EP2990498A1 - H-förmiger stahl und verfahren zur herstellung davon - Google Patents

H-förmiger stahl und verfahren zur herstellung davon Download PDF

Info

Publication number
EP2990498A1
EP2990498A1 EP14787733.6A EP14787733A EP2990498A1 EP 2990498 A1 EP2990498 A1 EP 2990498A1 EP 14787733 A EP14787733 A EP 14787733A EP 2990498 A1 EP2990498 A1 EP 2990498A1
Authority
EP
European Patent Office
Prior art keywords
rolling
section steel
content
flange
toughness
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP14787733.6A
Other languages
English (en)
French (fr)
Inventor
Kazutoshi Ichikawa
Hidetoshi Ito
Noriaki Onodera
Kazuaki MITSUYASU
Kohichi Yamamoto
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Steel Corp
Original Assignee
Nippon Steel and Sumitomo Metal Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nippon Steel and Sumitomo Metal Corp filed Critical Nippon Steel and Sumitomo Metal Corp
Publication of EP2990498A1 publication Critical patent/EP2990498A1/de
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C3/00—Structural elongated elements designed for load-supporting
    • E04C3/02—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces
    • E04C3/04—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of metal
    • E04C3/06—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of metal with substantially solid, i.e. unapertured, web
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/02—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling heavy work, e.g. ingots, slabs, blooms, or billets, in which the cross-sectional form is unimportant ; Rolling combined with forging or pressing
    • B21B1/026—Rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/001—Heat treatment of ferrous alloys containing Ni
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
    • C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
    • C21D8/1222—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/002—Bainite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/009—Pearlite
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C3/00—Structural elongated elements designed for load-supporting
    • E04C3/02—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces
    • E04C3/04—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of metal
    • E04C2003/0404—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of metal beams, girders, or joists characterised by cross-sectional aspects
    • E04C2003/0408—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of metal beams, girders, or joists characterised by cross-sectional aspects characterised by assembly or the cross-section
    • E04C2003/0421—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of metal beams, girders, or joists characterised by cross-sectional aspects characterised by assembly or the cross-section comprising one single unitary part
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C3/00—Structural elongated elements designed for load-supporting
    • E04C3/02—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces
    • E04C3/04—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of metal
    • E04C2003/0404—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of metal beams, girders, or joists characterised by cross-sectional aspects
    • E04C2003/0443—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of metal beams, girders, or joists characterised by cross-sectional aspects characterised by substantial shape of the cross-section
    • E04C2003/0452—H- or I-shaped

Definitions

  • the present invention relates to an H-section steel which is used in a structural member of a building used in a low temperature environment and a method of producing the same, and more particularly to an H-section steel for low temperature use having high strength and excellent toughness in a heat affected zone and a method of producing the same.
  • FPSO Floating Production, Storage and Offloading System
  • H-section steel has been used in a general building structure.
  • H-section steel having excellent toughness or fire resistance is suggested.
  • Charpy absorbed energy at about 0°C is required.
  • Charpy absorbed energy at -40°C is required.
  • a CTOD value at -10°C needs to be specified as well as Charpy impact test properties (absorbed energy).
  • a crack tip opening displacement (CTOD) test is one of the tests used to evaluate the fracture toughness of a structure having a defect.
  • CTOD crack tip opening displacement
  • An object of the present invention is to provide H-section steel which has high strength and excellent low temperature toughness and also has excellent weldability and heat affected zone toughness (HAZ toughness) so as to be useable in a structure in cold regions, and a method of producing H-section steel, in which the H-section is produced without the need for a large-scale of cooling facilities.
  • the H-section steel of the present invention is not a built-up H-section steel which is formed by welding a steel plate, but is a non-heat-treated rolled H-section steel which is formed by hot rolling, particularly, universal rolling and does not require a thermal refining treatment such as quenching or tempering.
  • the inventors intensively studied how to solve the above-described problems. As a result, it was found that the reduction in toughness due to a mechanism of fracture from a structure which is formed of a carbide such as pearlite or cementite as the origin was significant. Therefore, the inventors focused on fractures due to carbide as the origin, in order to enhance low temperature toughness, and examined a method of suppressing the generation of carbide which is the origin of brittle fracture.
  • the inventors found that by controlling the amounts of Nb and B to be in appropriate ranges, strength can be ensured even when the C content is reduced, and thus the generation of carbide which is the origin of fractures was suppressed, thereby enhancing the toughness of the base metal and the toughness of the heat affected zone.
  • the inventors found that in order to obtain a fine structure having good toughness, performing rolling while strictly suppressing the surface temperature of a flange is extremely effective. Specifically, it was found that during finish rolling, the rolling needs to be performed in one or more passes while the surface temperature of the flange is in a temperature range of 870°C or lower and 770°C or higher.
  • the present invention was completed on the basis of the above-described findings.
  • the generation of carbide which is the origin of brittle fracture was extremely suppressed and thus the low temperature toughness of the base metal and the heat affected zone was improved.
  • the summary of the present invention is as follows.
  • the H-section steel for low temperature use having high strength and excellent low temperature toughness can be produced by rolling without performing accelerated cooling.
  • a significant cost reduction due to a reduction in construction cost and a reduction of a construction period can be achieved.
  • a reduction in the toughness of the heat affected zone is small and excellent low temperature toughness is provided. Therefore, the reliability of a large building used in cold regions can be enhanced without damage to the economic efficiency. Therefore, the present invention makes a significant contribution to industry.
  • H-section steel according to an embodiment of the present invention (hereinafter, also referred to as an H-section steel according to this embodiment) will be described in detail.
  • the C is an effective element for strengthening steel, and the lower limit of the C content is 0.010%.
  • the C content is more than 0.014%, HAZ toughness is degraded, and thus HAZ toughness at a low temperature cannot be sufficiently ensured.
  • the thickness of a flange is great (for example, 26 mm or greater)
  • a pearlite structure is formed, and the pearlite structure is transformed into a martensite-island (martensite-austenite-constituent) structure after welding.
  • the martensite-island structure becomes an embrittlement phase, resulting in the deterioration of HAZ toughness. Therefore, the upper limit of the C content is 0.014%.
  • the C content is preferably less than 0.014%.
  • Si is a deoxidizing element, and contributes to strength enhancement. In order to obtain such an effect, the lower limit of the Si content is 0.05%. On the other hand, Si is an element which accelerates the generation of cementite. Therefore, the upper limit of the Si content is 0.50%. In order to suppress the generation of the martensite-island and further enhance the toughness of the base metal and the heat affected zone, the upper limit of the Si content is preferably 0.40%.
  • Mn is an element which increases the hardenability of steel, and is an effective element in accelerating the generation of bainite for ensuring the strength of the base metal.
  • the lower limit of the Mn content is 0.8%.
  • the lower limit of the Mn content is preferably 1.0%, and is more preferably 1.3%.
  • the upper limit of the Mn content is 2.0%.
  • Cu is an element which enhances the hardenability of steel and contributes to strengthening (increasing the strength) of the base metal through precipitation hardening.
  • the Cu content is 0.01% or more, a Cu phase precipitates on the dislocation of ferrite when a temperature range in which ferrite is generated is held during rolling and mild cooling is performed, resulting in an increase in the strength.
  • the lower limit of the Cu content is 0.01%.
  • a preferable lower limit of the Cu content is 0.30%.
  • the Cu content is 0.60% or more, the strength of the base metal is excessively increased, and thus low temperature toughness is reduced. Therefore, the Cu content is less than 0.60%.
  • the upper limit of the Cu content is preferably 0.50%.
  • Ni is a very effective element in increasing the strength and the toughness of the base metal.
  • the lower limit of the Ni content is 0.01 %.
  • a preferable lower limit of the Ni content is 0.20%.
  • increasing the Ni content to 0.50% or more causes an increase in alloy cost. Therefore, the Ni content is less than 0.50%.
  • the upper limit of the Ni content is preferably 0.40%.
  • Ti is an important element to the enhancement of the toughness of the base metal. Ti forms fine Ti-containing oxides or TiN, and thus contributes to the refinement of the grain size. In order to obtain this effect, the lower limit of the Ti content is 0.001%. Furthermore, in a case where the hardenability is increased by fixing N with Ti and thus ensuring solid solution B, the lower limit of the Ti content is preferably 0.010%. On the other hand, when the Ti content is more than 0.025%, coarse TiN is generated, and thus the toughness of the base metal is reduced. Therefore, the upper limit of the Ti content is 0.025%. In addition, in order to suppress the precipitation of TiC and further suppress a reduction in toughness through precipitation hardening, the upper limit of the Ti content is preferably 0.020%.
  • Nb is an element which increases the hardenability of steel.
  • the lower limit of the Nb content is 0.010%.
  • the lower limit of the Nb content is preferably 0.020%.
  • the upper limit of the Nb content is 0.070%.
  • the upper limit of the Nb content is preferably 0.060%, and is more preferably 0.040%.
  • N is bonded to fine Ti, forms TiN, and thus has an effect of refining grains.
  • the lower limit of the N content is 0.001%.
  • the upper limit of the N content is 0.009%.
  • the upper limit of the N content is preferably 0.005%.
  • the upper limit of the O content is 0.0035%.
  • the upper limit of the O content is preferably 0.0015%.
  • the O content is preferably as low as possible.
  • the lower limit of the O content may be 0.0005%.
  • the lower limit of the O content may be 0.0008%.
  • the Al is a deoxidizing element. In order to obtain this effect, the Al content is more than 0.005%. On the other hand, in order to prevent the generation of coarse oxides, the upper limit of the Al content is 0.040%. In addition, a reduction in the Al content is also effective in suppressing the generation of the martensite-island. Therefore, the upper limit of the Al content is preferably 0.020%, and is more preferably 0.010%.
  • B is an element which increases the hardenability of steel with a small amount of B and thus accelerates the formation of fine bainite structures that are effective in toughness enhancement.
  • the B content is more than 0.0003%.
  • the upper limit of the B content is 0.0015%.
  • the preferable upper limit of the B content is 0.0010%.
  • Nb+125 ⁇ B is preferably as high as possible, and the upper limit thereof is not specified.
  • the upper limit of Nb+125 ⁇ B is practically 0.2575%.
  • the amounts of P and S which are contained as impurities are not particularly limited.
  • P and S cause weld cracking and a reduction in toughness due to solidifying segregation, and thus need to be reduced as much as possible.
  • the P content is preferably limited to 0.02% or less, and is more preferably limited to 0.002% or less.
  • the S content is preferably limited to 0.002% or less.
  • the H-section steel according to this embodiment basically contains the above-described chemical composition and may further contain one or two or more types of V, Mo, Cr, Zr, Hf, REM, and Ca for the purpose of enhancing strength and toughness or controlling the forms of inclusions.
  • such elements do not need to be necessarily contained, and the lower limits of the amounts thereof are 0%.
  • V contributes to the refinement of structures and precipitation strengthening due to carbonitride.
  • the lower limit of the V content is desirably 0.01%.
  • the upper limit of the V content is preferably 0.10%.
  • Mo is an element which is dissolved in steel, increases the hardenability of the steel, and thus contributes to strength enhancement.
  • the lower limit of the Mo content is preferably 0.01%.
  • Mo carbide (Mo 2 C) precipitates, and thus an effect of enhancing the hardenability due to the dissolved Mo reaches the upper limit.
  • the heat affected zone is hardened, and thus the HAZ toughness is deteriorated. Therefore, the upper limit of the Mo content is 0.10%.
  • a more preferable upper limit of the Mo content is 0.05%.
  • the Cr is an element which increases the hardenability of steel and thus contributes to strength enhancement.
  • the lower limit of the Cr content is desirably 0.01%.
  • the Cr content is preferably less than 0.20%.
  • a preferable upper limit of the Cr content is 0.10%.
  • Both Zr and Hf are deoxidizing elements, are elements which generate nitride at a high temperature, and are effective elements in reducing the amount of N dissolved in steel.
  • the lower limit of the amount of any of the elements is desirably 0.001%.
  • the upper limit of the Zr content is 0.030% and the upper limit of the Hf content is 0.010%.
  • Both REM and Ca are deoxidizing elements, and elements which contribute to the control of the forms of sulfide. Therefore, in a case of obtaining this effect, the lower limit of the content is preferably 0.0001%.
  • oxides of REM and Ca easily float in molten steel, and thus practically, the upper limits of the REM content and the Ca content which are contained in steel are respectively 0.010% and 0.0050%.
  • REM is the abbreviation for Rare Earth Metal, and indicates 17 types of elements including Sc and Y in addition to lanthanides.
  • the metallographic structure of the H-section steel according to this embodiment is a structure mainly including fine grains of ferrite and bainite excellent in strength and toughness and has a limited fraction of pearlite.
  • the metallographic structure of the H-section steel according to this embodiment is a structure in which the distribution density of pearlite is 3.2 ⁇ 10 -3 units/ ⁇ m 2 or lower and the remainder practically contains ferrite and bainite.
  • the distribution density of pearlite is as low as possible.
  • the lower limit of the distribution density of pearlite may be 1.0 ⁇ 10 -5 units/ ⁇ m 2 .
  • the distribution density of pearlite is obtained by observing pearlite colonies (islands of pearlite in the JIS specification) in the above site with an optical microscope on the basis of JIS G 0551. Specifically, the number of pearlite colonies that are present in an optical micrograph often visual fields (the size of one visual field is preferably 120 ⁇ m ⁇ 160 ⁇ m) taken under 500 power magnification is counted, and the distribution density thereof is obtained.
  • the properties of the flange are important, and the observation of the metallographic structure and the measurement of the pearlite distribution density are performed on the thickness center portion and 1/4 flange width portion of the flange which is considered as a good representative of the entire structure in the cross-section perpendicular to the rolling direction of the H-section steel. That is, a sample is collected from the (1/4)F position of the cross-section of the H-section steel shown in FIG. 1 (the center portion of a thickness t 2 of the flange of the cross-section perpendicular to the rolling direction: (1/2)t 2 and 1/4 of the entire length B of the flange width: (1/4)B). Ferrite, bainite, and pearlite are distinguished from each other using an optical microscope, the number of pearlite colonies is measured, and then the distribution density thereof is obtained.
  • the thickness of the flange of the H-section steel according to this embodiment is 12 mm to 40 mm. This is because H-section steel having a thickness of 12 mm to 40 mm is widely used as the H-section steel used in a structure used in cold regions (a low temperature structure). In addition, when the thickness of the flange is greater than 40 mm, the cooling rate is reduced and thus the distribution density of pearlite may be increased.
  • the thickness of a web is preferably 12 mm to 40 mm similar to that of the flange.
  • the ratio (flange/web) of the flange thickness to the web thickness is preferably 0.5 to 2.0.
  • the flange/web ratio is higher than 2.0, the web may be deformed into a wavy shape.
  • the flange/web ratio is lower than 0.5, the flange may be deformed into a wavy shape.
  • the yield point or the 0.2% proof stress at room temperature is 345 MPa or higher and the tensile strength is 460 MPa to 550 MPa.
  • the Charpy impact absorbed energy of the base metal portion at -40°C is preferably 60 J or higher.
  • the CTOD value at -10°C is 0.25 mm or higher.
  • the Charpy impact absorbed energy and the CTOD value of the heat affected zone are equal to or higher than those of the base metal portion.
  • H-section steel It is difficult for the H-section steel to ensure strength and toughness compared to a case of producing a steel plate. The reason is that when an ultra thick H-section steel is produced from a material having a slab shape or a beam blank shape, it is difficult to ensure the work amount of a flange and a fillet portion (a portion where the flange and the web are joined together).
  • the chemical composition of molten steel is adjusted to be in the above-described ranges by an arbitrary method, and the molten steel is cast to obtain a steel slab.
  • the casing continuous casting is preferable from the viewpoint of productivity.
  • the thickness of the steel slab is preferably 200 mm or greater from the viewpoint of productivity.
  • the thickness of the steel slab is preferably 350 mm or smaller.
  • the steel slab is heated (heating process: S1), and hot rolling is performed on the heated steel slab (hot rolling process).
  • the heating temperature of the steel slab is preferably 1100°C to 1350°C.
  • the lower limit of the heating temperature is preferably 1100°C.
  • the lower limit of the heating temperature is more preferably 1150°C.
  • the heating is performed at 1200°C or higher.
  • the upper limit of the heating temperature is preferably 1350°C. In order to suppress coarsening of the structure, the upper limit of the heating temperature is more preferably 1300°C.
  • Hot rolling is performed subsequent to the heating process (hot rolling process: S2).
  • the rolling is performed by sequentially rolling the steel slab through a universal rolling apparatus line including a roughing mill, an intermediate rolling mill, and a finishing mill.
  • the roughing mill the steel slab extracted from the heating furnace is rolled into a predetermined size (rough rolling process: S21).
  • intermediate rolling is performed by the intermediate rolling mill (intermediate rolling process: S22).
  • controlled rolling in which rolling temperature and rolling reduction are controlled is performed.
  • the flange outer surface is water-cooled by cooling apparatuses which are disposed in the front and the rear of the reverse rolling, and the temperature of the flange outer surface is recuperated and the flange is rolled.
  • the water cooling when the temperature of the flange outer surface is reduced too much, the recuperating is delayed until the rolling is performed, and thus spray cooling is preferable.
  • finish rolling is performed (finish rolling process: S23).
  • finish rolling the rolling needs to be performed in one or more passes while the surface temperature of the flange is 770°C to 870°C.
  • the reason why the above-described rolling is performed is that work recrystallization is accelerated during the hot rolling (finish rolling) and thus austenite is refined such that toughness and strength are enhanced.
  • the surface temperature of the flange is lower than 770°C, shaping of the H-section steel is difficult, and thus the lower limit thereof is 770°C.
  • the surface temperature of the flange is higher than 870°C, strain is recovered, recrystallized grains grow and become coarsened, and thus the upper limit thereof is 870°C.
  • the upper limit of the number of passes of the rolling is not limited. However, when the rolling is performed in more than five passes at a surface temperature of 770°C to 870°C, the amount of strain per one pass is reduced and thus the effect of refining the grains may be reduced. Therefore, the number of passes is preferably five or less.
  • interpass water cooling rolling is preferably performed in one or more passes.
  • the interpass water cooling rolling is a method of cooling the surface temperature of the flange to 700°C or less and thereafter performing the rolling in the recuperating process.
  • a temperature difference occurs between the surface layer portion and the inner portion of the flange due to the water cooling between the rolling passes. Therefore, during the interpass water cooling rolling, even in a case where the rolling reduction is small, work strain can be introduced to the thickness inner portion.
  • the rolling temperature can be reduced by water cooling done within a short period of time, and thus productivity is enhanced.
  • air cooling process: S3 air cooling process: S3 Due to the air cooling, the structure of the H-section steel becomes a structure in which pearlite is partially generated and essentially consisting of ferrite and bainite.
  • the average temperature of the flange may be cooled to 400°C or less and thereafter be recuperated to a temperature range of 400°C to 500°C.
  • the average temperature is recuperated to 400°C to 500°C
  • martensite-island which is present in the microstructure in the rolled state can be decomposed.
  • the heating temperature is 400°C or higher and the holding time is 15 minutes or longer.
  • the upper limit of the heating temperature and the upper limit of the holding time are not particularly specified. However, from the viewpoint of manufacturing cost, it is preferable that the heating temperature is 500°C or lower and the holding time is 5 hours or shorter.
  • the recuperating of the temperature done after the cooling may be performed in a heat treatment furnace.
  • FIG. 2 shows a flowchart of an example of the production method.
  • a production process of performing primary rolling, and performing cooling to 500°C or lower, thereafter performing heating to 1100°C to 1350°C, and performing secondary rolling, that is a so-called two heat rolling may also be employed.
  • the amount of plastic deformation is small during the hot rolling, a reduction in temperature during the rolling process is also reduced, and thus the heating temperature can also be reduced.
  • the process of producing the H-section steel is shown in FIG. 2 and a production apparatus used in the heating process and the hot rolling process is shown in FIG. 3 .
  • the hot rolling was performed by the universal rolling apparatus line.
  • controlled cooling in which reverse rolling was performed while spray cooling was performed on the flange outer surface by using water cooling apparatuses 3a provided in the front and rear of an intermediate universal rolling mill 2b was performed.
  • air cooling was performed.
  • Table 2 PRODUCTION No. STEEL No.
  • a test piece was collected from the center portion ((1/2)t 2 ) of the thickness t 2 of a flange 5 of an H-section steel 4 at the 1/4 ((1/4)B position ((1/4)F of FIG. 1 ) of the entire length (B) of the flange width, and the mechanical properties thereof were measured.
  • the reason why the evaluation was performed on this point is that it was determined that the flange (1/4)F portion of FIG. 1 showed the average mechanical properties of the H-section steel.
  • a tensile test was performed on the basis of JIS Z 2241, and a Charpy impact test was performed on the basis of JIS Z 2242 at -40°C.
  • As a CTOD test piece the entire thickness of the flange portion was cut out and a smooth test piece was produced.
  • a notch position was set to be on the extension line of the original web surface.
  • the obtained flange portion of the base metal was cut out and a single bevel groove was provided to be used as a sample for performing welding.
  • Gas metal arc welding was performed on the sample with a weld heat input of 12 kJ/cm.
  • a test piece was collected so that to allow a Charpy impact test piece or a CTOD test piece notch is formed at a position of 2 mm from a fusion line (the boundary line between the welded metal and the base metal) on the vertical portion side of the groove, and the toughness of the heat affected zone was evaluated.
  • Production No. 31 is an example in which the C content is excessive and the toughness of the heat affected zone is reduced.
  • Production No. 32 is also an example in which the C content is excessive, the fraction of pearlite is excessive, and the toughness of the heat affected zone is reduced.
  • Production No. 33 is an example in which the B content and the value of Nb+125 ⁇ B are excessively low, appropriate hardenability cannot be obtained, and thus the toughness of the base metal and the heat affected zone is reduced.
  • Production No. 34 is an example in which the Si content is excessive, the fraction of pearlite is excessive, and thus the toughness of the heat affected zone is reduced.
  • Production No. 35 is an example in which the Mn content is excessive, the fraction of pearlite is excessive, and thus the toughness of the heat affected zone is reduced.
  • Production No. 36 is an example in which the Mn content is excessively low, and the strength of the base metal was not sufficiently obtained.
  • Production No. 37 is an example in which the Cu content is excessive, the strength of the base metal is excessively high, and thus the toughness of the base metal and the heat affected zone is reduced.
  • Production No. 38 is an example in which Cu is not contained and the strength of the base metal was not sufficiently obtained.
  • Production No. 39 is an example in which Ni is not contained and the toughness of the base metal and the heat affected zone is reduced.
  • Production No. 40 is an example in which the Al content is excessive and the toughness of the base metal and the heat affected zone is reduced.
  • Production No. 41 is an example in which the B content is excessive, the strength of the base metal is excessively large, and the toughness of the base metal and the heat affected zone is reduced.
  • Production No. 42 is an example in which the Nb content is excessive, the strength of the base metal is excessively large, and the toughness of the base metal and the heat affected zone is reduced.
  • Production No. 43 is an example in which the N content is excessive and the toughness of the base metal and the heat affected zone is reduced.
  • Production No. 44 is an example in which the N content is excessively low and the toughness of the base metal and the heat affected zone is reduced.
  • Production No. 45 is an example in which Expression 1 is not satisfied and the toughness of the base metal and the heat affected zone is reduced.
  • the H-section steel for low temperature use having high strength and excellent low temperature toughness can be produced by rolling without performing accelerated cooling.
  • a significant cost reduction due to a reduction in construction cost and a reduction in a construction period can be achieved.
  • a reduction in the toughness of the heat affected zone is small. Therefore, the reliability of a large building used in cold regions can be enhanced without damage to economic efficiency. Therefore, the present invention makes a significant contribution to the industry.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Architecture (AREA)
  • Electromagnetism (AREA)
  • Manufacturing & Machinery (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Heat Treatment Of Steel (AREA)
  • Metal Rolling (AREA)
EP14787733.6A 2013-04-26 2014-04-15 H-förmiger stahl und verfahren zur herstellung davon Withdrawn EP2990498A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2013094589 2013-04-26
PCT/JP2014/060745 WO2014175122A1 (ja) 2013-04-26 2014-04-15 Ｈ形鋼及びその製造方法

Publications (1)

Publication Number Publication Date
EP2990498A1 true EP2990498A1 (de) 2016-03-02

Family

ID=51791701

Family Applications (1)

Application Number Title Priority Date Filing Date
EP14787733.6A Withdrawn EP2990498A1 (de) 2013-04-26 2014-04-15 H-förmiger stahl und verfahren zur herstellung davon

Country Status (4)

Country Link
US (1) US20150361664A1 (de)
EP (1) EP2990498A1 (de)
JP (1) JPWO2014175122A1 (de)
WO (1) WO2014175122A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107790493A (zh) * 2017-10-23 2018-03-13 陕西海恩得工贸有限公司 一种钛棒的轧制方法

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015046091A1 (ja) * 2013-09-27 2015-04-02 独立行政法人産業技術総合研究所 ステンレス鋼部材の接合方法およびステンレス鋼
CN105499268B (zh) * 2016-01-16 2017-12-15 舞阳钢铁有限责任公司 一种高合金特厚钢板的轧制方法
KR102021726B1 (ko) * 2016-12-21 2019-09-16 닛폰세이테츠 가부시키가이샤 H형강 및 그 제조 방법
KR101928207B1 (ko) * 2017-07-24 2018-12-11 현대제철 주식회사 형강 및 그 제조 방법
CN108893675B (zh) * 2018-06-19 2020-02-18 山东钢铁股份有限公司 一种屈服强度500MPa级厚规格热轧H型钢及其制备方法
CN115369328B (zh) * 2022-09-22 2024-01-23 马鞍山钢铁股份有限公司 一种耐低温热轧型钢及其生产方法

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3733727B2 (ja) 1997-12-26 2006-01-11 Ｊｆｅスチール株式会社 圧延のままでフランジ厚み方向の靱性に優れる引張り強さが５９０ＭＰａ級の建築構造用極厚Ｈ形鋼の製造方法
JP2001009503A (ja) * 1999-06-30 2001-01-16 Kawasaki Steel Corp 圧延ｈ形鋼の製造方法
JP3873540B2 (ja) * 1999-09-07 2007-01-24 Ｊｆｅスチール株式会社 高生産性・高強度圧延ｈ形鋼の製造方法
KR101018055B1 (ko) 2006-02-08 2011-03-02 신닛뽄세이테쯔 카부시키카이샤 내화용 고강도 압연 강재 및 그 제조 방법
JP4757858B2 (ja) * 2006-09-04 2011-08-24 新日本製鐵株式会社 高温強度、靭性及び耐再熱脆化特性に優れた耐火鋼材並びにその製造方法
KR101139605B1 (ko) 2007-04-06 2012-04-27 신닛뽄세이테쯔 카부시키카이샤 고온 특성과 인성이 우수한 강재 및 그 제조 방법
JP4855553B2 (ja) * 2009-11-27 2012-01-18 新日本製鐵株式会社 高強度極厚ｈ形鋼及びその製造方法
CN102676919B (zh) * 2012-04-17 2014-12-31 马钢(集团)控股有限公司 一种屈服强度550MPa低合金热轧H型钢轧后冷却方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2014175122A1 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107790493A (zh) * 2017-10-23 2018-03-13 陕西海恩得工贸有限公司 一种钛棒的轧制方法

Also Published As

Publication number Publication date
JPWO2014175122A1 (ja) 2017-02-23
WO2014175122A1 (ja) 2014-10-30
US20150361664A1 (en) 2015-12-17

Similar Documents

Publication Publication Date Title
EP2949772B1 (de) Heissgewalztes stahlblech und verfahren zur herstellung davon
EP3042976B1 (de) Stahlblech für dickwandiges hochfestes leitungsrohr mit aussergewöhnlicher korrosionsbeständigkeit, quetschfestigkeitseigenschaften und duktilität bei niedrigen temperaturen sowie leitungsrohr
EP2392682B1 (de) Dickes heizgewalztes stahlblech mit hoher bruchfestigkeit sowie hervorragender niedrigtemperaturbeständigkeit sowie herstellungsverfahren dafür
EP2832890B1 (de) Hochfeste stahlplatte mit niedriger streckgrenze und mit hervorragender stammalterungsbeständigkeit, herstellungsverfahren dafür und hochfestes geschweisstes stahlrohr damit
EP2832889B1 (de) Hochfeste stahlplatte mit niedriger streckgrenze und mit hervorragender stammalterungsbeständigkeit, herstellungsverfahren dafür und hochfestes geschweisstes stahlrohr damit
EP2309014B1 (de) Kaltgewalzte dicke stahlbleche mit hoher bruchfestigkeit sowie hervorragender niedrigtemperaturbeständigkeit sowie herstellungsverfahren dafür
KR101247089B1 (ko) 라인 파이프용 강판 및 강관
EP1870484B1 (de) Hochfeste stahlplatte und herstellungsverfahren dafür und hochfestes stahlrohr
EP2990498A1 (de) H-förmiger stahl und verfahren zur herstellung davon
EP3276026B1 (de) Dickes stahlblech für baurohr, verfahren zur herstellung eines dicken stahlblechs für baurohr und baurohr
EP3276024B1 (de) Dicke stahlplatte für strukturrohr, verfahren zur herstellung der dicken stahlplatte für strukturrohr sowie strukturrohr
WO2020003499A1 (ja) 鋼管及び鋼板
JP4848966B2 (ja) 厚肉高張力鋼板およびその製造方法
WO2013089156A1 (ja) 低温靭性に優れた高強度ｈ形鋼及びその製造方法
EP3276025B1 (de) Stahlplatte für ein strukturrohr, verfahren zur herstellung einer stahlplatte für ein strukturrohr und strukturrohr
JP2007177318A (ja) 高張力鋼板の製造方法および高張力鋼板
JP2015190026A (ja) ラインパイプ用厚肉高強度電縫鋼管およびその製造方法
EP4095280A1 (de) Elektrogeschweisstes stahlrohr und verfahren zu seiner herstellung
JP2017071827A (ja) Ｈ形鋼及びその製造方法
EP3276027B1 (de) Stahlplatte für ein strukturrohr, verfahren zur herstellung einer stahlplatte für ein strukturrohr sowie strukturrohr
CA3159223A1 (en) Electric resistance welded steel pipe, method for producing the same, line pipe, and building structure
EP3425080B1 (de) H-förmiger stahl für niedrige temperaturen und verfahren zur herstellung davon
JP6421907B1 (ja) 圧延ｈ形鋼及びその製造方法
EP4029962A1 (de) Warmgewalztes stahlblech für elektrogeschweisste stahlrohre und verfahren zu deren herstellung, elektrogeschweisste stahlrohre und verfahren zu deren herstellung, leitungsrohre und baustruktur
CN111183238A (zh) 耐酸管线管用高强度钢板及其制造方法以及使用了耐酸管线管用高强度钢板的高强度钢管

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20150820

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

AX Request for extension of the european patent

Extension state: BA ME

DAX Request for extension of the european patent (deleted)
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION HAS BEEN WITHDRAWN

18W Application withdrawn

Effective date: 20160803