Silicon (Si)
1, improve the strength of the solid solution in steel and cold work hardening degree of toughness and plasticity of steel to reduce.
2, silicon can significantly improve the elastic limit of steel, yield limit and yield strength ratio, which is the general spring steel.
3, corrosion resistance. Silicon mass fraction of 15% -20% of high silicon cast iron, is very good acid-resistant materials. Steel containing silicon when heated in an oxidizing atmosphere, the surface will also form a layer of SiO2 film, thus improving the oxidation resistance of steel at high temperatures.
4, the main alloying elements in magnetic steel (content in the range of 0.40%, improve the tendency to thermal cracking, high content, prone to the formation of columnar crystals, increasing the tendency to thermal cracking).
5, reduce the critical cooling rate of steel, improve the hardenability of steel Disadvantages: deterioration of the welding performance of steel.
Silicon , chemical symbol is Si, the old name for silicon. Atomic number 14, relative atomic mass 28.0855, amorphous silicon and crystalline silicon two isotopes, belongs to the third cycle of the periodic table, IVA group of metal-like elements.
Silicon is also an extremely common element, however, it rarely appears in nature in the form of monomers, but in the form of complex silicates or silicon dioxide, widely present in rocks, gravel, dust. Silicon ranks eighth in the universe in terms of reserves. It is the second most abundant element in the earth's crust, constituting 26.4% of the total mass of the earth's crust, after oxygen (49.4%), which is the first.
Silicon is used in large quantities in the smelting of ferrosilicon alloys as an alloying element in the iron and steel industry, and as a reducing agent in the smelting of many kinds of metals. Silicon is also a good component in aluminum alloys, the vast majority of cast aluminum alloys contain silicon.
Silicon in the steelmaking process for the reducing agent and deoxidizing agent exists, so the sedentary steel generally have 0.15 ~ 0.30% silicon. If the silicon content of steel more than 0.5% even if it contains alloying elements containing silicon, silicon can significantly improve the elastic limit of steel, yield point and tensile strength, so commonly used as spring steel. High alloy content can improve the steel's heat resistance and corrosion resistance, live in 1% to 4% of the silicon content of mild steel, has a very high magnetic conductivity, commonly used in the electrical industry and silicon steel sheet. However, with the increase of silicon content will reduce the welding performance of steel.