Cementite


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Related to Cementite: austenite, martensite

cementite

[si′men‚tīt]
(metallurgy)
Fe3C A hard, brittle, crystalline compound occurring as lamellae or plates in steel. Also known as iron carbide.

Cementite

 

an iron carbide, Fe3C; a phase and structural component of iron-carbon alloys (seeIRON-CARBON ALLOYS). Cementite has an orthorhombic crystal lattice. It is very hard and brittle and is slightly magnetic at temperatures up to 210°C. It is a metastable phase; the formation of the stable phase—graphite—is in many cases difficult. Cementite is precipitated from a melt consisting of austenite and ferrite. Depending on the crystallization conditions and subsequent treatment, it can have various forms, such as equiaxial grains, lattices along grain boundaries, and plates; it can also exhibit a Widmannstatten structure. Cementite is a constituent of the structural components of steel and cast iron—ledeburite, pearlite, bainite, and tempered sorbite.

REFERENCE

Bunin, K. P., and A. A. Baranov. Metallografiia. Moscow, 1970.
References in periodicals archive ?
The first step of the analysis was the image segmentation, which aimed at discriminating pixels from the cementite and the ferrite phases.
Almost complete carbide spheroidisation and ferrite recrystallization took place in the centre of the specimen where only scarce cementite lamellae were preserved (Fig.
2]B it is formed mainly, and at the sufficient maintenance of carbon (Steel 70) goes as formation bore cementite [Fe.
The first is 2-4% alcoholic nitric acid (nital) used at room temperature to reveal the ferrite grain boundaries and phases as well as constituents such as cementite and pearlite.
A skilled melter can gauge from the degree of chill in a chill specimen just how much inoculation is necessary to eliminate cementite in a final gray iron casting.
The rate at which solidification occurs determines whether the carbon will be present as graphite flakes or in the combined form known as cementite.
Ferrite and ferrite with tertiary cementite was expected to form in the boundary zones.
During the heating of steel with spherodized cementite in ferrite matrix, the austenite phase nucleates at the ferrite-cementite boundary.
Among specific topics are the thermodynamics of phase transformations in steels, kinetics, proeutectoid ferrite and cementite transformations in steels, carbide-free bainite in steels, and nucleation and growth during the austenite-to-ferrite phase transformation in steels after plastic deformation.