Definition - What does Deoxidization mean?

Deoxidization refers to the removal of:

  • Oxygen from molten metals by use of suitable deoxidizers
  • Undesirable elements other than oxygen by the introduction of elements or compounds that readily react with them
  • Oxide films from metal surfaces by chemical or electrochemical reaction in metal finishing

It is important in the steelmaking process, as oxygen is often detrimental to the quality of steel produced. Deoxidization is mainly achieved by adding a separate chemical species to neutralize the effects of oxygen or by directly removing the oxygen. Deoxidization is the last stage in steelmaking and reduces corrosion potentiality.

Deoxidization also known as deoxidation.

Corrosionpedia explains Deoxidization

Deoxidization is a method used in metallurgy to remove the oxygen content or impurities during steel manufacturing. Deoxidized steel is steel that has some or all of the oxygen removed from the melt during the steelmaking process.

Deoxidizing of steel is very important because it increases various properties of steel like tensile strength, ductility, toughness, weldability, polishability and machinability. If deoxidization is not done properly, it forms non-metallic inclusions and gas pores, bubbles of gas that become trapped during the solidification process of steel.

Types of deoxidization include:

  • Metallic deoxidization - Involves adding specific metals into the steel. These metals react with the unwanted oxygen, forming a strong oxide that, compared to pure oxygen, reduces the steel's strength and qualities by a lesser amount.
  • Some commonly used metallic deoxidizers include:
    • Ferrosilicon, ferromanganese, calcium silicide
    • Manganese and calcium
    • Silicon carbide, calcium carbide
    • Aluminum dross
    • Titanium & carbon
    • Phosphorus, copper (I) phosphide

  • Vacuum deoxidization - Involves using a vacuum to remove impurities. A portion of the carbon and oxygen in steel reacts, forming carbon monoxide which floats up to the top of the liquid steel and is removed by a vacuum system.
  • Diffusion deoxidization - Relies on the idea that deoxidization of slag leads to the deoxidization of steel. This method is done using deoxidizing agents on the slag, such as coke or silicon.

The deoxidization of molten steel shows a paradox. By increasing the concentration of deoxidizer in the melt over some critical value, re-oxidation of steel takes place.

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