Ferromanganese
| Numeric designation | Ferromanganese |
|---|---|
| Chemical designation | Ferromangan |
Ferro-manganese is a master alloy of iron, manganese and carbon. It is produced by smelting iron and manganese ores in a blast furnace. The manganese content ranges from 30 to 80% and the carbon content from 2 to 6%. The sample analysed contains approximately 75% manganese and 25% iron.
The alloy initially solidifies in a crystalline state (austenite) with small microsegregations. On cooling, the austenite transforms into beta-manganese (cubic). On further cooling, the Mn-rich areas are converted to alpha-manganese. Beta-Mn appears bluish when etched (light grey in BSE) and contains approximately 76 mass % Mn and 4 mass % Si. Alpha Mn appears brown when etched (dark grey in BSE) and contains approximately 87% manganese by mass.
Both phases are hard and brittle, the alpha Mn being slightly harder at about 1300 HV0.2 than the beta Mn at 1080 HV0.2.
