Cementite


Also found in: Dictionary, Thesaurus, Wikipedia.
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.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

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.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Borchers et al., "Atomic-scale mechanisms of deformation-induced cementite decomposition in pearlite," Acta Materialia, vol.
According to the Fe-C phase diagram and bidirectional transition characteristics of the microstructure, the primitive pearlite in substrate begins to decompose into ferrite and cementite as temperature exceeds the eutectoid point, whereas pearlite transforms into austenite.
It can be seen in the SEM microstructure images that there are no residual cementite particles observed in the microstructures as an indication of inhomogeneous austenitization.
Baumann (1998) also holds that an extremely high level of deformation and shearing stress leads to dissolution of cementite and diffusion of carbon.
Image analysis of pearlite spheroidization based on the morphological charact-erization of cementite particles.
This layer has a microstructure consisting of iron carbide (cementite) embedded in a matrix of pearlite.
It shows that the matrix phases before melting are graphite, cementite and [alpha]-Fe.
Such sites exhibit lower hydrogen overvoltage than either cementite or iron.
According to the GOST 5640-59 standard, steel 08kp can contain structurally free cementite [Fe.sub.3]C.
Other subjects are carbon diffusion in cementite, diffusion of interstitial elements in Ti alloys used as biomaterials, reduction kinetics of iron ore materials by gases, specific features of Jahn-Teller structure phase transitions in nanocrystalline materials, and experimental studies of kiwi and pear fruit in ice-temperature storage.
The Cementite or Mmartensite and the Acicular Ferrite (AF) have higher hardness than that of Polygonal Ferrite (PF) explaining the lower hardness in the weld seam center.