Silicon Manganese Silicon Manganese is mostly used in steelmaking and foundry activities. Some 30 % of the manganese used today in steelmaking is still used for its properties as a deoxidant and a sulphide former. In this last case it combines with sulphur avoiding the formation of iron sulphides, which sulphides are low melting point phases which become liquid at hot rolling temperatures and which, consequently, generate surface cracking. The other 70% of the manganese is used purely as an alloying element. Steels usually contains anything from 0,2% to 2% manganese depending on grades as manganese is the cheapest alloying element among those which enhance some key mechanical properties such as strength and toughness.