Steel sheet and plated steel sheet

A steel sheet comprising

• a chemical composition consisting of, in mass percent:
• C:
• 0.01 to 0.20%;
• Si:
• 0.005 to 0.10%;
• Mn:
• 0.60 to 4.00%;
• Al:
• 0.55 to 3.00%;
• P:
• 0.10% or less;
• S:
• 0.03% or less;
• N:
• 0.01% or less;
• O:
• 0.01% or less;
• Ti:
• 0 to 2.00%;
• Nb:
• 0 to 2.00%;
• V:
• 0 to 0.30%;
• Cu:
• 0 to 2.00%;
• Ni:
• 0 to 2.00%;
• Mo:
• 0 to 1.00%;
• Cr:
• 0 to 2.00%;
• B:
• 0 to 0.01%;
• Ca:
• 0 to 0.010%;
• Mg:
• 0 to 0.010%;
• Zr:
• 0 to 0.050%;
• REM:
• 0 to 0.1%;
• Sb:
• 0 to 0.10%;
• Sn:
• 0 to 0.10%;
• and
• As:
• 0 to 0.5%,
• with the balance:
• Fe and impurities, and comprising
• a microstructure that includes,
• when a zone surrounded by a grain boundary that is measured to be 5.0° or more by an EBSD analysis is assumed to be a grain, and when
• a K value is a value obtained by multiplying an average value of Image Qualities in a grain by 10−3,
• a Y value is an average crystal misorientation (°) in the grain,
• a metallic phase 1 is a metallic phase the K value of which is less than 4.000,
• a metallic phase 2 is a metallic phase the K value of which is 4.000 or more and the Y value of which is 0.5 to 1.0,
• a metallic phase 3 is a metallic phase the K value of which is 4.000 or more and the Y value of which is less than 0.5, and
• a metallic phase 4 is a metallic phase that falls under none of metallic phases 1 to 3, and the metallic phase 4 comprises at least one of upper bainite, lower bainite, in area percent:
• the metallic phase 1:
• 1.0% or more and less than 35.0%;
• the metallic phase 2:
• 30.0% or more and 80.0% or less;
• the metallic phase 3:
• 5.0% or more and 50.0% or less;
• and
• the metallic phase 4:
• 5.0% or less.