With Flattening, Straightening, Or Tensioning By External Force Patents (Class 148/645)
  • Patent number: 10704117
    Abstract: Provided are a cold-rolled steel sheet which can preferably be used for manufacturing a high-strength galvanized steel sheet and methods for manufacturing the steel sheets. The cold-rolled steel sheet has a specified chemical composition, in which the Mn concentration in a surface layer of the steel sheet satisfies relational expression (1) and relational expression (2) below. 8?(Cp/Cc)×Mn . . . (1) (Cmin/Cc)×Mn?2.5 . . . (2) where Cp: maximum Mn concentration in a region within 0.5 ?m of the surface of a steel sheet in the thickness direction; Cc: average Mn concentration in a region from a position located 5 ?m from a surface of a steel sheet in the thickness direction to a position located 5 ?m from an opposite surface in the thickness direction; Cmin: minimum Mn concentration in a region from 0.5 ?m to 5 ?m from the surface of a steel sheet in the thickness direction; and Mn: Mn content (mass %).
    Type: Grant
    Filed: July 28, 2016
    Date of Patent: July 7, 2020
    Assignee: JFE Steel Corporation
    Inventors: Kenji Kawamura, Noriaki Kohsaka, Yoshimasa Funakawa, Mai Aoyama, Yoshitsugu Suzuki
  • Patent number: 10662496
    Abstract: Disclosed is a high-strength steel sheet having a tensile strength (TS) of 780 MPa or more and excellent in ductility, fatigue properties, balance between high strength and ductility, surface characteristics, and sheet passage ability that can be obtained by providing a predetermined chemical composition and a steel microstructure that contains, by area, 20-50% of ferrite, 5-25% of bainitic ferrite, and 5-20% of martensite, and that contains, by volume, 10% or more of retained austenite, in which the retained austenite has a mean grain size of 2 ?m or less, a mean Mn content in the retained austenite in mass % is at least 1.2 times the Mn content in the steel sheet in mass %, and the retained austenite has a mean free path of 1.2 ?m or less.
    Type: Grant
    Filed: August 5, 2015
    Date of Patent: May 26, 2020
    Assignee: JFE STEEL CORPORATION
    Inventors: Yoshiyasu Kawasaki, Hiroshi Matsuda, Kazunori Tahara, Takeshi Yokota, Kaneharu Okuda, Kazuhiro Seto
  • Patent number: 10662495
    Abstract: Disclosed is a high-strength steel sheet having a tensile strength (TS) of 780 MPa or more and excellent in ductility, fatigue properties, stretch flangeability, surface characteristics, and sheet passage ability that can be obtained by providing a predetermined chemical composition and a steel microstructure that contains, by area, 20-50% of ferrite, 5-25% of bainitic ferrite, 1-10% of martensite, and 5-15% of tempered martensite, and that contains, by volume, 10% or more of retained austenite, in which the retained austenite has a mean grain size of 2 ?m or less, a mean Mn content in the retained austenite in mass % is at least 1.2 times the Mn content in the steel sheet in mass %, the retained austenite has a mean free path of 1.2 ?m or less, and the tempered martensite has a mean free path of 1.2 ?m or less.
    Type: Grant
    Filed: August 5, 2015
    Date of Patent: May 26, 2020
    Assignee: JFE STEEL CORPORATION
    Inventors: Yoshiyasu Kawasaki, Hiroshi Matsuda, Kazunori Tahara, Takeshi Yokota, Kaneharu Okuda, Kazuhiro Seto
  • Patent number: 10643771
    Abstract: A method of manufacturing a non-oriented electrical steel sheet is disclosed. A method of manufacturing a non-oriented electrical steel sheet according to the present invention includes reheating slab consisting of Si: 2.0-4.0%, acid-soluble Al: 0.01-0.04%, Mn: 0.20% or less, Sb: 0.005-0.10%, N: 0.005% or less, S:0.005% or less, C: 0.005-0.015%, Fe in a balance amount, and other inevitable impurities in weight percent (wt %); hot rolling the slab to prepare a hot rolled steel sheet; cold rolling the hot rolled steel sheet to prepare a cold rolled steel sheet; primarily recrystallization-annealing the cold rolled steel sheet; and high-temperature annealing the cold rolled steel sheet subjected to the primarily recrystallization-annealing.
    Type: Grant
    Filed: December 5, 2014
    Date of Patent: May 5, 2020
    Assignee: POSCO
    Inventors: Hunju Lee, Sang-Woo Lee, Su-Yong Sin
  • Patent number: 10526687
    Abstract: Provided is an ultra-high-strength steel sheet having a component composition that includes specific amounts of each of C, Mn, and Al and a remainder of iron and unavoidable impurities, and in which the amounts of each of P, S, and N among the unavoidable impurities are limited to a specific amount. The ultra-high-strength steel sheet includes 2 area% or more of a region having a structure that includes 90% or more of martensite and 0.5% or more of residual austentite by area ratio relative to the entire structure, the local Mn concentration in said region being at least 1.1 times that of the Mn content of the entire steel sheet. The ultra-high-strength steel sheet has a tensile strength of 1470 MPa or more.
    Type: Grant
    Filed: February 8, 2016
    Date of Patent: January 7, 2020
    Assignee: KOBE STEEL, LTD.
    Inventors: Kosuke Shibata, Toshiya Nakata, Toshio Murakami, Takahiro Ozawa, Fumio Yuse, Atsuhiro Shiraki, Kenji Saito, Yukihiro Utsumi
  • Patent number: 10400299
    Abstract: There is provided a high-carbon hot-rolled steel sheet and method for producing the same. The steel sheet has excellent hardenability consistently, even when annealed in a nitrogen atmosphere, and excellent workability. The steel sheet has a hardness in the range of 65 or less in terms of HRB and a total elongation El of 40% or more before a quenching treatment is performed.
    Type: Grant
    Filed: July 8, 2014
    Date of Patent: September 3, 2019
    Assignee: JFE STEEL CORPORATION
    Inventors: Yuka Miyamoto, Takashi Kobayashi, Chikara Kami
  • Patent number: 10400298
    Abstract: There is provided is a high-carbon hot-rolled steel sheet and method for producing the same. The steel sheet has excellent hardenability consistently, even when annealed in a nitrogen atmosphere, and excellent formability. The steel sheet has a hardness in the range of 83 HRB or less and a total elongation of 30% or more before being subjected to a quenching treatment.
    Type: Grant
    Filed: July 8, 2014
    Date of Patent: September 3, 2019
    Assignee: JFE STEEL CORPORATION
    Inventors: Yuka Miyamoto, Takashi Kobayashi, Chikara Kami, Hayato Saito, Kaneharu Okuda
  • Patent number: 10260120
    Abstract: A process for reducing flatness deviations in an alloy article is disclosed. An alloy article may be heated to a first temperature at least as great as a martensitic transformation start temperature of the alloy. A mechanical force may be applied to the alloy article at the first temperature. The mechanical force may tend to inhibit flatness deviations of a surface of the alloy article. The alloy article may be cooled to a second temperature no greater than a martensitic transformation finish temperature of the alloy. The mechanical force may be maintained on the alloy article during at least a portion of the cooling of the alloy article from the first temperature to the second temperature.
    Type: Grant
    Filed: September 1, 2017
    Date of Patent: April 16, 2019
    Assignee: ATI PROPERTIES LLC
    Inventors: Glenn J. Swiatek, Ronald E. Bailey
  • Patent number: 10156005
    Abstract: A steel sheet includes a microstructure containing a volume fraction of 20% to 55% of ferrite having an average grain size of 7 ?m or less, a volume fraction of 5% to 15% of retained austenite, a volume fraction of 0.5% to 7% of martensite having an average grain size of 4 ?m or less, and a structure composed of bainite and/or tempered martensite and having an average grain size of 6 ?m or less, and a difference in nano-hardness between ferrite and the structure composed of bainite and/or tempered martensite being 3.5 GPa or less and a difference in nano-hardness between the structure composed of bainite and/or tempered martensite and martensite being 2.5 GPa or less.
    Type: Grant
    Filed: July 18, 2014
    Date of Patent: December 18, 2018
    Assignee: JFE Steel Corporation
    Inventors: Katsutoshi Takashima, Yoshihiko Ono, Kohei Hasegawa
  • Patent number: 10100385
    Abstract: A high-formability, super-high-strength, hot-dip galvanized steel plate, the chemical composition of which comprises, based on weight percentage, C: 0.15-0.25 wt %, Si: 1.00-2.00 wt %, Mn: 1.50-3.00 wt %, P?0.015 wt %, S?0.012 wt %, Al: 0.03-0.06 wt %, N?0.008 wt %, and the balance of iron and unavoidable impurities. The room temperature structure of the steel plate comprises 10-30% ferrite, 60-80% martensite and 5-15% residual austenite. The steel plate has a yield strength of 600-900 MPa, a tensile strength of 980-1200 MPa, and an elongation of 15-22%. Through an appropriate composition design, a super-high-strength, cold rolled, hot-dip galvanized steel plate is manufactured by continuous annealing, wherein no expensive alloy elements are added; instead, remarkable increase of strength along with good plasticity can be realized just by appropriate augment of Si, Mn contents in combination with suitable processes of annealing and furnace atmosphere control.
    Type: Grant
    Filed: February 21, 2013
    Date of Patent: October 16, 2018
    Assignee: Baoshan Iron & Steel Co., Ltd.
    Inventors: Yong Zhong, Li Wang, Weijun Feng, Liyang Zhang
  • Patent number: 10100383
    Abstract: Provided is martensitic steel which is used in structures such as buildings and bridges, and automotive underbody, and mechanical parts such as gears and is more suitably used for steel products such as thick steel sheets, shape steel, a deformed steel bar, steel bars, or steel wires. The martensitic steel has a microstructure of a martensite structure containing a chemical composition, by mass %, of Si: 1.0 to 3.5%, Mn: 4.5 to 5.5%, Al: 0.001 to 0.080%, Nb: 0.045% or less, and C having an amount in which the following regression equation (1) is satisfied and the maximum stress (TS) becomes 1800 to 2160 MPa, a balance being Fe and inevitable impurities of: P: 0.030% or less, S: 0.020% or less, and N: 0.010% or less, the martensitic steel having total elongation of 13 to 15%. TS(maximum stress) [MPa]=4000×C[mass %]+1050??(1).
    Type: Grant
    Filed: July 9, 2014
    Date of Patent: October 16, 2018
    Assignee: NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Toshihiro Hanamura, Shiro Torizuka
  • Patent number: 10000833
    Abstract: A thick, high-toughness high-strength steel plate has excellent strength and toughness in the central area through the plate thickness. The thick steel plate has a specific chemical composition and includes a microstructure having, throughout an entire region in the plate thickness direction, an average prior austenite grain size of not more than 50 ?m and a martensite and/or bainite phase area fraction of not less than 80%. A continuously cast slab having the specific chemical composition is heated to 1200° C. to 1350° C., hot worked with a strain rate of not more than 3/s and a cumulative working reduction of not less than 15%, and thereafter hot rolled and heat treated.
    Type: Grant
    Filed: March 11, 2014
    Date of Patent: June 19, 2018
    Assignee: JFE STEEL CORPORATION
    Inventors: Shigeki Kitsuya, Naoki Matsunaga, Katsuyuki Ichimiya, Kazukuni Hase, Shigeru Endo
  • Patent number: 9777358
    Abstract: A thick-walled high-strength steel plate with excellent low-temperature toughness (Charpy impact and CTOD properties of a weld bond) in a multilayer weld zone, and a method for manufacturing the steel plate.
    Type: Grant
    Filed: September 4, 2013
    Date of Patent: October 3, 2017
    Assignee: JFE STEEL CORPORATION
    Inventors: Katsuyuki Ichimiya, Masao Yuga, Kenji Hayashi
  • Patent number: 9725782
    Abstract: In a hot stamped steel, when [C] represents an amount of C (mass %), [Si] represents an amount of Si (mass %), and [Mn] represents an amount of Mn (mass %), an expression of 5×[Si]+[Mn])/[C]>10 is satisfied, a metallographic structure includes 80% or more of a martensite in an area fraction, and optionally, further includes one or more of 10% or less of a pearlite in an area fraction, 5% or less of a retained austenite in a volume ratio, 20% or less of a ferrite in an area fraction, and less than 20% of a bainite in an area fraction, TS×?, which is a product of TS that is a tensile strength and ? that is a hole expansion ratio is 50000 MPa·% or more, and a hardness of the martensite measured with a nanoindenter satisfies H2/H1<1.10 and ?HM<20.
    Type: Grant
    Filed: January 11, 2013
    Date of Patent: August 8, 2017
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Toshiki Nonaka, Satoshi Kato, Kaoru Kawasaki, Toshimasa Tomokiyo
  • Patent number: 9728312
    Abstract: A non-oriented electrical steel sheet containing: in mass %, C: 0.005% or less; Si: 0.1% to 2.0%; Mn: 0.05% to 0.6%; P: 0.100% or less; and Al: 0.5% or less, in which 10 pieces/?m3 or less in number density of non-magnetic precipitate AlN having an average diameter of 10 nm to 200 nm are contained, and an average magnetic flux density B50 in a rolling direction and in a direction perpendicular to rolling is 1.75 T or more. This non-oriented electrical steel sheet can be manufactured by two methods of a method of performing hot rolling annealing at a temperature of 750° C. to an Ac1 transformation point and a method of setting a coil winding temperature to 780° C. or higher and performing self annealing.
    Type: Grant
    Filed: November 9, 2012
    Date of Patent: August 8, 2017
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Masahiro Fujikura, Yoshiyuki Ushigami, Tesshu Murakawa, Shinichi Kanao, Makoto Atake, Takeru Ichie, Kojiro Hori
  • Patent number: 9605329
    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: Grant
    Filed: January 11, 2013
    Date of Patent: March 28, 2017
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Toshiki Nonaka, Satoshi Kato, Kaoru Kawasaki, Toshimasa Tomokiyo
  • Patent number: 9359663
    Abstract: Provided is a method for manufacturing a hot press formed steel member that has high strengths, an excellent balance between strength and ductility, and good deformation properties upon crush on collision (crashworthiness). The manufacturing method is highly efficient and allows a high degree of freedom with respect to the shape to be formed. The method manufactures a steel member by heating a steel sheet having a specific chemical composition and subjecting the steel sheet to at least one time of hot press forming. In the method, the heating temperature is equal to or higher than the Ac3 transformation temperature, and a starting temperature of the hot press forming is in the range from the heating temperature to martensite start (Ms) temperature. Cooling from [(Ms temperature)?150° C.] down to 80° C. is performed so that a tempering parameter (?) specified by Expression (1) is in the range from 7100 to 8030.
    Type: Grant
    Filed: January 17, 2014
    Date of Patent: June 7, 2016
    Assignee: Kobe Steel, Ltd.
    Inventors: Naoki Mizuta, Tatsuya Asai, Takayuki Yamano, Tetsuji Hoshika
  • Patent number: 9061335
    Abstract: A cooling apparatus for hot rolling is installed on a downstream side of a finishing mill of a continuous hot rolling mill, and cools a steel sheet rolled by the finishing mill while being conveyed. The cooling apparatus includes first pinch rolls which, during an interval when the steel sheet fed out from a final stand of the finishing mill moves from a position of the final stand to a position where a surface temperature of the steel sheet reaches 850° C. or less, pinch the steel sheet while applying tension of 3.9 MPa or greater.
    Type: Grant
    Filed: October 7, 2009
    Date of Patent: June 23, 2015
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Yoshihiro Serizawa, Shigeru Ogawa, Yoji Nakamura, Tooru Akashi, Noriyuki Hishinuma, Tetsuo Kishimoto
  • Patent number: 9062363
    Abstract: The present invention provides a hot coil for line pipe use which can reduce deviation in ordinary temperature strength and improve low temperature toughness despite the numerous restrictions in production conditions due to the coiling step and provides a method of production of the same, specifically makes the steel plate stop for a predetermined time between rolling passes in the recrystallization temperature range and performs cooling by two stages after hot rolling so as to thereby make the steel structure at the center part of plate thickness and effective crystal grain size of 3 to 10 ?m, make the total of the area ratios of bainite and acicular ferrite 60 to 99%, and make the absolute value of A-B 0 to 30% when the totals of the area ratios of bainite and acicular ferrite at any two portions are designated as respectively A and B.
    Type: Grant
    Filed: September 27, 2012
    Date of Patent: June 23, 2015
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Takuya Hara, Takeshi Kinoshita, Kazuaki Tanaka
  • Publication number: 20150144233
    Abstract: Provided is a mold steel for plastic injection that is excellent in fatigue strength and tensile strength and available for long term use, where the mold steel includes: 0.15 to 0.40 wt. % of carbon (C), 0.15 to 0.50 wt. % of silicon (Si), 0.70 to 1.50 wt. % of manganese (Mn), 0.50 to 1.20 wt. % of nickel (Ni), 1.50 to 2.50 wt. % of chrome (Cr), 0.25 to 0.70 wt. % of molybdenum (Mo), 0.20 wt. % or less of vanadium (V), 0.010 wt. % or less of boron (B), and a trace of iron (Fe) and a plurality of impurities.
    Type: Application
    Filed: November 26, 2014
    Publication date: May 28, 2015
    Applicant: DOOSAN HEAVY INDUSTRIES & CONSTRUCTION CO., LTD.
    Inventors: Young Chul PARK, Soo Mok LEE, Myeong Su JANG, Jei Yeong JEON
  • Patent number: 9034118
    Abstract: A method for manufacturing a hot-rolled sheet attains grain refinement of the steel sheet whose grain size is extremely fine. In particular, a ferrite grain size of less than average 2 ?m is obtained, which is not laminar but has ferrite grains with equiaxed morphology and exhibits high formability in forming. The method comprises the steps of rolling and cooling, wherein the rolling reductions, cooling steps, and temperature are closely regulated. A hot rolled sheet made from the method of manufacturing has a controlled ferrite grain in different regions of sheet thickness.
    Type: Grant
    Filed: March 11, 2013
    Date of Patent: May 19, 2015
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Suguhiro Fukushima, Manabu Eto, Tamotsu Sasaki, Kaori Kawano, Masayuki Wakita
  • Publication number: 20150129094
    Abstract: This bearing steel material satisfies a predetermined elemental composition, and is characterized by having, in the region (boundary region) from the boundary surface of spheroidal cementite to a position at 20 nm away in a base material, no greater than 0.6% (excluding 0%) of Si (boundary Si), no greater than 0.10% (excluding 0%) of Ni (boundary Ni), no greater than 0.10% (excluding 0%) of Cu (boundary Cu), no greater than 0.03% (including 0%) of Mo (boundary Mo), no greater than 0.10% (excluding 0%) of Mn (boundary Mn), and no greater than 0.9% (excluding 0%) of Cr (boundary Cr), and the circularity coefficient of the spheroidized cementite being at least 0.80. The bearing steel material exhibits favorable cold-workability during the production of a bearing component by means of cold working.
    Type: Application
    Filed: March 5, 2013
    Publication date: May 14, 2015
    Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)
    Inventors: Masaki Kaizuka, Yosuke Shindo
  • Publication number: 20150090370
    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 structure being a dual-phase structure consisting of a bainite phase and island martensite, 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, and the remainder of the structure is a bainite phase.
    Type: Application
    Filed: March 29, 2013
    Publication date: April 2, 2015
    Applicant: JFE Steel Corporation
    Inventors: Junji Shimamura, Kimihiro Nishimura
  • Publication number: 20150075682
    Abstract: The present invention provides a high tensile strength steel plate having a chemical composition containing, in percent by mass, 0.03% to 0.12% of C, 0.01% to 0.30% of Si, 0.5% to 1.95% of Mn, 0.008% or less of P, 0.005% or less of S, 0.015% to 0.06% of Al, 0.011% to 0.05% of Nb, 0.005% to 0.02% of Ti, 0.001% to 0.006% of N, 0.0005% to 0.003% of Ca, optionally, one or two or more of Cr, Mo, V, Cu, and Ni, in which Ceq is 0.44 or less, Ti/N is 1.5 to 3.5, and parameter formulas composed of specific elements for controlling the sulfide morphology and the degree of center segregation in the steel are satisfied, and the balance being Fe and incidental impurities, in which the hardness of the center segregation area of the steel sheet is further specified.
    Type: Application
    Filed: March 1, 2012
    Publication date: March 19, 2015
    Applicant: JFE Steel Corporation
    Inventors: Masao Yuga, Shigeki Kitsuya, Yusuke Terazawa, Minoru Suwa, Kenji Hayashi
  • Publication number: 20150047757
    Abstract: The present invention provides a steel sheet for a rotor core for an IPM motor, wherein the steel sheet has a magnetic flux density B8000 of 1.65 T or more as measured when magnetic field strength is 8000 A/m, and a residual magnetic flux density Br of 0.5 T or more as measured at that time, and optionally, a coercivity Hc of 100 A/m or more as measured after magnetization reaches 8000 A/m. By using the steel sheet of the present, invention for a rotor core of an IPM motor, it is possible to increase further an output torque in a high-speed rotational range and raise further the maximum, rotational speed.
    Type: Application
    Filed: March 27, 2013
    Publication date: February 19, 2015
    Applicant: NISSHIN STEEL CO., LTD.
    Inventors: Tomonaga Iwatsu, Yukio Katagiri, Susumu Fujiwara, Akito Kawamoto
  • Publication number: 20150041024
    Abstract: In a process for producing a cold- or hot-rolled steel strip from an ultrahigh-strength multiphase steel having a particular composition the required multiphase microstructure is generated during continuous heat treatment. The cold- or hot-rolled steel strip is heated in the continuous heat treatment furnace to a temperature in the range from 700 to 950° C. and the heat-treated steel strip is subsequently cooled from the heat treatment temperature at a cooling rate of from 15 to 100° C./s to a first intermediate temperature of from 300 to 500° C. followed by cooling at a cooling rate of from 15 to 100° C./s to a second intermediate temperature of from 200 to 250° C.; the steel strip is subsequently cooled at a cooling rate of from 2 to 30° C./s in air to room temperature or the cooling at a cooling rate of from 15 to 100° C./s is maintained from the first intermediate temperature to room temperature.
    Type: Application
    Filed: January 15, 2013
    Publication date: February 12, 2015
    Inventors: Thomas Schulz, Andreas Wedemeier, Wilfried Sprock, Volker Flaxa, Friedrich Luther, Ingwer Denks, Sven Schulz
  • Publication number: 20150041029
    Abstract: The present invention is a steel for a mechanical structure for cold working, the steel characterized in containing C, Si, Mn, P, S, Al, N, and Cr, the remainder being iron and inevitable impurities; the metal composition having pearlite and pro-eutectoid ferrite; the combined area of the pearlite and pro-eutectoid ferrite being 90% or more of the total composition; the area percentage A of the pro-eutectoid ferrite having the relationship A>Ae, where Ae=(0.8?Ceq)×96.75 (Ceq=[C]+0.1×[Si]+0.06×[Mn]?0.11×[Cr], and “(element names)” indicates the element content (percent in mass); and the mean grain size of the pro-eutectoid ferrite and the ferrite in the pearlite being 15 to 25 ?m.
    Type: Application
    Filed: April 4, 2013
    Publication date: February 12, 2015
    Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)
    Inventors: Koji Yamashita, Takehiro Tsuchida, Masamichi Chiba
  • Publication number: 20150037610
    Abstract: A high-strength cold-rolled steel sheet includes a composition having controlled amounts of carbon, silicon, manganese, phosphorous, sulfur, titanium, niobium, sol. Aluminum, chromium, molybdenum, vanadium, boron, calcium, REM, and iron. A microstructure thereof has a main phase of ferrite of at least 40 area %, and a second phase of a low-temperature transformation phase consisting either or both of martensite and bainite, which comprises at least 10 area % in total and retained austenite (?) at least comprising 3 area %. An average grain diameter of ferrite has a tilt angle of at least 15° is at most 5.0 mm, an average grain diameter of the low-temperature transformation-produced phase is at most 2.0 mm, an average grain diameter of lump-like retained ? having an aspect ratio of less than 5 is at most 1.5 mm, and an area fraction of the lump-like retained ? relative to the retained ? is at least 50%.
    Type: Application
    Filed: February 13, 2013
    Publication date: February 5, 2015
    Inventors: Kengo Hata, Toshiro Tomida, Norio Imai, Jun Haga, Takuya Nishio
  • Publication number: 20150034219
    Abstract: A steel sheet has a microstructure including ferrite phase: 40% to 60%, bainite phase: 10% to 30%, tempered martensite phase: 20% to 40%, and retained austenite phase: 5% to 20% by volume fraction, and satisfying a condition that a ratio of tempered martensite phase having major axis length ?5 ?m to a total volume fraction of the tempered martensite phase is 80% to 100%.
    Type: Application
    Filed: February 28, 2013
    Publication date: February 5, 2015
    Inventors: Hidetaka Kawabe, Takeshi Yokota, Reiko Sugihara, Shigeyuki Aizawa, Kazuki Nakazato
  • Publication number: 20150007914
    Abstract: The invention discloses a process and apparatus for micro-treating an iron-based alloy including heating and immediately quenching to room temperature to produce high tensile iron-based alloy with varying thicknesses. The process may or may not be practiced with or without tension, under various controllable tensions in order to create desirable effects. The micro-treated iron-based alloy contains desirable bainite to increase its formability and tensile strength. The varying thickness of the iron-based alloys is desirable for different applications, such as forming automobile panels.
    Type: Application
    Filed: July 8, 2013
    Publication date: January 8, 2015
    Applicant: SFP Works, LLC
    Inventors: Gary M. Cola, JR., Jeff W. Ziolkowski, Todd C. Ziolkowski
  • Publication number: 20140360632
    Abstract: A method of manufacturing a high strength steel sheet having excellent formability suitable for the material of an automotive part has a tensile strength (TS) of 980 MPa or more and total elongation (EL) is 25% or more. A steel slab has a chemical composition containing C: 0.03% to 0.35%, Si: 0.5% to 3.0%, Mn: 3.5% to 10.0%, P: 0.100% or less, S: 0.02% or less, and the remainder includes Fe and incidental impurities on a percent by mass basis is hot-rolled, a heat treatment is performed, in which an achieved temperature of Ac1 to Ac1+100° C. is held for 3 minutes or more, subsequently, cold rolling is performed at a rolling reduction of 20% or more and, annealing is performed, in which an achieved temperature of Ac1?30° C. to Ac1+100° C. is held for 1 minute or more.
    Type: Application
    Filed: October 17, 2012
    Publication date: December 11, 2014
    Applicant: JFE Steel Corporation
    Inventors: Hiroshi Hasegawa, Yoshiyasu Kawasaki, Tatsuya Nakagaito, Shinjiro Kaneko, Yasunobu Nagataki
  • Publication number: 20140332123
    Abstract: Provided are a high-strength steel sheet and a method for producing the same. A high-strength steel sheet has a composition containing 0.10% to 0.18% C, more than 0.5% to 1.5% Si, 0.5% to 1.5% Mn, 0.05% or less P, 0.005% or less S, and 0.05% or less Al on a mass basis, the remainder being Fe and inevitable impurities and also has a microstructure containing ferrite and pearlite. The volume fraction of the ferrite is 70% to 97%. The volume fraction of the pearlite is 3% or more. The volume fraction of cementite present at grain boundaries of the ferrite is 2% or less. The sum of the volume fractions of phases other than the ferrite, the pearlite, and the cementite is less than 3%. The average grain size of the ferrite is 7 ?m or less.
    Type: Application
    Filed: November 29, 2012
    Publication date: November 13, 2014
    Applicant: JFE STEELCORPORATION
    Inventors: Kouichi Nakagawa, Kenji Kawamura, Takeshi Yokota, Kazuhiro Seto
  • Patent number: 8882942
    Abstract: A Ni-added steel plate contains, by mass %, C: 0.03% to 0.10%, Si: 0.02% to 0.40%, Mn: 0.3% to 1.2%, Ni: 5.0% to 7.5%, Cr: 0.4% to 1.5%, Mo: 0.02% to 0.4%, Al: 0.01% to 0.08%, T.O: 0.0001% to 0.0050%, P: limited to 0.0100% or less, S: limited to 0.0035% or less, and N: limited to 0.0070% or less with a remainder composed of Fe and inevitable impurities, in which a Ni segregation ratio at a position of ¼ of a plate thickness away from a plate surface in a thickness direction is 1.3 or less, a fraction of austenite after deep cooling is 2% or more, an austenite unevenness index after deep cooling is 5.0 or less, and an average equivalent circle diameter of austenite after deep cooling is 1 ?m or less.
    Type: Grant
    Filed: July 7, 2011
    Date of Patent: November 11, 2014
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Hitoshi Furuya, Naoki Saitoh, Motohiro Okushima, Yasunori Takahashi, Takehiro Inoue, Ryuji Uemori
  • 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: 8864921
    Abstract: A method for annealing a strip of steel having a variable thickness in its length direction with at least thicker and thinner sections, wherein the strip has been cold rolled to form the thicker and thinner sections, one thicker and one thinner section having a length of at most a few meter. The annealing is performed by continuous annealing.
    Type: Grant
    Filed: March 19, 2008
    Date of Patent: October 21, 2014
    Assignee: Tata Steel Ijmuiden B.V.
    Inventors: Hai Wu, Camile Wilbert José Hol, Pieter Jacob Van Popta, Willem Cornelis Verloop
  • Publication number: 20140299237
    Abstract: The invention relates to a method for manufacturing a high-strength structural steel and to a high-strength structural steel product. The method comprises a providing step for providing a steel slab, a heating step (1) for heating said steel slab to 950 to 1300 C, a temperature equalizing step (2) for equalizing the temperature of the steel slab, a hot rolling step including a hot rolling stage of type I (5) for hot rolling the steel slab in the no-recrystallization temperature range below the recrystallization stop temperature (RST) but above the ferrite formation temperature A3, a quenching step (6) for quenching said hot-rolled steel at cooling rate of at least 20 C/s to a quenching-stop temperature (QT) between Ms and Mf temperatures, a partitioning treatment step (7, 9) for partitioning said hot-rolled steel in order to transfer carbon from martensite to austenite, and a cooling step (8) for cooling said hot-rolled steel to room temperature.
    Type: Application
    Filed: July 2, 2012
    Publication date: October 9, 2014
    Applicant: RAUTARUUKKI OYJ
    Inventors: Mahesh Chandra Somani, David Arthur Porter, Leo Pentti Karjalainen, Tero Tapio Rasmus, Ari Mikael Hirvi
  • 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: 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: 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
  • Patent number: 8834653
    Abstract: A method for straightening an age hardened metallic form includes heating an age hardened metallic form comprising one of a titanium alloy, a nickel alloy, an aluminum alloy, and a ferrous alloy to a straightening temperature of at least 25° F. below the age hardening temperature, and applying an elongation tensile stress for a time sufficient to elongate and straighten the form. The elongation tensile stress is at least 20% of the yield stress and not equal to or greater than the yield stress at the straightening temperature. The straightened form deviates from straight by no greater than 0.125 inch over any 5 foot length or shorter length. The straightened form is cooled while simultaneously applying a cooling tensile stress that balances the thermal cooling stress in the metallic form to thereby maintain a deviation from straight of no greater than 0.125 inch over any 5 foot length or shorter length.
    Type: Grant
    Filed: July 2, 2013
    Date of Patent: September 16, 2014
    Assignee: ATI Properties, Inc.
    Inventor: David J. Bryan
  • Publication number: 20140251514
    Abstract: In a method of producing a grain-oriented electrical steel sheet by hot rolling a steel slab comprising C: 0.001˜0.10 mass %, Si: 1.0˜5.0 mass %, Mn: 0.01˜1.0 mass %, one or two of S and Se: 0.01˜0.05 mass % in total, sol. Al: 0.003˜0.050 mass % and N: 0.001˜0.020 mass %, cold rolling, subjecting to primary recrystallization annealing, applying an annealing separator and finally subjecting to final annealing, the primary recrystallization annealing is conducted so as to control a heating rate S1 between 500 and 600° C. to not less than 100° C./s and a heating rate S2 between 600 and 700° C. to not less than 30° C./s but not more than 0.6×S1, and as a main ingredient of the annealing separator is used MgO having an expected value ?(A) of citric acid activity distribution of 3.5˜3.8, a cumulative frequency F of 25˜45% when an activity A is not less than 4.0.
    Type: Application
    Filed: October 16, 2012
    Publication date: September 11, 2014
    Applicant: JFE STEEL CORPORATION
    Inventors: Makoto Watanabe, Yukihiro Shingaki, Toshito Takamiya, Tomoyuki Okubo
  • Publication number: 20140246131
    Abstract: A high-tensile steel plate has a chemical composition containing, by mass, specific amounts of C, Mn, Si, P, S, Al, Ni, B, N, one or more elements selected from Cr, Mo, V, Cu, Ti, and Ca as needed, Ceq?0.80, and a center-segregation zone hardness index HCS satisfying 5.5[C]4/3+15[P]+0.90[Mn]+0.12[Ni]+0.53[Mo]?2.5. The hardness of a center-segregation zone satisfies HVmax/HVave?1.35+0.006/C?t/750. A steel having the above-described chemical composition is subjected to hot rolling at a specific slab-heating temperature at a specific rolling reduction ratio, subsequently reheated, cooled at a cooling rate of 0.3° C./s or more until the temperature of a central portion in a plate-thickness direction reaches 350° C. or less, and tempered to a specific temperature range.
    Type: Application
    Filed: October 1, 2012
    Publication date: September 4, 2014
    Applicant: JFE STEEL CORPORATION
    Inventors: Masao Yuga, Shigeki Kitsuya, Kenji Hayashi, Minoru Suwa
  • Publication number: 20140216612
    Abstract: The invention relates to a steel part, the composition of the steel of which comprises, the contents being expressed by weight: 0.040%?C?0.100%; 0.80%?Mn?2.00%; Si?0.30%; S?0.005%; P?0.030%; 0.010%?Al?0.070%; 0.015%?Nb?0.100%; 0.030%?Ti?0.080%; N?0.009%; Cu?0.100%; Ni?0.100%; Cr?0.100%; Mo?0.100%; and Ca?0.006%, the balance of the composition consisting of iron and inevitable impurities resulting from the smelting, the microstructure of the steel consisting of at least 75% equiaxed ferrite, martensite in an amount not less than 5% but not exceeding 20%, and bainite in an amount not exceeding 10%.
    Type: Application
    Filed: April 10, 2014
    Publication date: August 7, 2014
    Applicant: ArcelorMittal France
    Inventors: Jean-Pierre Laurent, Thierry Malot
  • Publication number: 20140190597
    Abstract: The present invention provides a hot coil for line pipe use which can reduce deviation in ordinary temperature strength and improve low temperature toughness despite the numerous restrictions in production conditions due to the coiling step and provides a method of production of the same, specifically makes the steel plate stop for a predetermined time between rolling passes in the recrystallization temperature range and performs cooling by two stages after hot rolling so as to thereby make the steel structure at the center part of plate thickness and effective crystal grain size of 3 to 10 ?m, make the total of the area ratios of bainite and acicular ferrite 60 to 99%, and make the absolute value of A-B 0 to 30% when the totals of the area ratios of bainite and acicular ferrite at any two portions are designated as respectively A and B.
    Type: Application
    Filed: September 27, 2012
    Publication date: July 10, 2014
    Inventors: Takuya Hara, Takeshi Kinoshita, Kazuaki Tanaka
  • Publication number: 20140166163
    Abstract: A process for manufacturing a cold rolled high strength dual phase steel. The process includes soaking a steel slab within a temperature range of 1200-1300° C., hot rolling the soaked steel slab in a roughing treatment and producing a transfer bar, and hot rolling the transfer bar in a finishing treatment and producing hot rolled strip. The hot rolled strip is cold rolled with at least a 55% reduction in thickness. The cold rolled sheet is intercritically annealed at a temperature between 790-840 ° C. and rapidly cooled to a temperature between 450-500 ° C. The rapidly cooled sheet has a ferrite plus martensite microstructure, a 0.2% yield strength of at least 550 MPa, a tensile strength of at least 980 MPa and a total elongation to failure of at least 10%.
    Type: Application
    Filed: December 13, 2013
    Publication date: June 19, 2014
    Applicant: THYSSENKRUPP STEEL USA, LLC
    Inventors: Ranbir Singh Jamwal, Joseph Frimpong, Bertram Wilhelm Ehrhardt, Harald Van Bracht, Roger Dale Boggs, Stanley Wayne Bevans
  • Publication number: 20140158258
    Abstract: A Ni-added steel plate includes, by mass %, C: 0.04% to 0.10%, Si: 0.02% to 0.12%, Mn: 0.3% to 1.0%, Ni: more than 7.5% to 10.0%, Al: 0.01% to 0.08%, T.O: 0.0001% to 0.0030%, P: limited to 0.0100% or less, S: limited to 0.0035% or less, N: limited to 0.0070% or less, and the balance consisting of Fe and unavoidable impurities, in which a Ni segregation ratio at an area of ¼ of a plate thickness away from a plate surface in a thickness direction is 1.3 or less, a fraction of austenite after a deep cooling is 0.5% or more, an austenite unevenness index after the deep cooling is 3.0 or less, and an average equivalent circle diameter of the austenite after the deep cooling is 1 ?m or less.
    Type: Application
    Filed: September 28, 2011
    Publication date: June 12, 2014
    Inventors: Hitoshi Furuya, Naoki Saitoh, Motohiro Okushima, Yasunori Takahashi
  • Publication number: 20140158259
    Abstract: A steel plate for linepipes having ultra-high strength and excellent low temperature toughness, and a method for manufacturing the same are disclosed. The steel plate has a strength of 930 MPa or more and excellent toughness even with much smaller amounts of alloying elements than that of conventional steel plates, and a method for manufacturing the same. The steel includes by weight %: 0.03-0.10% C; 0-0.6% Si; 1.6-2.1% Mn; 0-1.0% Cu; 0-1.0% Ni; 0.02-0.06% Nb; 0-0.1% V; 0.1-0.5% Mo; 0-1.0% Cr; 0.005-0.03% Ti; 0.01-0.06% Al; 0.0005-0.0025% B; 0.001-0.006% N; 0-0.006% Ca; 0.02% or less P; 0.005% or less S; and the balance Fe and unavoidable impurities. The microstructure includes at least about 75 area percent of a mixture of bainitic ferrite and acicular ferrite.
    Type: Application
    Filed: August 12, 2013
    Publication date: June 12, 2014
    Applicant: POSCO
    Inventors: Seong Soo Ahn, Jang Yong Yoo, Sang Hyun Cho
  • Publication number: 20140144559
    Abstract: The present invention provides a method for the fabrication of a martensitic steel sheet with a yield stress greater than 1300 MPa. The method includes the steps of obtaining a semi-finished steel product, the composition of which includes, whereby the contents are expressed in percent by weight: 0.15%?C?0.40%, 1.5%?Mn?3%, 0.005%?Si?2%, 0.005%?Al?0.1%, S?0.05%, P?0.1%, 0.025%?Nb?0.1%, and optionally: 0.01%?Ti?0.1%, 0%?Cr?4%, 0%?Mo?2%, 0.0005%?B?0.005%, 0.0005%?Ca?0.005%. The remainder of the composition is iron and the inevitable impurities resulting from processing. The semi-finished product is reheated to a temperature T1 in the range between 1050° C. and 1250° C., then the reheated semi-finished product is subjected to a roughing rolling at a temperature T2 in the range between 1050 and 1150° C.
    Type: Application
    Filed: April 20, 2012
    Publication date: May 29, 2014
    Inventors: Kangying Zhu, Olivier Bouaziz
  • Publication number: 20140120365
    Abstract: A hot-pressing steel sheet has excellent oxidation resistance to be capable of suppressing the formation of scales and ZnO during hot pressing as well as is excellent in cold pressing properties. A process of manufacturing a hot pressed member uses the steel sheet. The hot-pressing steel sheet includes a coating layer containing 10 to 25 mass % of Ni and a balance of Zn and inevitable impurities and having a mass per unit area of 10 to 90 g/m2, and a lubricating layer containing a solid lubricant, in the order named on the surface of a steel sheet.
    Type: Application
    Filed: May 23, 2012
    Publication date: May 1, 2014
    Applicant: JFE Steel Corporation
    Inventors: Tatsuya Miyoshi, Seiji Nakajima, Hiroki Nakamaru
  • Patent number: 8702880
    Abstract: A high strength and low yield ratio steel that has excellent characteristics such as low temperature toughness, a tensile strength of approximately 600 MPa or more and a low yield ratio of 80% or less. The high strength and low yield ratio steel includes, by weight percent: C: 0.02 to 0.12%, Si: 0.01 to 0.8%, Mn: 0.3 to 2.5%, P: 0.02% or less, S: 0.01% or less, Al: 0.005 to 0.5%, Nb: 0.005 to 0.10%, B: 3 to 50 ppm, Ti: 0.005 to 0.1%, N: 15 to 150 ppm, Ca: 60 ppm or less, and the balance of be and inevitable impurities, and further includes at least one component selected from the group consisting of by weight percent: Cr: 0.05 to 1.0%, Mo: 0.01 to 1.0%, Ni: 0.01 to 2.0%, Cu: 0.01 to 1.0% and V: 0.005 to 0.3%, wherein a finish cooling temperature is limited to 500 to 600° C. after the finish-rolling process.
    Type: Grant
    Filed: September 12, 2008
    Date of Patent: April 22, 2014
    Assignee: Posco
    Inventors: Jae Young Cho, Kyung Keun Um, Jong Kyo Choi