Deformed aluminum alloys, which is most often used for work at negative (low) and krïogennıx temperatures, are alloys 1100, 2014, 2024, 2090, 2219, 3003, 5083, 5456, 6061, 7005 and 7039.
low, negative and cryogenic temperatures
by the way, is, for example, GOST 21957-76, what krïogennımï temperatures below the temperature should be called 120 Kelvïnov (-153 ° C). So, that up to -153 ° C temperature just "low" or "negative", and only below -153 ° C - Cryogenic.
Aluminum alloys for cryogenic temperatures
Aluminium alloy 1100
We will call this fusion "fusion", not "aluminum" as is customary in international standards and publications. This alloy is similar to aluminum in blood pressure according to GOST 4784-97, only with additives of copper 0,05 to 0,20 %. When the content of copper to 0,05 % it is an alloy 1200 - analogue BP aluminum. At room temperatures and negative Alloy 1100 It has a relatively low strength in the annealed state O, and in the cold-worked condition H. The welded joints of the base metal, and welding metal retain good ductility down to very low temperatures. Tensile weld rod of alloy strength 1100 in the states G and H12 at a temperature of -196 ° C is about 190 MPa. Aluminum 1100 is used in the form of pipes, sheets, plates and rods in the non-critical components of cryogenic systems.
Aluminium alloy 2014 (AK8 according to GOST 4784-97)
Aluminum alloy 2014-T6 has a relatively high strength 480-490 MPa at room temperature and at subzero temperatures. It retains approximately unchanged plastic and viscous properties up to the temperature of liquid nitrogen (‒196 ° C). In this case, the elastic modulus (Young's modulus) increases with 75 to 83 GPa, and decreases with the Poisson ratio 0,34 to 0,32.
Aluminium alloy 2024 (D16 according to GOST 4784-97)
This aluminum alloy in the states T3, T4 and T8 has high strength 480-490 MPa and at room temperature, and at low temperatures. weld strength of the alloy below, than an alloy 2024. This alloy is used in aircraft and aerospace engineering and is connected by mechanical methods, for example, rivets.
Aluminium alloy 2090
This alloy refers to an aluminum-lithium alloy. Its formula (based on average content values): Al-2.7Cu-2.2Li-0.12Zr. lithium content - of 1,9 to 2,6 %. The cryogenic properties of such lightweight alloys (density 2,59 g / cm3) are of great importance for space technology. for instance, in the manufacture of fuel tanks for liquid hydrogen. The most prominent feature of aluminum alloy 2090 able T81 is, that the yield strength and tensile strength and elongation, and fracture toughness increases with decreasing temperature,, regardless of the longitudinal or transverse orientation of the test specimen. This property is also characteristic of some other aluminum alloys, for example, 2219-T87, but alloy 2090-T81 increase of mechanical properties is particularly high.
Aluminium alloy 2219
This aluminum alloy has a somewhat lower strength, than Alloy 2014-T6, but a higher viscosity at room temperature and at subzero temperatures. From the alloy sheets manufactured in 2219-T87 tanks of liquid oxygen and liquid hydrogen, which were used in space "shuttle".
Aluminium alloy 3003
Aluminium alloy 3003 used for the manufacture of brazed heat exchangers and other equipment for production of liquefied natural gas. Pipes are made from it (including, ribbed), sheets and plates. Easily connected by soldering or welding. Tensile strength of the alloy 3003 in G and H18 at room temperature is 110 and 200 MPa, and at a temperature of -195 ° C - 230 and 280 MPa. ease of processing, high ductility and toughness, both at room temperature, and at low temperatures, are the most important properties of these alloys.
Aluminium alloy 5083
This alloy is thermally hardenable. The maximum viscosity is achieved in the annealed condition. good welds, wherein the weld strength almost equal to the base metal strength. Widely used in the manufacture of tanks for transporting liquefied gas.
Aluminium alloy 5456
Another aluminum alloy netermouprochnyaemy, which is well-welded, and also has high plasticity and toughness at cryogenic temperatures. Is an alternative to the alloy 5083.
Aluminium alloy 6061
Aluminium alloy 6061 typically used in state T6. He is weldable and can, basically, be heat treated after welding. However, this is not recommended, because it significantly reduces weld ductility. One of the outstanding examples of the use of this alloy are welded body for pumps and motors, are used when pumping liquefied natural gas to gas distribution terminals. alloy 6061 make all possible types of aluminum "rolled": rods, tubes, profiles, sheets, plate. Alloy 6061 able T6 has a higher strength and lower ductility, than in the T4 condition. for instance, for a sheet of alloy 6061 at a temperature of -196 ° C in sample longitudinal tensile strength for the T6 condition is 450 MPa and elongation 10 %, and for state T4 – respectively 375 MPa 19 %. The strength of the welds, which have been heat-treated to T6 condition, have a lower strength, than the base metal.
Aluminium alloy 7005
Aluminum alloy sheet 7005 in states T6351 and T5351 has a higher strength, than a sheet of alloy 6061-T6, but higher ductility under identical, including, krïogennıx, temperatures. Weld strength sheet of an alloy 7005-T6351 without further heat treatment above, than the strength of the weld of the alloy sheet 6061 with an additional heat treatment in the state T6.
Aluminium alloy 7039
This alloy is well welded argon arc welding. Alloy 7039 able to T6, including welds, It retains good ductility and toughness at cryogenic temperatures. It recommended for cryogenic pressure vessels.
Источник: Aluminum and Aluminium Alloys, AMS International, 1993.