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- Nachgewiesen in: USPTO Patent Grants
- Sprachen: English
- Patent Number: 10900,099
- Publication Date: January 26, 2021
- Appl. No: 16/079265
- Application Filed: March 02, 2017
- Assignees: NIPPON STEEL CORPORATION (Tokyo, JP)
- Claim: 1. A steel H-shape comprising, by mass %, C: 0.05% to 0.13%, Mn: 0.80% to 2.00%, Nb: 0.011% to 0.060%, Ti: 0.005% to 0.025%, O: 0.0005% to 0.0100%. V: 0% to 0.08%, Cu: 0% to 0.40%, Ni: 0% to 0.70%, Mo: 0% to 0.10%, Cr: 0% to 0.20%, Si: limited to 0.50% or less, Al: limited to 0.008% or less, Ca: limited to 0.0010% or less, REM: limited to 0.0010% or less, Mg: limited to 0.0010% or less, N: limited to 0.0120% or less, and a remainder including Fe and impurities, wherein a CEV obtained b the following Expression (1) is 0.40 or less, wherein at a ¼ position from an outer side across a thickness of a flange and a ⅙ position from an outer side across a flange width, a sum of an area ratio of one or both of ferrite and bainite is 90% or more, and an area ratio of a hard phase consisting of one or both of MA and pseudo-pearlite is 10% or less, wherein an effective grain size is 20.0 μm or less, and a grain size of the hard phase is 10.0 μm or less, wherein Charpy absorbed energy at −40° C. is 60 J or greater, wherein 30 pieces/mm 2 or more Ti oxides having an equivalent circle diameter ranging from 0.01 to 3.0 μm are included, and wherein a thickness of the flange is 12 to 50 mm, CEV=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15 (1) where, C, Mn, Cr, Mo, V, Ni, and Cu each indicate an amount of the element by mass %.
- Claim: 2. The steel H-shape according t comprising, by mass %, one or two or more selected from the group consisting of V: 0.01% to 0.08%, Cu: 0.01% to 0.40%, Ni: 0.01% to 0.70%, Mo: 0.01% to 0.10%, and Cr: 0.01% to 0.20%.
- Claim: 3. A method of manufacturing the steel H-shape according to claim 1 , the method comprising: melting a steel including the same chemical composition as that of the steel H-shape according to claim 1 ; casting the steel obtained through the melting to obtain a slab; heating the slab to a temperature ranging from 1,100° C. to 1,350° C., and then performing hot rolling at a finishing temperature ranging from (Ar 3 -30)° C. to 900° C. to obtain a steel H-shape; and performing an accelerated cooling of the steel H-shape, in which inner and outer surfaces of a flange are subjected to water cooling at a cooling rate exceeding 15° C./sec, wherein in the melting, Ti is added after oxygen concentration of a molten steel immediately before addition of the Ti is adjusted to a range from 0.0015 to 0.0110 mass %, and wherein in the accelerated cooling, the water cooling is performed such that a cooling stop temperature at a ⅙ position from an outer side across a flange width of the steel H-shape is 300° C. or lower at a surface temperature, and a maximum temperature of the surface temperature after recuperating is 350° C. to 700° C.
- Claim: 4. A method of manufacturing the steel H-shape according to claim 2 , the method comprising: melting a steel including the same chemical composition as that of the steel H-shape according to claim 2 ; casting the steel obtained through the melting to obtain a slab; heating the slab to a temperature ranging from 1 , 100 ° C. to 1 , 350 ° C., and then performing hot rolling at a finishing temperature ranging from (Ar 3 -30)° C. to 900° C. to obtain a steel H-shape; and performing an accelerated cooling of the steel H-shape, in which inner and outer surfaces of a flange are subjected to water cooling at a cooling rate exceeding 15° C./sec, wherein in the melting, Ti is added after oxygen concentration of a molten steel immediately before addition of the Ti is adjusted to a range from 0.0015 to 0.0110 mass %, and wherein in the accelerated cooling, the water cooling is performed such that a cooling stop temperature at a ⅙ position from an outer side across a flange width of the steel H-shape is 300° C. or lower at a surface temperature, and a maximum temperature of the surface temperature after recuperating is 350° C. to 700° C.
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- Other References: Machine translation of JP04-279248A. (Year: 1992). cited by examiner ; Chinese Office Action and Search Report, dated Mar. 20, 2019, for counterpart Chinese Application No. 201780012914.1, with an English translation. cited by applicant ; International Search Report, issued in PCT/JP2017/008275, PCT/ISA/210, dated Jun. 6, 2017. cited by applicant ; Notice of Allowance for JP 2018-503395 dated Jul. 24, 2018. cited by applicant ; Written Opinion of the International Searching Authority, issued in PCT/JP2017/008275, PCT/ISA/237, dated Jun. 6, 2017. cited by applicant ; Chinese Office Action and Search Report dated Aug. 30, 2019, for counterpart Chinese Application No. 201780012914.1, with partial English translation. cited by applicant ; Extended European Search Report dated Sep. 26, 2019, for counterpart European Application No. 17760128.3. cited by applicant ; Korean Office Action dated Aug. 19, 2019, for counterpart Korean Application No. 10-2018-7023882, with English translation. cited by applicant
- Primary Examiner: Su, Xiaowei
- Attorney, Agent or Firm: Birch, Stewart, Kolasch & Birch, LLP
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