Abstract: In a rolled H-shape steel, at a (?)F position from an outer edge surface in a flange width-direction a microstructure at a depth of 100 ?m from an outer surface in the flange thickness-direction and a microstructure at a depth of (½)tf from the outer surface in the flange thickness-direction contain 95% or more of ferrite and pearlite and 5% or less of a residual structure by area ratio, the difference in Vickers hardness therebetween is 50 Hv or less, the yield strength is 385 to 505 N/mm2, the tensile strength is 550 to 670 N/mm2, the yield ratio is 0.80 or less, an elongation is 16.0% or more, the V-notch Charpy absorbed energy at 0° C. is 70 J or more, the height is 700 to 1000 mm, the flange width is 200 to 400 mm, the flange thickness is 22 to 40 mm, and the web thickness is 16 mm or more.

Abstract: An H-section steel has a predetermined chemical composition, in which a Mg-containing oxide having an equivalent circle diameter of 0.005 ?m to 0.5 ?m is contained at a total number density of 100 pieces/mm2 to 5000 pieces/mm2, a thickness of a flange is 100 mm to 150 mm, at a strength evaluation portion which is at a ? position from a surface of the flange in a length direction and at a ¼ position from the surface in a thickness direction, a fraction of bainite in a steel structure is 80% or more, and the average prior austenite grain size is 70 ?m or more, and at a toughness evaluation portion which is at a ½ position from the surface of the flange in the length direction and at a ¾ position from the surface of the flange in the thickness direction, the average prior austenite grain size in a steel structure is 200 ?m or less.

Abstract: An H-section steel has a predetermined chemical composition in which Ti oxides having a grain size of 0.01 ?m to 3.0 ?m 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 ? 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 ?m to 200 ?m.

Abstract: This H-beam steel has a composition including C, Si, Mn, Cu, Ni, V, Al, Ti, B, N, and O, and further including at least one of Mo and Nb, in which Ceq obtained in Equation 1 described below falls in a range of 0.37 to 0.50, the thickness of a flange falls in a range of 100 to 150 mm, and the area fraction of bainite at a depth of one quarter of the thickness of the flange from the external surface of the flange is 60% or more. Ceq=C+Mn/6+(Mo+V)/5+(Ni+Cu)/15??Equation 1, where C, Mn, Mo, V, Ni, and Cu represent the amount of each element contained.

Abstract: An H-section steel has a predetermined chemical composition in which a thickness of a flange is 100 mm to 150 mm, at a strength evaluation position an area fraction of bainite in a steel structure is 80% or more, yield strength or 0.2% proof strength is 450 MPa or more, tensile strength is 550 MPa or more and 680 MPa or less, at a toughness evaluation position an average austenite grain size in the steel structure is 150 ?m or less, and (Mg, Mn)S having a particle size of 0.005 ?m to 0.5 ?m is included at a density of 1.0×105 pieces/mm2 to 1.0×107 pieces/mm2.

Abstract: An H-section steel has a predetermined chemical composition, in which a Mg-containing oxide having an equivalent circle diameter of 0.005 ?m to 0.5 ?m is contained at a total number density of 100 pieces/mm2 to 5000 pieces/mm2, a thickness of a flange is 100 mm to 150 mm, at a strength evaluation portion which is at a ? position from a surface of the flange in a length direction and at a ¼ position from the surface in a thickness direction, a fraction of bainite in a steel structure is 80% or more, and the average prior austenite grain size is 70 ?m or more, and at a toughness evaluation portion which is at a ½ position from the surface of the flange in the length direction and at a ¾ position from the surface of the flange in the thickness direction, the average prior austenite grain size in a steel structure is 200 ?m or less.

Abstract: An H-section steel has a predetermined chemical composition in which Ti oxides having a grain size of 0.01 ?m to 3.0 ?m 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 ? 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 ?m to 200 ?m.

Abstract: There is provided an H-section steel in which a number density of oxide particles having an equivalent circle diameter of 0.005 ?m to 2.0 ?m per unit area is 100 pieces/mm2 to 5000 pieces/mm2, the oxide particles includes Ca, Al, and O as a composition, the amount of Ca is 5% or more, the amount of Al is 5% or more, and a total amount of Ca and Al is 50% or more by mass ratio excluding O in the oxide particles, a thickness of the flange is 100 mm to 150 mm, a bainite fraction in a metallographic structure of the flange is 80% or more at a strength evaluation position, and an average prior austenite grain size in the metallographic structure of the flange is 200 ?m or less at a toughness evaluation position.

Abstract: An H-section steel has a predetermined chemical composition in which a thickness of a flange is 100 mm to 150 mm, at a strength evaluation position an area fraction of bainite in a steel structure is 80% or more, yield strength or 0.2% proof strength is 450 MPa or more, tensile strength is 550 MPa or more and 680 MPa or less, at a toughness evaluation position an average austenite grain size in the steel structure is 150 ?m or less, and (Mg, Mn)S having a particle size of 0.005 ?m to 0.5 ?m is included at a density of 1.0×105 pieces/mm2 to 1.0×107 pieces/mm2.

Abstract: An H-section steel has a predetermined chemical composition, an Nb content and a B content satisfy Nb+125×B?0.075%, a thickness of a flange is 12 mm to 40 mm, and in a thickness center portion and ¼ flange width portion of the flange, a metallographic structure of a cross-section perpendicular to a rolling direction contains pearlite having a distribution density of 3.2×10?3 units/?m2 or lower and the remainder is formed of ferrite and bainite.

Abstract: There is provided an H-section steel in which a number density of oxide particles having an equivalent circle diameter of 0.005 ?m to 2.0 ?m per unit area is 100 pieces/mm2 to 5000 pieces/mm2, the oxide particles includes Ca, Al, and O as a composition, the amount of Ca is 5% or more, the amount of Al is 5% or more, and a total amount of Ca and Al is 50% or more by mass ratio excluding O in the oxide particles, a thickness of the flange is 100 mm to 150 mm, a bainite fraction in a metallographic structure of the flange is 80% or more at a strength evaluation position, and an average prior austesiite grain size in the metallographic structure of the flange is 200 ?m or less at a toughness evaluation position.

Abstract: This H-beam steel has a composition including C, Si, Mn, Cu, Ni, V, Al, Ti, B, N, and O, and further including at least one of Mo and Nb, in which Ceq obtained in Equation 1 described below falls in a range of 0.37 to 0.50, the thickness of a flange falls in a range of 100 to 150 mm, and the area fraction of bainite at a depth of one quarter of the thickness of the flange from the external surface of the flange is 60% or more. Ceq=C+Mn/6+(Mo+V)/5+(Ni+Cu)/15 ??Equation 1, where C, Mn, Mo, V, Ni, and Cu represent the amount of each element contained.