Bainite

Bainite

Bainite is a phase that exists in steel microstructures after certain heat treatments. First described by Davenport E. S. and Edgar Bain, it is one of the decomposition products that may form when austenite (the face centered cubic crystal structure of iron) is cooled past a critical temperature of 723 °C (about 1333 °F). Davenport and Bain originally described the microstructure as being similar in appearance to tempered martensite.

A fine non-lamellar structure, bainite commonly consists of ferrite, carbide, and retained austenite. In these cases it is similar in constitution to pearlite, but with the ferrite forming by a displacive mechanism similar to martensite formation, usually followed by precipitation of carbides from the supersaturated ferrite or austenite.

The temperature range for transformation to bainite is between those for pearlite and martensite. When formed during continuous cooling, the cooling rate to form bainite is higher than that required to form pearlite, but lower than that to form martensite, in steel of the same composition.

The microstructures of martensite and bainite at first seem quite similar; this is a consequence of the two phases sharing many aspects of their transformation mechanisms. However, morphological differences do exist on the resolution level of the TEM and can be used in microstructural evaluation. Under a simple light microscope, the microstructure of bainite appears dark (i.e., it has low reflectability).

Bainite is generally stronger but less ductile than pearlite.

External links

* [http://www.msm.cam.ac.uk/phase-trans/newbainite.html Online textbook devoted to bainite] , from Cambridge University Press and the Institute of Materials, Minerals and Mining
* [http://www.msm.cam.ac.uk/phase-trans/2004/Bain.Alloying/ecbain.html The Alloying Elements in Steel, by Edgar C. Bain]
* [http://www.msm.cam.ac.uk/phase-trans/bainite.html Overview of Bainite in multiple languages]


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Look at other dictionaries:

  • Bainite — Bainite. См. Бейнит. (Источник: «Металлы и сплавы. Справочник.» Под редакцией Ю.П. Солнцева; НПО Профессионал , НПО Мир и семья ; Санкт Петербург, 2003 г.) …   Словарь металлургических терминов

  • bainite — ● bainite nom féminin Constituant micrographique des aciers constitué par un agrégat de cristaux de ferrite et de cristaux extrêmement fins de carbure de fer …   Encyclopédie Universelle

  • Bainite — Cet article est lié aux composés du fer et du carbone Fer Carbone Phases …   Wikipédia en Français

  • bainite — /bay nuyt/, n. Metall. an aggregate of iron carbide and ferrite, formed from austenite below the temperature at which pearlite forms and above that at which martensite forms. [1930 35; after Edgar C. Bain (1891 1971), American physicist and… …   Universalium

  • bainite — noun A type of steel formed after certain tempering processes …   Wiktionary

  • bainite — an austenitic transformation product found in some steels and cast irons; it forms at temperatures between those at which pearlite and martensite transformations occur; the microstructure consists of alpha ferrite and a fine dispersion of… …   Mechanics glossary

  • bainite — bain·ite …   English syllables

  • bainite — Costituente strutturale formato da cementite aciculare in una matrice ferritica, con una durezza compresa fra 30 e 55 HRC …   Glossario di Metallurgia

  • bainite — ˈbāˌnīt noun ( s) Etymology: Edgar C. Bain b1891 American physicist and metallurgist + English ite : a transformation product in solid steel developed from austenite at temperatures intermediate between those where pearlite and martensite form …   Useful english dictionary

  • lower bainite — Смотри нижний бейнит …   Энциклопедический словарь по металлургии

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