(Chemical symbol, Mn). A gray-white, nonmagnetic metallic element resembling iron, but harder and very brittle. It alloys readily with iron, copper, and nickel, forming important commercial alloys. Manganese is an essential alloying element used in steel; it increases hardness, strength, wear resistance, and other properties. Manganese minerals are widely distributed with oxides, the most common of which are silicates and carbonates. Atomic weight, 54.93; atomic number 25; melting point, 1260 “C (2300oF?); boiling point, 1900°C (3452°F).
Metallic manganese is obtained by the reduction of manganese oxide with sodium, magnesium or aluminum, or by electrolysis. High-grade ores containing manganese are mined in India, Brazil, Russia, and South Africa. Some ores are found in the United States but the greater tonnage is imported. For steel making, manganese is imported in the form of ferromanganese. Ferromanganese is prepared by melting mixed ores of iron and manganese in either a blast furnace or electric furnace.
Ferromanganese is an indispensable alloying element used in steel making, principally to deoxidize and desulfurize the steel. Some manganese is used for this purpose in all steels. All steels contain a small amount of residual manganese.
Manganese is an effective and inexpensive agent for cleansing molten steel of impurities that would decrease the strength and ductility of the finished product. A manganese content up to about 0.80% is commonly present in finished steel for the sole purpose of combining with sulfur and phosphorus to off-set embrittlement and hot shortness.
Higher content (10 to 15%) of manganese in steel increases the toughness and also increases the hardening capability of the steel. An exception, however, is
when manganese is present in steel between 3 to 4%, it tends to promote embrittlement of the steel.
Manganese is added to magnesium-aluminum alloys to improve corrosion resistance.