High-strength steel sheet and method for manufacturing same

A high-strength steel sheet, comprising,

• as a chemical composition, by mass %:
• C:
• 0.020 to 0.090%;
• Si:
• 0.01 to 2.00%;
• Mn:
• 1.00 to 3.00%;
• Ti:
• 0.010 to 0.200%;
• Al:
• 0.005 to 1.000%;
• P:
• 0.100% or less;
• S:
• 0.0100% or less;
• N:
• 0.0100% or less;
• Ni:
• 0 to 2.00%;
• Cu:
• 0 to 2.00%;
• Cr:
• 0 to 2.00%;
• Mo:
• 0 to 2.00%;
• Nb:
• 0 to 0.100%;
• V:
• 0 to 0.100%;
• W:
• 0 to 0.100%;
• B:
• 0 to 0.0100%;
• REM:
• 0 to 0.0300%;
• Ca:
• 0 to 0.0300%;
• Mg:
• 0 to 0.0300%;
• and
• a remainder of Fe and impurities,
• wherein 0.100≤Ti+Nb+V≤0.450 is satisfied,
• a microstructure contains, by volume percentage, 95% or more of tempered martensite and bainite in total, and a remainder consists of ferrite and pearlite,
• the microstructure contains 5.0×109 pieces/mm3 or more of, per unit volume, precipitate having an equivalent circle diameter of 5.0 nm or less and containing Ti,
• Hvs/Hvc which is a ratio of an average hardness Hvs at a position of a depth of 20 m from a surface to an average hardness Hvc at a position of 0.20 to 0.50 mm from the surface is 0.85 or more,
• a tensile strength is 980 MPa or more, and
• a product of the tensile strength and elongation is 12,000 MPa×% or more.