Ferroalloys (Ferro Alloy), in a broad sense, refer to a product that is added to molten iron as a deoxidizer, element additive, etc. during steelmaking. To make the steel have certain characteristics or meet certain requirements.
Ferro alloy is composed of iron and one or more elements, mainly used in iron and steel smelting.
In the iron and steel industry, all intermediate alloys for steelmaking, whether they contain iron or not (such as Calcium Silicon), are generally called “Ferro alloys”. It is also customary to include certain pure metal additives and oxide additives. Such as pure metal additives for steelmaking include aluminum, titanium, nickel, silicon metal, manganese metal, chrome metal, and so on. Certain easily reducible oxides such as MoO and NiO are also used to replace iron alloys. In addition, there are Nitrided Ferro alloys, such as Nitrided Ferrochrome, Nitrided Ferromanganese, Nitrided ferrosilicon, etc. after nitriding treatment, as well as exothermic ferro alloys mixed with exothermic agents.
The Characteristics of Ferro Alloys
- The main elements of ferro alloys generally have higher melting points, or their oxides are difficult to reduce,
- It is difficult to smelt pure metal, but it is easier to reduce and smelt if it is together with iron.
- Ferroalloys are used in iron and steel smelting. The iron contained in it is not only harmless, but also beneficial because it is easy to melt in molten steel.
- Therefore, the deoxidation and addition of alloys in the steelmaking production process are mostly added in the form of ferroalloys.
- Ferroalloys are generally very brittle and cannot be used as metallic materials.
Ferro Alloys Uses
Deoxidizer: In the process of steelmaking, oxygen is removed from molten steel, and some ferroalloys can also remove other impurities in steel such as sulfur, phosphorus, nitrogen, etc.
As a steelmaking deoxidizer, the most widely used are silicomanganese, ferromanganese and ferrosilicon. Strong deoxidizers are aluminum (aluminum iron), calcium silicon, ferro silicon zirconium, etc. (see steel deoxidation reaction).
Alloy additives: Add alloy elements to the steel to improve the performance of the steel according to the requirements of the steel composition.
Nodulizer: an additive that crystallizes graphite in cast iron into a spherical shape, called “nodulizer”. The main component of “spheroidizing agent” is nodularizing elements, such as Mg, Ce, Ca, etc. Spheroidal graphite in ductile cast iron is formed by spheroidizing molten cast iron, making it much stronger than gray cast iron and tougher than malleable cast iron, while maintaining a series of advantages of gray cast iron. However, the “spheroidizer” used in the casting of ductile iron can increase the tendency of the weld to produce “white mouth” and hardened structure, and induce cracks in the weld and heat-affected zone (especially the fusion zone). Therefore, the weldability of ductile iron is worse than that of gray cast iron. Ferro silicon magnesium is mainly used as nodulizer.
Inoculant: Added to the molten iron before casting the cast iron to improve the crystallization structure of the casting.
Commonly used as alloy additives are: ferromanganese, ferrochrome, ferrosilicon, ferrotungsten, ferromolybdenum, ferrovanadium, ferrotitanium, ferronickel, niobium (tantalum) iron, rare earth ferroalloy, ferroboron, ferrophosphorus, etc.
Ferro Alloys Types
There are many kinds of ferroalloys, and there are many classification methods. Generally, they are classified according to the following methods:
(1) According to the classification of main elements in ferro alloys, there are mainly series of ferro alloys such as silicon, manganese, chromium, vanadium, titanium, tungsten, and molybdenum.
(2) According to the classification of carbon content in ferro alloys, there are high carbon, medium carbon, low carbon, micro carbon, ultra micro carbon and other varieties.
(3) Multi-element ferro alloys containing two or more alloying elements, the main varieties are silicon-aluminum alloy, silicon-calcium alloy, manganese-silicon-aluminum alloy, silicon-calcium-aluminum alloy, silicon-barium-calcium alloy, etc.
Ferro Alloys Production
Classified by production method: There are blast furnace ferroalloys, electric furnace ferroalloys, extra-furnace method (metal thermal method) ferroalloys, vacuum solid-state reduction ferroalloys, electrolytic ferroalloys, and special ferroalloys such as oxide briquettes and heating ferroalloys.
Ferrosilicon, ferromanganese, silicon manganese, ferrochrome, ferrotungsten, ferrovanadium, ferronickel, ferromolybdenum, ferrotitanium, rare earth magnesium silicon, rare earth ferrosilicon, silicon calcium alloy, silicon barium alloy, silicon aluminum alloy, tantalum niobium, Ferrophosphorus, Ferroboron, etc.