i.e. Carburizing, Carbo-nitriding, is the process which gives a hard surface to (low carbon) steels. It is accomplished by maintaining a carbon-rich atmosphere in contact with the mild steel while maintaining the temperature generally in the 1550o-1700oF range. Followed by rapid cooling via liquid bath. The carbon combines with the mild steel surface to produce a thin high carbon layer which hardens when quenched. NATIONAL HEAT TREAT has 3 Atmosphere Batch furnaces that can perform this process.