What Is Ferrotungsten? Composition, Grades and Applications
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Definition and Composition
Ferrotungsten is an alloy of tungsten and iron, produced by reducing tungsten-bearing materials in a furnace and supplied as lumps or granules for melting. It is the standard way to introduce tungsten into steel because the alloy dissolves more readily than the pure metal.
Commercial grades are specified mainly on tungsten content, with limits on carbon, sulphur, phosphorus and other residuals that would be harmful in the final steel.
Standard Grades: FeW75 and FeW80
FeW75 specifies a minimum of about 75% tungsten, and FeW80 specifies about 80% minimum. The higher grade carries less iron and fewer residuals per unit of tungsten, so it is used where the alloy addition must be efficient and clean.
Because the price is based on contained tungsten, the grade only makes sense when read together with the assay and the accepted sizing range.
Use in Tool and High-Speed Steels
Tungsten forms hard carbides that give tool steels their wear resistance and their ability to hold hardness at temperature. High-speed steels used for drills, taps and milling cutters rely on tungsten carbides for hot hardness, which is exactly what makes them cut at speed without softening.
Ferrotungsten lets the steelmaker reach the target tungsten range without adding excessive iron or residuals.
Use in Superalloys and Other Applications
Tungsten also strengthens nickel- and cobalt-based superalloys used in turbine and high-temperature service, and it appears in wear-resistant and heavy alloys. In each case the addition is made as ferrotungsten so the tungsten dissolves uniformly.
Buying and Storage Notes
Confirm the tungsten assay, the carbon level and the sizing before purchase, and keep the material dry and separated from other ferroalloys to avoid mix-ups. A certificate of analysis with each lot allows the melt shop to adjust the charge accurately and to verify recovery after casting.
Frequently Asked Questions
Q: What is ferrotungsten?
An iron-tungsten alloy used to add tungsten to steel and superalloys in a form that melts and dissolves reliably.
Q: What is the difference between FeW75 and FeW80?
FeW80 has a higher minimum tungsten content, roughly 80%, versus about 75% for FeW75.
Q: Why is tungsten used in high-speed steel?
It forms hard carbides that give the steel wear resistance and hot hardness for cutting tools.
Q: How is ferrotungsten priced?
Usually on a contained-tungsten basis, so the assay and the grade determine the value.
Q: What residuals matter?
Carbon, sulphur and phosphorus are the main ones, because they affect the final steel properties.
