Vacuum CAP
Vacuum Induction Degassing of Metals
The VCAP furnace is designed for Induction Melting a solid charge in an air atmosphere (or vacuum), with final degassing stage under vacuum. The final pouring of the metal is performed in air or under protective atmosphere of inert gas. Configuration is based on the Inductotherm range of steel shell induction furnaces which are fully adapted by Consarc for vacuum treatment of liquid metal.
The furnace shell is fully sealed for vacuum operation and a sealing flange/apron is provided on top of the unit. Following an air melt operation (or vacuum / inert gas if required), a water cooled vacuum lid can be placed on top of the furnace, either by factory crane or dedicated lift/swing pivot arm (option). This furnace shell is connected to a multi stage mechanical vacuum pumping system which can evacuate the atmosphere above the molten bath.
The induction melting coil is powered from an Inductotherm VIP Power supply with the power and frequency matched for fast melt rates (high productivity) and optimum stirring (metallurgical quality) in the liquid state. The stirring frequency ensures that the alloy is fully homogenised and that fresh liquid metal is cycled to the surface of the bath to aid the degassing procedure.
Once the atmosphere is evacuated, the degassing procedure and intensified C-O reaction allows removal of undesirable gases, Hydrogen, Nitrogen and Oxygen to much lower levels than would be possible in air.
At the end of the degassing sequence, the vacuum lid can be removed and a protection ring is placed around the sealing flange. The furnace is then ready for tilt pouring into the customers transfer ladle or moulds. The pouring process is normally carried out in air (option for protective atmosphere).
Applications and Materials
The VCAP furnaces are available to suit a wide variety of melting application in sizes ranging from 80kg - 20Tonnes (other sizes available on request). Typical applications might include:
- Low and high carbon steels
- Tool and Die Steels
- Stainless Steels
- Nickel based alloys
- Cobalt based alloys
- Non Ferrous alloys.
Metallurgical considerations
Some typical processes that can be performed in the VCAP range include:
- Air melting from solid charge (Option for vacuum melting)
- Controlled atmosphere melting from solid charge
- Alloy homogenization and chemistry adjustment
- Vacuum degassing (hydrogen and nitrogen removal)
- Reduction of low vapour pressure tramp elements e.g.Pb, Cd, Bi, Zn
- Deoxidation using combination of vacuum and C-O reaction
- Decarburisation - Intensified C-O reaction at low pressure enabling excellent decarburization for extra low carbon levels
- Argon purging of metal with porous plug.
Some of the more important customer product advantages from VCAP operation are:
- Generally significant improvement of mechanical properties, such as yield strength, ductility impact strength, fatigue and stress rupture elevated temperature properties
- Improvement of technological characteristics, like hot workability, weldability and machinability
- Better microcleanliness due to strong carbon deoxidation and smaller residual inclusions
- Significantly reduced scatter in product properties and characteristics, less rejections.
