Production mannered null mass of the high intensity H section above TS590MPa which is superior in earthquake-proof Characteristic and small

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°C, and is thereafter hot-rolled at ≤1,100°C, at a cumulative draft of ≥20%, and, at a rolling finishing temperature of 800 to 1,000°C. Immediately after that, the steel is subjected to accelerated cooling at a cooling rate of ≥2°C/s, and, at a cooling stopping temperature of 600 to 300°C.;COPYRIGHT: (C)2002,JPO