| 摘要 |
PROBLEM TO BE SOLVED: To provide a hot rolled steel sheet having excellent ductility and fatigue characteristics by controlling the composition, crystal grain size, hot rolling conditions or the like within specified ranges, and to provide its production method. SOLUTION: This hot rolled steel sheet excellent in fatigue characteristics and ductility has a composition containing, by mass, 0.0009 to 0.0045% C, 0.05 to 0.7% Mn, 0.04 to 0.09% P, 0.002 to 0.01% S, <=0.006% N and Ti: (4C+3.4N)×1.2 to 0.75%, and the balance Fe with inevitable impurities, and in which the average crystal grain size of ferrite in a position of the thickness of 1/4 to the inside of the sheet thickness from the steel sheet surface is <=10μm.
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