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How much boron is usually present in boron-containing steel?

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A labeled diagram of the periodic table entry for boron shows its atomic number 5, symbol B, electron configuration, atomic weight range, and classification as a solid, weakly acidic, other nonmetal with a rhombohedral crystal structure at room temperature. — boron Properties of boron.

In boron-containing steel, the element is typically present in the range of 0.001 to 0.005 percent by weight. It is commonly added to the steel in the form of the iron alloy ferroboron to improve the material's hardenability.12