Iron-based high-temperature alloys
Iron-based high-temperature alloy is a material with certain strength and resistance to oxidation and gas corrosion at 600~800 degrees Celsius. It is mainly an austenitic alloy with iron as the base and a certain amount of chromium and nickel.
Nickel in iron-based high-temperature alloys is the main element to form and stabilize austenite, and in the aging process to form Ni3 (Ti, Al) precipitation strengthening phase. Chromium is mainly used to improve oxidation resistance, gas corrosion resistance. Molybdenum and tungsten are used to strengthen the solid solution. Aluminum, titanium and niobium are used for precipitation strengthening. Carbon, boron, zirconium and other elements are used to strengthen grain boundaries. Iron-based high-temperature alloys can be divided into deformed and cast high-temperature alloys according to the manufacturing process, and into process-hardened, solution-reinforced and precipitation-reinforced high-temperature alloys according to the strengthening method (see Strengthening of Metals). The composition and properties of some typical iron-based high-temperature alloys are shown in the table. Organization The matrix of iron-based high-temperature alloys is austenite, and the main precipitation-reinforced phases are γ' [Ni3 (Ti, Al)] and γ" (Ni3Nb) phases. In addition, there are trace carbides, borides, Laves (such as Fe2Mo) phase and δ phase. Compared with the organization of nickel-based high-temperature alloys, the phase organization in iron-based alloys is more complex and less stable, and it is easy to precipitate η (such as Ni3Ti), σ (such as FexCry), G (such as Fe6Ni16Si7), μ (such as Fe7Mo6) and Laves and other harmful phases (see alloy phases).
The heat treatment of the alloy is mainly solution treatment and aging treatment to obtain suitable grain size, reasonable distribution and size of the strengthening phase, favorable grain boundary state, so that the alloy has good overall performance. For example, the material used in the manufacture of turbine disc parts, the grain size is generally 4-5; γ' phase size is about 100-500 dots, uniformly distributed in the matrix; grain boundaries have a uniform distribution of spheroidized precipitation phase (such as carbide, Laves, etc.).
Nickel in iron-based high-temperature alloys is the main element to form and stabilize austenite, and in the aging process to form Ni3 (Ti, Al) precipitation strengthening phase. Chromium is mainly used to improve oxidation resistance, gas corrosion resistance. Molybdenum and tungsten are used to strengthen the solid solution. Aluminum, titanium and niobium are used for precipitation strengthening. Carbon, boron, zirconium and other elements are used to strengthen grain boundaries. Iron-based high-temperature alloys can be divided into deformed and cast high-temperature alloys according to the manufacturing process, and into process-hardened, solution-reinforced and precipitation-reinforced high-temperature alloys according to the strengthening method (see Strengthening of Metals). The composition and properties of some typical iron-based high-temperature alloys are shown in the table. Organization The matrix of iron-based high-temperature alloys is austenite, and the main precipitation-reinforced phases are γ' [Ni3 (Ti, Al)] and γ" (Ni3Nb) phases. In addition, there are trace carbides, borides, Laves (such as Fe2Mo) phase and δ phase. Compared with the organization of nickel-based high-temperature alloys, the phase organization in iron-based alloys is more complex and less stable, and it is easy to precipitate η (such as Ni3Ti), σ (such as FexCry), G (such as Fe6Ni16Si7), μ (such as Fe7Mo6) and Laves and other harmful phases (see alloy phases).
The heat treatment of the alloy is mainly solution treatment and aging treatment to obtain suitable grain size, reasonable distribution and size of the strengthening phase, favorable grain boundary state, so that the alloy has good overall performance. For example, the material used in the manufacture of turbine disc parts, the grain size is generally 4-5; γ' phase size is about 100-500 dots, uniformly distributed in the matrix; grain boundaries have a uniform distribution of spheroidized precipitation phase (such as carbide, Laves, etc.).
What is the material of high temperature alloy?
What is superalloy?
What is austenite?
Iron-based alloys
Ni-Cr-Mo alloys
Ni-Cr-Mo-Cu alloys
Nickel-copper (Ni-Cu) alloy
Low alloy steel
High alloy steel