Steel sheet for hot stamping use

A steel sheet for hot stamping use,

• a chemical composition of the steel sheet comprising, by mass %,
• C:
• 0.35% to 0.75%,
• Si:
• 0.005% to 0.25%,
• Mn:
• 0.5% to 3.0%,
• sol. Al:
• 0.0002% to 3.0%,
• Cr:
• 0.05% to 1.00%,
• B:
• 0.0005% to 0.010%,
• Nb:
• 0.01% to 0.15%,
• Mo:
• 0.005% to 1.00%,
• Ti:
• 0% to 0.15%,
• Ni:
• 0 to 3.00%,
• P:
• 0.10% or less,
• S:
• 0.10% or less,
• N:
• 0.010% or less, and
• a balance of Fe and unavoidable impurities,
• a microstructure of the steel sheet comprising at least one of lower bainite, martensite, and tempered martensite in an area ratio of 90% or more,
• a grain boundary solid solution ratio Z defined by Z=(mass % of one or both of Nb and Mo at grain boundaries)/(mass % of one or both of Nb and Mo) being 0.4 or more,
• an X-ray random intensity ratio of {112}<111> of the crystal grains forming the above lower bainite, martensite, or tempered martensite being 2.8 or more,
• number densities of total of grain size 50 nm or less cementite and epsilon carbides being 1×1016/m2 or more.