of spacecraft and have become important competitors for aluminum alloys and even Al-Li alloys. In addition, aluminum-steel, aluminum-titanium and other laminated aluminum-based super high-strength composite materials have also been developed in recent years.
(4) Research and development and application of a variety of advanced and special deformation processing and heat treatment processes, such as superplastic extrusion, semi-solid extrusion, isothermal extrusion, composite extrusion, reverse extrusion, and non-lubricated perforation extrusion , Flat extrusion, variable section extrusion, hydrostatic extrusion and other advanced extrusion technology and new deformation heat treatment process, etc., to improve the overall performance and special properties of alloy materials. Such as in the development of large section extruded profiles and rods, to 2024, 2124, 2324, 2424, 7175, 7475, and 7055, 7155 and other aluminum alloys in the gradual strengthening of the impurity control, from the quality of the Fe and Si in the earlier brands The 0.5% decline in the score is less than 0.1% of the newer grade, which greatly reduces the number and size of internal defects that can be a source of cracks in the modern fracture mechanics theory, improves the distribution and morphology of the precipitated phases, and uses advanced technology. The process produces high-quality large ingots, uses large deformation for extrusion processing, pre-stretches after quenching, fully eliminates internal residual stress, and then performs single-stage or multi-stage artificial aging, and develops in the fields of aerospace, weapons, ships, and other fields. Widely-used large-sized extruded profiles and bars suitable for different applications such as T351, T7451, T851, T651, T7651, T7351, T7451, T77, T7751, and T79.
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