The hardening is a heat treatment that is used, generically on steels, in order to give the piece specific mechanical properties. The main causes of imperfections in the heat treatment in general and in particular are of quenching the oxidation and deformation of the pieces.
With the hardening treatment in vacuum atmosphere tends to eliminate these factors trying to get some good results in:
- absence of decarburization
- reducing distortions
- high cleaning
- high temperature uniformity
Obviously, from this it follows that the vacuum hardening the critical factors to get quality treatment are:
- the tightness of the oven (see article on the research of losses) to ensure a clean atmosphere.
- a degree of vacuum adjusted to the need of treatment (with pressures from a minimum of 10 mbar ^ -1 to a maximum 10 ^ -3 and beyond).
- heating units appropriate to the treatment temperatures for some alloys that can reach up to 1250 ° C.
- efficiency and uniformity of cooling, to exit the transformation temperature at the time indicated by the data sheet of the material.
More generally, the phases of the heat treatment of hardening are:
- warming of the atmosphere (which can also occur in convection) with intermediate stops
- stay at the selected temperature
- cooling
