The product charged into the furnace was heated to 530-600˚C in a mixed gas atmosphere of NH3, N2, CO2, then the carburization was carried out by nitriding with N component decomposed from NH3 and C component decomposed from CO2 to produce a compound layer coating of iron carbonitride about 5-20µm on the product surface.

The compound layer produced was dense, combining high hardness and moderate toughness, contribute mainly to improve wear resistance of part surface, and since the surface is covered with compound layer coating, thereby improving corrosion resistance too.

In addition, by performing oil cooling after gas soft nitriding, a solid solution nitrogen diffusion layer is formed directly below the compound layer to the inside around 0.5mm, and also effective on fatigue resistance improvement.

Applicable steel types correspond widely from low carbon steel to alloy steel, cast iron, and sintering (However it cannot be applied to stainless steel with passive film).

Also, because of the lower transformation point temperature without quenching, deformation or distortion after Heat Treatment is very small, so there are many cases where assembly is possible without post-processing.