| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of producing a rolled H-type shape that has excellent toughness in a fillet part. SOLUTION: Steel having a composition containing 0.02 to 0.50% Mo, 0.001 to 0.070% Nb, and 0.005 to 0.10% V, and satisfying a carbon equivalent (Ceq.) of <=0.44%, and 2Nb+V<=0.20% is heated at 1,100 to 1,350 deg.C, and hot rolling is performed so that the cumulative draft in a fillet part is controlled in >=20% at <=1,100 deg.C, and is finished at 800 to 1,000 deg.C. The inside and outside faces of the flange are then subjected to controlled cooling at a flow rate of water per unit area of >=500 [l/min.m<2> ], and at the flow rate of water ratio (flow rate of water at the inside face/flow rate of water at the outside face) of 0.3 to 1.2, and a cooling stopping temperature is controlled in the range of an Ms point to Ar3 -200 deg.C, and, after that, the steel is left cooled. |
