Manganese is mainly used for desulfurization and deoxidation of steel in iron and steel industry; It is also used as an additive of alloy to improve the strength, hardness, elastic limit, wear resistance and corrosion resistance of steel; In high alloy steel, it is also used as austenitizing alloy element and for refining stainless steel, special alloy steel, stainless steel electrode, etc. The main functions of manganese in low alloy steel are as follows:
(1) Manganese and iron form a solid solution, which can improve the hardness and strength of ferrite and austenite in steel. Manganese is often used to improve the strength of carbon manganese steel, but it reduces the ductility of the material and increases the sensitivity of stress corrosion cracking. In general carbon manganese steel and low alloy steel, its content is 1% ~ 2%.
(2) Manganese is a good desensitizer and desulfurizer. Manganese and sulfur form MNS, which can prevent the hot embrittlement caused by sulfur, so as to improve the hot workability of steel. Therefore, industrial steels generally contain a certain amount of manganese.
(3) Because manganese can reduce the critical transition temperature in steel, the low-temperature impact toughness of carbon manganese steel is better than that of carbon steel.
(4) Manganese can strongly increase the hardenability of carbon manganese steel. When the manganese content is high, there is an unfavorable tendency to coarsen the grain of the steel and increase the tempering brittleness of the steel.
(5) Manganese has an adverse effect on the weldability of steel. In order to improve the weldability of steel, the carbon content of steel should be appropriately reduced within the allowable range. High quality low hydrogen electrode and corresponding welding process shall also be used during welding.
