The VD system is one of the widest used degassing systems in commercial use. In that system a ladle is placed in a vacuum tank and sealed with a vacuum cover for an operation under vacuum conditions. The ladle has to be equipped with a porous plug for inert gas stirring. Vacuum will be created by the steam ejector- or mechanical vacuum pumps.
During the vacuum treatment carbon, oxygen, nitrogen and hydrogen can be reduced in various steps depending on the melt conditions. Additionally, the VD system can be equipped with vacuum alloy hoppers so that an analysis correction and adjustment can be executed during vacuum treatment. Advantages of this system include good homogenization as well as higher alloys yields.
For VOD treatment, one can take advantage of the fact that, under vacuum, decarburization with oxygen occurs before chromium oxidation and thus a low carbon content is achieved with little loss of chromium. When using this system, an oxygen lance is installed on top of the vacuum cover.
Most production programs nowadays require a combination of VD and VOD operation. For that purpose the equipment can be designed for both types of operations.
Altogether, the VD-VOD – treatment offers the following process advantages:
Variations:
USP‘s of INTECO Design:
