Steel material

A steel material consisting of, in mass %,

• C:
• 0.10 to 0.45%,
• Si:
• 1.00% or less,
• Mn:
• 0.01 to 1.00%,
• P:
• 0.050% or less,
• S:
• 0.0050% or less,
• Al:
• 0.001 to 0.100%,
• Cr:
• 0.1 to 2.0%,
• Mo:
• 0.20 to 2.00%,
• N:
• 0.010% or less,
• W:
• 0 to 0.50%,
• Co:
• 0 to 0.50%,
• Ni:
• 0 to 0.50%,
• rare earth metal:
• 0 to 0.020%,
• Cu:
• 0 to 0.50%, and
• B:
• 0 to 0.0100%,
• further containing one or more elements selected from a group consisting of:
• Ca:
• 0.0005 to 0.0200%, and
• Mg:
• 0.0005 to 0.0200%,
• further containing one or more elements selected from a group consisting of:
• Ti:
• 0.001 to 0.300%,
• Nb:
• 0.001 to 0.300%, and
• V:
• 0.01 to 0.50%,
• with the balance being Fe and impurities, and
• satisfying Formula (1) and Formula (2),
• wherein:
• a yield strength is 862 MPa or more;
• and
• in the steel material,
• a number density of MX-type precipitates which have an equivalent circular diameter of 100 nm or less and in which, when a total content of Mo, Nb, V, and Ti is defined as 100% by mass, a content of Mo is more than 50% by mass is 20/μm2 or more:
• Mn
• ×
• Sp
• ≤
• 12.
• (
• 1
• )
• 0.05
• ≤
• 7
• ×
• Ti
• +
• 2
• ×
• Nb
• +
• 3
• ×
• V
• ≤
• 0.8
• (
• 2
• )
• where, in Formula (1), a content of Mn in percent by mass is substituted for “Mn”, and a content of S in ppm is substituted for “Sp”;
• a content of a corresponding element in percent by mass is substituted for each symbol of an element in Formula (2);
• note that, when a corresponding element is not contained, “0” is substituted for the symbol of the relevant element.