Importance

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Abstract

The present invention intends a hot-rolled steel sheet with a sheet thickness in a range of 2 to 15 mm, having component composition including C: 0.3% or less by mass %, Si: 0.5% or less, Mn: in a range of 0.2 to 1%, P: 0.05% or less, S: 0.05% or less, Al: in a range of 0.01 to 0.1%, N: in a range of 0.008 to 0.025%, and the remainder being iron and unavoidable impurities. The hot-rolled steel sheet includes an amount of solute N: not less than 0.007%, and ferrite grains existing at a position of t/4 in depth (t: the sheet thickness) includes the ferrite grains, a sheet plane orientation thereof, within 10° from the (123) plane, having an area ratio: not less than 20%, the ferrite grains, a sheet plane orientation thereof, within 10° from the (111) plane, having an area ratio: not less than 5%, and the ferrite grains, a sheet plane orientation thereof, within 10° from the (001) plane, having an area ratio: 20% or less, the average grain size of the ferrite grains existing at the position of t/4 in depth being in a range of 3 to 35 μm.

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First Claim