Pack carburizing is a process in which carbon monoxide derived from a solid compound decomposes at the metal surface into nascent carbon and carbon dioxide. In addition to discussing the pros and cons of pack carburizing, this article provides information on the carburizing medium, compounds, furnaces, and containers used in pack carburizing. The successful operation of the pack carburizing process depends on the control of principal variables such as carbon potential, temperature, time, case depth, and steel composition. The three types of furnaces most commonly used for pack carburizing are the box, car-bottom, and pit types. Carburizing containers are made of carbon steel, aluminum-coated carbon steel, or iron-nickel-chromium heat-resisting alloys. The article also provides information on the packing procedure of workpieces.

Carburization is the process of intentionally increasing the carbon content of a steel surface so that a hardened case can be produced by martensitic transformation during quenching. Like carburizing, carbonitriding involves heating above the upper critical temperature to austenitize the steel. This article introduces the fundamentals, types, advantages and limitations, and the complications of various forms of carburizing, namely, pack carburizing, liquid carburizing or salt bath carburizing, gas carburizing, and low-pressure (vacuum) carburizing. The related process of carbonitriding is also briefly described in the article.