(Chemical symbol: B). A soft brown, crystalline, trivalent non-metallic element used in hard alloys and abrasives. It is found in nature only in combination with other elements and is obtained by heating boron trioxide with magnesium powder. Atomic number, 5; atomic weight: 10.82; melting point: 2300°C (4172°F); specific gravity of crystals, 2.45.
The addition of boron to steel in the range of .0025% to .0030% gives steel a greater depth of hardenability. The addition of more than .003% adds very little additional hardenability, and if over .006% boron is added, the steel rapidly loses ductility and breaks up much like steel with high sulphur content. If .O 1 % boron is added, the steel will break up during rolling.