| 摘要 |
PROBLEM TO BE SOLVED: To provide a hot rolled steel sheet which is superior in shape stability of a final product even when spheroidizing annealing after hot rolling is skipped, and from which a cold rolled steel sheet satisfying hardness requirement can be obtained, and to provide a method for manufacturing it.SOLUTION: A hot rolled steel sheet includes, by mass, 0.13-0.20% of C, 0.25% or less of Si, 0.3-1.0% of Mn, 0.030% or less of P, 0.02% or less of S, 0.08% or less of Al and 0.008% or less of N, and the remainder being Fe and inevitable impurities, and has a micro structure which contains, in area rate, 15% or less of bainite, and 30% or less of pearlite + cementite, and the remainder being ferrite as a main phase. The hot rolled steel sheet can be obtained by hot rolling under a finish rolling end temperature of Artransformation point or higher, and a coiling temperature of 580-680°C. |
