Carburizing

Carburizing, the raising of the carbon content of the surface of a low-carbon steel, is the first step in a case-hardening process. Carburizing is done by exposing the steel to a suitable atmosphere, a carbon rich gas, a liquid or a powder. The steel is held at a temperature corresponding to the austenitic phase. The ab­sorption and diffusion of carbon into the austenite region, about 900°C (1652°F), is main­tained at that temperature until the desired weight of carbon has been introduced into the steel. A typical application for this process is fasteners.