In iron or steel a very hard micro-constituent with an acicular (needle-like) appearance; produced in heat-treating by quenching or with alloys.
Crystal type of iron (magnetic), which is characteried by a cubic body centered lattice structure. The acicular and very hard or brittle microstructure is formed, when austenite is quenched at comparably high cooling speeds, so that the carbon has no time for diffusion.
A terrific material with distinctive needle like structure which is always present in heat treat hardenable steel.
A component of iron useful for determining heat treating techniques used, it is a solution of iron and up to 1% carbon.
A microconstituent in quenched steel characterized by an acicular, or needle-like, pattern. It has the maximum hardness of any of the decomposition products of austenite.
A steel phase resulting from the diffusionless transformation of austenite rapidly cooled at low temperatures.
A solution over-saturated with carbon in Alpha Iron achieved by rapid cooling (hardening) of the austenite. It is generally formed in steel at temperatures neat to or a little over 300 °C. Possesses elevated hardness.
a solid solution of carbon in alpha-iron that is formed when steel is cooled so rapidly that the change from austenite to pearlite is suppressed; responsible for the hardness of quenched steel
With most steels, cooling as rapidly as possible from their quenching temperature develops a distinctive tructure called martensite. In this form, the steel is at its maximum hardness.
A phase of hardened metal. In the case of steel it is formed by quenching the material when it is heated to the critical range. The result is a tough, britle material that when viewed under a microscope, resembles a pile of straw.
An unstable polymorphic phase of iron which forms at temperatures below the eutectoid because the face-centered cubic structure of austenite becomes unstable. It changes spontaneously to a body-centered structure by shearing action, not diffusion.
a metastable Fe-C composition consisting of supersaturated carbon in iron that is the product of a diffusionless (athermal) transformation from austenite.
A generic term for microstructures formed by diffusionless phase transformation in which the parent and product phases have a specific crystallographic relationship. Martensite is characterized by an acicular pattern in the microstructure in both ferrous and nonferrous alloys. In alloys where the solute atoms occupy interstitial positions in the martensitic lattice (such as carbon in iron), the structure is hard and highly strained; but where the solute atoms occupy substitutional positions (such as nickel in iron), the martensite is soft and ductile. The amount of high-temperature phase that transforms to martensite on cooling depends to a large extent on the lowest temperature attained, there being a rather distinct beginning temperature (Ms) and a temperature at which the transformation is essentially complete (Mf).
This phase of steel has the same composition as austenite from which it transformed. The difference being that martensite is a super-saturated solid solution in alpha iron (ferrite) with a body-centered tetragonal crystal lattice. Austenite is a super saturated solid solution of carbon in gamma iron with a face-centered cubic crystal lattice.
A microconstituent or structure in hardened steel, characterized by an acicular or needle-like pattern, and having the maximum hardness of any of the decomposition products of an austenite.
A brittle micro-constituent of steel formed when the steel is heated above its critical temperature and rapidly quenched. This occurs in wire rope as a result of frictional heating and the mass cooling effect of the cold metal beneath. Martensite cracks very easily, and such cracks can propagate from the surface through the entire wire.
a super-saturated solid solution of carbon in ferrite. The carbon atoms distort the BCC ferrite into a BC-tetragonal structure.
A hard supersaturated solid solution of iron characterized by an acicular (needle-like) microstructure.
The hard constituent produced when steel is cooled from the hardening temperature at a speed greater than its critical cooling rate. Martensite is an acicular phase when seen in the microstructure of steel.
Crystallographic description of the low temperature phase of a shape memory alloy, which starts to form during cooling of the high temperature phase Austenite when the M-temperature is passed. The formation of Martensite is completed below the M-temperature. But the Martensite can also be induced during loading of the Austenite above M. This is related to a large amount of recoverable strain and is called _Superelasticity.
is the structure in quenched steel.
A generic term used for microstructures formed by diffusionless phase transformations. A constituent found in hardened steel; has a needle like microstructure. See Mf, Ms.
In steel, a metalstable transition phase with a body-centered-tetragonal crystal structure formed by diffusionless transformation of austenite generally during cooling between the Ms and Mf temperatures. (2) A distinctive neddle like structure existing in steel as a transition stage in the transformation of austenite. It is the hardest constituent of steel of eutectoid composition. It is produced by rapid cooling from quenching temperature and is the chief constituent of hardened carbon tool steels. Martensite is magnetic. (3) In an alloy, a metastable transitional structure intermediate between two allotropic modifications whose abilities to dissolve a given solute differ considerably, the high-temperature phase transformed to martensite depends to a large extent upon the temperature attained in cooling, there being a rather distinct beginning temperature. (4) A metastable phase of steel, formed by a transformation of austenite below the Ms (or Ar) temperature. It is an interstitial supersaturated solid solution of carbon in iron having a body-centered tetragonal lattice. Its microstructure is characterized by an acicular, or needle-like, pattern.
A microstructural form found in steel when it has been cooled from its austenitic state to room temperature at a greater than the critical cooling rate of the steel. It is a metastable solid solution with a body-centred tetragonal structure and its hardness depends primarily upon the carbon content of the steel.
Martensite, named after the German metallurgist Adolf Martens (1850-1914), is any crystal structure that was formed by displacive transformation, as opposed to much slower diffusive transformations. It includes a class of hard minerals occurring as lathe- or plate-shaped crystal grains. When viewed in cross-section, the lenticular (lens-shaped) crystal grains appear acicular (needle-shaped), which is how they are sometimes incorrectly described.