FeSi75, FeSi72, FeSi65 Ferrosilicon Grades Compared: A Procurement Guide for Steelmaking and Foundry
Ferrosilicon is the most widely consumed ferroalloy in global steelmaking - roughly 5 kg of FeSi is used per metric ton of crude steel produced. But not all ferrosilicon is the same. The three grades covered here - FeSi75, FeSi72, and FeSi65 - differ in silicon content, aluminum limits, and impurity profiles. This article provides a technical comparison grounded in GB/T 2272-2020, the Chinese national standard for ferrosilicon, and industry practice so procurement managers can specify the right grade for their process.
Key Takeaways
FeSi75 (Si ≥75%, Al 0.1–2.0% depending on sub-grade) is the premium choice for high-grade steel deoxidation, ductile iron inoculation, and electrical steel - where tight inclusion control matters.
FeSi72 (Si ≥72%, Al ≤2.0%) is the economical workhorse for standard carbon steel, rebar, and structural steel production. It delivers roughly 96% of the silicon units of FeSi75 at a lower cost per ton.
FeSi65 (Si ≥65%, Al ≤2.0–3.0%) is the budget option for bulk deoxidation in less demanding melts. Higher silicon grades may be partially substituted by FeSi65 when Si specification targets are flexible.
Particle size selection is process-dependent. 10–50 mm is standard for EAF/BOF steelmaking; 3–10 mm for foundry inoculation; 0–3 mm for cored wire. Using the wrong size reduces silicon recovery and increases cost.
Low-aluminum sub-grades (Al ≤0.5%, ≤0.1%) are essential for bearing steel, spring steel, and electrical steel where Al₂O₃ inclusions degrade fatigue life and surface quality. The cost premium is justified by reduced rejection rates.
| What is the price of ferro silicon? China's export ferrosilicon prices on July 14 // Ferrosilicon price today // Ferro Silicon Lumps Price | ||||
| Unit: USD/ton | ||||
| product | Brand | Quote | Rise and Fall | Remark |
| Ferrosilicon | 72 | 1000-1030 | -- | FOB Tianjin Port |
| Ferrosilicon | 75 | 1080-1100 | -- | FOB Tianjin Port |
| What is the price of ferro silicon? Special ferrosilicon prices in China on July 14 // Ferro Silicon Price Per Ton // Ferro Silicon Factory | |||||
| Unit: Yuan/ton, natural block, ex-factory cash price including tax | |||||
| Mainstream price of low aluminum ferrosilicon in China | |||||
| Product Name | Specification | area | price | Rise and Fall | Remark |
| Low Aluminum Ferrosilicon | Si75Al<0.1 | Qinghai | 6700-6750 | -- | Factory price including tax |
| Low Aluminum Ferrosilicon | Si75Al<0.5 | Qinghai | 6400-6450 | -- | Factory price including tax |
| Low Aluminum Ferrosilicon | Si75Al<0.1 | Inner Mongolia | 6700-6750 | -- | Factory price including tax |
| Low Aluminum Ferrosilicon | Si75Al<0.5 | Inner Mongolia | 6400-6450 | -- | Factory price including tax |
| Note: The above prices are for reference only. Enterprises can set prices according to their own circumstances. | |||||
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1. Ferrosilicon at a Glance: What It Is and Why It Matters
Ferrosilicon (FeSi) is an iron-silicon alloy produced by carbothermic reduction of quartz (SiO₂) in the presence of iron-bearing materials in a submerged electric arc furnace. The silicon content of commercial FeSi ranges from 15% to 95%, with the 65–75% range accounting for the vast majority of steelmaking and foundry consumption.
In steelmaking, ferrosilicon serves two primary functions: deoxidation (removing dissolved oxygen from molten steel to prevent porosity and oxide inclusions) and alloying (adding silicon to achieve target mechanical and magnetic properties). In foundries, FeSi also acts as an inoculant - promoting the formation of fine, uniformly distributed graphite in cast iron - and as a component of magnesium-ferrosilicon nodulizers for ductile iron production.
ZhenAn International, headquartered in Anyang, Henan Province, China, supplies ferrosilicon in all three grades from two production bases totaling 30,000 m², with an annual capacity of 150,000+ metric tons. The company holds ISO 9001:2015 certification and provides SGS-inspected shipments to over 100 countries.
2. Chemical Composition: FeSi75 vs. FeSi72 vs. FeSi65
The table below presents the typical chemical composition of the three grades. FeSi75 has the richest aluminum sub-grade structure under GB/T 2272-2020, reflecting its use in high-value steel applications where inclusion control is critical. FeSi72 and FeSi65 have fewer sub-grade options and are oriented toward bulk deoxidation.
| Element | FeSi75 (Standard) | FeSi72 | FeSi65 |
|---|---|---|---|
| Silicon (Si) | ≥ 75.0% | ≥ 72.0% | ≥ 65.0% |
| Carbon (C) | ≤ 0.20% | ≤ 0.20% | ≤ 0.20% |
| Phosphorus (P) | ≤ 0.035% | ≤ 0.035% | ≤ 0.04% |
| Sulfur (S) | ≤ 0.025% | ≤ 0.025% | ≤ 0.03% |
| Manganese (Mn) | ≤ 0.40% | ≤ 0.50% | ≤ 0.50% |
| Chromium (Cr) | ≤ 0.30% | ≤ 0.50% | ≤ 0.50% |
Source: Commercial specifications per GB/T 2272-2020, confirmed against supplier mill certificates. Values represent standard grade; tighter limits available on request. FeSi75 aluminum limits depend on sub-grade selection - see Table 2.
2.1 FeSi75 Aluminum Sub-Grades (GB/T 2272-2020)
Aluminum is the most important impurity to control, because residual aluminum forms hard Al₂O₃ inclusions that reduce fatigue life in bearing steel, cause surface defects in sheet products, and clog submerged entry nozzles during continuous casting. GB/T 2272-2020 defines five aluminum sub-grades for FeSi75, each with progressively more stringent limits:
| Sub-Grade | Aluminum (Al) Max | Typical Application |
|---|---|---|
| FeSi75Al0.1 | ≤ 0.10% | Electrical steel, ultra-clean bearing steel, special alloys |
| FeSi75Al0.5 | ≤ 0.50% | Bearing steel, spring steel, high-quality structural steel |
| FeSi75Al1.0 | ≤ 1.0% | General alloy steel, pipeline steel, pressure vessel steel |
| FeSi75Al1.5 | ≤ 1.5% | Carbon structural steel, rebar, wire rod |
| FeSi75Al2.0 | ≤ 2.0% | General deoxidation where inclusion control is not critical |
Source: GB/T 2272-2020. The Al0.5 and Al0.1 sub-grades command a price premium - typically 5–10% above standard FeSi75 - reflecting the additional refining required during production.
For FeSi72 and FeSi65, aluminum is typically specified as a single maximum limit (≤2.0% for FeSi72, ≤2.0–3.0% for FeSi65) rather than through discrete sub-grades. Custom low-Al variants of FeSi72 are available but less common.
3. Deoxidation: How Silicon Content Affects Performance
When ferrosilicon is added to molten steel, silicon reacts with dissolved oxygen according to the reaction:
2FeO + Si → 2Fe + SiO₂
The silica (SiO₂) produced is less dense than liquid steel and floats into the slag layer. The higher the silicon content of the ferrosilicon, the more oxygen it can remove per kilogram of alloy added.
3.1 Practical Silicon Unit Comparison
For procurement purposes, calculate the cost per delivered silicon unit rather than cost per ton of alloy. One metric ton of each grade delivers the following approximate silicon units (assuming minimum Si content):
| Grade | Si Delivered per MT | Relative FeSi Consumption (to deliver equal Si) |
|---|---|---|
| FeSi75 | 750 kg | 1.00× (baseline) |
| FeSi72 | 720 kg | 1.04× (+4%) |
| FeSi65 | 650 kg | 1.15× (+15%) |
Values based on minimum silicon content per commercial specification. Actual silicon recovery rate (typically 70–92%) further depends on addition timing, bath temperature, and stirring conditions - factors independent of the grade selected.
Silicon recovery - the percentage of added silicon that actually enters the steel - ranges from approximately 70% for early solid additions to 85–92% for late liquid-steel additions or injection through cored wire. When comparing grades, apply your plant's historical recovery rate to the theoretical silicon delivered per ton to estimate the effective cost per recovered silicon kilogram.
4. Foundry Applications: Inoculation and Nodulization
In cast iron production, ferrosilicon's role shifts from deoxidation to microstructure control. Two distinct functions matter:
4.1 Inoculation
When added to molten cast iron just before pouring, ferrosilicon promotes the formation of fine, uniformly distributed Type-A graphite flakes (in gray iron) or graphite nodules (in ductile iron). This improves tensile strength, reduces chill depth, and produces more consistent mechanical properties across the casting section. FeSi75 is the standard inoculant grade because its high silicon content provides rapid dissolution and a strong graphitizing effect with minimal addition volume.
4.2 Nodulization (Ductile Iron)
Ferrosilicon serves as the carrier alloy in magnesium-ferrosilicon (MgFeSi) nodulizers - typically containing 5–9% Mg, 42–48% Si, and the balance iron. The FeSi base provides the silicon needed for graphite promotion, while magnesium drives the spheroidization of graphite from flakes to nodules. FeSi75 with low aluminum (≤1.0%) is preferred for nodulizer production because excess aluminum interferes with magnesium recovery.
| Application | Recommended Grade | Typical Size | Key Specification |
|---|---|---|---|
| Gray iron inoculation | FeSi75 | 3–10 mm | Si ≥75%, Al ≤1.5%, Ca 0.5–1.5% (beneficial) |
| Ductile iron inoculation | FeSi75 | 1–6 mm | Si ≥75%, Al ≤1.0%, low Ti desirable |
| Nodulizer base alloy | FeSi75 (low Al) | 10–30 mm | Si 42–48% (in MgFeSi), Al ≤1.0% |
| General foundry deoxidation | FeSi72 or FeSi65 | 8–15 mm | Standard commercial specification |
Foundry-specific ferrosilicon grades may include controlled calcium levels (0.5–2.0%) to enhance inoculation effectiveness. Confirm these requirements with your foundry metallurgist before ordering.
5. Particle Size Selection by Process
Particle size affects dissolution rate, silicon recovery, dust generation, and handling logistics. The table below maps each common ferrosilicon size range to its standard process application:
| Size Range | Process | Rationale |
|---|---|---|
| 0–3 mm (powder/fines) | Cored wire filling, powder injection | Fine particle size ensures uniform packing density inside the steel sheath and rapid dissolution in the melt after injection. |
| 1–3 mm | Secondary metallurgy, precision casting | Fast dissolution for late-stage composition trimming. In thin-walled precision castings (wall <10 mm), fine powder improves density by ~30%. |
| 3–10 mm | Foundry inoculation, medium furnaces | Balanced dissolution rate ensures even distribution in the ladle before pouring. Standard for ladle inoculation in iron foundries. |
| 10–50 mm | EAF, BOF, ladle furnace (standard steelmaking) | The most widely specified size globally. Particles dissolve at a controlled rate, achieve deep deoxidation, and are easy to handle and charge with conventional equipment. |
| 50–100 mm | Large furnaces, bulk charging | Minimizes oxidation losses during charging. Requires longer dissolution time; suitable for furnaces with sufficient residence time and stirring. |
| Natural block (as-crushed) | General purpose, on-site sizing | Lower cost (no precision screening). Mills with in-house crushing and screening capability may prefer this option. |
Screening tolerance: oversize and undersize material combined should not exceed 10% of total lot weight per standard commercial practice. For cored wire applications, tighter tolerances (±5%) are typical.
6. Packaging, Documentation, and Quality Assurance
For international procurement, packaging and documentation are as important as the alloy specification itself.
6.1 Packaging Options
1 MT bulk bags (FIBC): Standard export packaging. Woven polypropylene with inner polyethylene liner. UV-stabilized for outdoor storage. Four lifting loops for crane/forklift handling.
25 kg / 50 kg bags on pallets: Suitable for smaller-volume buyers or facilities without bulk-bag handling equipment. Shrink-wrapped on wooden fumigated pallets (ISPM 15 compliant).
Steel drums: For fine powder grades (0–3 mm) where moisture protection is critical. Used primarily for cored-wire-grade material.
All packaging is labeled with grade, lot number, chemical specification, net weight, and ZhenAn manufacturer identification. Custom labeling (buyer brand, destination marking) is available for contract orders.
6.2 Quality Documentation
Every shipment includes:
Certificate of Analysis (COA): Batch-specific chemical analysis for Si, Al, C, P, S, Mn, Cr, and any other elements specified in the purchase contract.
SGS (or equivalent) Inspection Report: Third-party verification of chemical composition, particle size distribution, and packing condition. Available upon request or as a contractual requirement.
Particle Size Distribution Report: Sieve analysis showing percentage within specification, oversize, and undersize fractions.
Packing List & Certificate of Origin: Standard shipping documentation. Form E / Form F certificates available for applicable preferential trade arrangements.
7. How to Specify Ferrosilicon in a Purchase Order
A complete ferrosilicon specification should include the following six elements. An example follows:
Example Purchase Order Specification:
Product: Ferrosilicon FeSi75Al1.0
Chemical: Si ≥75.0%, Al ≤1.0%, C ≤0.20%, P ≤0.035%, S ≤0.025%
Size: 10–50 mm (≥90% within range, ≤5% oversize, ≤5% undersize)
Packaging: 1 MT bulk bags with inner liner
Quantity: 100 MT (±5% tolerance)
Documentation: COA per lot, SGS inspection at loading port
Delivery: FOB Tianjin / CIF [destination port]
Including all six elements eliminates ambiguity and ensures the supplier can quote and deliver exactly what your process requires.
Frequently Asked Questions
What is the difference between FeSi75, FeSi72, and FeSi65 ferrosilicon?
The three grades differ primarily in silicon content: FeSi75 contains ≥75% Si, FeSi72 contains ≥72% Si, and FeSi65 contains ≥65% Si. FeSi75 offers the strongest deoxidation power and is preferred for high-grade steel and ductile iron inoculation. FeSi72 is an economical alternative for general steelmaking - it requires approximately 4% more material by weight to deliver the same silicon units. FeSi65 is used in bulk deoxidation where cost is the primary concern and silicon specification targets are flexible. FeSi75 also offers five aluminum sub-grades (Al ≤0.1% through ≤2.0%) for applications requiring strict inclusion control, such as bearing steel and electrical steel.
How does the deoxidation reaction of ferrosilicon work in steelmaking?
Silicon in ferrosilicon reacts with dissolved oxygen in molten steel according to 2FeO + Si → 2Fe + SiO₂. The resulting silica (SiO₂) is lighter than liquid steel and floats into the slag layer, where it is removed. FeSi75, with higher silicon content per kilogram, achieves faster and more complete deoxidation. Silicon recovery rates typically range from 70% to 92% depending on addition method - late additions to deoxidized steel or injection through cored wire yield higher recovery than early solid additions to an oxidizing bath. Properly deoxidized steel has fewer oxide inclusions, better mechanical properties, reduced porosity, and improved surface quality.
Which ferrosilicon particle size should I choose for my application?
Particle size selection depends on your furnace type and addition method. Use 0–3 mm for cored wire production and powder injection systems. Use 3–10 mm for foundry inoculation and medium-capacity furnaces. Use 10–50 mm for electric arc furnaces (EAF), basic oxygen furnaces (BOF), and ladle furnaces - this is the most commonly specified size in global steelmaking. Use 50–100 mm for large submerged arc furnaces and bulk alloy charging. Natural block (as-crushed, unscreened) material is available at lower cost for mills that perform their own sizing. Always confirm size distribution tolerances with your supplier before ordering.
What is the role of aluminum in ferrosilicon, and why do low-Al grades matter?
Aluminum is a naturally occurring impurity in ferrosilicon, introduced from the quartz raw material and the reduction process. In standard steelmaking, aluminum levels up to 2.0% are acceptable because the resulting Al₂O₃ inclusions are not critical to end-use performance. However, for bearing steel, spring steel, electrical steel, and other high-cleanliness grades, low-aluminum ferrosilicon (Al ≤0.5% or ≤0.1%) is required because hard, non-deformable Al₂O₃ inclusions reduce fatigue life by acting as stress concentrators, impair surface quality in thin-gauge products, and can clog submerged entry nozzles during continuous casting. The price premium for low-Al grades (5–10%) is typically recovered through reduced rejection rates in high-value steel production.
How is ferrosilicon typically packaged for international shipping?
Standard export packaging is 1-metric-ton bulk bags (FIBC) made of woven polypropylene with inner polyethylene liners. These are UV-stabilized for outdoor storage and have four lifting loops. For smaller-volume buyers, 25 kg or 50 kg woven bags on fumigated wooden pallets (ISPM 15 compliant) are standard. Fine powder grades (0–3 mm) may ship in sealed steel drums for moisture protection. All packaging carries lot number, grade, chemical specification, net weight, and manufacturer identification. ZhenAn ships from Tianjin Port with full documentation including COA, SGS inspection reports, packing list, and certificate of origin.
Can I use FeSi72 instead of FeSi75 for steelmaking deoxidation?
Yes, FeSi72 can substitute for FeSi75 in many general steelmaking applications. The deoxidation chemistry is identical - only the quantity required changes. You need approximately 4% more FeSi72 by weight to deliver the same mass of silicon as FeSi75. FeSi75 remains the better choice when: (a) tight silicon specification control is required in the final steel grade, (b) producing high-grade steel (bearing, spring, electrical, tool steel) where impurity limits are critical, or (c) the aluminum content must be strictly controlled through a certified Al sub-grade. FeSi72 is the economical choice for standard carbon steel, rebar steel, structural steel, and wire rod production where minor impurity variations are within tolerance. Calculate your effective cost per recovered silicon kilogram before making the substitution decision.
References
GB/T 2272-2020 - Ferrosilicon (硅铁). National Standard of the People's Republic of China. https://openstd.samr.gov.cn/bzgk/std/newGbInfo?hcno=F93D0B06FA81F6070F10BF51822BB152 (accessed 2026-08-06)
HS Ferroalloy - Ferro Silicon: Grades, Composition, and Applications. https://hsferroalloy.com/ferro-silicon/ (accessed 2026-08-06)
HS Ferroalloy - Grades of Ferrosilicon and Their Applications. https://hsferroalloy.com/grades-of-ferrosilicon-and-their-applications/ (accessed 2026-08-06)
ZX Ferroalloy - Specific Requirements for Ferrosilicon Size in Different Industries. https://zxferroalloy.com/resource/specific-requirements-for-ferrosilicon-size-in-different-industries/ (accessed 2026-08-06)
ZhenAn / Ferro-Silicon-Alloy.com - What Size Ferrosilicon for Steelmaking? Complete Particle Size Selection Guide. https://www.ferro-silicon-alloy.com/news/what-size-ferrosilicon-for-steelmaking-comple-85576345.html (accessed 2026-08-06)
Caishuku Material Database - FeSi75Al1.5 per GB/T 2272-2020. https://www.caishuku.com/material/detail_3006345.html (accessed 2026-08-06)
Caishuku Material Database - FeSi65 per GB/T 2272-2020. https://www.caishuku.com/material/detail.php?mid=3007761 (accessed 2026-08-06)
Elkem - What is Ferrosilicon? https://www.elkem.com/products/silicon/ferrosilicon/ (accessed 2026-08-06)
Beifang Alloy - Ferro Silicon 70/75 Grade: Specifications, Properties, and Applications. https://www.beifangalloy.com/ferro-silicon-70-75-grade-specifications-properties-and-applications/ (accessed 2026-08-06)
Original source article - ZhenAn International, "High Quality Ferrosilicon 75%/72%/65% for Steelmaking." https://www.metal-alloy.com/info/high-quality-ferrosilicon-75-72-65-for-stee-103043805.html (published 2025-07-13, accessed 2026-08-06)
All technical data has been cross-referenced against the cited sources as of the update date (August 6, 2026). Chemical composition ranges are based on GB/T 2272-2020 and representative commercial specifications. Actual mill certificates may vary within the allowable tolerance of the applicable standard. If you identify an error, contact us at market@zanewmetal.com so we can correct it.
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