Annealing in vacuum
Generally speaking, all annealing processes can be provided by ALD’s HTS-division. When annealing under vacuum the following benefits are provided compared to annealing under atmosphere:
- avoiding intergranular oxidation (IGO) and surface oxidation
- avoiding de-carburized areas
- metallic, blank surfaces
- clean surfaces of parts after heat treatment, no washing of parts necessary
The most popular annealing processes are the following:
Stress-relief annealing is performed at temperatures about 650°C aiming to reduce the inner stress of the components. These residual stresses are caused by prior process steps such as casting and green machining operations.
Residual stresses can lead to unwanted distortion during the heat treatment process especially for thin-walled components. Therefore it is recommended to eliminate these stresses before the “real” heat treatment operation by stress-relief annealing.
Recrystallisation annealing is needed after cold forming operations to gain back the initial microstructure.
Other annealing treatments such as:
- Precipitation hardening or
- Solution annealing
are offered as well by ALD’s HTS-division.