AerMet alloy is an ultra-high strength type of
martensitic alloy steel
Alloy steel is steel that is alloyed with a variety of elements in total amounts between 1.0% and 50% by weight to improve its mechanical properties. Alloy steels are broken down into two groups: low alloy steels and high alloy steels. The differe ...
. The main alloying elements are
cobalt
Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, p ...
and
nickel
Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow t ...
, but
chromium
Chromium is a chemical element with the symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard, and brittle transition metal.
Chromium metal is valued for its high corrosion resistance and hard ...
,
molybdenum
Molybdenum is a chemical element with the symbol Mo and atomic number 42 which is located in period 5 and group 6. The name is from Neo-Latin ''molybdaenum'', which is based on Ancient Greek ', meaning lead, since its ores were confused with lead ...
and
carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon ma ...
are also added. Its exceptional properties are
hardness
In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. In general, different materials differ in their hardness; for example hard ...
,
tensile strength
Ultimate tensile strength (UTS), often shortened to tensile strength (TS), ultimate strength, or F_\text within equations, is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials ...
,
fracture toughness
In materials science, fracture toughness is the critical stress intensity factor of a sharp crack where propagation of the crack suddenly becomes rapid and unlimited. A component's thickness affects the constraint conditions at the tip of a ...
and
ductility
Ductility is a mechanical property commonly described as a material's amenability to drawing (e.g. into wire). In materials science, ductility is defined by the degree to which a material can sustain plastic deformation under tensile str ...
.
Aermet is weldable with no preheating needed.
AerMet alloy is not corrosion resistant, so it must be sealed if used in a moist environment. AerMet is a registered trademark of
Carpenter Technology Corporation
Carpenter Technology Corporation develops, manufactures, and distributes stainless steels and corrosion-resistant alloys. In fiscal year 2018, the company's revenues were derived from the aerospace and defense industry (55%), the industrial and ...
.
Three types of AerMet alloys are currently available: AerMet 100 (also known as AerMet-for-Tooling), AerMet 310 and AerMet 340 alloy.
Examples of applications include armor, fasteners, airplane landing gear, ordnance, jet engine shafts, structural members and drive shafts.
[
]
Properties
AerMet 100 Alloy
The UNS number is K92580. The alloy has a modulus of elasticity of 28,200 ksi and a density of 0.285 lb/in3 (7.89 g/cm3). AerMet 100 alloy is somewhat more difficult to machine than 4340 at HRC 38. Therefore, carbide tools are usually used. Standard shapes that are available include round, sheet, welding wire, billet, plate, strip and wire.[
AerMet alloy is special in that it must be hardened twice in order to reach its maximum effectiveness. The first hardening application is a solution treatment at for 1 hour. It is then quenched to a temperature of over 1 to 2 hours. It then must be cold treated, where the material is cooled to for 1 hour. The second hardening process is aging, where the material is heated to for 5 hours.][
]
AerMet 310 Alloy
AerMet 310 is harder and stronger than AerMet 100 alloy while maintaining ductility and toughness. Standard shapes include round bar, wire, billet, plate, and strip. AerMet 310 is hardened with the same procedure as AerMet 100.[
]
AerMet 340 Alloy
AerMet 340 alloy has a higher strength than AerMet 310.
AerMet 340 is hardened differently from the other two varieties. The first hardening application is a solution treatment at for 1 hour. It is then quenched to a temperature of over 1 to 2 hours. The material may then be cold treated, where the material is cooled to for 1 hour. The second hardening process is aging, where the material is heated to for 3 to 8 hours. If the cold treatment is skipped, the part can be aged twice to get the same results.[
]
See also
* Maraging steel
Maraging steels (a portmanteau of " martensitic" and "aging") are steels that are known for possessing superior strength and toughness without losing ductility. ''Aging'' refers to the extended heat-treatment process. These steels are a special cla ...
(Precipitation-hardened steels with similar strength.)
* USAF-96 USAF-96 is a high-strength, high-performance, low-alloy, low-cost steel, developed for new generation of bunker buster type bombs, e.g. the Massive Ordnance Penetrator and the improved version of the GBU-28 bomb known as EGBU-28. It was developed ...
and Eglin steel Eglin steel (ES-1) is a high- strength, high-performance, low-alloy, low-cost steel, developed for a new generation of bunker buster type bombs, e.g. the Massive Ordnance Penetrator and the improved version of the GBU-28 bomb known as EGBU-28. It ...
(Inexpensive precipitation-hardened steels with high strength and lower nickel content. USAF-96 also needs no tungsten.)
References
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Steels