Ferroboron - Properties, Applications

Topics Covered

Chemical Composition
Physical Properties
Manufacturing Process


Ferroboron is a type of ferroalloy that is made up of boron and iron, with the boron varying between 17.5% to 20%. Its CAS number is 11108–67-1.

Ferroboron can improve the quenching degree and mechanical behavior of steel and in high-quality alloy steel, boron takes the place of chromium, molybdenum and nickel, and does not affect their mechanical behavior. Ferroboron is stable under normal storage and handling conditions.

A key benefit of adding ferroboron to an alloy is that it can drastically increase the magnetic susceptibility of the end alloy, thereby making it suitable for the production of Nd-Fe-B magnets. Another benefit is it can drastically increase the deep quench ability of the end alloy.

The following sections will discuss about the various properties of ferroboron in detail.

Chemical Composition

The following table shows the chemical composition of ferroboron.

Element Content (%)
Boron, B 17 min
Silicon, Si 2 max
Aluminum, Al 1 max
Carbon, C 0.5 max
Sulfur, S 0.05 max
Phosphorous, P 0.05 max
Iron, Fe Balance

Physical Properties

The following table discusses the physical properties of ferroboron.

Properties Metric Imperial
Density 3.3 g/cm3 0.119 lb/in3
Melting point >1500°C >2732°F

Manufacturing Process

Ferroboron can be manufactured using two methods. Carbothermic reduction of boric acid in the presence of carbon steel using an electric arc furnace and aluminothermic reduction of boric acid in the presence of iron (sometimes along with magnesium) to achieve lower carbon content.


The following are the common application areas of ferroboron:

  • To improve the hardenability of C-Mn and low alloy steels
  • Improvement of steel and nitrogen scavenging
  • As low loss materials for NdFeB magnets
  • In the production of low carbon cold working wire rod
  • In the production of automotive sheet steels
  • Incorporation into amorphous metal materials for transformer cores
  • In hot spray painting
  • Improvement of hardenability of low alloyed steels
  • In the boration surface treatment of steels
  • In the reduction of nitrogen
  • Manufacturing of metallic glass.

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