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.