High-temperature alloy fasteners
High-temperature alloy fasteners
High-temperature alloy fasteners are the connecting parts between the compressor and the rotor, between the rotor and the transmission system, between the casing, the aircraft wing, the fuselage and other key parts of the high-speed rotating aerospace engine. They must have high tensile strength and shear strength. Shear strength, high durability and creep resistance, fatigue resistance and stress relaxation resistance, excellent corrosion resistance, and matching thermal expansion coefficient and other excellent properties. There are many kinds of high-temperature alloy fasteners for aerospace, involving high-strength bolts and screws, self-locking nuts, high-lock nuts, rivets, special fasteners, etc. Typical high-temperature alloy materials for aerospace fasteners mainly include GH2132, GH4169, and GH4738 . GH2132 (A286) is an age-hardening iron-based superalloy, which is obtained by comprehensive strengthening of a small amount of elements such as molybdenum, titanium, aluminum, vanadium and trace boron, with Fe-25Ni-15Cr as the matrix, mainly through the aging precipitation of γ'Ni3 (Ti, Al) phase, the alloy has high yield strength and durable creep strength at -253 ~ 500 ℃, and has good processing plasticity and weldability, and is widely used in the production of compressor disks for aerospace , rotor blades and fasteners, etc. There are many types of fasteners produced by GH2132, and its main products include 900 MPa-level nuts, 1100 MPa-level HB series bolts, 1300 MPa-level NAS series high-strength bolts and test mandrels. GH4169 (Inconel718) is a precipitation-strengthened nickel-based superalloy, the matrix is austenite (γ phase), the main strengthening phase is γ″ phase and γ'Ni3 (Al, Ti, Nb) phase, the alloy is at -253 ~ 650 ℃ has good comprehensive performance, the yield strength below 650 ℃ ranks first in the deformed superalloy, and has good fatigue resistance, radiation resistance, oxidation resistance and corrosion resistance, which can ensure long-term tissue stability. Fasteners, turbine disks, oil and gas wells and oil and gas pipelines are widely used in fields such as oil and gas pipelines, accounting for more than 1/3 of the annual output of superalloys in the world. Among them, aeroengine fasteners are used in harsh environments, and their connectors are required to have high temperature resistance, high Strength, high fatigue resistance, and good anti-loosening properties are required. More than 90% of the bolts used in aero-engines are GH4169. GH4169 fasteners are mainly used as high-strength bolts, nuts, screws, screw sleeves, etc., concentrated There are two strength levels of 1275 MPa and 1512 MPa.
GH4738 (Waspaloy) is a γ' Ni3 (Al, Ti) phase precipitation-hardening nickel-based superalloy. By reducing the C content and increasing the Al + Ti content, the content of the γ' phase (precipitation hardening phase) is increased, thereby improving the alloy's Strength; reduce the content of inclusion-forming elements S and O, improve the purity of the alloy, and significantly improve the fatigue performance of the alloy. It has high strength, oxidation resistance, corrosion resistance, good thermal processing and welding performance, and cold It has excellent comprehensive properties such as good deformation processing performance, and has good strength and toughness matching, so it has become an important material for aerospace fasteners above 700 °C.