Speaker
Description
VIM/VIDP-Process is widely used for melting high value charge materials, refining, alloying under vacuum or protective atmosphere and finally for casting under defined environmental conditions. The equipment is suitable and dedicated for manufacturing high end grades, especially used in the aerospace industry. Besides those well-defined and specified alloy manufacturing routes where the VIM/VIDP-Process acts as starting point of triple melting, there is a field of potential use of vacuum melting for grades with medium quality requirements. For this market segment ALD’s preferred technical approach is the VID as the primary melting and refining tool. While refining and alloying in VID is done under the same conditions as in VIM/VIDP-Process the ingot casting itself is performed under inert gas shrouding. Due to the easy furnace body accessibility even liquid charging is possible. In these production routes the VID is well integrated and is a valuable tool for fine trimming of quality requirements. However, due to the heat generation by induction this solution experiences some metallurgical restrictions. For example; managing slag is difficult.
In this paper it will be shown how plasma processes accelerate kinetics of gas/melt interface reactions and how the integration of thermal plasma sources opens the field of opportunities performing additional metallurgical refining treatments in VID. By this means, refining steps usually to be performed prior or after VID-Process could be integrated directly into the VID, allowing for higher quality or for reducing the number of additional melting and refining processes.
Furthermore, due to the nature of thermal plasma processes in situ gas alloying (e.g. nitrogenization) becomes very effective. With additional features even direct iron ore reduction by hydrogen could be performed in this equipment, combining the best of both worlds – the global melt bath movement by electromagnetic forces from induction and the enhanced interface activation by plasma.
| Speaker Company/University | Henrik Franz, ALD Vacuum Technologies GmbH, Hanau, Germany |
|---|