Carbonitriding is one of the heat-treating processes under various gas atmospheres and temperatures mainly to improve hardness, wear-resistance, and fatigue or tensile strength properties of industrial parts in order to prolong their lifespan and improve their properties to suit specific usability.
Carbonitriding is a process in which carbon and nitrogen are simultaneously infiltrated into the surface of steel at a temperature of about 800°C to 880°C, lower than ordinary gas carburizing, and then quenched and hardened. In gas carbonitriding, NH3 gas is added to a normal gas carburizing atmosphere, and nitriding and carburizing are performed simultaneously by
the N component decomposed from NH3. Since the hardenability is improved by nitriding, it is possible to treat non-alloy steel such as SPCC and low carbon steel which cannot be applied by gas carburizing, and the reduction of material cost is also a great advantage. Since it can be quenched at a lower temperature than gas carburizing, deformation, and distortion due to heat treatment can be reduced. Characteristics of gas carbonitriding are including
- Applicable steel type: Low carbon steel (low carbon steel such as SP material, SS material, S10C), case hardening steel (low carbon alloy steel such as SCM / SCr / SNCM)
- Quenching is possible at low temperatures, reducing quench deformation (Excluding case-hardened steel)
- Since the hardenability is improved by the influence of nitrogen, quenching becomes easy even with carbon steel, which is advantageous in terms of quenching cracking.
- Compared to gas carburization, the abnormal hardening layer on the outermost surface is suppressed, and a uniform hardened layer can be generated.
- Improved temper softening resistance compared to gas carburizing.