Ferrosilicon is the most important and widely used composite deoxidizer and alloying additive in the steel industry. AON METALS' 70/72/75 series fesi is produced from high-quality coke, steel scrap, and quartz (or silica) as raw materials, smelted at high temperatures in an electric arc furnace, with the silicon content precisely controlled within the 70%-75% range.

Its core roles in steelmaking:

Precipitation deoxidation: Utilizing the strong affinity between silicon and oxygen, silicon reacts with dissolved oxygen in molten steel to form SiO₂, creating easily floating silicate products, thereby reducing the oxygen content in the steel and improving its density.

Alloying: Silicon is an essential alloying element for most steel grades, significantly improving the strength, hardness, elastic limit, and heat resistance of steel. Silicon's solid solution strengthening effect in steel is second only to phosphorus.

Heating Assistance: The ferrosilicon deoxidation reaction (2FeO + Si = SiO₂ + 2Fe) is a strongly exothermic reaction, which helps to increase the tapping temperature and reduce energy consumption.

70 72 75 Ferrosilicon Deoxidizer

chemical composition

Grade	Chemical composition						Application Scenarios and Key Roles
	Si	Al	Ca	Mn	C	P/S
FeSi75Al0.5-A	74.0-80.0	≤0.5	≤1.0	≤0.4	≤0.1	Strict control	High-end special steel, pipeline steel, automotive steel: Low aluminum control reduces Al₂O₃ inclusions and improves steel purity.
FeSi75Al1.0-A	74.0-80.0	≤1.0	≤1.0	≤0.4	≤0.1	Strict control	Alloy structural steel, spring steel: Conventional deoxidation and alloying, high cost-effectiveness.
FeSi75Al1.5-A	74.0-80.0	≤1.5	≤1.0	≤0.4	≤0.1	Strict control	General carbon steel, low alloy steel: Cost-priority deoxidizer choice.
FeSi75-B	72.0-80.0	Negotiation	≤1.0	≤0.5	≤0.2	routine	Cast steel, cast iron: Used as an inoculant base material or deoxidizer.
FeSi65	65.0-72.0	-	-	≤0.6	-	routine	Cost-sensitive smelting: Used in applications where silicon content requirements are not strict.
FeSi Powder	72.0-80.0	≤1.5	≤1.0	≤0.5	≤0.2	routine	Welding material coatings, mineral processing heavy media, exothermic agents: Particle size customized according to application.

Customizable Size:

Blocks: 10-50mm, 10-60mm, 10-100mm (Suitable for electric furnaces and ladle additives)

Granules: 1-3mm, 3-8mm (Suitable for casting inoculation and cored wire)

Powder: 0-1mm, 40-200 mesh (Suitable for welding materials and exothermic agents)

Quality Control:

Pre-furnace Analysis: Real-time monitoring using a direct-reading spectrometer to ensure component accuracy.

Particle Size Guarantee: Standardized vibrating sieving system to ensure size distribution meets customer requirements.

Cleanliness: After sieving, the product undergoes magnetic separation to remove any impurities, ensuring product purity.

Metallurgical Principles and Application Advantages of Ferrosilicon Deoxidation

1. Highly Effective Deoxidation, Enhancing Steel Purity

Principle: Silicon has a much higher affinity for oxygen than iron. When ferrosilicon is added to molten steel, the following reaction occurs: [Si] + 2[O] = SiO₂(s). The generated SiO₂ combines with MnO, FeO, etc., in the molten steel to form low-melting-point silicates (such as 2MnO·SiO₂, 2FeO·SiO₂). These liquid products easily collide, aggregate, and float into the slag, thus effectively reducing the total oxygen content and non-metallic inclusions in the steel.

Data: In conventional smelting, using 75% ferrosilicon for precipitation deoxidation can reduce the oxygen content of molten steel by 40-60% and the total amount of inclusions by more than 30%.

2. Moderate Reaction Rate, Strong Process Controllability

Unlike the rapid oxidation of aluminum, the deoxidation reaction of ferrosilicon is mild and easy to control. This makes it an ideal deoxidizer in the steelmaking process: it can quickly reduce oxygen potential without causing excessive reaction leading to boiling and splashing of molten steel or the formation of large amounts of difficult-to-remove clusters of Al₂O₃ inclusions.

3. Economical and efficient, with low overall cost

Cost-effectiveness: Silicon is an abundant element in the Earth's crust, and the production cost of ferrosilicon is far lower than that of deoxidizers such as aluminum and calcium. Under the premise of meeting deoxidation requirements, using ferrosilicon for pre-deoxidation or final deoxidation is one of the lowest-cost options per ton of steel.

Alloying added value: The added silicon not only deoxidizes but is also absorbed by the molten steel as an alloying element (typically with a recovery rate of 85%-95%), directly contributing to the mechanical properties of the steel, achieving "one investment, two returns."

4. Improved physicochemical properties of molten steel

Lowering liquidus temperature: The increase in silicon content in molten steel slightly lowers its liquidus temperature, which is beneficial to the continuous casting process.

Increase resistivity: Silicon can significantly increase the resistivity of steel, therefore silicon steel sheets (electrical steel) are a key material for manufacturing transformers and motor cores.

70 72 75 Ferrosilicon Deoxidizer

FAQ

Q: How much difference is there in deoxidation effect between 70 ferrosilicon and 75 ferrosilicon?

A: 70 ferrosilicon has a silicon content 5-8 percentage points lower. Adding the same 2 kg of silicon results in 0.1-0.16% less silicon introduction. For plain carbon steel, this difference is acceptable; for alloy steel, 75 ferrosilicon is recommended.

Q: How much more expensive is low-aluminum ferrosilicon (Al≤0.5%) than ordinary ferrosilicon?

A: Generally, it's 200-500 yuan/ton more expensive. For customers making automotive steel sheets and pipeline steel, this price difference is acceptable; for ordinary rebar, it's not necessary.

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