Vacuum hardening is the hardening of components under a controlled partial pressure, during which temperatures of up to 1,300°C can be reached. The aim of this process variant is the creation of bright metallic workpiece surfaces which render further mechanical processing unnecessary.
Hardening is the heating and subsequent cooling of steel at such a speed that there is a considerable increase in hardness, either on the surface or throughout. In the case of vacuum hardening, this process is done in vacuum furnaces in which temperatures of up to 1,300°C can be reached. The quenching methods will differ with regards to the material treated but gas quenching using nitrogen is most common.
In most cases hardening takes place in conjunction with subsequent reheating, the tempering. Depending on the material, hardening improves the hardness and wear resistance or regulates the ratio of toughness to hardness.
fields of application
Practically all technically interesting steel alloys, such as spring steels, cold-worked steels, quenched and tempered steels, anti-friction bearing steels, hot-worked steels and tool steels, as well as a large number of high-alloy stainless steels and cast-iron alloys, can be hardened.
Vacuum hardening however, is mostly used for high-alloy steels and steels that require a bright metallic workpiece surface.