Steel material and method for producing same

A steel, having a chemical composition consisting of:

• in mass %,
• C:
• 0.15% to 0.35%;
• Si:
• 0.8% to 2.5%;
• Mn:
• 0.8% to 2.5%;
• Al:
• 0.03% to 2.0%;
• N:
• 0.002% to 0.010%;
• P:
• 0.01% or less;
• S:
• 0.01% or less;
• O:
• 0.01% or less;
• B:
• 0.0001% to 0.005%;
• Nb:
• 0.0% to 0.05%;
• Ti:
• 0.0% to 0.2%;
• V:
• 0.0% to 0.05%;
• Mo:
• 0.0% to 1.0%;
• Cr:
• 0.0% to 1.0%;
• Ni:
• 0.01% to 1.0%;
• Cu:
• 0.05% to 1.0%;
• at least one of Ca, Mg and REM (rare earth metals):
• 0.0005% to 0.01%;
• and the balance being Fe and impurities,
• wherein the steel has a martensite phase or/and a bainite phase in which ε-carbide having a size of 2 nm or more to 150 nm or less is dispersedly precipitated at a density of 1×106 or more per 1 mm2, and wherein the ε-carbide has a hexagonal crystal structure containing hydrogen trapping carbon vacancy sites inside a crystal grain thereof, the hydrogen trapping carbon vacancy sites being stable from 0° C. to about 300° C., and wherein the steel is substantially free of cementite.