| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a fine-grained hot rolled steel sheet having excellent workability as hot-rolled, and suitable as the stock for a high strength member used for automobiles, various industrial machineries and building. SOLUTION: In the method for producing a hot rolled steel sheet where finish rolling is performed using a tandem rolling mill line after rough rolling, rolling is performed at an Ar<SB>3</SB>point or above by a rolling mill before one step from the final one in the tandem rolling mill line, thereafter, cooling is performed to a temperature range of an Ar<SB>3</SB>point-20°C or below at the average cooling rate of≥50°C/s, further, rolling is performed at a draft of≤20% by the final rolling mill in the tandem rolling stock line, and within 0.4 s after that, cooling is performed to 720°C. COPYRIGHT: (C)2009,JPO&INPIT
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