Application of ferrosilicon and manganese-silicon alloy
Ferrosilicon and silicomanganese alloys are the most widely used ferroalloys in steelmaking. They are mainly used as deoxidizers and alloying agents in steelmaking to eliminate excessive oxygen and sulfur in molten steel and improve the quality and performance of steel. In recent years, the proportion of ferrosilicon and manganese-silicon alloy in consumption has changed greatly. Because Mn-Si alloy can not only deoxidize, but also increase the manganese content in steel and improve the strength of steel, the proportion of Mn-Si alloy used as deoxidizer is gradually higher than that of ferrosilicon. In addition to steelmaking, ferrosilicon is also used for smelting magnesium.
Used as deoxidizer. The steelmaking process is a process of decarbonizing molten iron and removing harmful impurities such as phosphorus and sulfur by blowing oxygen or adding oxidant. In the process of smelting pig iron into steel, the oxygen content in molten steel gradually increases and generally exists in molten steel in the form of FeO. If the residual excess oxygen in steel is not removed, it can not be cast into qualified billet and steel with good mechanical properties can not be obtained.
Therefore, it is necessary to add some elements with stronger oxygen binding force than iron, and their oxides are easily excluded from molten steel and enter slag. According to the binding strength of various elements in molten steel to oxygen, the order from weak to strong is: chromium, manganese, carbon, silicon, vanadium, titanium, boron, aluminum, zirconium and calcium. Therefore, ferroalloys composed of silicon, manganese, aluminum and calcium are often used for steelmaking and deoxidation.
Used as alloy additive. Alloying elements can not only reduce the impurity content in steel, but also adjust the chemical composition of steel. Commonly used alloying elements include silicon, manganese, chromium, molybdenum, vanadium, titanium, tungsten, cobalt, boron and niobium. Steel grades with different alloy elements and alloy contents have different characteristics and uses.
Used as reducing agent. In addition, ferrosilicon can be used as reducing agent for producing ferroalloys such as ferromolybdenum and ferrovanadium, and ferrosilicon-chromium alloy and ferrosilicon-manganese alloy can be used as reducing agent for refining low-carbon ferrochromium and low-carbon ferromanganese respectively.
In a word, silicon can significantly improve the elasticity and magnetic permeability of steel. Therefore, when smelting structural steel, tool steel, spring steel and silicon steel for transformer, silicon alloy should be used. General steel contains 0. 15%-0.35% silicon, structural steel contains 0.40%- 1.75% silicon, tool steel contains 0.30%- 1.80% silicon, spring steel contains 0.40%-2.80% silicon, and stainless acid-resistant steel contains. Manganese can reduce the brittleness of steel, improve its hot workability, and improve its strength, hardness and wear resistance. "No manganese, no steel", the consumption of manganese in iron and steel industry accounts for more than 90% of its output. Manganese is an indispensable functional basic raw material for producing high-quality steel, which can remove impurities such as sulfur and oxygen during steelmaking and improve the physical properties of steel by improving strength, hardness and wear resistance. At present, no other elements can replace the role of manganese in steel production.