R. VAC+® covers all vacuum hardening processes provided by RÜBIG Heat Treatments. Precise process control and outstanding quality standards ensure consistent hardness, high strength and an optimum component framework.
Detailed descriptions of our procedures are presented in our technical data sheets that are available for download.
Vacuum hardening is the hardening procedure for deformation sensitive precision or formed components and tools which make high demands on a clean, bright surface.
Quenching is done by means of a gas stream with overpressure which can be adjusted in order to adapt the cooling conditions to the component requirements. The workpieces stay metallically blank and do not show impacts of the surface (scaling, decarburation) resulting in a minor effort for the hard machining as compared to other hardening procedures (inert gas hardening).
For this reason, expensive single and serial production tools as well as high-quality moulds and components are heat treated in vacuum furnaces. This heat treatment allows the highest demands to be met:
A modern process control guarantees optimum reproducibility. Several thermocouples at the component surface and in the component core are the basis for an accurate process control and thus process safety. The heat treatment provisions are developed together with the customer according to the application. An intensive cooperation with the steel manufacturers ensures the highest level of quality.
The homogeneous and geometry-oriented charging of the tools and components form the basis for a minor dimensional change and minimum deformation.
Helivac® is a special procedure of vacuum hardening which is applied in case of extremely high demands on the component characteristics. Using helium instead of nitrogen as the quenching agent gives the following advantages:
The low underpressure carburising (or low pressure carburising/lpc) with subsequent gas quenching is a modern version of case hardening. In comparison to the conventional gas carburising with oil quenching, the advantages of the vacuum technique in combination with the gas quenching come to bear:
Advantages of the underpressure carburising:
Vacuum brazing or high-temperature brazing under vacuum is a thermal joining procedure in order to join materials/ components in a firm and bonded manner. With this procedure, complex geometries (for example, complicated cooling channels) and/or several joints/welds can be joined within one process. Due to the high temperature in combination with a reduced pressure range (0.08 – 1 mbar), the material-dependent oxide coating is broken thermally, thus eliminating the application of flux. Due to an optimum process management and corresponding solders, the components can not only be joined in a firm and bonded manner but also hardened (vacuum hardening). That is why we mainly use copper based and/or nickel based solders. In order to achieve optimum soldered joints, the corresponding gaps and solder depots must already be considered at the design stage.
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Hardening or precipitation (tempering) must always be understood in combination with a previous solution annealing and quenching. With this treatment, fine precipitations (coherent, partly coherent or incoherent) are formed over time in the basic matrix depending on the material and temperature. These fine precipitations (phases) affect the movements of displacements and, therefore, increase the strength.
The strength/hardness and the mechanical characteristics are determined by the precipitation temperature. Depending on the material (e.g. special rust-proof steels, maraging steels, aluminium alloys, bronze alloys), the precipitation temperature is between 150-500°C.