Standard Ferrosilicon Grades (By Silicon Content)
| Grade | Si Content (%) | Fe Content (%) | Key Impurities | Primary Applications |
|---|---|---|---|---|
| FeSi 15 | 14–16% | ~80% | High C, Al, P | Cast iron production (low-cost Si addition) |
| FeSi 45 | 43–47% | ~50% | Moderate Al, C | Steelmaking deoxidation, general foundry use |
| FeSi 65 | 63–68% | ~30% | Low Al, C | Most common for steelmaking, Mg production |
| FeSi 75 | 72–78% | ~20% | Very low Al, C | High-grade steel, specialty alloys |
| FeSi 90 | 87–95% | <10% | Ultra-low impurities | Semiconductors, solar silicon |
Specialized Ferrosilicon Alloys
(1) Ferrosilicon Magnesium (FeSiMg)
Composition: FeSi + 3–10% Mg, + Ca, RE (Rare Earth).
Purpose: Used in ductile iron (nodular cast iron) production to spheroidize graphite.
Grades:
FeSiMg 3 (3–5% Mg) – Basic nodularizer.
FeSiMg 7 (6–8% Mg) – High-efficiency treatment.
FeSiMgCa (Mg + Calcium) – Reduces dross formation.
(2) High-Purity Ferrosilicon
Si ≥ 75%, ultra-low Al (<0.5%), C (<0.1%).
Used in: Electrical steel, solar-grade silicon, chemicals.
(3) Ferrosilicon Barium (FeSiBa)
Contains Ba (4–12%) for enhanced deoxidation in high-grade steel.
Improves fluidity and reduces nozzle clogging in continuous casting.
(4) Ferrosilicon Zirconium (FeSiZr)
Used in heat-resistant alloys and special steel coatings.
How to Choose the Right Grade
| Application | Recommended Grade | Reason |
|---|---|---|
| Steelmaking (Deoxidation) | FeSi 65–75% | Optimal Si/Al balance |
| Ductile Iron Production | FeSiMg 5–7% | Ensures graphite nodulization |
| Stainless Steel Alloying | FeSi 75% (Low C, Al) | Prevents impurity pickup |
| Magnesium Production | FeSi 65% (Low Al) | Efficient MgO reduction |
| Semiconductors | FeSi 90% (High Purity) | Minimal contamination |
Key Standards for Ferrosilicon Grades
Different countries follow specific standards for FeSi classification:
China: GB/T 2272 (e.g., FeSi75-A, FeSi75-B).
Europe: EN ISO 5445 (e.g., FeSi45, FeSi65).
USA: ASTM A100 (e.g., Grade A – 75% Si).
Russia: GOST 1415 (e.g., FSi75, FSi65).
Example (GB/T 2272):
FeSi75-A: Si ≥ 75%, Al ≤ 1.5%, C ≤ 0.2% (High-grade steel).
FeSi75-C: Si ≥ 72%, Al ≤ 2%, C ≤ 0.4% (General steelmaking).
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