Decarburization


Also found in: Dictionary, Thesaurus, Wikipedia.
Related to Decarburization: decarbonization

Decarburization

 

the reduction of the carbon concentration in steels and alloys that takes place upon heating in oxidizing media, as well as in hydrogen (dry or wet).

Decarburization of steel and alloys may produce both harmful and beneficial effects. Decarburization during heat treatment or during heating prior to rolling or forging extends into the interior of the metal to a depth that depends on the temperature and duration of heating, and it leads to degradation of surface properties in the finished articles and to rejects.

Decarburization is the result of various complex reactions: C + ½O2 = CO; C + O2 = CO2; C + CO2 = 2CO; C + H2O = CO + H2; C + 2H2 = CH4; C + FeO = CO + Fe. The reactions are initiated and proceed at appreciable rates at temperatures above 700°C. Decarburization may be eliminated by heating in furnaces with a protective atmosphere or under vacuum. Decarburization in open furnaces is minimized by reducing the residence time of metal at high temperatures (for example, in walking-beam furnaces) or by using rapid electrical contact heating of the metal. Decarburized layers formed during production may be removed mechanically (on grinding machines). Annealing of metal in reducing gas mixtures containing natural gas or other hydrocarbons is also used; this results in enrichment of the surface of articles with carbon (restorative carburizing).

As a type of chemical heat treatment, decarburization improves the properties of metals and alloys in which carbon is an undesirable impurity (transformer steel and stainless steels). Refining decarburization is achieved by heating in gaseous media of fixed composition, which is selected to prevent the base metal from participating in chemical reactions. Transformer steel is annealed in N2-H2-H2O mixtures. In this case, the ratio of the H2 concentration to the H2O concentration is such that the iron is not oxidized, whereas the carbon forms CO and is removed. Stainless steels and similar alloys, which contain readily oxidizable alloying elements, are subjected to refining annealing in dry hydrogen.

L. A. SHVARTSMAN

decarburization

The loss of carbon at the surface of carbon steel when it is heated for processing or in modifying its mechanical properties.
References in periodicals archive ?
Besides decarburization small surface roughness also can be seen in Fig.
As a result of the implementation of this step in the manufacturing of powder-forged connecting rods, oxidation is reduced by 50%, total decarburization is reduced by 70%, and complete decarburization can be totally eliminated.
As we are traversing the path of Decarburization we as a corollary are taking the path of Hydrogenation.
Argon oxygen decarburization (AOD) and continuous casting (CC) steelmaking slags, with calcium oxide contents of 56.8 wt% and 52.0 wt%, respectively, were obtained from a stainless steel producer and sieved to <500 [micro]m to remove coarse particles.
This form of the process, using DC melting in air, produced a quality level which was higher than that in air melting, but which was soon overtaken by the advances in vacuum technology, both in vacuum-induction melting (VIM) and vacuum-arc remelting (VAR), as well as advances in the various methods of secondary treatment of electric furnace steels such as vacuum degassing, ladle metallurgy and ultimately argon-oxygen decarburization. In the same timeframe, developments in the Soviet Union, primarily due to Prof.
These include the noticeable reduction of grain growth, decarburization and oxidation of the pin/main surface.
Exposure to oxygen at the austenitizing temperatures causes scaling and decarburization of the surface of tools.
For example, after heat treating, parts can be checked for hardness, tensile strength, and many other cracks, decarburization, and many other factors which might be affected by the treatment.
The potential for an even closer energy cooperation between the EU and Egypt is enormous, and I hope this visit will herald a new phase of closer and more intense relations amongst us." "Egypt can lead the way of the clean energy transition in the Eastern Mediterranean and thus contribute to the Paris climate goals and the worldwide decarburization effort.
At the interface of Ti steel, ferritic structure presents at the titanium carbide layer, which indicates local decarburization.