Vacuum Case Hardening

One of the most important processes of heat treatment is the case hardening or carburizing process. Parts are heated up to 1 000 °C and by adding specific gases (hydrocarbons) into the atmosphere of the furnace the part’s surface is enriched by absorbing carbon. Following this treatment the part is quenched in order to achieve the required properties, which results in higher resistance against stress and friction on the component’s surface. The core of the part remains somewhat softer and more ductile, which allows the part to carry high stresses through its entire life. For example, all gear parts for transmissions are treated this way.

The traditional way is to run this two step process (carburizing and quenching) in furnaces working under specific CO, but also oxygen containing atmospheres for carburizing and is using specific oils for quenching.

This process has some disadvantages, such as reduced product quality, high energy consumption, distortion of the parts, washing problems to remove the quenching oil, but also fire and explosion risks as well as negative influences on the environment like CO2 emission. These disadvantages can be clearly eliminated by using vacuum carburizing and high pressure gas quenching.