Transverse Impact Anisotropy and Fatigue Limits in High Alloy Consolidated Steels
Transverse impact anisotropy drops high-alloy consolidated steel toughness up to 66 percent, requiring directional stress alignment to prevent fatigue failure.
Aermet 100
Meaning
Ultra-high-strength steel represents a specialized category of ferrous alloys engineered to deliver exceptional hardness, tensile strength, and fracture toughness for demanding structural applications. Aermet 100 sits within this class as a proprietary alloy containing cobalt and nickel, optimized for resistance to stress corrosion cracking and fatigue. It is used in aerospace landing gear, driveshafts, and high-load fasteners where catastrophic failure must be prevented under extreme stress.
The alloy requires precise vacuum induction melting and vacuum arc remelting to minimize impurities and ensure uniform mechanical properties.
Material Composition
Carbon provides the hardness through martensitic transformation, while cobalt and nickel enhance toughness and stabilize the matrix during thermal treatment. Chromium and molybdenum are added to promote carbide precipitation, which prevents grain coarsening and improves tempering resistance. This precise chemical balance yields a material that can be heat treated to a tensile strength exceeding one thousand seven hundred megapascals while retaining high ductility.
Sourcing teams must verify the chemical certification of each melt run to ensure compliance with aerospace standards.
Processing Requirement
Machining must occur in the annealed state before final heat treatment due to the extreme hardness developed during the tempering cycle. The heat treatment process involves solution annealing, sub-zero cooling to ensure complete martensitic transformation, and subsequent aging to precipitate strengthening phases. Any deviation from the specified temperature profile can result in retained austenite, which reduces the yield strength and fatigue resistance of the finished component.
Sourcing Specification
Procurement contracts should define the minimum fracture toughness and impact energy required for each delivery lot to guarantee performance. Sourcing from certified mills with demonstrated experience in vacuum metallurgy is critical to avoid issues with microscopic inclusions that can act as fatigue initiation sites. The material represents a premium cost option, meaning its selection is justified only where weight reduction and high structural integrity are the primary engineering drivers.