Rolled H-section steel, method for producing the same, and flange-welded joint of rolled H-section steel

摘要

PROBLEM TO BE SOLVED: To provide a rolling H-shaped steel good in weldability and toughness and achieving high strength and low yield ratio, a manufacturing method therefor and a flange weld joint of the rolling H-shaped steel.SOLUTION: Thee is provided a rolling H-shaped steel containing, by mass%, C:0.10 to 0.25%, Si:0.05 to 0.50%, Mn:0.70 to 1.80%, V:0.06 to 0.20%, N:0.001 to 0.004% and Ti:0.003 to 0.015%, Nb, Al and O limited to predetermined value or less, satisfying Ti/N:3.0 to 15.0, having Ceq of 0.420 or less, metallic structure consisting of ferrite and pearlite, ferrite particle diameter of 15.0 to 50.0 μm and ferrite/pearlite hardness ratio of 0.60 or less. There is provided a manufacturing method including heating a steel piece to 1100 to 1350°C, hot rolling at a finishing temperature of 800°C or more and then air cooling. There is provided a flange weld joint of the rolling H-shaped steel having weld bead of a final layer formed from a groove shoulder side to a groove back side.SELECTED DRAWING: Figure 1