Ferrosilicon Grades And Their Differences

Ferrosilicon Grades And Their Differences

Ferrosilicon (FeSi) is classified into different grades based on its silicon content, impurity levels, and alloying additions. Each grade has specific industrial applications due to variations in chemical composition and performance.
 

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).

GOST 1415 (CIS standard, 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).
 

Packaging, Handling & Delivery

Ferrosilicon is typically supplied in lump form (10-100mm) or as granules (1-10mm) depending on the intended application and furnace type. Bulk shipments are packed in 1-ton jumbo bags with polyethylene liners to prevent moisture absorption. Smaller lots can be packaged in 25kg or 50kg woven polypropylene bags palletized for safe handling. Ferrosilicon must be stored in dry conditions because contact with moisture can generate flammable hydrogen gas. Our logistics team coordinates container loading, customs documentation, and port delivery to ensure timely arrival. Standard lead time ranges from 15 to 30 days after order confirmation and deposit receipt.
 

FAQ

Q: What is the difference between FeSi 65 and FeSi 75?

A: FeSi 75 contains 72-78% silicon and is used for high-grade steel and specialty alloys. FeSi 65 contains 63-68% silicon and is the most common grade for general steelmaking and magnesium production.

Q: Can ferrosilicon be used in powder form?

A: Yes, pulverized ferrosilicon is used in powder metallurgy, welding electrode coatings, and as a suspension agent in mineral processing. Particle sizes such as 100 mesh and 200 mesh are commonly available.