Steel sheet

A steel sheet having a chemical composition comprising, by mass %,

• C:
• 0.200 to 0.350%,
• Si:
• 0.01 to 2.00%,
• Mn:
• 1.40 to 4.00%,
• P:
• 0.1000% or less,
• S:
• 0.0200% or less,
• Al:
• 2.00% or less,
• N:
• 0.0200% or less,
• O:
• 0.0200% or less,
• Cr:
• 0 to 2.000%,
• Mo:
• 0 to 1.000%,
• Ti:
• 0 to 0.500%,
• Nb:
• 0 to 0.500%,
• B:
• 0 to 0.0100%,
• Cu:
• 0 to 1.000%,
• Ni:
• 0 to 1.000%,
• W:
• 0 to 0.100%,
• V:
• 0 to 1.000%,
• Ta:
• 0 to 0.100%,
• Co:
• 0 to 3.000%,
• Sn:
• 0 to 1.000%,
• Sb:
• 0 to 0.500%,
• As:
• 0 to 0.050%,
• Mg:
• 0 to 0.050%,
• Zr:
• 0 to 0.050%,
• Ca:
• 0 to 0.0500%,
• Y:
• 0 to 0.0500%,
• La:
• 0 to 0.0500%,
• Ce:
• 0 to 0.0500%,
• Bi:
• 0 to 0.0500%, and
• balance:
• Fe and impurities, and
• satisfying 1.00≤[Si]+[Al]≤2.20, where [Si] and [Al] are the contents of the elements (mass %), and
• a microstructure comprising, by area ratio,
• ferrite:
• 15 to 40%,
• tempered martensite:
• 40 to 65%,
• retained austenite:
• 10 to 20%,
• bainite:
• 10 to 30%,
• pearlite:
• 0 to 10%, and
• as-quenched martensite:
• 0 to 10%, wherein
• a value of an average value of an Mn concentration in the ferrite divided by an Mn concentration of a base material is 0.980 or less, and
• a value of an average value of an Mn concentration in the retained austenite divided by the Mn concentration of the base material is 1.150 to 2.000.