| 摘要 |
An H-section steel has a predetermined chemical composition in which Ti oxides having a grain size of 0.01 μm to 3.0 μm are included at a density of 30 pieces/mm2 or more, a thickness of a flange is 100 mm to 150 mm, an area fraction of bainite at a ⅙ position from a surface of the flange in a length direction and at a ¼ position from the surface thereof in a thickness direction is 80% or more, a yield strength or 0.2% proof stress is 450 MPa or more, and a tensile strength is 550 MPa or more, a Charpy absorbed energy at 21° C. at a ½ position from the surface of the flange in the length direction and at a ¾ position from the surface thereof in the thickness direction is 100 J or more, and an average austenite grain size is 50 μm to 200 μm. |
| 主权项 |
1. An H-section steel comprising, by mass %:
C: 0.05% to 0.16%; Si: 0.01% to 0.50%; Mn: 0.80% to 2.00%; Ni: 0.05% to 0.50%; V: 0.01% to 0.20%; Ti: 0.005% to 0.030%; N: 0.0010% to 0.0100%; O: 0.0005% to 0.0100%; Cr: 0% to 0.50%; Cu: 0% to 0.30%; Mo: 0% to 0.30%; W: 0% to 0.50%; Al: limited to 0.005% or less; Nb: limited to 0.010% or less; B: limited to 0.0005% or less; and a remainder including of Fe and impurities, wherein a carbon equivalent Ceq obtained by the following Equation 1 is 0.35% to 0.50%, a density of Ti oxides having a grain size of 0.01 μm to 3.0 μm is 30 pieces/mm2 or more, a thickness of a flange is 100 mm to 150 mm, at a ⅙ position from a surface of the flange in a length direction and at a ¼ position from the surface thereof in a thickness direction, an area fraction of bainite is 80% or more, a yield strength or 0.2% proof stress is 450 MPa or more, and a tensile strength is 550 MPa or more, and at a ½ position from the surface of the flange in the length direction and at a ¾ position from the surface thereof in the thickness direction, a Charpy absorbed energy at 21° C. is 100 J or more, and an average austenite grain size is 50 μm to 200 μm,
Ceq═C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15 Equation 1 here, C, Mn, Cr, Mo, V, Ni, and Cu represent the amount % of each element and the amount of an element not contained is 0%. |
