Ferrosilicon (FeSi) is an iron–silicon alloy whose chemical composition is primarily defined by silicon content, supported by controlled levels of iron and minor impurities such as carbon, aluminum, calcium, and trace elements. The exact composition varies by grade (FeSi 75, FeSi 72, FeSi 65), but the silicon range is typically 65%–75%, making it a key material for steelmaking deoxidation and alloying control.
| Element | FeSi 75 | FeSi 72 | FeSi 65 | Function in Alloy |
|---|---|---|---|---|
| Silicon (Si) | 74–76% | 70–73% | 63–66% | Main alloying & deoxidizing element |
| Iron (Fe) | Balance | Balance | Balance | Base matrix metal |
| Carbon (C) | ≤0.20% | ≤0.20% | ≤0.25% | Affects steel purity |
| Aluminum (Al) | ≤2.0% | ≤2.0% | ≤2.5% | Inclusion control element |
| Calcium (Ca) | ≤0.5% | ≤0.5% | ≤0.5% | Improves slag modification |
| Phosphorus (P) | ≤0.04% | ≤0.04% | ≤0.05% | Impurity control |
| Sulfur (S) | ≤0.02% | ≤0.02% | ≤0.03% | Affects steel cleanliness |
Silicon is the functional core of ferrosilicon. In steelmaking, it performs three critical roles:
Strong deoxidizer in molten steel (steelmaking deoxidizer FeSi)
Alloying element to improve strength and hardness
Stabilizer of steel microstructure during cooling
Higher silicon content (such as FeSi 75) provides stronger deoxidation efficiency and better recovery rate, which is why it is widely used in metallurgical grade FeSi production.
Even small amounts of impurities significantly influence performance:
Carbon (C): Affects steel brittleness and reaction behavior
Aluminum (Al): Impacts inclusion formation and steel cleanliness
Sulfur (S): Reduces mechanical strength if not controlled
Phosphorus (P): Can increase steel brittleness in high concentrations
This is why a reliable ferrosilicon supplier strictly controls impurity levels in production.
FeSi 75: Higher silicon content (74–76%), stronger deoxidation capability
FeSi 72: Slightly lower silicon (70–73%), more cost-balanced for general use
FeSi 75: Standard metallurgical grade FeSi for general steelmaking
Low Al FeSi: Optimized for ultra-clean steel with reduced inclusion risk
These differences directly affect performance in ferrosilicon for casting and steel refining operations.
Precise chemical composition ensures:
Stable furnace reaction behavior
Predictable silicon recovery rate
Consistent steel quality across batches
Reduced slag loss and energy waste
This is a key capability of a professional ferrosilicon alloy manufacturer.
High Si (FeSi 75): Premium steel, EAF refining, deoxidation
Medium Si (FeSi 72): General steelmaking and cost control
Lower Si (FeSi 65): Foundry and ductile iron applications
In ductile iron production, nodular iron ferrosilicon composition is adjusted to improve graphite formation and mechanical strength.
Ferrosilicon Lump (10–50mm): Standard furnace charging
Ferrosilicon Granule (3–10mm): Controlled ladle addition
Ferrosilicon Powder (100 mesh): Rapid reaction metallurgy
Metallurgical Grade FeSi: High stability composition control
It is primarily composed of silicon (65–75%) and iron, with small controlled impurities.
Because it determines deoxidation strength and alloying efficiency.
Not always, but higher silicon improves recovery and efficiency in steelmaking.
Carbon, aluminum, sulfur, and phosphorus are strictly controlled.
No, it varies between FeSi 75, FeSi 72, and FeSi 65 grades.
It removes oxygen and improves steel strength and stability.
It influences graphite formation and reduces casting defects.
Yes, depending on furnace type and steel grade requirements.
We supply full-range ferrosilicon with controlled chemical composition:
✔ FeSi 75% Silicon
✔ FeSi 72 Alloy
✔ FeSi 65 Grade
✔ Low Aluminum Ferrosilicon
✔ High Purity Metallurgical Grade FeSi
✔ Ferrosilicon Lump (10–50mm)
✔ Ferrosilicon Granule (3–10mm)
✔ Ferrosilicon Powder (100 mesh)
✔ Nodular Iron Ferrosilicon
✔ Steelmaking Deoxidizer FeSi
WhatsApp: +86 15518824805
Send your required grade and application to receive optimized composition recommendations and quotation.
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