1. precipitation deoxidation
Precipitation deoxidation method is to add directly to the liquid steel block deoxidant, such as ferrosilicon, ferromanganese, aluminium and so on. Oxygen absorber will react with dissolved oxygen to form oxides, and form a precipitate to float to the slag layer. This method of deoxidation is fast, simple and low cost. However, this method may leave residual oxides, affecting the purity of the steel. Usually, manufacturers of common steel grades will choose this method.
2. Diffusion deoxidation
Diffusion deoxidation method is to add deoxidising agents, such as carbon powder and ferrosilicon powder, into the slag. This method will reduce the FeO content in the slag, and promote the oxygen in the liquid steel to diffuse into the slag. This method can reduce the internal inclusions in the steel and improve the purity. However, it has a slow reaction speed and needs to be combined with stirring or extended refining time. This method is commonly used in electric furnace steelmaking or furnace refining.
3. Vacuum deoxidation
Vacuum deoxidation method is to reduce the pressure in a vacuum environment, prompting the carbon in the liquid steel and oxygen reaction to generate CO bubbles escape. This method does not need to add deoxidiser, can reduce inclusions, suitable for high purity steel. However, the equipment used in this method is complex and costly. This method is commonly used in the production of high-end alloy steel and bearing steel.
4. Synthetic slag deoxidation
Synthetic slag deoxidation is the use of pre-melted alkaline or neutral synthetic slag to cover the liquid steel, adsorb oxides and promote deoxidation reactions. This method can be combined with other methods to improve the deoxidising efficiency as required. This method is often used in out-of-furnace refining.
