Decarburization

For the corrosion caused by exposure to hydrogen, see Hydrogen embrittlement.

Decarburization (or decarbonization) is the process of decreasing carbon content, which is the opposite of carburization.

The term is typically used in metallurgy, describing the decrease of the content of carbon in metals (usually steel). Decarburization occurs when the metal is heated to temperatures of 700 °C or above when carbon in the metal reacts with gases containing oxygen or hydrogen.[1] The removal of carbon removes hard carbide phases resulting in a softening of the metal, primarily at the surfaces which are in contact with the decarburizing gas.

Decarburization can be either advantageous or detrimental, depending on the application for which the metal will be used. It is thus both something that can be done intentionally as a step in a manufacturing process, or something that happens as a side effect of a process (such as rolling) and must be either prevented or later reversed (such as via a carburization step).

The decarburization mechanism can be described as three distinct events: the reaction at the steel surface, the interstitial diffusion of carbon atoms and the dissolution of carbides within the steel.[2]

  1. ^ Cite error: The named reference TSB was invoked but never defined (see the help page).
  2. ^ Alvarenga H.D.; Van de Putte T.; Van Steenberge N.; Sietsma J.; Terryn H. (Apr 2009). "Influence of carbide morphology and microstructure on the kinetics of superficial decarburization of C-Mn Steels". Metall. Mater. Trans. A. 46: 123–133. doi:10.1007/s11661-014-2600-y. S2CID 136871961.