Definition, Betydelse & Synonymer | Engelska ordet AUSTENITE

Definition av AUSTENITE

1. (metallurgi) austenit

Exempel på hur man kan använda AUSTENITE i en mening

• As a result of the quenching, the face-centered cubic austenite transforms to a highly strained body-centered tetragonal form called martensite that is supersaturated with carbon.
• Davenport and Edgar Bain, it is one of the products that may form when austenite (the face-centered cubic crystal structure of iron) is cooled past a temperature where it is no longer thermodynamically stable with respect to ferrite, cementite, or ferrite and cementite.
• The rate of dissolution of the different carbides into the austenite form of the iron determines the high-temperature performance of steel (slower is better, making for a heat-resistant steel).
• In metallurgy, quenching is most commonly used to harden steel by inducing a martensite transformation, where the steel must be rapidly cooled through its eutectoid point, the temperature at which austenite becomes unstable.
• When the iron or steel is cooled rapidly by quenching, the higher carbon content on the outer surface becomes hard due to the transformation from austenite to martensite, while the core remains soft and tough as a ferritic and/or pearlite microstructure.
• For example, in steel between austenite, ferrite, pearlite, bainite, cementite, and martensite, (See: Iron-carbon phase diagram).
• Much effort was expended on consideration of the austenite - martensite - cementite phases found in the iron - carbon phase diagram that underlies steel production.
• The inner depths of the material however, do not cool so rapidly, and in work-pieces that are large, the cooling rate may be slow enough to allow the austenite to transform fully into a structure other than martensite or bainite.
• The transformation from austenite to martensite is mostly accomplished through quenching, but in general it is driven further and further toward completion as temperature decreases.
• Niobium carbide is a frequent intentional product in microalloyed steels due to its extremely low solubility product in austenite, the lowest of all the refractory metal carbides.
• Types of heat treatments include the production of a fine grain structure; controlling the nature, size, and distribution of various transformation products (such as ferrite, austenite, pearlite, bainite, and martensite in steel); inducing precipitation hardening; and, controlling the toughness.
• To perform a full anneal on a steel for example, steel is heated to slightly above the austenitic temperature and held for sufficient time to allow the material to fully form austenite or austenite-cementite grain structure.
• Its primary crystalline structure is austenite (face-centered cubic) and it prevents steels from being hardenable by heat treatment and makes them essentially non-magnetic.
• At the atomic level, the four phases of auto steel include martensite (the hardest yet most brittle), bainite (less hard), ferrite (more ductile), and austenite (the most ductile).
• At high temperatures, nitinol assumes an interpenetrating simple cubic structure referred to as austenite (also known as the parent phase).
• Ledeburite-II (at ambient temperature) is composed of cementite-I with recrystallized secondary cementite (which separates from austenite as the metal cools) and (with slow cooling) of pearlite.
• 5-3% Mn (the former strengthens the martensite, and the latter causes solid solution strengthening in ferrite, while both stabilize the austenite), Cr & Mo (to retard pearlite or bainite formation), Si (to promote ferrite transformation), V and Nb (for precipitation strengthening and microstructure refinement).
• The beta designation maintains continuity of the Greek-letter progression of phases in iron and steel: α-Fe, β-Fe, austenite (γ-Fe), high-temperature δ-Fe, and high-pressure hexaferrum (ε-Fe).
• In this process, austenite is transformed to martensite by step quenching, at a rate fast enough to avoid the formation of ferrite, pearlite, or bainite.
• In steel it produces a bainite microstructure whereas in cast irons it produces a structure of acicular ferrite and high carbon, stabilized austenite known as ausferrite.

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