Hot-rolled steel sheet and production method therefor

A hot-rolled steel sheet comprising, as a chemical composition, by mass %:

• C:
• 0.010% to 0.200%;
• Si:
• 1.00% or less;
• Mn:
• 3.0% or less;
• P:
• 0.040% or less;
• S:
• 0.004% or less;
• Al:
• 0.10% or less;
• N:
• 0.004% or less;
• Nb:
• 0% to 0.20%;
• Ti:
• 0% to 0.15%;
• Mo:
• 0% to 1.00%;
• Cu:
• 0% to 0.50%;
• Ni:
• 0% to 0.50%;
• and
• a remainder of Fe and impurities,
• wherein a metallographic structure includes 90 vol % or greater of martensite and 0 vol % to 10 vol % of a residual structure, the residual structure including one or both of bainite and ferrite,
• an average prior austenite grain size in an L-section parallel to a rolling direction and an average prior austenite grain size in a C-section parallel to a direction orthogonal to the rolling direction are 1.0 μm to 10.0 μm,
• an aspect ratio which is a ratio of the average prior austenite grain size in the L-section and the average prior austenite grain size in the C-section is 1.8 or less,
• an average grain size of the residual structure in the L-section and an average grain size of the residual structure in the C-section are 5.0 μm or less, and
• an aspect ratio which is a ratio of the average grain size of the residual structure in the L-section and the average grain size of the residual structure in the C-section is 2.0 or less.