| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a high strength rolled wide flange shape which has low heat input weldability. SOLUTION: A steel having a composition containing, by mass, 0.05 to 0.12% C, 0.05 to 0.5% Si, 0.6 to 1.6% Mn, 0.2 to 0.5% Mo, 0.02 to 0.06% V and <=0.0003% B, and, if required containing, one or more kinds selected from 0.05 to 0.5% Cu, 0.05 to 0.5% Ni, 0.05 to 0.1% Cr and 0.005 to 0.05% Nb, and also satisfying Ceq<=0.45%, and the balance substantially Fe with inevitable impurities is heated at 1,100 to 1,350 deg.C, and is thereafter hot-rolled at <=1,100 deg.C, at a cumulative draft of >=20%, and, at a rolling finishing temperature of 800 to 1,000 deg.C. Immediately after that, the steel is subjected to accelerated cooling at a cooling rate of >=2 deg.C/s, and, at a cooling stopping temperature of 600 to 300 deg.C.
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