Vacuum Hardening

Servis Heat Treatment have a number of vacuum furnaces which are used for hardening or annealing. This process involves either hardening or softening of certain steels which respond to Vacuum treatments.This is carried out in a vacuum atmosphere by heating parts at high temperatures ranging from 750 degrees c to 1300 degrees c.

The parts are then rapidly cooled by quenching under up to 5 bar positive pressure using Nitrogen gas. Cooling at this rate transforms the structure of the steel.The steel must now be tempered as it is at its hardest and most brittle. This must be done quickly to prevent cracking as the steel at this poiint contains many stresses. Tempering increases the toughness of the steel and reduces it to the required hardness value.

Sub Zero Treatment

Occasionally Sub zero or deep freezing is required for certain steels e.g. High speed steel after the vacuum hardening process. This is done to transform the structure of the steel further and in some cases can increase hardness values of the component. Note that this is always done prior to tempering.