H-Section steel

摘要

There is provided an H-section steel in which 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/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 μm or less at a toughness evaluation position.

主权项

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%, anda 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/mm2 to 5000 pieces/mm2, 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.