| 摘要 |
PURPOSE:To obtain the title H-shape steels having a uniform quality and a high flange/web thickness ratio by differentiating the roll finishing temps. of the web and flange of the billet having a specified composition, rolling the billet at a specified total draft of the web, and cooling the flange forcibly and naturally. CONSTITUTION:The thin-walled H-shape steels wherein the thickness of the web is controlled to <=20mm and the thickness ratio of flange/web is adjusted to >=1.5 are produced by the following method. Namely, the billet contg., by weight, 0.01-0.13% C, 0.05-0.90% Si, 0.05-0.50% Mn, <=0.030% P, <=0.03% S, and 0.005-0.500% Sol Al is prepared. The billet is rolled under conditions where the roll finishing temp. of the web is made lower than the 730 deg.C transformation point, the roll finishing temp. of the flange is made >=130 deg.C higher than the transformation temp., and the total draft of the web at <=800 deg.C is controlled to >=30%. The flange is then forcibly cooled at the rate of 5-35 deg.C/sec, cooling is stopped at 400-650 deg.C, the flange is then naturally cooled, and the thin-walled H-shape steels having desired toughness and strength are obtained. |
