| 摘要 |
<p>An H-steel used for a building structure such as a column material in a high-rise and super high-rise building structure. Specifically, a 590MPa class very thick H-steel excellent in flange-thickness-direction toughness as rolled, wherein more diffusive αq is finely dispersed into αB in a very low carbon steel bainite structure with Mn and Cu compositions adjusted to within proper ranges to greatly improve a flange-depth-direction toughness with a 590MPa class tensile strength ensured, the H-steel characterized by containing 0.001 to 0.025 wt.% of C, not more than 0.6 wt.% of Si, 0.4 to 1.6 wt.% Mn, not more than 0.025 wt.% of P, not more than 0.010 wt.% of S, not more than 0.1 wt.% of Al, 0.6 to 2.0 wt.% of Cu, 0.25 to 2.0 wt.% of Ni, 0.001 to 0.050 wt.% of Ti and 0.0002 to 0.0030 wt.% of B and by satisfying the relations, Mn/Cu≤2.0 and 250≤117Mn(wt.%)163Cu(wt.%)≤350.</p> |
