Vacuum treatment of molten steel in RH (Ruerhstal Heraeus) and VTD (Vacuum Tank Degasser): a comparative study

On the beginning of their development, RH and VTD were applied to produce quality steel in term of low hydrogen content for reducing of 'hair crack' formation. In the mean time, both of these technologies are installed in steelworks in order to obtain high quality of steel products containing low hydrogen content, low nitrogen content, ultra low carbon content, low total oxygen content as well as ultra low sulphur content. The criteria of technology selection of these vacuum treatment techniques are strictly dictated by the steel grade to be produced. Intensive slag-metal interaction was observed during molten steel treatment on VTD which promotes a good condition for sulphur removal. On the other hand, less slag-metal interaction is taken place during RH treatment