Cold-rolled steel sheet and method for manufacturing same, and hot-stamp formed body

A cold-rolled steel sheet having a chemical composition comprising, in terms of mass %:

• C:
• 0.1% to 0.3%;
• Si:
• 0.01% to 2.0%;
• Mn:
• 1.5% to 2.5%;
• P:
• 0.001% to 0.6 %;
• S:
• 0.001% to 0.01%;
• N:
• 0.0005% to 0.01%;
• Al:
• 0.01% to 0.05%;
• B:
• 0% to 0.002%;
• Mo:
• 0% to 0.5%;
• Cr:
• 0% to 0.5%;
• V:
• 0% to 0.1%;
• Ti:
• 0% to 0.1%;
• Nb:
• 0% to 0.05%;
• Ni:
• 0% to 1.0%;
• Cu:
• 0% to 1.0%;
• Ca:
• 0% to 0.005%;
• REM:
• 0% to 0.005%;
• and
• rest including Fe and impurities, wherein
• a structure before and after a hot-stamping includes
• a ferrite:
• 30 area % to 90 area %,
• a martensite:
• 0 area % or more and less than 20 area %,
• a pearlite:
• 0 area % to 10 area %,
• a retained austenite:
• 5 volume % to 20 volume %, and
• a rest structure:
• a bainite,
• a hardness of the retained austenite measured with a nano indenter before and after the hot-stamping satisfies Expression 1 and Expression 2,
• a tensile strength and a ductility satisfy a relation of TS×El≥20000 MPa·%,
• H2/H1<1.1:
• Expression 1,
• σHM<20:
• Expression 2,
• and
• the “H1” represents the hardness of the retained austenite existing within a thickness surface portion before and after the hot-stamping, the thickness surface portion being an area within 200 μm in the thickness direction of a surface of the cold-rolled steel sheet, the “H2” represents the hardness of the retained austenite existing within a thickness center portion before and after the hot-stamping, the thickness center portion being an area within ±100 μm along the thickness direction of a center plane of the cold-rolled steel sheet in the thickness direction, the “σHM” represents a variance of the hardness of the retained austenite within the thickness center portion before or after the hot-stamping, “TS” represents the tensile strength of the cold-rolled steel sheet in terms of MPa, and “El” represents the ductility of the cold-rolled steel sheet in terms of %.