H-section steel and method of producing the same

Patent metadata

Field	Value
Publication number	US-2016376675-A1
Application number	US-201415039753-A
Country	US
Kind code	A1
Filing date	Dec 5, 2014
Priority date	Dec 16, 2013
Publication date	Dec 29, 2016
Grant date	—

Abstract

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/mm 2 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.

First claim

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 C eq 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/mm 2 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,
C eq ═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%.

2 . The H-section steel according to claim 1 , comprising, by mass %,
one of or two or more of Cr: 0.01% to 0.50%, Cu: 0.01% to 0.30%, Mo: 0.001% to 0.30%, and W: 0.01% to 0.50%.

3 . A method of producing the H-section steel according to claim 1 , the method comprising:
a refining process of deoxidizing a molten steel to allow a concentration of oxygen in the molten steel to be 0.0005% to 0.0100%, then adding Ti, and adjusting components of the molten steel to include 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, and to have a carbon equivalent C eq obtained by the following Equation 2 of 0.35% to 0.50%; a casting process of casting the molten steel to obtain a steel piece; a heating process of heating the steel piece to 1100° C. to 1350° C.; a hot rolling process of performing hot rolling on the heated steel piece so that a surface temperature of the steel piece is 800° C. or higher, thereby obtaining an H-section steel; and a cooling process of water-cooling the H-section steel after the hot rolling process, wherein in the cooling process, water cooling conditions are controlled so that the cooled surface temperature bounce back to within a temperature range of 300° C. to 700° C. after heat-recuperation,
C eq ═C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15   Equation 2.

4 . The method of producing the H-section steel according to claim 3 ,
wherein the components of the molten steel include, by mass %, one of or two or more of Cr: 0.01% to 0.50%, Cu: 0.01% to 0.30%, Mo: 0.001% to 0.30%, and W: 0.01% to 0.50%.

5 . A method of producing the H-section steel according to claim 2 , the method comprising:
a refining process of deoxidizing a molten steel to allow a concentration of oxygen in the molten steel to be 0.0005% to 0,0100%, then adding Ti, and adjusting components of the molten steel to include 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, and to have a carbon equivalent C eq obtained by the following Equation 2 of 0.35% to 0.50%; a casting process of casting the molten steel to obtain a steel piece; a heating process of heating the steel piece to 1100° C. to 1350° C.; a hot rolling process of performing hot rolling on the heated steel piece so that a surface temperature of the steel piece is 800° C. or higher, thereby obtaining an H-section steel; and a cooling process of water-cooling the H-section steel after the hot rolling process, wherein in the cooling process, water cooling conditions are controlled so that the cooled surface temperature bounce back to within a temperature range of 300° C. to 700° C. after heat-recuperation,
C eq ═C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15   Equation 2.

6 . The method of producing the H-section steel according to claim 5 ,
wherein the components of the molten steel include, by mass %, one of or two or more of Cr: 0.01% to 0.50%, Cu: 0.01% to 0.30%, Mo: 0.001% to 0.30%, and W: 0.01% to 0.50%.

Assignees

• Nippon Steel & Sumitomo Metal Corp

Inventors

• Mizoguchi Masaki
• Ichikawa Kazutoshi
• MITSUYASU Kazuaki
• Sugiyama Hirokazu

Classifications

• C21D8/00

  Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment (hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation C21D1/02) · CPC title

• C22C38/02

  containing silicon · CPC title

• C21D1/60

  Aqueous agents · CPC title

• C22C38/42

  with copper · CPC title

• B22D11/009

  of work of special cross-section, e.g. I-beams, U-profiles · CPC title