It is a metal ferroalloy that is used to add silicon (Si) and manganese (Mn) as additives during the steel production process. Due to its lower carbon (C) content, it is a preferred additive in the manufacture of low carbon steels. Si-Mn is a ferroalloy composed mainly of manganese (MN) and iron (Fe) and usually with much lower proportions of minor elements such as C, phosphorus (P) and sulfur (S). Sometimes this ferroalloy is also called ferro-silicon-manganese. Both manganese and silicon play an important role in steelmaking as oxidizing, desulfurizing, and alloying agents.Silicon is the primary and stronger oxidizer. Mn is a milder deoxidizer than Si, but increases effectiveness due to the formation of stable Mn silicates and aluminates. It also acts as a desulfurizer. Manganese is used as an alloying element in almost all types of steel. The interesting and special point is the modification effect it has on the iron carbon system (Fe-C) by increasing the hardenability of steel.