| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacture of a steel plate capable of high speed cutting while maintaining excellent cutting quality at the time of laser cutting for a hot rolled steel plate for use in a steel structure. SOLUTION: This steel plate excellent in laser cutting property is produced by performing descaling before or during rolling at the time of hot rolling of a steel plate, regulating final reduction of area (R) at finish rolling and finish rolling temp. (FT) to 5-25% and 950-650 deg.C, respectively, and also regulating cooling rate(CR) directly after finish rolling and coiling temp.(CT) to (5 to 60) deg.C/s and 550-250 deg.C. It is further desirable to perform, within the above manufacturing conditions, hot rolling under the conditions satisfying inequality FT×(1-R/100)×(7.5FT-4.5CR-13.5Cr.CT+1800CT)<=4.40×10<8> .
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