What Is Silicon Used For In Steel?

  • FS Metal
  • Jan 31, 2023
  • Blog

Ferrosilicon alloys are added to the steelmaking process, and the higher the purity of the ferrosilicon alloy, the higher the internal silicon content and the lower the impurities. Silicon has a very important role in steel, and it can effectively improve the various properties of steel.

Effect Of Silicon On The Microstructure And Heat Treatment Of Steel

  1. Silicon, as an alloying element in steel, is greater than 0.4% by mass and is present in ferrite or austenite as a solid solution, capable of narrowing the austenitic phase zone.

  2. Silicon increases the annealing, normalizing, and quenching temperatures of steel and improves hardenability in sub-eutectoid steels.

  3. Silicon does not form carbides in steel, but it can effectively promote the graphitization of carbon, which tends to occur in medium and high-carbon steels with the high silicon content.

  4. In carburizing steel, silicon reduces the thickness of the polarizing layer and the concentration of carbon.

  5. Silicon effectively reduces the oxygen in the molten steel.

The effect of silicon on the mechanical properties of steel

  1. Silicon increases the hardness and strength of ferrite and austenite in steel, which is stronger than manganese, nickel, chromium, tungsten, aluminum, and vanadium.

  2. Silicon can significantly increase the elastic limit, yield strength, and flexural strength ratio of steel, and improve fatigue strength.

  3. When the mass fraction of silicon exceeds 3%, the plasticity and toughness of the steel are significantly reduced.

  4. Silicon causes ribbons to form in the steel, resulting in lower transverse properties than longitudinal properties.

  5. Enhances the wear resistance of the steel.

The effect of silicon on the physics, chemistry, and processing of steel

  1. Silicon reduces the density, thermal conductivity, electrical conductivity, and resistance temperature coefficient of steel.

  2. The amount of eddy current loss of silicon steel sheet is significantly lower than that of pure iron, with lower coercivity, reluctance, and hysteresis loss higher permeability and magnetic inductance strength.

  3. Silicon improves the oxidation resistance of steel at high temperatures.

Application of silicon in steel

  1. The addition of silicon in ordinary low-alloy steel increases strength and improves local corrosion resistance, and in tempered steel improves hardenability and temper resistance, and is one of the main alloying elements in a multi-alloy structure.

  2. Silicon is widely used in the production of spring steel.

  3. Mild and ultra-low carbon steels contain 1.0% to 4.5% silicon by mass and are widely used in electric motors and transformers.

  4. In stainless and corrosion-resistant steels, silicon is used in conjunction with molybdenum, tungsten, chromium, aluminum, titanium, and nitrogen to improve corrosion resistance and resistance to high-temperature oxidation.

  5. Graphite steels with high silicon content can be used for cold mold materials.

  6. Graphite steels with high silicon content can be used for cold mold materials.