Carburizing is a case hardening process in which a metal part or component of low carbon content is heated in a carbon-rich gas atmosphere. The process of heating the metal component in a high carbon environment allows for diffusion of carbon atoms directly into the surface of the part that needs to be case hardened.

The amount of carbon and resultant case depth that gets diffused into the metal surface depends upon the carbon potential of the atmosphere, the temperature at which it is heated and the time it is exposed to that temperature. Higher temperatures, longer carburizing cycle times, and higher carbon potentials will increase the amount of carbon diffused into the surface and the depth of case. The hardening of both case and core material does not actually occur until the metal is rapidly quenched.

After quenching, carburized parts are tempered down to meet the customer requirements for case and core hardness. Tempering dramatically improves ductility and toughness with a minor loss in hardness and strength.

Carburizing Properties

•Increases surface hardness

•Improves wear resistance and fatigue strength

•The core of the material being hardened is tough and ductile

•Typically works best with low carbon and alloy steels with a carbon content between 0.05% to 0.30% C

•Surface of parts should be clean and free of rust or scale


•Parts which require increased wear resistance and fatigue strength

•Parts made from low carbon content steels