Gas atmosphere carburizing and low-pressure carburizing (LPC) in vacuum are the most common methods in use today. Processes such as pack or salt bath carburizing and plasma (aka ion) carburizing are also possible but not widely used.

In carburizing, steel or certain non-ferrous metals (e.g., titanium) are heated to the austenite range, which causes solid-state transformation in the crystal structure. This change creates a high solubility for carbon. Next, the metal is brought in contact with an environment high in carbon, and the carbon absorbs into the surface of the metal. The carbon then diffuses inward, lowering the surface carbon content to allow for further absorption of carbon.