Patent ID: 8557060

Claim:
A steel material with excellent hydrogen embrittlement resistance, the steel material having a chemical composition consisting of, by weight, C: 0. 10-1.00%, Si: 0.05-2.0%, Mn: 0.2-2.0%, W: 0.05-3.5%, and V: 0.1-1.5%, satisfying the inequality 0.3<W/V<7.0, and a balance Fe and unavoidable impurities; wherein the steel material comprises at least 0.1 vol % of precipitates of carbide, oxide, nitride or a composite compound thereof in a sheet form with a length of no greater than 50 nm and a length to thickness ratio of 3 to 20, and a face-centered cubic structure, wherein the precipitates of carbide, oxide, nitride or composite compound comprises at least 30 atomic percent V and at least 8 atomic percent W; and wherein, after being dipped in 1000 cc of a 20% wt % aqueous NH 4 SCN solution at 50° C., and subsequently held for 100 hours in air at 25° C., a hydrogen analysis raising the temperature at a rate of 100° C./hr yields a hydrogen evolution peak in a temperature range of 180° C. to 600° C. and an evolved hydrogen concentration of 0.5 ppm or higher by weight with an activation energy of 25 to 50 kJ/mol.