What Is Ferromanganese
Ferromanganese is an iron manganese alloy produced by the reduction of manganese ore in blast furnaces or electric furnaces. It is one of the most important ferroalloys in steel production, supplying manganese to the steel melt together with iron.
The alloy is classified by its carbon content into low-carbon, medium-carbon and high-carbon grades. The manganese content typically ranges from 65 to 80 percent, with the balance mainly iron and carbon.
High Carbon Ferromanganese
High carbon ferromanganese contains carbon above about 7 percent and is the most economical source of manganese for steel. It is used in the production of carbon steel and low alloy steel, where the carbon addition is acceptable and even useful.
The high carbon grade is produced in large submerged arc or blast furnaces, which keeps its cost low and makes it the most widely traded ferromanganese product.
Medium Carbon Ferromanganese
Medium carbon ferromanganese has a carbon content between about 1.0 and 2.0 percent and a manganese content of about 70 to 85 percent. It is produced by refining high carbon ferromanganese, and it is used when the carbon addition must be limited.
This grade suits medium carbon steels and alloy steels where the carbon contribution of the manganese source must be carefully controlled.
Low Carbon Ferromanganese
Low carbon ferromanganese contains carbon below about 1 percent and a high manganese content of about 80 percent. It is the most expensive grade because of the additional refining, and it is used in low carbon steel, stainless steel and welding consumables.
The low carbon grade allows the steelmaker to add manganese without disturbing the carbon balance of the melt.
Role in Steelmaking
Deoxidation: manganese combines with oxygen and reduces oxide inclusions.
Desulfurization: manganese combines with sulfur to form manganese sulfide.
Alloying: manganese raises strength, hardness and hardenability.
Hot workability: manganese sulfide prevents hot shortness during rolling.
The composition limits of ferromanganese grades are defined in standards such as GB/T 3795, which specify the manganese, carbon, silicon, phosphorus and sulfur ranges for each grade.
Frequently Asked Questions
Q: What is ferromanganese?
It is an iron manganese alloy used in steelmaking, with manganese content from 65 to 80 percent.
Q: What are the main grades?
High carbon, medium carbon and low carbon ferromanganese, classified by carbon content.
Q: Which grade is used for low carbon steel?
Low carbon ferromanganese, because it adds manganese without disturbing the carbon balance.
Q: What does manganese do in steel?
It deoxidizes and desulfurizes the melt, and improves strength, hardness and hot workability.
Q: Which standard defines the grades?
Standards such as GB/T 3795 define the composition of ferromanganese grades.
