Carburising

What is carburising?

Also known as case hardening, carburising is a surface hardening process in which carbon is added (diffused) into the surface of low-carbon steel in a solid, liquid or gas medium.

After carburising, the material is usually hardened by oil quenching. The result is a hard, wear-resistant surface with a softer but tough core that withstands impact.

How is it done?

Carburising takes place through a gas–metal reaction when the steel is heated to the austenite phase in a CO-containing atmosphere. A temperature of 850–950 °C is used, known as the carburising temperature. How deep the carbon travels from the surface depends on the temperature and the holding time; the deeper the required case, the longer the cycle.

Which steels and parts?

It is generally applied to unalloyed or low-alloy steels containing less than 0.2% carbon, known as case-hardening steels.

Carburising steels are used to make gears, shafts, piston pins, valves, chain links, sprockets, discs, rolling bearings and some measuring and inspection instruments.

For a quote

Carburising is usually applied together with hardening and tempering, as one step of the case hardening process. State the steel grade, the required surface hardness and case depth, and the areas that must not be carburised in the quote form.