Molybdenum Containing Patents (Class 148/334)
  • Publication number: 20130087253
    Abstract: A high strength steel sheet has tensile strength of at least 1470 MPa and (tensile strength×total elongation) of at least 29000 MPa·% with a composition including, by mass %, C: 0.30% to 0.73%, Si: 3.0% or less, Al: 3.0% or less, Si+Al: at least 0.7%, Cr: 0.2% to 8.0%, Mn: 10.0% or less, Cr+Mn: at least 1.0%, P: 0.1% or less, S: 0.07% or less, N: 0.010% or less, and remainder as Fe and incidental impurities; and processing the steel sheet such that microstructure satisfies area ratio of martensite with respect to the microstructure of 15% to 90%; content of retained austenite of 10% to 50%; at least 50% of the martensite is constituted of tempered martensite and area ratio of the tempered martensite with respect to the microstructure is at least 10%; and area ratio of polygonal ferrite with respect to the microstructure is 10% or less.
    Type: Application
    Filed: February 28, 2011
    Publication date: April 11, 2013
    Applicant: JFE STEEL CORPORATION
    Inventors: Hiroshi Matsuda, Yoshimasa Funakawa, Yasushi Tanaka
  • Publication number: 20130068449
    Abstract: A hardfacing composition composed of an Fe—Cr alloy. The alloy is comprised of 80 wt % iron, about 2 wt % to about 20 wt % Cr, less than 1 wt % Si and less than 1 wt % C. The alloy's microstructure is at least 80 vol % martensite; and less than 20 vol % austenite.
    Type: Application
    Filed: September 16, 2011
    Publication date: March 21, 2013
    Applicant: NATIONAL OILWELL VARCO,LP.
    Inventors: Raju PILLAI, Jiinjen A. SUE, Parul W. DHALL
  • Patent number: 8398787
    Abstract: A high-strength steel sheet is provided which, even when subjected to long-term stress-relief annealing after welding, decreases little in strength and which has satisfactory low-temperature HAZ toughness. The high-strength steel sheet has a chemical composition adequately regulated and has a CP value defined by the following equation (1) of 5.40% or higher and a carbon equivalent (Ceq) defined by the following equation (2) of 0.45% or lower. CP value=125[Ti]+111[Nb]+60[V]+15[Mo] (1) ([Ti], [Nb], [V], and [Mo] indicate the contents (mass %) of Ti, Nb, V, and Mo, respectively.) Ceq=[C]+[Mn]/6+([Cr]+[Mo]+[V])/5+([Cu]+[Ni])/15 (2) ([C], [Mn], [Cr], [Mo], [V], [Cu], and [Ni] indicate the contents (mass %) of C, Mn, Cr, Mo, V, Cu, and Ni, respectively.
    Type: Grant
    Filed: March 16, 2009
    Date of Patent: March 19, 2013
    Assignee: Kobe Steel, Ltd.
    Inventor: Makoto Kariyazaki
  • Publication number: 20130061988
    Abstract: A steel contains, by weight: C: 0.3% to 0.5%, Si: 0.1% to 0.5%, Mn: 1% or less, P: 0.03% or less, S: 0.005% or less, Cr: 0.3% to 1%, Mo: 1% to 2%, W: 0.3% to 1%, V: 0.03% to 0.25%, Nb: 0.01% to 0.15%, Al: 0.01% to 0.1%, the remainder of the chemical composition of the steel being constituted by Fe and impurities or residuals resulting from or necessary to steel production and casting processes. The steel can be used to produce seamless tubes for hydrocarbon wells with a yield strength after heat treatment of 862 MPa or more or even 965 MPa or more.
    Type: Application
    Filed: May 19, 2011
    Publication date: March 14, 2013
    Applicant: VALLOUREC MANNESMANN OIL & GAS FRANCE
    Inventors: Laurent Delattre, Herve Marchebois, Michel Piette, Christoph Bosch, Michaela Hoerstemeier, Joachim Konrad
  • Patent number: 8394209
    Abstract: A high-strength steel sheet according to the present invention not only is suitably adjusted in its chemical elements composition, but also has a DE value defined by the following Equation (1) of 0.0340% or more, and a carbon equivalent Ceq defined by the following Equation (2) of 0.45% or less: DE value=[Ti]+[Nb]+0.3[V]+0.0075[Cr]??(1) where, [Ti], [Nb], [V], and [Cr] represent contents (mass %) of Ti, Nb, V, and Cr, respectively; Ceq=[C]+[Mn]/6+([Cr]+[Mo]+[V])/5+([Cu]+[Ni])/15 ??(2) where, [C], [Mn], [Cr], [Mo], [V], [Cu], and [Ni] represent contents (mass %) of C, Mn, Cr, Mo, V, Cu, and Ni, respectively. A high-strength steel sheet resistant to strength reduction and good in low-temperature toughness of HAZ even when subjected for a long time to a stress-relief annealing process after being processed by welding, is provided.
    Type: Grant
    Filed: January 26, 2009
    Date of Patent: March 12, 2013
    Assignee: Kobe Steel, Ltd.
    Inventors: Manabu Izumi, Makoto Kariyazaki
  • Patent number: 8388771
    Abstract: A high strength steel sheet contains, in percent by mass, 0.03 to 0.2% of C, 0.5 to 2.5% of Si, 1 to 3.0% of Mn, 0.01 to 0.5% of Cr, 0.01 to 0.5% of Mo, 0.02 to 0.15% of Al, 0.15% or less of Ti, 0.15% or less of No, and 0.15% or less of V; wherein the remainder includes Fe and inevitable impurities, and the content of Si satisfies the following formula (1), ??4.1?[Si]??2.4??(1), provided, ?=6.9×([C]+[Mn]/6+[Cr]/5+[Mo]/4+[Ti]/15+[Nb]/17+[V]/14)1/2 is given, wherein [ ] shows the quantity (mass percent) of each element contained in the steel sheet. The high strength steel sheet is improved in formability (particularly, elongation), and excellent in balance between strength and elongation.
    Type: Grant
    Filed: September 6, 2011
    Date of Patent: March 5, 2013
    Assignee: Kobe Steel, Ltd.
    Inventors: Yuichi Futamura, Katsuhiro Yamamoto, Masaaki Miura
  • Patent number: 8389128
    Abstract: A high tensile-strength galvanized steel sheet includes C: at least 0.05% but less than 0.12%, Si: at least 0.01% but less than 0.35%, Mn: 2.0% to 3.5%, P: 0.001% to 0.020%, S: 0.0001% to 0.0030%, Al: 0.005% to 0.1%, N: 0.0001% to 0.0060%, Cr: more than 0.5% but not more than 2.0%, Mo: 0.01% to 0.50%, Ti: 0.010% to 0.080%, Nb: 0.010% to 0.080%, and B: 0.0001% to 0.0030%, the remainder being Fe and unavoidable impurities, wherein the high tensile-strength galvanized steel sheet has a microstructure that contains 20% to 70% by volume ferrite having an average grain size of 5 ?m or less. The high tensile-strength galvanized steel sheet has a tensile strength of at least 980 MPa, and excellent formability and weldability.
    Type: Grant
    Filed: April 7, 2008
    Date of Patent: March 5, 2013
    Assignee: JFE Steel Corporation
    Inventors: Shusaku Takagi, Hidetaka Kawabe, Kohei Hasegawa, Toshihiko Ooi, Yasuaki Okita, Michitaka Sakurai
  • Publication number: 20130048158
    Abstract: Disclosed is high strength spring steel that can limit the depth of pitting occurring when corroded and therefore possesses high strength as well as excellent pitting corrosion resistance and corrosion fatigue property, with a composition containing: C: greater than 0.35 mass % and less than 0.50 mass %; Si: greater than L75 mass % and less than or equal to 3.00 mass %; Mn: 0.2 mass % to 1.0 mass %; Cr: 0.01 mass % to 0.04 mass %; P: 0.025 mass % or less; S: 0.025 mass % or less; Mo: 0.1 mass % to 1.0 mass %; and 0: 0.0015 mass % or less, under a condition that a PC value calculated by PC=4.2×([C]+[Mn])+0.1×(1/[Si]+1/[Mo])+20.3×[Cr]+0.001×(1/[N]) is greater than 3.3 and equal to or less than 8.0. Also disclosed is a preferred method for manufacturing the same.
    Type: Application
    Filed: February 28, 2011
    Publication date: February 28, 2013
    Applicant: JFE STEEL CORPORATION
    Inventors: Minoru Honjo, Kazukuni Hase, Hideto Kimura
  • Publication number: 20130037180
    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: Application
    Filed: January 26, 2011
    Publication date: February 14, 2013
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Kohichi Sano, Chisato Wakabayashi, Hiroyuki Kawata, Riki Okamoto, Naoki Yoshinaga, Kaoru Kawasaki, Natsuko Sugiura, Nobuhiro Fujita
  • Publication number: 20130037182
    Abstract: A mechanical steel part in steel with high characteristics, characterized in that its composition, comprising in weight percentages, is 0.05%?C?0.25%; 1.2%?Mn?2%; 1%?Cr?2.5%; wherein the contents of C, Mn and Cr are such that (830-270C %-90 Mn %-70Cr %)?560; 0<Si?1.55; 0<Ni?1%; 0<Mo?0.5%; 0<Cu?1%; 0<V?0.3%; 0<Al?0.1%; 0<B?0.005%; 0<Ti?0.03%; 0<Nb?0.06%; 0<S?0.1%; 0<Ca?0.006%; 0<Te?0.03%; 0<Se?0.05%; 0<Bi?0.05%; 0<Pb?0.1%; the remainder of the steel part being iron and impurities resulting from processing, and wherein the in that its structure of the steel is bainitic and contains no more than a total of 20% of martensite and/or pro-eutectoid ferrite and/or pearlite.
    Type: Application
    Filed: April 7, 2011
    Publication date: February 14, 2013
    Applicant: ASCOMETAL
    Inventor: Thomas Sourmail
  • Patent number: 8372219
    Abstract: Gun barrel for firearms made from a deformed material and method for producing the gun barrel material. The material has a chemical composition in % by weight of: Content C Si Mn P S Cr Mo Min 0.28 0.08 0.15 3.6 1.2 Max 0.36 0.26 0.35 0.005 0.002 4.4 1.8 Content Ni V W Ti As + Sn + Sb Fe Min 0.42 Rest Max <0.5 0.5? 0.15 0.08 0.007 and impurities due to smelting. The material has a hardness of at least 46 to 48 HRC.
    Type: Grant
    Filed: April 5, 2011
    Date of Patent: February 12, 2013
    Assignee: Boehler Edelstahl GmbH & Co. KG
    Inventors: Devrim Caliskanoglu, Herbert Schweiger, Ingo Siller
  • Patent number: 8361256
    Abstract: A seamless steel pipe produced by heating a steel billet, which has a chemical composition C: 0.15 to 0.20%, Si: not less than 0.01% to less than 0.15%, Mn: 0.05 to 1.0%, Cr: 0.05 to 1.5%, Mo: 0.05 to 1.0%, Al?0.10%, V: 0.01 to 0.2%, Ti: 0.002 to 0.03%, B: 0.0003 to 0.005% and N: 0.002 to 0.01%, further optionally one or more of Ca, Mg and REM in a specific amount, under the provision that the conditions “C+(Mn/6)+(Cr/5)+(Mo/3)?0.43” and “Ti×N<0.0002?0.0006×Si” are satisfied, with the balance being Fe and impurities, wherein P?0.025%, S?0.010% and Nb<0.005% among the impurities, to a temperature of 1000 to 1250° C. followed by pipe-making rolling at a final rolling temperature 900 to 1050° C., and then quenching the resulting steel pipe directly from a temperature not lower than the Ar3 transformation point followed by tempering at a temperature range from 600° C.
    Type: Grant
    Filed: January 24, 2008
    Date of Patent: January 29, 2013
    Assignee: Sumitomo Metal Industries, Ltd.
    Inventors: Yuji Arai, Keiichi Nakamura
  • Patent number: 8361246
    Abstract: A pearlite rail contains, by mass %, 0.65 to 1.20% of C; 0.05 to 2.00% of Si; 0.05 to 2.00% of Mn; and the balance composed of Fe and inevitable impurities, wherein at least part of the head portion and at least part of the bottom portion has a pearlite structure, and the surface hardness of a portion of the pearlite structure is in a range of Hv320 to Hv500 and a maximum surface roughness of a portion of the pearlite structure is less than or equal to 180 ?m.
    Type: Grant
    Filed: August 13, 2010
    Date of Patent: January 29, 2013
    Assignee: Nippon Steel Corporation
    Inventors: Masaharu Ueda, Kyohei Sonoyama, Takuya Tanahashi, Teruhisa Miyazaki, Katsuya Iwano
  • Patent number: 8357252
    Abstract: High tensile strength steels that have both favorable delayed fracture resistance and a tensile strength of 600 MPa or higher and are suitably used in construction machinery, tanks, penstocks, and pipelines, as well as methods for manufacturing such steels are provided. The safety index of delayed fracture resistance (%) is 100×(X1/X0), where X0: reduction of area of a specimen substantially free from diffusible hydrogen, and X1: reduction of area of a specimen containing diffusible hydrogen.
    Type: Grant
    Filed: January 31, 2008
    Date of Patent: January 22, 2013
    Assignee: JFE Steel Corporation
    Inventors: Akihide Nagao, Kenji Oi, Kenji Hayashi, Nobuo Shikanai
  • Patent number: 8353992
    Abstract: Steel sheet having a composition of ingredients containing substantially, by mass %, C: 0.005 to 0.200%, Si: 2.50% or less, Mn: 0.10 to 3.00%, N: 0.0100% or less, Nb: 0.005 to 0.100%, and Ti: 0.002 to 0.150% and satisfying the relationship of Ti?48/14×N?0.0005, having a sum of the X-ray random intensity ratios of the {100}<001> orientation and the {110}<001> orientation of a ? sheet thickness part of 5 or less, having a sum of the maximum value of the X-ray random intensity ratios of the {110}<111> to {110}<112> orientation group and the X-ray random intensity ratios of the {211}<111> orientation of 5 or more, and having a high rolling direction Young's modulus measured by the static tension method and a method of production of the same are provided.
    Type: Grant
    Filed: November 7, 2007
    Date of Patent: January 15, 2013
    Assignee: Nippon Steel Corporation
    Inventors: Natsuko Sugiura, Naoki Maruyama, Manabu Takahashi, Yohji Nakamura, Koji Hanya
  • Publication number: 20130008570
    Abstract: Disclosed is an ultra high strength steel plate with at least 1100 MPa of tensile strength that has both an excellent strength-stretch balance and excellent bending workability, and a method for producing the same. The metal structure of the steel plate has martensite, and the soft phases of bainitic ferrite and polygonal ferrite. The area of the aforementioned martensite constitutes 50% or more, the area of the aforementioned bainitic ferrite constitutes 15% or more, and the area of the aforementioned polygonal ferrite constitutes 5% or less (including 0%). When the circle-equivalent diameter of the aforementioned soft phases is measured, the coefficient of variation (standard deviation/mean value) is less or equal to 1.0. The ultra high strength steel plate has at least 1100 MPa of tensile strength.
    Type: Application
    Filed: March 25, 2011
    Publication date: January 10, 2013
    Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel Ltd)
    Inventors: Muneaki Ikeda, Yukihiro Utsumi, Masaaki Miura
  • Patent number: 8337643
    Abstract: A hot rolled steel sheet having a dual phase microstructure with a martensite phase of less than 35% by volume and a ferrite phase of more than 50% by volume and a composition containing by percent weight: 0.01?C?0.2; 0.3?Mn?3; 0.2?Si?2; 0.2?Cr+Ni?2; 0.01?Al?0.10; Mo less than about 0.2%, 0.0005?Ca?0.01, with the balance iron and incidental ingredients. Hot rolled sheet for cold rolling, the silicon range may be from about 0.05% to about 2%, and the amount of molybdenum may be up to 0.5%. Also, the hot rolled steel sheet has a tensile strength of at least 500 megapascals, a hole expansion ratio more than about 50%, and a yield strength/tensile strength ratio less than 70%.
    Type: Grant
    Filed: July 22, 2008
    Date of Patent: December 25, 2012
    Assignee: Nucor Corporation
    Inventor: Weiping Sun
  • Publication number: 20120318410
    Abstract: Regarding contents of C, Si, Mn and Cr, a value of parameter P represented by the following (equation 1) is 1000 or more. A metallic structure contains wire-drawn pearlite in an area ratio of 98% or more, a diameter is 0.05 mm to 0.18 mm, a tensile strength is 4000 MPa or more, and a twist number in a twist test in which a grip-to-grip distance is 100 mm, and a tension equal to a tensile strength×a cross-sectional area of wire×0.5 is applied, is 5 or more. P=1098×[C]+98×[Si]?20×[Mn]+167×[Cr]??(equation 1) (in the (equation 1), [C], [Si], [Mn] and [Cr] indicate contents (mass %) of C, Si, Mn and Cr, respectively.
    Type: Application
    Filed: April 7, 2011
    Publication date: December 20, 2012
    Inventors: Toshimi Tarui, Kenichi Nakamura, Masashi Sakamoto
  • Patent number: 8328957
    Abstract: In an electric resistance welded steel pipe with excellent weld toughness for a line pipe, the area fraction of minute defects each having a maximum length of less than 50 ?m in a projection plane of an electric resistance welded seam is in the range of 0.000006 to 0.026, and the absorbed energy at ?40° C. measured by a method for an impact test of metallic materials is 315 J or more.
    Type: Grant
    Filed: May 18, 2007
    Date of Patent: December 11, 2012
    Assignee: JFE Steel Corporation
    Inventors: Hiroyasu Yokoyama, Kazuhito Kenmochi, Takatoshi Okabe, Yukinori Iizuka
  • Patent number: 8328958
    Abstract: Embodiments of the present application are directed towards steel compositions that provide improved properties under corrosive environments. Embodiments also relate to protection on the surface of the steel, reducing the permeation of hydrogen. Good process control, in terms of heat treatment working window and resistance to surface oxidation at rolling temperature, are further provided.
    Type: Grant
    Filed: December 27, 2010
    Date of Patent: December 11, 2012
    Assignee: Tenaris Connections Limited
    Inventors: Gustavo López Turconi, Alfonso Izquierdo Garcia, Toshihiko Fukui
  • Patent number: 8317945
    Abstract: Disclosed is a steel plate having a specific chemical component composition. The steel plate has an F value defined by the following expression (1) and satisfying the following condition: 3.20?(F value)?4.50, has a tempered bainite microstructure having an average equivalent area diameter of grains surrounded by high-angle boundaries with a difference in orientation between two grains of 15° or more of 4 ?m or less, and has a tensile strength of 585 MPa or more: F value=9.4×[Mo]+8.1×[V]+4.7×[Cr]??(1) wherein [Mo], [V] and [Cr] represent contents (percent by mass) of Mo, V, and Cr, respectively. The steel plate having this configuration surely has satisfactory drop weight properties and high base metal toughness only by controlling the contents of necessary alloy elements.
    Type: Grant
    Filed: June 15, 2010
    Date of Patent: November 27, 2012
    Assignee: Kobe Steel, Ltd.
    Inventor: Hiroaki Kou
  • Publication number: 20120291927
    Abstract: Drawn heat treated steel wire for high strength spring use is provided containing, by mass %, C: 0.67% to less than 0.9%, Si: 2.0 to 3.5%, Mn: 0.5 to 1.2%, Cr: 1.3 to 2.5%, N: 0.003 to 0.007%, and Al: 0.0005% to 0.003%, having Si and Cr satisfying the following formula: 0.3%?Si?Cr?1.2%, and having a balance of iron and unavoidable impurities, having as impurities, P: 0.025% or less and S: 0.025% or less, furthermore having a circle equivalent diameter of undissolved spherical carbides of less than 0.2 ?m, further having, as a metal structure, at least residual austenite in a volume rate of over 6% to 15%, having a prior austenite grain size number of #10 or more, and having a circle equivalent diameter of undissolved spherical carbides of less than 0.2 ?m.
    Type: Application
    Filed: July 5, 2011
    Publication date: November 22, 2012
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Masayuki Hashimura, Tetsushi Chida
  • Patent number: 8313589
    Abstract: An object of the present invention is to provide at a low cost a low-alloy steel having a high strength and excellent high-pressure hydrogen environment embrittlement resistance characteristics under a high-pressure hydrogen environment. The invention is a high-strength low-alloy steel excellent in high-pressure hydrogen environment embrittlement resistance characteristics, which is characterized in that the steel has a composition comprising C: 0.10 to 0.20%, Si: 0.10 to 0.40%, Mn: 0.50 to 1.20%, Cr: 0.20 to 0.80%, Cu: 0.10 to 0.50%, Mo: 0.10 to 1.00%, V: 0.01 to 0.10%, B: 0.0005 to 0.005% and N: 0.01% or less, by mass, with the balance consisting of Fe and unavoidable impurities.
    Type: Grant
    Filed: August 21, 2008
    Date of Patent: November 20, 2012
    Assignee: The Japan Steel Works, Ltd.
    Inventors: Koichi Takasawa, Yoru Wada, Ryoji Ishigaki, Yasuhiko Tanaka
  • Patent number: 8303734
    Abstract: The present invention provides a high strength thick steel material excellent in toughness and weldability reduced in amount of C and amount of N, containing suitable amounts of Si, Mn, Nb, Ti, B, and O, having contents of C and Nb satisfying C—Nb/7.74?0.004, having a density of Ti-containing oxides of a particle size of 0.05 to 10 ?m of 30 to 300/mm2, and having a density of Ti-containing oxides of a particle size over 10 ?m of 10/mm2 or less, produced by treating steel by preliminary deoxidation to adjust the dissolved oxygen to 0.005 to 0.015 mass %, then adding Ti and, furthermore, vacuum degassing the steel for 30 minutes or more, smelting it, then continuously casting it to produce a steel slab or billet, heating the steel slab or billet to 1100 to 1350° C., hot rolling the slab or billet to a thickness of 40 to 150 mm, then cooling it.
    Type: Grant
    Filed: September 26, 2008
    Date of Patent: November 6, 2012
    Assignee: Nippon Steel Corporation
    Inventors: Suguru Yoshida, Hiroshi Kita, Teruhisa Okumura, Hirokazu Sugiyama, Teruyuki Wakatsuki
  • Patent number: 8298353
    Abstract: A transformation toughened, high-strength steel alloy useful in plate steel applications achieves extreme fracture toughness (Cv > 80 ft-lbs corresponding to KId=200 ksi.in ½) at strength levels of 150-180 ksi yield strength, is weldable and formable. The alloy is characterized by dispersed austenite stabilization for transformation toughening to a weldable, bainitic plate steel and is strengthened by precipitation of M2C carbides in combination with copper and nickel. The desired microstructure is a matrix containing a bainite-martensite mix, BCC copper and M2C carbide particles for strengthening with a fine dispersion of optimum stability austenite for transformation toughening. The bainite-martensite mix is formed by air-cooling from solution treatment temperature and subsequent aging at secondary hardening temperatures to precipitate the toughening and strengthening dispersions.
    Type: Grant
    Filed: June 22, 2011
    Date of Patent: October 30, 2012
    Assignee: Northwestern University
    Inventors: Arup Saha, Gregory B. Olson
  • Patent number: 8277576
    Abstract: A steel material composition, in particular for producing piston rings and cylinder sleeves, contains the following elements in the cited fractions relative to 100% by weight of the steel material: 0.5-1.2% by weight C, 0-3.0% by weight Cr, 72.0-94.5% by weight Fe, 3.0-15.0% by weight Mn and 2.0-10.0% by weight Si. It can be produced by melting the starting materials and casting the melt into a pre-fabricated mold.
    Type: Grant
    Filed: October 13, 2009
    Date of Patent: October 2, 2012
    Assignee: Federal-Mogul Burscheid GmbH
    Inventor: Laszlo Pelsoeczy
  • Publication number: 20120225761
    Abstract: A forged roll for use, inter alia, in the cold rolling industry and a method of producing a forged roll as described. The roll has a steel composition, by weight, with 0.8 to less than 1% C, 0.2 to 0.5% Mn, 0.2 to 2.0% Si, 7.0 to 13.0% Cr, 0.6 to 1.6% Mo, more than 1.0 to 3.0% V, the remainder being Fe and impurities. The steel is tempered martensite with retained austenite at less than 5% per volume with eutectic carbides of less than 5% by volume, a hardness between 780-840 HV, and internal compressive stresses of between ?300 to ?500 MPa.
    Type: Application
    Filed: March 4, 2011
    Publication date: September 6, 2012
    Applicant: Åkers AB
    Inventors: Claude Gaspard, Catherine Vergne, Daniel Batazzi
  • Patent number: 8257513
    Abstract: The present invention provides a high strength steel sheet with 780 MPa class tensile strength excellent in bending workability and fatigue strength. The high strength steel sheet is (1) a steel sheet whose steel composition contains: C: 0.05-0.20%; Si: 0.6-2.0%; Mn: 1.6-3.0%; P: 0.05% or below; S: 0.01% or below; Al: 0.1% or below; and N: 0.01% or below, the balance comprising iron and inevitable impurities, in which (2) a microstructure comprises a polygonal ferrite structure and a structure formed by low-temperature transformation, in which, when a sheet plane located at a depth of 0.1 mm from a surface of the steel sheet is in the observation under a scanning electron microscope with respect to twenty sights in total in different positions in the sheet-width direction, the maximum value of the areal proportion of the polygonal ferrite (Fmax) and the minimum value of the areal proportion of the ferrite (Fmin) in a 50 ?m×50 ?m area in each sight satisfy Fmax?80%, Fmin?10%, and Fmax?Fmin?40%.
    Type: Grant
    Filed: May 28, 2008
    Date of Patent: September 4, 2012
    Assignee: Kobe Steel, Ltd.
    Inventors: Michiharu Nakaya, Tetsuji Hoshika
  • Patent number: 8252125
    Abstract: The present invention, among other things, relates to a method for producing a workpiece by press hardening a semi-finished product, which is distinguished by the fact that the semi-finished product consists of a steel which has a high content of silicon of at least 0.9 wt. %, with a simultaneously small content of manganese of less than 0.9 wt. %, a small carbon content of less than 0.25 wt. %, and a high chromium content of more than 1.20 wt. %, and which by heating is brought to a state in which the structure of the steel that is used is at least partially transformed to austenite, also optionally fully transformed to austenite, and the thus-heated semi-finished product is hot shaped so that after the hot deformation shaping, a structure is present in the workpiece that has a complex phase structure with predominantly martensite and ferrite fractions. In addition, a workpiece is described, which is produced according to this method, as well as uses of such a workpiece.
    Type: Grant
    Filed: October 16, 2009
    Date of Patent: August 28, 2012
    Assignee: Benteler Automobiltechnik GmbH
    Inventors: Hubertus Giefers, Karsten Bake, Andreas Frehn, Alexander Redenius, Uwe Diekmann
  • Publication number: 20120211131
    Abstract: Embodiments of the present disclosure comprise carbon steels and methods of manufacture. In one embodiment, quenching and tempering procedure is performed in which a selected steel composition is formed and heat treated to yield a slightly tempered microstructure having a fine carbide distribution. In another embodiment, a double austenizing procedure is disclosed in which a selected steel composition is formed and subjected to heat treatment to refine the steel microstructure. In one embodiment, the heat treatment may comprise austenizing and quenching the formed steel composition a selected number of times (e.g., 2) prior to tempering. In another embodiment, the heat treatment may comprise subjecting the formed steel composition to austenizing, quenching, and tempering a selected number of times (e.g., 2). Steel products formed from embodiments of the steel composition in this manner (e.g., seamless tubular bars and pipes) will possess high yield strength, e.g.
    Type: Application
    Filed: February 18, 2011
    Publication date: August 23, 2012
    Applicant: Siderca S.A.I.C.
    Inventors: Eduardo Altschuler, Teresa Perez, Edgardo Lopez, Constantino Espinosa, Gonzalo Gomez
  • Publication number: 20120211128
    Abstract: A steel part having a homogeneous multiphase microstructure in each region of the part, the microstructure containing ferrite, wherein the steel part is obtained by a process involving: cutting a blank from a strip of steel, having a specified composition; optionally, the blank undergoes prior cold deformation; the blank is heated to reach a soak temperature Ts above Ac1 but below Ac3 and held at this soak temperature Ts for a soak time ts adjusted so that the steel, after the blank has been heated, has an austenite content equal to or greater than 25% by area; the heated blank is transferred into a forming tool to hot-form the part; and the part is cooled within the tool at a cooling rate V such that the microstructure of the steel, after cooling the part, is a multiphase microstructure containing ferrite and being homogeneous in each region of the part.
    Type: Application
    Filed: January 5, 2012
    Publication date: August 23, 2012
    Applicant: ArcelorMittal France
    Inventors: Jacques CORQUILLET, Jacques DEVROC, Jean-Louis HOCHARD, Jean-Pierre LAURENT, Antoine MOULIN, Nathalie ROMANOWSKI
  • Publication number: 20120211132
    Abstract: Embodiments of the present disclosure comprise carbon steels and methods of manufacture. In one embodiment, a double austenizing procedure is disclosed in which a selected steel composition is formed and subjected to heat treatment to refine the steel microstructure. In one embodiment, the heat treatment may comprise austenizing and quenching the formed steel composition a selected number of times (e.g., 2) prior to tempering. In another embodiment, the heat treatment may comprise subjecting the formed steel composition to austenizing, quenching, and tempering a selected number of times (e.g., 2). Steel products formed from embodiments of the steel composition in this manner (e.g., seamless tubular bars and pipes) will possess high yield strength, at least about 175 ksi (about 1200 MPa) while maintaining good toughness.
    Type: Application
    Filed: February 18, 2011
    Publication date: August 23, 2012
    Applicant: Siderca S.A.I.C.
    Inventors: Eduardo Altschuler, Teresa Perez, Edgardo Lopez, Constantino Espinosa, Gonzalo Gomez
  • Patent number: 8246762
    Abstract: The invention provides medical devices comprising high-strength alloys which degrade over time in the body of a human or animal, at controlled degradation rates, without generating emboli. In one embodiment the alloy is formed into a bone fixation device such as an anchor, screw, plate, support or rod. In another embodiment the alloy is formed into a tissue fastening device such as staple. In yet another embodiment, the alloy is formed into a dental implant or a stent.
    Type: Grant
    Filed: January 7, 2010
    Date of Patent: August 21, 2012
    Assignee: Bio DG, Inc.
    Inventors: Gordon F. Janko, Herbert R. Radisch, Jr., Thomas A. Trozera
  • Patent number: 8241559
    Abstract: The invention relates to a steel material having a high silicon content, and to a method for the production thereof, the steel material being particularly suitable for piston rings and cylinder sleeves. In addition to iron and production-related impurities, the steel material contains 0.5 to 1.2 wt. % carbon, 3.0 to 15.0 wt. % silicon and 0.5 to 4.5 wt. % nickel. Also, the steel material can contain small amounts of the following elements Mo, Mn, Al, Co Nb, Ti, V, Sn, Mg, B, Te Ta La, Bi, Zr, Sb, Ca, Sr, Cer, rare earth metals and nucleating agents such as NiMg, MiSiMg, FeMg and FeSIMg. due to the high Si content, a degree of saturation higher than 1.0 is attained, with the melting temperature of the steel material corresponding to normal cast iron. The steel material can be produced according to a conventional cast-iron technique and has a high resistance to wear and tear and a high structural strength (minimal distortion).
    Type: Grant
    Filed: May 7, 2007
    Date of Patent: August 14, 2012
    Assignee: Federal-Mogul Burscheid GmbH
    Inventor: Laszlo Pelsoeczy
  • Publication number: 20120186704
    Abstract: A seamless steel tube contains 0.15% to 0.50% C, 0.1% to 1.0% Si, 0.3% to 1.0% Mn, 0.015% or less P, 0.005% or less S, 0.01% to 0.1% Al, 0.01% or less N, 0.1% to 1.7% Cr, 0.4% to 1.1% Mo, 0.01% to 0.12% V, 0.01% to 0.08% Nb, and 0.0005% to 0.003% B or further contains 0.03% to 1.0% Cu on a mass basis and has a microstructure which has a composition containing 0.40% or more solute Mo and a tempered martensite phase that is a main phase and which contains prior-austenite grains with a grain size number of 8.5 or more and 0.06% by mass or more of a dispersed M2C-type precipitate with substantially a particulate shape.
    Type: Application
    Filed: June 23, 2010
    Publication date: July 26, 2012
    Applicant: JFE STEEL CORPORATION
    Inventors: Kenichiro Eguchi, Yuji Tanaka, Mitsuo Kimura, Yasuhide Ishiguro, Katsumi Yamada, Haruo Nakamichi
  • Patent number: 8192565
    Abstract: The present invention provides a steel for machine and structural use which is capable of maintaining mechanical characteristics such as strength by reducing a S content as well as of exhibiting excellent machinability (particularly tool life) in intermittent cutting (such as hobbing) with the high speed tool, and a method useful for producing the steel for machine and structural use. The steel for machine and structural use according to the invention secures 0.002% or more of solute N in the steel and has a chemical composition which is appropriately adjusted and satisfies a relationship of the following expression (1): (0.1×[Cr]+[Al])/[O]?150 . . . (1), in which [Cr], [Al], and [0] represent a Cr content (mass %), an Al content (mass %), and an O content (mass %), respectively.
    Type: Grant
    Filed: June 23, 2008
    Date of Patent: June 5, 2012
    Assignee: Kobe Steel, Ltd.
    Inventors: Tomokazu Masuda, Takehiro Tsuchida, Masaki Shimamoto, Motohiro Horiguchi, Shinsuke Masuda, Koichi Akazawa, Shogo Murakami, Mutsuhisa Nagahama, Hiroshi Yaguchi, Koichi Sakamoto
  • Publication number: 20120132327
    Abstract: Disclosed is a high strength steel sheet having excellent hydrogen embrittlement resistance. The steel sheet has a tensile strength of 1180 MPa or more, and satisfies the following conditions: with respect to an entire metallographic structure thereof, bainite, bainitic ferrite and tempered martensite account for 85 area % or more in total; retained austenite accounts for 1 area % or more; and fresh martensite accounts for 5 area % or less (including 0 area %).
    Type: Application
    Filed: May 28, 2010
    Publication date: May 31, 2012
    Applicants: VOESTALPINE STAHL GMBH, Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)
    Inventors: Yoichi Mukai, Kouji Kasuya, Michiharu Nakaya, Michitaka Tsunezawa, Fumio Yuse, Junichiro Kinugasa, Sandra Traint, Andreas Pichler
  • Publication number: 20120125489
    Abstract: High strength steel wire for spring containing, by mass %, C: 0.67% to less than 0.75%, Si: 2.0 to 2.5%, Mn: 0.5 to 1.2%, Cr: 0.8 to 1.3%, V: 0.03 to 0.20%, Mo: 0.05 to 0.25%, W: 0.05 to 0.30%, and N: 0.003 to 0.007%, having a total of contents of Mn and V of 0.70%?Mn+V?1.27% and a total of contents of Mo and W of 0.13%?Mo+W?0.35%, limiting P: 0.025% or less, S: 0.025% or less, and Al: 0.003% or less, and having a balance of iron and unavoidable impurities, having a microstructure comprised of, by volume percent, over 6% to 15% of retained austenite and tempered martensite, having a prior-austenite grain size number of 10 or more, having a density of presence of spheroidal carbides with a circle equivalent diameter of 0.2 to 0.5 ?m of 0.06 particles/?m2 or less, having a density of presence of spheroidal carbides with a circle equivalent diameter of over 0.5 ?m of 0.01 particles/?m2 or less, and having a tensile strength of 2100 to 2350 MPa.
    Type: Application
    Filed: July 9, 2010
    Publication date: May 24, 2012
    Inventors: Masayuki Hashimura, Hitoshi Demachi, Takayuki Kisu, Shoichi Suzuki, Motonobu Suehiro, Jun Kawaguchi, Keiichi Maekawa, Atsushi Murakami
  • Patent number: 8177925
    Abstract: In a high-tensile steel plate according to the invention, the carbon equivalent Pcm represented in Expression (1) is from 0.180% to 0.220%, the surface hardness is a Vicker's hardness of 285 or less, the ratio of a Martensite Austenite constituent in the surface layer is not more than 10%, the ratio of a mixed structure of ferrite and bainite inside beyond the surface layer is not less than 90%, the ratio of the bainite in the mixed structure is not less than 10%, the thickness of the lath of bainite is not more than 1 ?m, the length of the lath is not more than 20 ?m, and the segregation ratio as the ratio of the Mn concentration in the center segregation part relative to the Mn concentration at a part in a depth equal to ¼ of the thickness of the plate from the surface is not more than 1.3. Pcm=C+Si/30+(Mn+Cu+Cr)/20+Ni/60+Mo/15+V/10+5B . . . (1) where the element symbols in Expression (1) represent the % by mass of the respective elements.
    Type: Grant
    Filed: March 8, 2006
    Date of Patent: May 15, 2012
    Assignee: Sumitomo Metal Industries, Ltd.
    Inventors: Nobuaki Takahashi, Masahiko Hamada, Shuji Okaguchi, Akihiro Yamanaka, Ichirou Seta
  • Patent number: 8168009
    Abstract: “HARD ALLOYS WITH DRY COMPOSITION”, presenting a composition of alloy elements consisting, in mass percentage, of Carbon between 0.5 and 2.0; Chrome between 1.0 and 10.0; Tungsten-equivalent, as given by ratio 2Mo+W, between 7.0 and 14.0; Niobium between 0.5 and 3.5. Niobium can be partially or fully replaced with Vanadium, at a ratio of 2% Niobium to each 1% Vanadium; Vanadium between 0.5 and 3.5. Vanadium can be partially or fully replaced with Niobium, at a ratio of 2% Niobium to each 1% Vanadium; Cobalt lower than 8, the remaining substantially Iron and impurities inevitable to the preparation process. As an option to refine carbides, the steel of the present invention can have content of Nitrogen controlled, below 0.030 and addition of Cerium or other earth elements at content between 0.005 and 0.020. For the same purpose, Silicon and Aluminum can be optionally added, at content between 0.5 and 3.0% for both of them.
    Type: Grant
    Filed: July 18, 2007
    Date of Patent: May 1, 2012
    Inventors: Rafael Agnelli Mesquita, Celso Antonio Barbosa
  • Patent number: 8168011
    Abstract: The invention provides wire rod excellent in drawability and steel wire made from the wire rod as starting material with high productivity at good yield and low cost. A hard steel wire rod of a specified composition is heated in a specified temperature range to conduct post-reaustenization patenting and thereby obtain a high-carbon steel wire excellent in ductility that has a pearlite structure of an area ratio of 97% or greater and the balance of non-pearlite structures including bainite, degenerate-pearlite and pro-eutectoid ferrite and whose fracture reduction of area RA satisfies Expressions (1), (2) and (3) below: RA?RAmin??(1), where RAmin=a?b×pearlite block size (?m), a=?0.0001187×TS (MPa)2+0.31814×TS (MPa)?151.32??(2) b=0.0007445×TS (MPa)?0.3753??(3).
    Type: Grant
    Filed: April 18, 2007
    Date of Patent: May 1, 2012
    Assignee: Nippon Steel Corporation
    Inventors: Shingo Yamasaki, Seiki Nishida, Makio Kikuchi
  • Publication number: 20120093679
    Abstract: The invention relates to a method for the production of tools for a chip-removing machining of metallic materials and to a tool with improved wear resistance and/or high toughness. The invention further provides an alloyed steel with a chemical composition comprising carbon, silicon, manganese, chromium, molybdenum, tungsten, vanadium, and cobalt as well as aluminum, nitrogen, and iron. The alloyed steel may be used to make tools to a hardness of greater than 66 HRC and increased chip-removing machining performance.
    Type: Application
    Filed: October 17, 2011
    Publication date: April 19, 2012
    Applicant: BOEHLER EDELSTAHL GMBH & CO. KG
    Inventors: Gert KELLEZI, Devrim CALISKANOGLU, Andreas BAERNTHALER
  • Publication number: 20120085465
    Abstract: A carburized component with improved fatigue strength has a base steel containing, by mass %, C: 0.15-0.25%, Si: 0.03-0.50%, Mn: more than 0.60% and not more than 1.5%, P?0.015%, S: 0.006-0.030%, Cr: 0.05-2.0%, Al?0.10%, N?0.03%, and O?0.0020%, and optionally at least one element selected from Mo, Cu, Ni, B, Ti, Nb and V, the balance being Fe and impurities. A surface hardened layer portion satisfies: (a) average carbon concentration in the region from the outermost surface to a point of 0.2 mm depth of 0.35-0.60 mass %, (b) surface roughness Rz?15 ?m, and (c) ?r(0)?-800 MPa, ?r(100)?-800 MPa, and residual stress intensity index Ir?80000, wherein Ir is calculated by [Ir=?|?r(y)|dy], where y ?m is the depth from the outermost surface and ?r(y) is the residual stress for the points from the outermost surface to a depth of 100 ?m with the range of y from 0 to 100 (?m).
    Type: Application
    Filed: November 28, 2011
    Publication date: April 12, 2012
    Applicants: SINTOKOGIO, LTD., SUMITOMO METAL INDUSTRIES, LTD.
    Inventors: Yutaka Neishi, Takanari Hamada, Hidekazu Sueno, Yuji Kobayashi, Hideaki Sugiura
  • Patent number: 8147623
    Abstract: To provide a steel pipe as a fuel injection pipe with high material strength, high internal pressure limit free from fatigue failure, prolonged fatigue life, and high reliability. A steel pipe as a fuel injection pipe of 500 N/mm2 or higher tensile strength comprising, by mass, C: 0.12 to 0.27%, Si: 0.05 to 0.40%, and Mn: 0.8 to 2.0%, and the balance being Fe and impurities, the contents of Ca, P, and S in the impurities being Ca: 0.001% or less, P: 0.02% or less, and S: 0.01% or less, respectively, characterized in that the maximum diameter of nonmetallic inclusions present in at least in a region extending from the inner surface of the steel pipe to a depth of 20 ?m is 20 ?m or less. Further, this steel pipe may contain, in place of a portion of Fe, at least one selected from among Cr: 1% or less, Mo: 1% or less, Ti: 0.04% or less, Nb: 0.04% or less, and V: 0.1% or less.
    Type: Grant
    Filed: October 2, 2008
    Date of Patent: April 3, 2012
    Assignee: Sumitomo Metal Industries, Ltd.
    Inventors: Kikuo Asada, Osamu Endo, Katsunori Nagao, Keisuke Hitoshio
  • Patent number: 8128762
    Abstract: Disclosed is a high-strength steel sheet which has a predetermined component composition, structurally has a ferrite matrix structure and bainitic and martensitic second phase structures, and has a ferrite fraction of from 50 to 86 percent by area, a bainite fraction of from 10 to 30 percent by area, and a martensite fraction of from 4 to 20 percent by area, relative to the entire structure, in which the bainite area fraction is larger than the martensite area fraction, the ferrite has an average grain size of 2.0 to 5.0 ?m, and the ratio of the average ferrite hardness (Hv) to the tensile strength (MPa) of the steel sheet is equal to or more than 0.25. The steel sheet excels both in TS-EL balance and TS-? balance at high strengths on the order of 590 to 780 MPa.
    Type: Grant
    Filed: July 7, 2009
    Date of Patent: March 6, 2012
    Assignee: Kobe Steel, Ltd.
    Inventor: Seiko Watanabe
  • Patent number: 8110292
    Abstract: The present invention provides high strength steel plate with excellent low temperature toughness, high strength steel pipe using this as a base metal, and methods of production of the same. The steel plate of the present invention contains Mo: 0.05 to 1.00% and B: 0.0003 to 0.0100%, has a Ceq of 0.30 to 0.53, has a Pcm of 0.10 to 0.20, and has a metal structure which has an area percentage of polygonal ferrite of 20 to 90% and has a balance of a hard phase comprised of one or both of bainite and martensite. To obtain this steel plate, strain-introducing rolling is performed with a start temperature of not more than Ar3+60° C., an end temperature of Ar3 or more, and a reduction ratio of 1.5 or more, then the plate is air-cooled and then acceleratedly cooled from Ar3?100° C. to Ar3?10° C. in temperature by 10° C./s or more.
    Type: Grant
    Filed: April 4, 2009
    Date of Patent: February 7, 2012
    Assignee: Nippon Steel Corporation
    Inventors: Taishi Fujishiro, Shinya Sakamoto, Takuya Hara, Hitoshi Asahi
  • Publication number: 20120014831
    Abstract: The present invention provides a wire rod with a composition at least including: C: 0.95-1.30 mass %; Si: 0.1-1.5 mass %; Mn: 0.1-1.0 mass %; Al: 0-0.1 mass %; Ti: 0-0.1 mass %; P: 0-0.02 mass %; S: 0-0.02 mass %; N: 10-50 ppm; O: 10-40 ppm; and a balance including Fe and inevitable impurities, wherein 97% or more of an area in a cross-section perpendicular to the longitudinal direction of the wire rod is occupied by a pearlite, and 0.5% or less of an area in a central area in the cross-section and 0.5% or less of an area in a first surface layer area in the cross-section are occupied by a pro-eutectoid cementite.
    Type: Application
    Filed: October 19, 2010
    Publication date: January 19, 2012
    Inventors: Shingo Yamasaki, Toshiyuki Manabe, Daisuke Hirakami, Nariyasu Muroga
  • Patent number: 8097096
    Abstract: The present invention provides a fire resistant steel material excellent in high temperature strength, toughness, and reheating embrittlement resistance containing, by mass %, C: 0.001% to 0.030%, Si: 0.05% to 0.50%, Mn: 0.4% to 2.0%, Nb: 0.03% to 0.50%, Ti: 0.005% to less than 0.040%, N: 0.0001% to less than 0.0050%, and Al: 0.005% to 0.030%, limiting P: 0.03% or, less and S: 0.02% or less, satisfying C—Nb/7.74?0.005 and 2?Ti/N?12, and having a balance of Fe and unavoidable impurities and, further, a process for production of a fire resistant material comprising heating a steel slab comprised of this chemical composition to 1100 to 1350° C. and hot rolling it by a cumulative reduction rate at 1000° C. or less of 30% or more.
    Type: Grant
    Filed: July 30, 2007
    Date of Patent: January 17, 2012
    Assignee: Nippon Steel Corporation
    Inventors: Suguru Yoshida, Kita Hiroshi, Hirokazu Sugiyama, Yoshiyuki Watanabe, Yasushi Hasegawa
  • Patent number: 8097207
    Abstract: Method for reducing the segregated seams of a steel which has high mechanical strength and high wear resistance and whose composition comprises by weight: 0.30%?C?1.42%; 0.05%?Si?1.5%; Mn?1.95%; Ni?2.9%; 1.1%?Cr?7.9%; 0.61%?Mo?4.4%; optionally V?1.45%, Nb?1.45%, Ta?1.45% and V+Nb/2+Ta/4?1.45%; less than 0.1% of boron, less than 0.19% of (S+Se/2+Te/4), less than 0.01% of calcium, less than 0.5% of rare earths, less than 1% of aluminum, less than 1% of copper; the balance being iron and impurities resulting from the production operation. The composition further complies with: 800?D?1150 with D=540(C)0.25+245(Mo+3V+1.5Nb+0.75Ta)0.30+125Cr0.20+15.8Mn+7.4Ni+18Si. According to the method, the molybdenum is completely or partially replaced with double the proportion of tungsten so that W>0.21%, and Ti, Zr, C are adjusted so that, after adjustment, Ti+Zr/2?0.2W, (Ti+Zr/2)×C?0.07, Ti+Zr/2?1.49% and D is unchanged at approximately 5%. Steel obtained and method for producing a steel workpiece.
    Type: Grant
    Filed: May 10, 2010
    Date of Patent: January 17, 2012
    Assignee: Industeel Creusot
    Inventors: Jean Beguinot, Dominique Viale
  • Patent number: 8097099
    Abstract: The present invention provides an abrasion resistant steel having a hardness of HB400 to HB520, having little change of hardness during long term use, and superior in toughness, characterized by containing, by mass %, C: 0.21% to 0.30%, Si: 0.30 to 1.00%, Mn: 0.32 to 0.70%, P: 0.02% or less, S: 0.01% or less, Cr: 0.1 to 2.0%, Mo: 0.1 to 1.0%, B: 0.0003 to 0.0030%, Al: 0.01 to 0.1%, and N: 0.01% or less, further containing one or more of V: 0.01 to 0.1%, Nb: 0.005 to 0.05%, Ti: 0.005 to 0.03%, Ca: 0.0005 to 0.05%, Mg: 0.0005 to 0.05%, and REM: 0.001 to 0.
    Type: Grant
    Filed: August 18, 2006
    Date of Patent: January 17, 2012
    Assignee: Nippon Steel Corporation
    Inventors: Naoki Saitoh, Tatsuya Kumagai, Katsumi Kurebayashi, Hirohide Muraoka