Types of Ferro Alloys: What Each One Is and What It Is Used For

What Is a Ferro Alloy?

A ferro alloy is an iron-based master alloy that carries a high, specified content of one alloying element, typically somewhere between a third and nine-tenths of its weight. It is not a finished engineering material. Nobody machines a part from ferro vanadium; it exists only to be dissolved into a much larger heat of steel or iron.

There are three practical reasons for adding an element as a ferro alloy rather than as pure metal. First, it is cheaper: the ores of chromium, tungsten and niobium often contain iron anyway, and leaving it in avoids an expensive separation. Second, it dissolves more readily. Pure tungsten melts at about 3,420°C, far above the temperature of liquid steel, while an iron-tungsten alloy goes into solution far more easily. Third, the element arrives in a known, certified quantity, so the melt shop can calculate its addition to a fraction of a per cent.

The trade divides ferro alloys into two groups. Bulk ferro alloys such as ferro manganese, silico manganese, ferro silicon and high-carbon ferro chrome are used in large tonnages for deoxidation and basic alloying. Noble or special ferro alloys such as ferro tungsten, ferro vanadium, ferro niobium and ferro molybdenum carry costlier elements and are added in smaller amounts for specific properties.

What Are the Main Types of Ferro Alloys?

The main types of ferro alloys used for special and stainless steels are ferro chrome, ferro tungsten, ferro niobium, ferro vanadium and ferro molybdenum. The table below sets out the main element, the range the relevant ISO standard allows, and the steels each one usually goes into.

The rest of each alloy is mainly iron, with carbon, silicon, aluminium, phosphorus, sulfur and residual metals held to limits set by the grade. Tariff lines beyond six digits vary by country, so the HS subheadings above are a starting point for a conversation with a customs broker, not a final classification.

What Is the Difference Between HC, LC and Nitrided Ferro Chrome?

The three main kinds of ferro chrome differ in carbon and nitrogen, not in chromium. All of them typically carry 60–70% chromium, but a steelmaker chooses between them by how much carbon the steel can tolerate.

• High-carbon (HC) ferro chrome, often called charge chrome, carries several per cent carbon. The Indian ferrochromium standard, IS 1170, places high-carbon grades at 4–10% carbon. It is the bulk feed for stainless steel, where the excess carbon is removed later in the converter.
• Medium-carbon grades sit between about 0.5% and 4% carbon in the same standard and are less common in trade.
• Low-carbon (LC) ferro chrome is refined down to 0.5% carbon or less, with extra-low grades below 0.05%. It is used for low-carbon stainless grades, trim additions late in refining, and welding electrodes. See LC ferro chrome scrap.
• Nitrided ferro chrome is low-carbon ferro chrome that has absorbed nitrogen, a few per cent in smelted grades and more in sintered ones. It supplies chromium and nitrogen together for nitrogen-bearing austenitic and duplex stainless steels. See nitrided ferro chrome scrap.

LC, HC and nitrided material all look like grey, brittle, crystalline lumps. Handheld XRF reads chromium and iron but cannot see carbon or nitrogen, so the only reliable way to tell them apart is a laboratory analysis. Our guide to XRF, OES and laboratory analysis explains which method measures which element.

Which Ferro Alloys Are Used for Tool Steels and High-Strength Steels?

Ferro tungsten, ferro vanadium and ferro molybdenum are the usual additions for tool steels, while ferro niobium and ferro vanadium are the usual additions for high-strength low-alloy (HSLA) steels. The difference comes down to how each element behaves inside the steel.

Ferro Tungsten

Tungsten forms hard carbides and keeps steel hard at red heat, which is why it appears in high-speed and hot-work tool steels. Ferro tungsten is very dense and is normally supplied as crushed lumps. Our article on uses of ferro tungsten covers its grades and explains how it differs from pure tungsten and tungsten carbide.

Ferro Vanadium

Vanadium forms fine carbides and nitrides that strengthen steel and refine its grain. Small additions go into HSLA plate and reinforcing bar; larger ones into tool and high-speed steels. Grades are named by vanadium content, from FeV40 up to FeV80. The ferro vanadium grades and scrap guide explains how to tell them apart.

Ferro Niobium

Ferro niobium is an alloy of iron and niobium. It contains no nickel, and descriptions that call it an iron-nickel alloy, which still circulate on some trade websites, are simply wrong. The confusion may come from nickel-niobium, a separate master alloy made for superalloy melting. Standard ferro niobium is added in tiny amounts, often well below 0.1% of the steel, to refine grain size in pipeline and structural steels. A higher-purity vacuum grade serves nickel-base superalloys such as Inconel 718, which needs about 5% niobium.

Ferro Molybdenum

Ferro molybdenum carries 55–75% molybdenum under ISO 5452 and is used for molybdenum-bearing stainless steels, alloy steels and tool steels. In our own range, molybdenum appears as pure molybdenum scrap from furnace parts and machining rather than as ferro molybdenum.

How Are Ferro Alloys Made?

Ferro alloys are made by reducing an ore concentrate or oxide of the main element in the presence of iron, then crushing and screening the solid alloy to the sizes steel plants order. The reducing agent depends on the element.

Aluminothermic reduction, using aluminium as the reducing agent, is the common route for high-grade ferro vanadium and for ferro niobium. Silicothermic reduction in an electric arc furnace typically gives lower-grade ferro vanadium. Ferro tungsten is made by thermite or electric furnace methods, and its solid product can be segregated, so one lump does not always represent a whole melt. That is why sampling rules in the standards insist on taking increments across a lot.

Which Pure Metals Are Traded Alongside Ferro Alloys?

Several pure and minor metals move through the same buyers, warehouses and paperwork as ferro alloys, even though they are not iron-based. They are described by purity rather than by a ferro alloy grade.

• Pure molybdenum, usually 99.9% or higher, from vacuum furnace hot zones, glass melting electrodes and machining.
• Pure tungsten, commonly about 99.95%, from furnace parts, electrodes, wire and sheet.
• Cobalt metal, from cathode, briquette or powder grades, used in superalloys, carbide binders and magnets.
• Misch metal, a mixed rare-earth alloy of about half cerium and a quarter lanthanum, used in steel treatment, lighter flints and hydrogen storage alloys. See what misch metal is and how it is traded.
• Selenium metallicum, elemental selenium of 99.5% or 99.9% purity, used in glass, electrolytic manganese and pigments.
• Tungsten carbide, a cemented material of tungsten carbide grains and a cobalt binder. It is recycled through its own specialist routes, covered in the tungsten carbide scrap guide.

Keeping these apart from look-alikes matters. TZM is not pure molybdenum, tungsten heavy alloy is not pure tungsten, and cobalt-base hardfacing is not cobalt metal. Each goes to a different buyer.

Where Does Ferro Alloy Scrap Come from?

Most ferro alloy scrap is not used parts. It is alloy that has dropped out of the normal supply chain while keeping its chemistry. The usual sources are:

• fines and undersize produced when lumps are crushed and screened;
• melts or lots that miss a buyer's chemistry or size specification;
• surplus stock left when a steel plant stops making a grade that needed that alloy;
• opened bags and drums that were only partly used, sometimes with labels lost or wrong;
• spillage and floor sweepings around charging areas, which are usually mixed and contaminated.

Because the chemistry is unchanged, a clean off-grade lot is described in the same terms as fresh material: grade, measured analysis, size range and quantity. The economics of putting this material back to work are covered in why ferro alloy scrap is worth recycling.

How Do You Check a Ferro Alloy Lot Before You Buy or Sell It?

Check the main element first, then the elements that cannot be seen on a handheld analyser, then size and condition. Ferro alloys look alike, labels are often wrong after repacking, and small differences in carbon or nitrogen decide which melt shop can use a lot.

A producer certificate is useful, but for older or mixed lots buyers normally want a fresh analysis on a representative sample. The certificate tells you what the material was; the new analysis tells you what it is now. Our note on reading a mill test certificate applies to producer certificates as well.

How Do You Choose a Ferro Alloy Supplier in India?

Choose a ferro alloy supplier in India on evidence, not on claims: ask for the analysis of the actual lot, its size class, its packing and its origin before you discuss terms. A good supplier answers these without hesitation.

• Analysis of the lot itself. Not a typical sheet, but a certificate or recent analysis tied to the bags you will receive.
• Size class. Steel plants specify lump size for a reason: fines can be lost to the fume system, and oversize lumps dissolve slowly.
• Packing and labelling. Jumbo bags or drums, labelled by grade and lot, so mixed grades cannot slip through.
• Export documents. Invoice, packing list, certificate and the correct HS subheading. See documents for exporting alloy scrap.

Mipra Steel, from its head office in Khetwadi, Mumbai, buys and supplies ferro alloy and metal scrap described by grade, including LC and nitrided ferro chrome, ferro tungsten, ferro niobium and ferro vanadium, and handles import and export enquiries. Buyers in Japan, South Korea and the Gulf often ask for the same evidence listed above. To discuss a lot, see the ferro alloy and metal scrap overview or send us the grade, form, quantity and photos, and we'll review your enquiry.

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