| abstract |
In order to realize a bolt steel used for a bolt that exhibits excellent hydrogen embrittlement resistance even at high strength, it has a characteristic point of containing C: 0.30 to 0.50%, Si: 1.0 to 2.5%, and Mn: 0.1 to 1.5%, P: 0.015% or less (excluding 0%), S: 0.015% or less (excluding 0%), Cr: 0.15 to 2.4%, Al: 0.010 to 0.10%, and N: 0.001 to 0.10%, And contains Cu: 0.1~0.50% and Ni: 0.1~1.0% to satisfy [Ni]/[Cu]≧0.5, and contains Ti: 0.05~0.2% and V: 0.2% or less (including 0%) to satisfy [Ti ]+[V]: 0.085~0.30%, the remainder is iron and unavoidable impurities. |