Nickel Containing Patents (Class 148/336)
  • Patent number: 10196726
    Abstract: Provided is a high-strength hot-rolled steel sheet consisting of, in mass %, C: 0.01% to 0.2%, Si: 0% to 2.5%, Mn: 0% to 4.0%, Al: 0% to 2.0%, N: 0% to 0.01%, Cu: 0% to 2.0%, Ni: 0% to 2.0%, Mo: 0% to 1.0%, V: 0% to 0.3%, Cr: 0% to 2.0%, Mg: 0% to 0.01%, Ca: 0% to 0.01%, REM: 0% to 0.1%, B: 0% to 0.01%, P: less than or equal to 0.10%, S: less than or equal to 0.03%, O: less than or equal to 0.01%, one or both of Ti and Nb: 0.01% to 0.30% in total, and the balance being Fe and inevitable impurities. The steel sheet has a structure in which a total volume fraction of tempered martensite or lower bainite is 90% or more, a dislocation density thereof is greater than or equal to 5×1013 (1/m2) and less than or equal to 1×1016 (1/m2) and 1×106 (numbers/mm2) or more iron-based carbides are included therein.
    Type: Grant
    Filed: February 25, 2014
    Date of Patent: February 5, 2019
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Masafumi Azuma, Hiroshi Shuto, Tatsuo Yokoi, Yuuki Kanzawa, Akihiro Uenishi
  • Patent number: 9644372
    Abstract: This H-beam steel contains, in mass %, C, Si, Mn, Al, Ti, N, O, Nb, and B. The H-beam steel has composition in which the amount of Nb and the amount of B satisfy, in mass %, 0.070?Nb+125B?0.155, and has a metal structure in which, in a microstructure, an area fraction of bainite is not less than 70%, a total of an area fraction of pearlite and an area fraction of cementite is not more than 15%, and the remainder is at least one of ferrite and island martensite. The effective crystalline-grain size of the bainite is not more than 40 ?m, and the thickness of a flange falls in a range of 12 to 40 mm.
    Type: Grant
    Filed: December 12, 2012
    Date of Patent: May 9, 2017
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Kazutoshi Ichikawa, Teruyuki Wakatsuki, Noriaki Onodera, Kohichi Yamamoto
  • Patent number: 9592575
    Abstract: The weld metal of the present invention is formed by gas shield arc welding using a flux-cored wire, has a predetermined chemical component composition, and contains 20% or more of Ti. The amount of Ti-containing oxide particles having a circle-equivalent diameter of 0.15-1.0 ?m is at least 5000 per square mm, the amount of V per total mass of weld metal present as a compound within the weld metal is 0.002% or more, and the average circle equivalent diameter of V-containing carbide present in the weld metal is 15 nm or less.
    Type: Grant
    Filed: April 6, 2012
    Date of Patent: March 14, 2017
    Assignee: Kobe Steel, Ltd.
    Inventors: Hidenori Nako, Takuya Kochi, Wataru Urushihara, Munenobu Sato, Yoshihiko Kitagawa
  • Patent number: 9188253
    Abstract: A steel pipe with dual phase structure includes, as chemical composition, by mass %, C: 0.07% to 0.15%, Si: 0.1% to 0.5%, Mn: 0.8% to 1.9%, Nb: 0.020% to 0.10%, P: limited to 0.05% or less, S: limited to 0.01% or less, Al: limited to 0.1% or less, and a balance consisting of iron and unavoidable impurities, wherein, when [X] is amount of element X in mass %, carbon equivalent Ceq defined by Equation of Ceq=[C]+[Mn]/6 is 0.25 to 0.40 and [Nb]×[C]?0.002 is satisfied, and includes, as metallographic structure, by area %, ferrite of 80% to 98% and martensite, residual austenite, or mixture thereof of 2% to 20% in total, wherein average grain size of ferrite is 1 ?m to less than 8 ?m and average grain size of martensite, residual austenite, or mixture thereof is 0.1 ?m to 2 ?m.
    Type: Grant
    Filed: July 13, 2011
    Date of Patent: November 17, 2015
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Mitsuru Sawamura, Hitoshi Asahi, Eiji Tsuru, Jun Agata
  • Publication number: 20150144231
    Abstract: In a steel sheet having a specific chemical composition and having a microstructure including ferrite that is a soft first phase by 20-50% in terms of the area ratio, the remainder being tempered martensite and/or tempered bainite that is a hard second phase, the microstructure of steel of a surface layer section of the steel sheet from the surface to the depth of 100 ?m and a center section of t/4-3t/4 (t is the sheet thickness) is controlled.
    Type: Application
    Filed: May 29, 2013
    Publication date: May 28, 2015
    Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)
    Inventors: Tomokazu Masuda, Katsura Kajihara, Toshio Murakami, Masaaki Miura, Muneaki Ikeda
  • Publication number: 20150101715
    Abstract: A steel wire for spring is provided which exhibits high strength even without adding a large amount of alloy elements, and is for obtaining a cold winding spring having excellent coiling performance and improved hydrogen embrittlement resistance. The steel wire for spring is characterized in that C: 0.40-0.65% (mass %), Si: 1.0-3.0%, Mn: 0.6-2.0%, P: 0.015% or less (exclusive of 0%), S: 0.015% or less (exclusive of 0%), and Al: 0.015 percent by mass or less (excluding 0%) of S, and Al: 0.001-0.10% are satisfied, with the remainder consisting of iron and inevitable impurities, tempered martensite: 70 area % or more and retained austenite: 6-15 area % with respect to the total microstructure, the prior austenite grain size number obtained by a method stipulated in JIS G 0551 is No. 10.0 or more, and the tensile strength is 1,900 MPa or more.
    Type: Application
    Filed: May 20, 2013
    Publication date: April 16, 2015
    Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)
    Inventors: Atsuhiko Takeda, Nao Yoshihara
  • Patent number: 8992697
    Abstract: A high strength press-formed member includes a steel sheet constituting the member including a composition including by mass %, C: 0.12% to 0.69%, Si: 3.0% or less, Mn: 0.5% to 3.0%, P: 0.1% or less, S: 0.07% or less, Al: 3.0% or less, N: 0.010% or less, Si+Al: at least 0.
    Type: Grant
    Filed: February 28, 2011
    Date of Patent: March 31, 2015
    Assignee: JFE Steel Corporation
    Inventors: Hiroshi Matsuda, Yoshimasa Funakawa, Yasushi Tanaka
  • Patent number: 8980022
    Abstract: This case hardening steel has a chemical composition including, by mass %: C: 0.1 to 0.6%; Si: 0.02 to 1.5%; Mn: 0.3 to 1.8%; P: 0.025% or less; S: 0.001 to 0.15%; Al: over 0.05 to 1.0%; Ti: 0.05 to 0.2%; N: 0.01% or less; and O: 0.0025% or less, and further including, by mass %, one or more of Cr: 0.4 to 2.0%, Mo: 0.02 to 1.5%, Ni: 0.1 to 3.5%, V: 0.02 to 0.5%, and B: 0.0002 to 0.005%, and the balance consisting of iron and unavoidable impurities.
    Type: Grant
    Filed: January 13, 2010
    Date of Patent: March 17, 2015
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Kei Miyanishi, Masayuki Hashimura, Shuuji Kozawa, Manabu Kubota, Tatsuro Ochi
  • Patent number: 8974610
    Abstract: A high-strength welded steel pipe is obtained by welding a seam weld portion of a steel plate that are formed in a pipe shape. In the high-strength welded steel pipe, a base metal of the steel plate includes, by mass %, C: 0.010% to 0.080%, Si: 0.01% to 0.50%, Mn: 0.50% to 2.00%, S: 0.0001% to 0.0050%, Ti: 0.003% to 0.030%, Mo: 0.05% to 1.00%, B: 0.0003% to 0.0100%, O: 0.0001% to 0.0080%, N: 0.006% to 0.0118%, P: limited to 0.050% or less, Al: limited to 0.008% or less, and the balance of Fe and inevitable impurities, Ceq is 0.30 to 0.53, Pcm is 0.10 to 0.20, [N]?[Ti]/3.4 is less than 0.003, the average grain size of the prior ? grains in heat affected zones in the steel plate is 250 ?m or less, and the prior ? grains include bainite and intragranular bainite.
    Type: Grant
    Filed: February 4, 2011
    Date of Patent: March 10, 2015
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Taishi Fujishiro, Takuya Hara, Yoshio Terada, Shinya Sakamoto, Hitoshi Asahi
  • Publication number: 20150059912
    Abstract: A steel plate has a chemical composition containing, by mass %, C: 0.03% or more and 0.08% or less, Si: 0.01% or more and 1.0% or less, Mn: 1.2% or more and 3.0% or less, P: 0.015% or less, S: 0.005% or less, Al: 0.08% or less, Nb: 0.005% or more and 0.07% or less, Ti: 0.005% or more and 0.025% or less, N: 0.010% or less, O: 0.005% or less and the balance being Fe and inevitable impurities, a metallographic structure including a bainite phase and island martensite, and a polygonal ferrite in surface portions within 5 mm from the upper and lower surfaces, wherein the area fraction of the island martensite is 3% to 15%, the equivalent circle diameter of the island martensite is 3.0 ?m or less, the area fraction of the polygonal ferrite in the surface portions is 10% to less than 80%.
    Type: Application
    Filed: March 29, 2013
    Publication date: March 5, 2015
    Inventors: Junji Shimamura, Kimihiro Nishimura
  • Publication number: 20150047749
    Abstract: A low alloy steel subjected to post weld heat treatment, containing, by mass percent, of C: 0.01 to 0.15%, Si: 3% or less, Mn: 3% or less, and Al: 0.08% or less, one or more kinds of elements selected from Ti, V and Nb: the range satisfying Formula (1), and the balance being Fe and impurities, wherein in the impurities, N: 0.01% or less, P: 0.05% or less, S: 0.03% or less, and O: 0.03% or less: 0.1×[C(%)]?[Ti(%)]+[V(%)]+0.5×[Nb(%)]?0.2??(1) where, the symbol of element in the formula represents the content (mass %) of each element. In the alloy steel, a HAZ subjected to PWHT, especially short-time PWHT, has excellent hydrogen embrittlement resistance in wet hydrogen sulfide environments or the like.
    Type: Application
    Filed: December 17, 2012
    Publication date: February 19, 2015
    Inventors: Hiroyuki Hirata, Tomohiko Omura, Kenji Kobayashi, Kaori Kawano, Kota Tomatsu, Kazuhiro Ogawa
  • Patent number: 8951366
    Abstract: A high-strength cold-rolled steel sheet includes, by mass %, C: 0.10% to 0.40%, Mn: 0.5% to 4.0%, Si: 0.005% to 2.5%, Al: 0.005% to 2.5%, Cr: 0% to 1.0%, and a balance of iron and inevitable impurities, in which an amount of P is limited to 0.05% or less, an amount of S is limited to 0.02% or less, an amount of N is limited to 0.006% or less, the microstructure includes 2% to 30% of retained austenite by area percentage, martensite is limited to 20% or less by area percentage in the microstructure, an average particle size of cementite is 0.01 ?m to 1 ?m, and 30% to 100% of the cementite has an aspect ratio of 1 to 3.
    Type: Grant
    Filed: January 26, 2011
    Date of Patent: February 10, 2015
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Kohichi Sano, Chisato Wakabayashi, Hiroyuki Kawata, Riki Okamoto, Naoki Yoshinaga, Kaoru Kawasaki, Natsuko Sugiura, Nobuhiro Fujita
  • Patent number: 8951367
    Abstract: A cold rolled steel sheet with excellent bendability contains C at 0.15 to 0.30%, Si at 0.01 to 1.8%, Mn at 1.5 to 3.0%, P at not more than 0.05%, S at not more than 0.005%, Al at 0.005 to 0.05% and N at not more than 0.005%, the balance being Fe and inevitable impurities, and has a steel sheet superficial soft portion satisfying: Hv(S)/Hv(C)?0.8??(1) wherein Hv(S) is hardness of the steel sheet superficial soft portion, and Hv(C) is hardness of a steel sheet core portion, 0.10?t(S)/t?0.30??(2) wherein t(S) is thickness of the steel sheet superficial soft portion, and t is the sheet thickness.
    Type: Grant
    Filed: February 16, 2011
    Date of Patent: February 10, 2015
    Assignee: JFE Steel Corporation
    Inventors: Kenji Kawamura, Kazuhiro Seto
  • Patent number: 8945719
    Abstract: This steel plate for cold forging includes a hot-rolled steel plate, wherein the hot-rolled steel plate includes: in terms of percent by mass, C: 0.13% to 0.20%; Si: 0.01% to 0.8%; Mn: 0.1% to 2.5%; P: 0.003% to 0.030%; S: 0.0001% to 0.008%; Al: 0.01% to 0.07%; N: 0.0001% to 0.02%; and O: 0.0001% to 0.0030%, with a remainder being Fe and inevitable impurities, an A value represented by the following formula (1) is in a range of 0.0080 or less, a thickness of the hot-rolled steel plate is in a range of 2 mm to 25 mm, and an area percentage of pearlite bands having lengths of 1 mm or more in a region of 4/10t to 6/10t when a plate thickness is indicated by t in a cross section of a plate thickness that is parallel to a rolling direction of the hot-rolled steel plate is in a range of not more than a K value represented by the following formula (2), A value=O%+S%+0.033Al%??(1) K value=25.5×C%+4.5×Mn%?6??(2).
    Type: Grant
    Filed: January 25, 2011
    Date of Patent: February 3, 2015
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Masayuki Abe, Kengo Takeda, Shuji Yamamoto, Yasushi Tsukano, Shinichi Yamaguchi
  • Publication number: 20150017471
    Abstract: There are provided a high-strength hot-rolled steel sheet securing low-temperature toughness and having excellent stretch flangeability by controlling a structural fraction and a hardness difference among structures, and a manufacturing method thereof. A hot-rolled steel sheet contains: C: 0.01 to 0.2%; Si: 0.001 to 2.5% or less; Mn: 0.10 to 4.0% or less; P: 0.10% or less; S: less than 0.03%; Al: 0.001 to 2.0%; N: less than 0.01%; Ti: (0.005+48/14[N]+48/32[S]) % or more and 0.3% or less; Nb: 0 to 0.06%; Cu: 0 to 1.2%; Ni: 0 to 0.6%; Mo: 0 to 1%; V: 0 to 0.2%; Cr: 0 to 2%; Mg: 0 to 0.01%; Ca: 0 to 0.01%; REM: 0 to 0.1%; and B: 0 to 0.002%, and has: an texture in which, at a central portion of a sheet thickness located between ? to ? thickness positions of the sheet thickness from a surface of the steel sheet, an average value of X-ray random intensity ratios of a group of {100}<011> to {223}<110> orientations of a sheet plane is 6.
    Type: Application
    Filed: December 27, 2012
    Publication date: January 15, 2015
    Inventors: Hiroshi Shuto, Tatsuo Yokoi, Yuuki Kanzawa, Nobuhiro Fujita, Ryohta Niiya, Shinya Saitoh
  • Patent number: 8932415
    Abstract: Provided is a welding metal in which a predetermined chemical component composition is satisfied, the A value as specified by formula (1) is 3.8% to 9.0%, and the surface area percentage of carbide having a circle-equivalent diameter of 0.20 ?m or greater in the welding metal is 4.0% or less. A value=0.8×[C]?0.05×[Si]+0.5×[Mn]+0.5×[Cu]+[Ni]?0.5×[Mo]+0.2×[Cr]??(1) (Provided that [C], [Si], [Mn], [Cu], [Ni], [Mo] and [Cr] are the C, Si, Mn, Cu, Ni, Mo and Cr content (by mass percent), respectively) The welding metal is useful as a material for a pressure vessel of a nuclear power plant as the welding metal is high in strength and has good low-temperature toughness and drop-weight characteristics.
    Type: Grant
    Filed: January 24, 2011
    Date of Patent: January 13, 2015
    Assignee: Kobe Steel, Ltd.
    Inventors: Hidenori Nako, Yoshitomi Okazaki, Ken Yamashita, Minoru Otsu, Hideaki Takauchi
  • Patent number: 8932414
    Abstract: Disclosed is a high-strength steel plate with excellent warm workability that has a component composition comprising, in mass %, 0.05 to 0.4% C, 0.5 to 3% Si+Al, 0.5 to 3% Mn, no more than 0.15% P (not including 0%), and no more than 0.02% S (including 0%), with the remainder comprising iron and impurities, and a composition that includes a total of 45 to 80% martensite and/or bainitic ferrite in terms of the area ratio relative to the entire composition, 5 to 40% polygonal ferrite in terms of the area ratio relative to the entire composition, and 5 to 20% retained austenite in terms of the area ratio relative to the entire composition, wherein the C concentration (C?R) within said residual austenite is in the range of 0.6 mass % to less than 1.0 mass %, and that furthermore may include bainite. In the high-strength steel plate, TRIP effects are achieved to the fullest extent in warm working, and increased ductility over prior steel plates is reliably achieved.
    Type: Grant
    Filed: March 22, 2011
    Date of Patent: January 13, 2015
    Assignee: Kobe Steel, Ltd.
    Inventors: Hideo Hata, Toshio Murakami, Yukihiro Utsumi
  • Publication number: 20150010775
    Abstract: A hot stamped steel according to the present invention satisfies an expression of (5×[Si]+[Mn])/[C]>11 when [C] represents an amount of C by mass %, [Si] represents an amount of Si by mass %, and [Mn] represents an amount of Mn by mass %, a metallographic structure after hot stamping includes 40% to 90% of a ferrite and 10% to 60% of a martensite in an area fraction, a total of an area fraction of the ferrite and an area fraction of the martensite is 60% or more, a hardness of the martensite measured with a nanoindenter satisfies an H2/H1<1.10 and ?HM<20, and TS×?, which is a product of a tensile strength TS and a hole expansion ratio ? is 50000 MPa·% or more.
    Type: Application
    Filed: January 11, 2013
    Publication date: January 8, 2015
    Inventors: Toshiki Nonaka, Satoshi Kato, Kaoru Kawasaki, Toshimasa Tomokiyo
  • Patent number: 8926766
    Abstract: Provided is a low yield ratio, high strength and high uniform elongation steel plate having excellent strain ageing resistance equivalent to API 5L X70 Grade or lower and a method for manufacturing the same. In particular, the steel plate contains 0.06% to 0.12% C, 0.01% to 1.0% Si, 1.2% to 3.0% Mn, 0.015% or less P, 0.005% or less S, 0.08% or less Al, 0.005% to 0.07% Nb, 0.005% to 0.025% Ti, 0.010% or less N, and 0.005% or less O on a mass basis, the remainder being Fe and unavoidable impurities. The low yield ratio, high strength and high uniform elongation steel plate has a metallographic microstructure that is a two-phase microstructure consisting of bainite and M-A constituent, the area fraction of the M-A constituent being 3% to 20%, the equivalent circle diameter of the M-A constituent being 3.0 ?m or less.
    Type: Grant
    Filed: September 28, 2010
    Date of Patent: January 6, 2015
    Assignee: JFE Steel Corporation
    Inventors: Junji Shimamura, Nobuyuki Ishikawa, Nobuo Shikanai
  • Publication number: 20150004433
    Abstract: A steel sheet includes, by mass %: C: 0.020% to 0.080%; Si: 0.01% to 0.10%; Mn: 0.80% to 1.80%; and Al: more than 0.10% and less than 0.40%; and further includes: Nb: 0.005% to 0.095%; and Ti: 0.005% to 0.095%, in which a total amount of Nb and Ti is 0.030% to 0.100%, and the steel sheet includes, as a metallographic structure, ferrite, bainite, and other phases, an area fraction of the ferrite is 80% to 95%, an area fraction of the bainite is 5% to 20%, a total fraction of the other phases is less than 3%, a tensile strength is 590 MPa or more, and a fatigue strength ratio as a fatigue strength to the tensile strength is 0.45 or more.
    Type: Application
    Filed: February 7, 2013
    Publication date: January 1, 2015
    Inventors: Hiroyuki Tanaka, Kunio Hayashi, Toshio Ogawa, Koichi Goto, Kazuaki Nakano
  • Patent number: 8920713
    Abstract: A steel for a welded structure includes the following composition: by mass %, C at a C content [C] of 0.010 to 0.065%; Si at a Si content [Si] of 0.05 to 0.20%; Mn at a Mn content [Mn] of 1.52 to 2.70%; Ni at a Ni content [Ni] of 0.10% to 1.50%; Ti at a Ti content [Ti] of 0.005 to 0.015%; O at an O content [O] of 0.0010 to 0.0045%; N at a N content [N] of 0.002 to 0.006%; Mg at a Mg content [Mg] of 0.0003 to 0.003%; Ca at a Ca content [Ca] of 0.0003 to 0.003%; and the balance composed of Fe and unavoidable impurities. A steel component parameter PCTOD is 0.065% or less, and a steel component hardness parameter CeqH is 0.235% or less.
    Type: Grant
    Filed: May 21, 2010
    Date of Patent: December 30, 2014
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Yoshiyuki Watanabe, Kazuhiro Fukunaga, Akihiko Kojima, Ryuji Uemori, Rikio Chijiiwa
  • Patent number: 8920582
    Abstract: A steel material which is suitable for hot press working or hot three-dimensional bending and direct quench and which can be used to manufacture a high-strength formed article with sufficient quench hardening even by short time heating at a low temperature has a chemical composition comprising, in mass percent, C: 0.05-0.35%, Si: at most 0.5%, Mn: 0.5-2.5%, P: at most 0.03%, S: at most 0.01%, sol. Al: at most 0.1%, N: at most 0.01%, and optionally at least one element selected from the group consisting of B: 0.0001-0.005%, Ti: 0.01-0.1%, Cr: 0.18-0.5%, Nb: 0.03-0.1%, Ni: 0.18-1.0%, and Mo: 0.03-0.5% and has a steel structure in which the spheroidization ratio of carbides is 0.60-0.90.
    Type: Grant
    Filed: August 22, 2012
    Date of Patent: December 30, 2014
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Kazuo Hikita, Nobusato Kojima
  • Publication number: 20140367002
    Abstract: A hot-press formed product can be achieved which has regions corresponding to a shock resistant portion and an energy absorption portion within a single formed product without applying a welding method and achieves the balance of high strength and elongation with a high level according to each region by means of having a first forming region exhibiting a metal structure containing martensite: 80-97 area % and retained austenite: 3-20 area % respectively, the remaining structure being 5 area % or less, and a second forming region exhibiting a metal structure containing annealed martensite or annealed bainite: 30-97 area %, martensite as quenched: 0-67 area %, and retained austenite: 3-20 area %.
    Type: Application
    Filed: March 15, 2013
    Publication date: December 18, 2014
    Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)
    Inventors: Junya Naitou, Toshio Murakami, Shushi Ikeda, Keisuke Okita
  • Publication number: 20140366994
    Abstract: A steel sheet and a method for producing the same are disclosed. The steel sheet has a composition containing 0.015% to 0.05% C, less than 0.10% Si, 0.1% to 2.0% Mn, 0.20% or less P, 0.1% or less S, 0.01% to 0.10% Al, 0.005% or less N, and 0.06% to 0.5% Ti in percent by mass, C and Ti satisfying the inequality Ti*/C?4, where Ti* (mass percent)=Ti-3.4N and Ti, C, and N represent the content (mass percent) of each element. The steel sheet has a microstructure which contains a ferrite phase as a base, in which the average grain diameter of the ferrite phase is 7 ?m or more, and in which the ratio of the rolling-direction average grain diameter to thickness-wise average grain diameter of the ferrite phase is 1.1 or more.
    Type: Application
    Filed: December 10, 2012
    Publication date: December 18, 2014
    Applicant: JFE STEEL CORPORATION
    Inventors: Taro Kizu, Koichiro Fujita
  • Publication number: 20140370329
    Abstract: When the amount of C, the amount of Si and the amount of Mn are respectively represented by [C], [Si] and [Mn] in unit mass %, the cold rolled steel sheet satisfies a relationship of (5×[Si]+[Mn])/[C]>10, the metallographic structure contains, by area ratio, 40% to 90% of a ferrite and 10% to 60% of a martensite, further contains one or more of 10% or less of a pearlite by area ratio, 5% or less of a retained austenite by volume ratio and 20% or less of a bainite by area ratio, the hardness of the martensite measured using a nanoindenter satisfies H20/H10<1.10 and ?HM0<20, and TS×? representing the product of TS that is a tensile strength and ? that is a hole expansion ratio is 50000 MPa·% or more.
    Type: Application
    Filed: January 11, 2013
    Publication date: December 18, 2014
    Inventors: Toshiki Nonaka, Satoshi Kato, Kaoru Kawasaki, Toshimasa Tomokiyo
  • Publication number: 20140363694
    Abstract: A low density high strength steel sheet including 0.15% to 0.25% C, 2.5% to 4% Mn, 0.02% or less P, 0.015% or less S, 6% to 9% Al and 0.01% or less N, the balance being iron and inevitable impurities, wherein 1.7·(Mn—Al)+52.7·C is at least 3 and at most 4.5. A method of producing the low density and high strength steel sheet.
    Type: Application
    Filed: February 21, 2012
    Publication date: December 11, 2014
    Applicant: TATA STEEL NEDERLAND TECHNOLOGY BV
    Inventors: Cheng Liu, Radhakanta Rana
  • Publication number: 20140342184
    Abstract: The present invention provides a high-strength steel sheet having a tensile strength of 980 MPa or more and also excellent bending property stably over the entire steel sheet, due to a predetermined chemical composition in combination with a specific microstructure wherein an average crystallized grain diameter of ferrite phase is 10 ?m or less, a volume fraction of ferrite phase is within the range from 30% to 70%, a volume fraction of the total of martensite and retained austenite phases is 10% or less, and a ratio of interphases each having an interphase nano-hardness difference within 4 GPa is 90% or more.
    Type: Application
    Filed: December 26, 2012
    Publication date: November 20, 2014
    Applicant: JFE STEEL CORPORATION
    Inventors: Shusaku Takagi, Shinjiro Kaneko
  • Publication number: 20140342185
    Abstract: A cold rolled steel sheet according to the present invention satisfies an expression of (5×[Si]+[Mn])/[C]>11 when [C] represents an amount of C by mass %, [Si] represents an amount of Si by mass %, and [Mn] represents an amount of Mn by mass %, a metallographic structure before hot stamping includes 40% to 90% of a ferrite and 10% to 60% of a martensite in an area fraction, a total of an area fraction of the ferrite and an area fraction of the martensite is 60% or more, a hardness of the martensite measured with a nanoindenter satisfies an H2/H1<1.10 and ?HM<20 before the hot stamping, and TS×? which is a product of a tensile strength TS and a hole expansion ratio ? is 50000 MPa·% or more.
    Type: Application
    Filed: January 11, 2013
    Publication date: November 20, 2014
    Inventors: Toshiki Nonaka, Satoshi Kato, Kaoru Kawasaki, Toshimasa Tomokiyo
  • Publication number: 20140338801
    Abstract: A high-strength hot-rolled steel sheet including a chemical composition containing, in percent by mass, 0.05% to 0.12% of C, 0.05% to 1.0% of Si, 0.5% to 1.8% of Mn, 0.04% or less of P, 0.0030% or less of S, 0.005% to 0.07% of Al, 0.006% or less of N, 0.05% to 0.15% of Ti, and the balance being Fe and incidental impurities, in which, in a region in the range of ? to ? of the sheet thickness, the content of Ti*, which is Ti existing as precipitates, is 0.3×[Ti] to 0.6×[Ti], where [Ti] is the Ti content, and the steel sheet has a microstructure in which the area fraction of the bainite phase in the entire structure is more than 95%.
    Type: Application
    Filed: December 26, 2012
    Publication date: November 20, 2014
    Applicant: JFE STEEL CORPORATION
    Inventors: Katsumi Nakajima, Hayato Saito, Yoshimasa Funakawa
  • Publication number: 20140332119
    Abstract: A high strength cold rolled steel sheet has a chemical composition including, by mass %, C: 0.06 to 0.13%, Si: 1.2 to 2.3%, Mn: 0.6 to 1.6%, P: not more than 0.10%, S: not more than 0.010%, Al: 0.01 to 0.10% and N: not more than 0.010%, the balance comprising Fe and inevitable impurities. The steel sheet includes a microstructure containing not less than 90% in terms of volume fraction of ferrite with an average grain diameter of less than 20 ?m and 1.0 to 10% in terms of volume fraction of pearlite with an average grain diameter of less than 5 ?m. The ferrite has an average Vickers hardness of not less than 130. The steel sheet has a yield ratio of not less than 65% and a tensile strength of not less than 590 MPa.
    Type: Application
    Filed: December 3, 2012
    Publication date: November 13, 2014
    Applicant: JFE STEEL CORPORATION
    Inventors: Katsutoshi Takashima, Yuki Toji, Kohei Hasegawa
  • Patent number: 8883072
    Abstract: The present invention provides, in a ?? phase precipitation strengthening type Ni-base alloy, an alloy excellent in heat treatment capability and weldability and suitable for joint with a ferritic steel. Further, the present invention provides a welded turbine rotor having the strength, ductility, and toughness simultaneously over the whole welded structure when a precipitation strengthening type Ni-base alloy having a heatproof temperature of 675° C. or higher is joined to a ferritic steel. A Ni-base alloy according to the present invention contains cobalt, chromium, aluminum, carbon, boron, and at least either tungsten or molybdenum with the remainder being nickel and inevitable impurities, having an alloy composition including 12 to 25 percent by mass of Co, 10 to 18 percent by mass of Cr, 2.0 to 3.6 percent by mass of Al, 0.01 to 0.15 percent by mass of C, 0.001 to 0.03 percent by mass of B, the total amount of tungsten and molybdenum being 5.0 to 10 percent by mass.
    Type: Grant
    Filed: September 1, 2009
    Date of Patent: November 11, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Jun Sato, Shinya Imano, Hiroyuki Doi
  • Publication number: 20140326369
    Abstract: Provided are a steel for a mechanical structure for cold working, and a method for manufacturing the same, whereby softening and variations in hardness can be reduced even when a conventional spheroidizing annealing process is performed. A steel having a predetermined chemical composition, the total area ratio of pearlite and pro-eutectoid ferrite being at least 90 area % with respect to the total metallographic structure of the steel, the area ratio (A) of pro-eutectoid ferrite satisfying the relationship A>Ae with an Ae value expressed by a predetermined relational expression, the average equivalent circular diameter of bcc-Fe crystal grains being 15-35 ?m, and the average of the maximum grain diameter and the second largest grain diameter of the bcc-Fe crystal grains being 50 ?m or less in terms of equivalent circular diameter.
    Type: Application
    Filed: December 11, 2012
    Publication date: November 6, 2014
    Applicant: KABUSHIKI KAISHA KOBE SEIKO SHO (Kobe Steel, Ltd.)
    Inventors: Kouji Yamashita, Takehiro Tsuchida, Masamichi Chiba
  • Patent number: 8876986
    Abstract: Disclosed is a high-strength cold-rolled steel sheet having improved stretch-flange formability and excellent hydrogen embrittlement resistance. In addition to Fe, C, Si, Mn, P, S, N, and Al, the steel sheet contains V or at least one element of Nb, Ti and Zr. The contents of the at least one element of Nb, Ti and Zr, if present, satisfy the expression of [% C]?[% Nb]/92.9×12?[% Ti]/47.9×12?[% Zr]/91.2×12>0.03. The steel sheet has an area ratio of tempered martensite of 50% or more with ferrite as the remainder. The number of precipitates having a circle-equivalent diameter of 1 to 10 nm is 20 particles or more per 1 ?m2 of the tempered martensite. The number of precipitates containing V or the at least one element of Nb, Ti and Zr and having a circle-equivalent diameter of 20 nm or more is 10 particles or less per 1 ?m2 of the tempered martensite.
    Type: Grant
    Filed: October 1, 2009
    Date of Patent: November 4, 2014
    Assignee: Kobe Steel, Ltd.
    Inventors: Hideo Hata, Toshio Murakami, Akira Ibano, Fumio Yuse, Junichiro Kinugasa
  • Patent number: 8876987
    Abstract: A high strength pressed member has excellent ductility and stretch flangeability and tensile strength of 780-1400 MPa, with a predetermined steel composition and steel microstructure relative to the entire microstructure of steel sheet, where area ratio of martensite 5-70%, area ratio of retained austenite 5-40%, area ratio of bainitic ferrite in upper bainite 5% or more, and total thereof is 40% or more, 25% or more of martensite is tempered martensite, polygonal ferrite area ratio is above 10% and below 50% to the entire microstructure of steel sheet, and average grain size is 8 ?m or less, average diameter of a group of polygonal ferrite grains is 15 ?m or less, the group of polygonal ferrite grains represented by a group of ferrite grains of adjacent polygonal ferrite grains, and average carbon content in retained austenite is 0.70 mass % or more and tensile strength is 780 MPa or more.
    Type: Grant
    Filed: October 2, 2012
    Date of Patent: November 4, 2014
    Assignee: JFE Steel Corporation
    Inventors: Hiroshi Matsuda, Yoshimasa Funakawa, Kaneharu Okuda, Kazuhiro Seto
  • Patent number: 8871039
    Abstract: The present invention provides a thick welded steel pipe excellent in low temperature toughness in which contents of Mn and Mo satisfy (Expression 1) below, Pcm obtained by (Expression 2) below is 0.16 to 0.19, and a metal structure of a base material steel plate consists of ferrite being 30 to 95% in an area ratio and a low temperature transformation structure, and in a metal structure of a coarse-grained HAZ, an area ratio of grain boundary ferrite is 1.5% or more, the total area ratio of the grain boundary ferrite and intragranular ferrite is not less than 11% nor more than 90%, an area ratio of MA is 10% or less, and its balance is composed of bainite. 1.2325?(0.85×[Mn]?[Mo])?1.5215??(Expression 1) and Pcm=[C]+[Si]/30+([Mn]+[Cu]+[Cr])/20+[Ni]/60+[Mo]/15+[V]/10??(Expression 2).
    Type: Grant
    Filed: September 13, 2011
    Date of Patent: October 28, 2014
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Yasuhiro Shinohara, Takuya Hara, Naoki Doi, Eiichi Yamashita
  • Publication number: 20140305553
    Abstract: A high-strength cold-rolled steel sheet has a chemical composition including C of 0.05% to 0.30%, Si of greater than 0% to 3.0%, Mn of 0.1% to 5.0%, P of greater than 0% to 0.1%, S of greater than 0% to 0.02%, Al of 0.01% to 1.0%, and N of greater than 0% to 0.01%, in mass percent, with the remainder including iron and inevitable impurities. The steel sheet has a microstructure containing ferrite as a soft primary phase in an area percentage of 20% to 50% with the remainder including tempered martensite and/or tempered bainite as a hard secondary phase. The ferrite grains are adapted to contain cementite particles having an appropriate size in an appropriate number density.
    Type: Application
    Filed: December 11, 2012
    Publication date: October 16, 2014
    Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)
    Inventors: Tomokazu Masuda, Hideo Hata, Katsura Kajihara, Toshio Murakami, Masaaki Miura, Muneaki Ikeda
  • Publication number: 20140305550
    Abstract: A high strength hot rolled steel sheet has a matrix that has a ferrite phase with an area ratio of 95% or more with respect to an overall structure; and a structure where a fine carbide is dispersedly precipitated, the fine carbide containing Ti and V having an average particle size of less than 10 nm in the matrix, the fine carbide has a volume fraction of 0.0050 or more with respect to the overall structure, a proportion of a number of carbides with a particle size of 30 nm or more containing Ti is less than 10% with respect to a total number of carbides, the high strength hot rolled steel sheet has a tensile strength of 980 MPa or more.
    Type: Application
    Filed: November 6, 2012
    Publication date: October 16, 2014
    Inventors: Tamako Ariga, Yoshimasa Funakawa, Yasunobu Uchida
  • Publication number: 20140295210
    Abstract: A hot rolled steel sheet includes a composition including: C: 0.03% to less than 0.07%; Si: 0.3% or less; Mn: 0.5% to 2.0%; P: 0.025% or less; S: 0.005% or less; N: 0.0060% or less; Al: 0.1% or less; Ti: 0.07% to 0.11%; and V: 0.08% to less than 0.15% on a mass percent basis, such that Ti and V contents satisfy: 0.18?Ti+V?0.24 (where Ti and V are contents of the elements (by mass %)), the balance including Fe and inevitable impurities, a matrix having a ferrite phase with an area ratio of 95% or more; and a structure where fine carbide is dispersedly precipitated in the matrix, the fine carbide containing Ti and V has an average particle size of less than 10 nm, and a volume fraction of the fine carbide is 0.0020 or more, wherein the steel sheet has a tensile strength of 780 MPa or more.
    Type: Application
    Filed: November 6, 2012
    Publication date: October 2, 2014
    Inventors: Tamako Ariga, Yoshimasa Funakawa, Noriaki Moriyasu
  • Publication number: 20140290810
    Abstract: A high strength cold rolled steel sheet includes a chemical composition containing, by mass %, C: 0.010% or more and 0.060% or less, Si: more than 0.5% and 1.5% or less, Mn: 1.0% or more and 3.0% or less, P: 0.005% or more and 0.100% or less, S: 0.010% or less, sol.Al: 0.005% or more and 0.500% or less, N: 0.0100% or less, Nb: 0.010% or more and 0.100% or less, Ti: 0.015% or more and 0.150% or less and the balance comprising Fe and inevitable impurities. The microstructure includes, in area fraction, 70% or more of a ferrite phase and 3% or more of a martensite phase. The tensile strength is 440 MPa or more and an average r value is 1.20 or more.
    Type: Application
    Filed: August 23, 2012
    Publication date: October 2, 2014
    Applicant: JFE STEEL CORPORATION
    Inventors: Hideyuki Kimura, Yasunobu Nagataki, Kaneharu Okuda, Kenji Kawamura
  • Patent number: 8845825
    Abstract: The present invention provides spring use heat treated steel which is cold coiled, can achieve both sufficient atmospheric strength and coilability, has a tensile strength of 2000 MPa or more, and can improve the performance as a spring by heat treatment after spring fabrication, that is, high strength spring-use heat treated steel characterized by containing, by mass %, C: 0.45 to 0.9%, Si: 1.7 to 3.0%, and Mn: 0.1 to 2.0%, restricting N: to 0.007% or less, having a balance of Fe and unavoidable impurities, and satisfying, in terms of the analyzed value of the extracted residue after heat treatment, [amount of Fe in residue on 0.2 ?m filter/[steel electrolysis amount]×100?1.1.
    Type: Grant
    Filed: March 29, 2007
    Date of Patent: September 30, 2014
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Masayuki Hashimura, Tatsuro Ochi, Takayuki Kisu, Hiroshi Hagiwara
  • Patent number: 8840738
    Abstract: A cold-rolled steel sheet of the present invention which has a composition containing, in terms of % by mass, C: 0.05-0.30%, Si: 3.0% or less (including 0%), Mn: 0.1-5.0%, P: 0.1% or less (including 0%), S: 0.010% or less (including 0%), and Al: 0.001-0.10%, and remainder being mainly iron, and which has a structure comprising, in terms of area ratio, 10-80% ferrite, less than 5% (including 0%) of the sum of retained austenite and martensite, and a hard phase as the remainder. The steel sheet gives a KAM value frequency distribution curve in which the relationship between the proportion of frequency having a KAM value ?0.4, XKAM?0.4°, and the area ratio of ferrite, V? satisfies XKAM?0.4°/V??0.8 and the proportion of frequency having a KAM value in the range of 0.6-0.8, XKAM=0.6-0.8° is 10-20%. In the hard phase adjoining the ferrite, cementite, grains having an equivalent circle diameter of 0.1 ?m or larger exist so that three or less such cementite grains are dispersed per ?m2 of the hard phase.
    Type: Grant
    Filed: April 2, 2010
    Date of Patent: September 23, 2014
    Assignee: Kobe Steel, Ltd.
    Inventors: Toshio Murakami, Akira Ibano, Hideo Hata, Kenji Saito
  • Patent number: 8840834
    Abstract: An ultra-high strength steel sheet has a tensile strength of 1400 MPa or higher that can achieve both high strength and good formability and an advantageous method for manufacturing the steel sheet and includes a composition including, on a mass basis C: 0.12% or more and 0.50% or less; Si: 2.0% or less; Mn: 1.0% or more and 5.0% or less; P: 0.1% or less; S: 0.07% or less; Al: 1.0% or less; and N: 0.008% or less, with the balance Fe and incidental impurities. The steel microstructure includes, on an area ratio basis, 80% or more of autotempered martensite, less than 5% of ferrite, 10% or less of bainite, and 5% or less of retained austenite; and the mean number of precipitated iron-based carbide grains each having a size of 5 nm or more and 0.5 ?m or less and included in the autotempered martensite is 5×104 or more per 1 mm2.
    Type: Grant
    Filed: January 29, 2009
    Date of Patent: September 23, 2014
    Assignee: JFE Steel Coporation
    Inventors: Hiroshi Matsuda, Reiko Mizuno, Yoshimasa Funakawa, Yasushi Tanaka
  • Publication number: 20140261916
    Abstract: A high strength-high ductility cold rolled steel sheet is provided. The steel sheet has a recovery annealed microstructure, a yield strength greater than 820 megapascals (MPa) and a percent elongation to failure greater than 3.5%. In some instances, the steel alloy sheet has a Rockwell B hardness greater than 100 and may or may not exhibit a yield strength-to-tensile strength ratio between 0.25 and 1.00.
    Type: Application
    Filed: July 18, 2013
    Publication date: September 18, 2014
    Inventors: Chris John Paul Samuel, Marisa Vann, Bertram Wilhelm Ehrhardt, Stanley Wayne Bevans
  • Publication number: 20140261918
    Abstract: Improved steel compositions and methods of making the same are provided. The present disclosure provides advantageous wear resistant steel. More particularly, the present disclosure provides high manganese (Mn) steel having enhanced wear resistance, and methods for fabricating high manganese steel compositions having enhanced wear resistance. The advantageous steel compositions/components of the present disclosure improve one or more of the following properties: wear resistance, ductility, crack resistance, erosion resistance, fatigue life, surface hardness, stress corrosion resistance, fatigue resistance, and/or environmental cracking resistance. In general, the present disclosure provides high manganese steels tailored to resist wear and/or erosion.
    Type: Application
    Filed: March 4, 2014
    Publication date: September 18, 2014
    Applicant: ExxonMobil Research and Engineering Company
    Inventors: HyunWoo Jin, Ning Ma, Raghavan Ayer, Russell Robert Mueller, Hak-Cheol Lee, Jong-Kyo Choi, In-Shik Suh
  • Publication number: 20140261919
    Abstract: A low carbon-high manganese steel sheet and process for manufacturing the sheet is provided. The process includes soaking a steel slab with a desired chemical composition within a temperature range of 1200-1350° C., followed by hot rolling of the slab into hot strip. The cold rolled sheet is continuously annealed within a temperature range of 730-850° C. and temper rolled between 1.0-2.0%. The temper rolled sheet has a yield strength greater than 280 megapascals (MPa), a tensile strength greater than 400 MPa, an elongation to fracture greater than 30%, an n-value greater than 0.15, and a bakehard index between 15-35 MPa.
    Type: Application
    Filed: February 25, 2014
    Publication date: September 18, 2014
    Applicant: THYSSENKRUPP STEEL USA, LLC
    Inventors: Chris John Paul Samuel, Bertram Wilhelm Ehrhardt, Joseph Frimpong, Stanley Wayne Bevans
  • Publication number: 20140261903
    Abstract: A bake hardenable steel and a process for manufacture of a bake hardenable steel. Steel alloy slabs with a predefined chemical composition are hot rolled into hot rolled strip. The hot rolled strip is cold rolled and continuously annealed on a continuous annealing line and then rapidly cooled to at least 600° C. using a cooling rate of between 20-100 K/sec, and optionally cooled to at least 140° C. using a cooling rate of between 3-20 K/sec. As such, the cold rolled and annealed sheet is not subjected to an overageing treatment and yet still exhibits excellent and well defined bake hardening values. For example BH2 values between 25 and 45 MPa are exhibited by the low alloy steel grades. In addition, the bake hardeneable steel sheet has a minimum yield strength of 220 MPa and in some instances has a minimum yield strength as high as 380 MPa.
    Type: Application
    Filed: March 17, 2014
    Publication date: September 18, 2014
    Applicant: AM/NS CALVERT LLC
    Inventors: Joseph Frimpong, Bertram Wilhelm Ehrhardt, Stanley Wayne Bevans, Harald Van Bracht
  • Publication number: 20140261915
    Abstract: A process for producing high strength steel is provided. The process includes providing a steel slab having a chemical composition in weight percent within a range of 0.025-0.07 C, 1.20-1.70 Mn, 0.050-0.085 Nb, 0.022 max Ti, 0.065 max N, 0.0040 max S, 0.10-0.45 Si, 0.070 max P, with the balance being Fe and incidental impurities. The steel slab is soaked within a temperature range of 1150-1230° C., hot rolled using a roughing treatment in order to produce a transfer bar and further hot rolled using a finishing treatment in order to produce hot rolled strip. The hot rolled strip is cooled using a cooling rate between 10-100° C./second (sec) and coiled within a temperature range of 580-400° C. Finally, the coiled hot rolled strip has a yield strength of at least 80 ksi and a DWTT transition temperature equal or less than ?20° C.
    Type: Application
    Filed: March 14, 2014
    Publication date: September 18, 2014
    Applicant: AM/NS CALVERT LLC
    Inventors: Bertram Wilhelm Ehrhardt, Chris John Paul Samuel, Ranbir Singh Jamwal, Gerald McGloin, Stanley Wayne Bevans, Markus Wilhelm Forsch, Rudolf Schonenberg
  • Publication number: 20140251513
    Abstract: A high-strength hot rolled steel sheet with excellent bendability and low-temperature toughness includes a chemical composition including, in mass %, C: 0.08 to 0.25%, Si: 0.01 to 1.0%, Mn: 0.8 to 2.1%, P: not more than 0.025%, S: not more than 0.005% and Al: 0.005 to 0.10%, the balance including Fe and inevitable impurities, and a microstructure having a bainite phase and/or a tempered martensite phase as a main phase, the average grain diameter of prior austenite grains being not more than 20 ?m as measured with respect to a cross section parallel to a rolling direction and not more than 15 ?m as measured with respect to a cross section perpendicular to the rolling direction.
    Type: Application
    Filed: October 31, 2012
    Publication date: September 11, 2014
    Inventors: Chikara Kami, Kazuhiko Yamazaki
  • Publication number: 20140246128
    Abstract: Provided is a hot-rolled steel sheet that has a chemical composition including, by mass %: C: 0.060% to 0.150%; Si: 0.15% to 0.70%; Mn: 1.00% to 1.90%; P: 0.10% or less; S: 0.010% or less; Al: 0.01% to 0.10%; N: 0.010% or less; Nb: 0.010% to 0.100%; and the balance including Fe and incidental impurities. The hot-rolled steel sheet has a microstructure containing ferrite of 18 ?m or less in average grain size by a volume fraction of at least 75% and pearlite of at least 2 ?m in average grain size by a volume fraction of at least 5%, the balance being low-temperature-induced phases, the pearlite having a mean free path of at least 5.0 ?m.
    Type: Application
    Filed: September 27, 2012
    Publication date: September 4, 2014
    Inventors: Katsutoshi Takashima, Yuki Toji, Kohei Hasegawa
  • Patent number: 8821652
    Abstract: Steel for induction hardening wherein coarsening of austenite crystal grains can be prevented even at a high temperature of over 1100° C. such as which occurs at projecting parts of steel parts at the time of induction hardening, the steel for induction hardening characterized by containing, by mass %, C: 0.35 to 0.6%, Si: 0.01 to 1%, Mn: 0.2 to 1.8%, S: 0.001 to 0.15%, Al: 0.001 to 1%, Ti: 0.05 to 0.2%, and Nb: 0.001 to 0.04%, restricting N: 0.0060% or less, P: 0.025% or less, and O: 0.0025% or less, satisfying Nb/Ti?0.015, and having a balance of iron and unavoidable impurities.
    Type: Grant
    Filed: October 7, 2010
    Date of Patent: September 2, 2014
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Shuji Kozawa, Manabu Kubota