Steel sheet, plated steel sheet, method for producing hot-rolled steel sheet, method for producing cold-rolled full hard steel sheet, method for producing steel sheet, and method for producing plated steel sheet

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

• C:
• 0.04% or more and 0.15% or less;
• Si:
• 0.3% or less;
• Mn:
• 1.0% or more and 2.6% or less;
• P:
• 0.1% or less;
• S:
• 0.01% or less;
• Al:
• 0.01% or more and 0.1% or less;
• N:
• 0.015% or less;
• at least one of Ti and Nb:
• 0.01% or more and 0.07% or less in total;
• and
• a balance being Fe and unavoidable impurities,
• wherein the steel sheet has a steel microstructure of 50% or more of ferrite and in a range of 10% or more and 50% or less of martensite in terms of an area ratio,
• a standard deviation of nano-hardness of the steel microstructure is 1.50 GPa or less,
• the steel sheet has a tensile strength of 590 MPa or more,
• the steel sheet has FL/TS of 0.51 or more and EL×TS of 15000 MPa·% or more, where FL is a fatigue limit, EL is an elongation, and TS is the tensile strength.