H-Section steel

1. An H-section steel comprising:

a flange; and

a web,

wherein the steel includes, as a chemical composition, 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%,

Al: 0.005% to 0.100%,

Ti: 0.005% to 0.030%,

N: 0.0010% to 0.0200%,

O: 0.0001% to 0.0100%,

Ca: 0.0003% to 0.0040%,

Cr: 0% to 0.50%,

Cu: 0% to 0.50%,

Mo: 0% to 0.20%,

Nb: 0% to 0.05%, and

a balance consisting of Fe and impurities,

a carbon equivalent Ceq obtained by the following expression (1) is 0.35% to 0.50%,

a number density of oxide particles having an equivalent circle diameter of 0.005 μm to 2.0 μm per unit area is 100 pieces/mm 2 to 5000 pieces/mm 2 ,

the oxide particle includes Ca, Al, and O as a composition,

an amount of Ca is 5% or more, an 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 particle,

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 which is a ⅙ position from a surface of the flange in a length direction and is a ¼ position from the surface of the flange in a thickness direction, and

an average prior austenite grain size in the metallographic structure of the flange is 200 μm or less at a toughness evaluation position which is a ½ position from the surface of the flange in the length direction and is a ¾ position from the surface of the flange in the thickness direction,

Ceq=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15  Expression (1),

here, C, Mn, Cr, Mo, V, Ni, and Cu in the expression represent an amount (mass %) of each element, and elements which are not added are indicated as 0.

2. The H-section steel according to claim 1 ,

wherein, the steel includes as a chemical composition, by mass %:

Cr: 0.01% to 0.50%;

Cu: 0.01% to 0.50%;

Mo: 0.001% to 0.20%; and

Nb: 0.001% to 0.05%.

3. The H-section steel according to claim 1 ,

wherein a yield strength or a 0.2% proof stress is 450 MPa or more, a tensile strength is 550 MPa or more, and a Charpy absorbed energy at 21° C. is 100 J or more at the strength evaluation position.

4. The H-section steel according to claim 1 , wherein the oxide particle contains Ti.

5. The H-section steel according to claim 1 , wherein the steel is produced by universal rolling.

6. The H-section steel according to claim 2 ,

wherein a yield strength or a 0.2% proof stress is 450 MPa or more, a tensile strength is 550 MPa or more, and a Charpy absorbed energy at 21° C. is 100 J or more at the strength evaluation position.

7. The H-section steel according to claim 2 , wherein the oxide particle contains Ti.

8. The H-section steel according to claim 3 , wherein the oxide particle contains Ti.

9. The H-section steel according to claim 6 , wherein the oxide particle contains Ti.

10. The H-section steel according to claim 2 , wherein the steel is produced by universal rolling.

11. The H-section steel according to claim 3 , wherein the steel is produced by universal rolling.

12. The H-section steel according to claim 4 , wherein the steel is produced by universal rolling.

13. The H-section steel according to claim 6 , wherein the steel is produced by universal rolling.

14. The H-section steel according to claim 7 , wherein the steel is produced by universal rolling.

15. The H-section steel according to claim 8 , wherein the steel is produced by universal rolling.

16. The H-section steel according to claim 9 , wherein the steel is produced by universal rolling.