The role of manganese in low alloy steels
1) Mn forms a solid solution with iron, which can improve the hardness and strength of ferrite and austenite in steel. Manganese is often used in carbon manganese steels to improve the strength of the steel, but it reduces the ductility of the material and increases the susceptibility to 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. Mn and sulfur form Mns, which can prevent the thermal embrittlement caused by sulfur, thus improving the hot working property of steel. Therefore, industrial steels generally contain a certain amount of manganese.
(3) Because manganese in steel can reduce the critical transition temperature, 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, it has the disadvantageous tendency to coarsen the grain and increase the temper brittleness of the steel.
(5) Manganese has a negative effect on the weldability of steel. In order to improve the weldability of the steel, the carbon content of the steel should be appropriately reduced to the extent permitted. It is also necessary to use high quality low hydrogen electrode and corresponding welding process.
