Strip, Sheet, Or Plate Patents (Class 148/661)
  • Patent number: 9957585
    Abstract: A steel strip continuous annealing device has a vertical annealing furnace 10 in which a heating zone 14, a soaking zone 16, and a cooling zone 18 are arranged in this order, and anneals a steel strip P passing through the zones 14, 16, and 18 in the order while being conveyed in the vertical direction in the vertical annealing furnace 10. The heating zone 14, the soaking zone 16, and the cooling zone 18 communicate through an atmosphere separation portion 36. One of a gas delivery port 38 and a gas discharge port 40 is positioned in an upper part and the other one of the gas delivery port 38 and the gas discharge port 40 is positioned in a lower part in each of the heating zone 14, the soaking zone 16, and the cooling zone 18.
    Type: Grant
    Filed: February 18, 2014
    Date of Patent: May 1, 2018
    Assignee: JFE STEEL CORPORATION
    Inventors: Hideyuki Takahashi, Tadashi Nara
  • Patent number: 9828651
    Abstract: A method for manufacturing a high-strength cold-rolled steel sheet includes a temperature distribution forming step of forming a temperature distribution in a width direction of a steel sheet such that a temperature of the steel sheet increases from an end of the steel sheet in the width direction toward a center part of the steel sheet in the width direction, and a water quenching step of performing water quenching treatment on the steel sheet by immersing, in cooling water, the steel sheet on which the temperature distribution is formed in the width direction.
    Type: Grant
    Filed: March 19, 2012
    Date of Patent: November 28, 2017
    Assignee: JFE Steel Corporation
    Inventors: Yoshimichi Hino, Gentaro Takeda
  • Patent number: 9499875
    Abstract: A large continuous annealing device that anneals a steel strip by multiple passes in a vertical annealing furnace and is capable of quickly switching the atmosphere in the furnace is provided. A steel strip continuous annealing device 100 has a vertical annealing furnace 10 in which a heating zone 14, a soaking zone 16, and a cooling zone 18 are arranged in this order, and anneals a steel strip P passing through the zones 14, 16, and 18 in the order while being conveyed in the vertical direction in the vertical annealing furnace 10. Adjacent zones communicate through a communicating portion 30 or 32 connecting upper parts or lower parts of the zones. A gas delivery port 38 is provided in each zone, in the position opposite in the vertical direction to the position of the communicating portion with the immediately preceding zone in the steel strip P passing order.
    Type: Grant
    Filed: February 18, 2014
    Date of Patent: November 22, 2016
    Assignee: JFE STEEL CORPORATION
    Inventor: Hideyuki Takahashi
  • Patent number: 9121087
    Abstract: A high-strength steel sheet has good ductility and stretch-flangeability and has a tensile strength (TS) of 980 MPa or more. The steel sheet contains 0.17%-0.73% C, 3.0% or less Si, 0.5%-3.0% Mn, 0.1% or less P, 0.07% or less S, 3.0% or less Al, and 0.010% or less N, in which Si+Al is 0.7% or more.
    Type: Grant
    Filed: September 4, 2009
    Date of Patent: September 1, 2015
    Assignee: JFE Steel Corporation
    Inventors: Hiroshi Matsuda, Yoshimasa Funakawa, Yasushi Tanaka
  • Publication number: 20150101713
    Abstract: A method for forming and treating a steel article of a high strength and ductile alloy. The method includes the steps of providing a starting steel composition for the steel article, preheating the composition, heating the starting material to a peak temperature range in less than forty seconds, holding the heated steel composition at the peak temperature range for between two and sixty seconds, quenching the heated steel composition from the peak temperature range to below 177° C. (350° F.) at a temperature rate reduction of 200 to 3000° C./sec (360 and 5400° F./sec), removing residual quench media from the surface of the quenched steel composition, tempering the quenched steel composition at a temperature of 100 to 704° C. (212 to 1300° F.); and air cooling the tempered steel composition to less than 100° C. (212° F.) to form a steel having desired mechanical properties.
    Type: Application
    Filed: August 15, 2014
    Publication date: April 16, 2015
    Applicant: BUFFALO ARMORY LLC
    Inventors: John BATISTE, Richard CLARE, JR., Jack HEINZ, Brent NICHOLSON
  • Publication number: 20150101712
    Abstract: Provided is a method that enables manufacture, with good productivity, of a high-strength cold-rolled steel with improved elongation (EL), stretch-flangeability (?), bendability (R), and balance of these properties (TS×EL×?/1000), outstanding composite workability as evaluated by Erichsen test, and a tensile strength of at least 980 MPa. A steel material satisfying a prescribed constituent composition is held and soaked for at least fifty seconds at a temperature at or above the Ac3 point, after which the steel material is cooled at an average cooling rate of at least 15° C./sec to a discretionary temperature (T) that satisfies expression (1) below, held for 5-180 seconds in a temperature range that satisfies expression (1) below, then heated to a temperature region that satisfies expression (2) below, held for at least 50 seconds in this temperature region, and then cooled. 300° C.?T1 (° C.)<400° C. ??(1) 400° C.?T2 (° C.)<540° C.
    Type: Application
    Filed: February 28, 2013
    Publication date: April 16, 2015
    Applicant: KABUSHIKI KAISHA KOBE SEIKO SHO (KOBE STEEL, LTD.)
    Inventors: Yuichi Futamura, Michiharu Nakaya
  • Patent number: 8993120
    Abstract: A hot-dip galvanizing layer or an alloyed hot dip galvanizing layer is formed on the surface of a base steel sheet in which in volume fraction, 40 to 90% of a ferrite phase and 5% or less of a retained austenite phase are contained, and a ratio of non-recrystallized ferrite to the entire ferrite phase is 50% or less in volume fraction, and further a grain diameter ratio being a value of, of crystal grains in the ferrite phase, an average grain diameter in the rolling direction divided by an average grain diameter in the sheet width direction is 0.75 to 1.33, a length ratio being a value of, of hard structures dispersed in island shapes, an average length in the rolling direction divided by an average length in the sheet width direction is 0.75 to 1.33, and an average aspect ratio of inclusions is 5.0 or less.
    Type: Grant
    Filed: September 28, 2012
    Date of Patent: March 31, 2015
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Hiroyuki Kawata, Naoki Maruyama, Akinobu Murasato, Akinobu Minami, Takeshi Yasui, Takuya Kuwayama, Hiroyuki Ban, Kaoru Hiramatsu
  • Publication number: 20150086808
    Abstract: A high-strength cold-rolled steel sheet has a specific chemical composition and has a steel microstructure meeting conditions: a total content of bainitic ferrite (BF) and tempered martensite (TM) is 65% (in area percent, hereinafter the same for steel microstructure) or more; a fresh martensite (M) content is 3% to 18%; a retained austenite content is 5% or more; and a polygonal ferrite (F) content is 5% or less. The steel sheet has a specific average KAM<1.00° of 0.50° or more and has a tensile strength of 980 MPa or more. The high-strength cold-rolled steel sheet excels in formability and shape fixability.
    Type: Application
    Filed: March 6, 2013
    Publication date: March 26, 2015
    Applicant: KABUSHIKI KAISHA KOBE SEIKO SHO (Kobe Steel, Ltd.)
    Inventors: Kouji Kasuya, Yuichi Futamura, Yukihiro Utsumi
  • Publication number: 20150059935
    Abstract: The present invention relates to high strength cold rolled steel sheet suitable for applications in automobiles, construction materials and the like, specifically high strength steel excellent in formability. In particular, the invention relates to cold rolled steel sheets having a tensile strength of at least 780 MPa.
    Type: Application
    Filed: April 2, 2013
    Publication date: March 5, 2015
    Applicant: VOESTALPINE STAHL GMBH
    Inventors: Thomas Hebesberger, Daniel Krizan, Stefan Paul, Andreas Pichler
  • Publication number: 20150047753
    Abstract: The invention relates to a method for producing a component from transformable steel by hot forming, in which a plate first is cut out of a strip or sheet as the pre-material, and is then heated to forming temperature and pre-formed, having an at least partially martensitic transformation structure after forming. Instead of a press mould hardening, the at least partially martensitic transformation structure is created in the pre-material, or in the plate to be formed, by austenitisation and quenching already before forming, and then the thus-conditioned plate is reheated after forming, while maintaining the at least partially martensitic transformation structure, to a temperature below the Ac1 transformation temperature, and formed at this temperature.
    Type: Application
    Filed: February 27, 2013
    Publication date: February 19, 2015
    Inventors: Friedrich Luther, Thomas Evertz, Stefan Muetze, Michael Braun
  • Publication number: 20150047758
    Abstract: A method for manufacturing a high-strength cold-rolled steel sheet includes a temperature distribution forming step of forming a temperature distribution in a width direction of a steel sheet such that a temperature of the steel sheet increases from an end of the steel sheet in the width direction toward a center part of the steel sheet in the width direction, and a water quenching step of performing water quenching treatment on the steel sheet by immersing, in cooling water, the steel sheet on which the temperature distribution is formed in the width direction.
    Type: Application
    Filed: March 19, 2012
    Publication date: February 19, 2015
    Applicant: JFE STEEL CORPORATION
    Inventors: Yoshimichi Hino, Gentaro Takeda
  • 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: 20150034215
    Abstract: A high-strength multi-phase steel having tensile strengths of no less than 580 MPa, preferably with a dual-phase structure for a cold-rolled or hot-rolled steel strip having improved forming properties, in particular for lightweight vehicle construction is disclosed, containing the following elements (contents in % by mass): C 0.075 to ?0.105; Si 0.200 to ?0.300; Mn 1.000 to ?2.000; Cr 0.280 to ?0.480; Al 0.10 to ?0.060; P ?0.020; Nb ?0.005 to ?0.025; N ?0.0100; S ?0.0050; the remainder iron, including conventional steel-accompanying elements not mentioned above.
    Type: Application
    Filed: February 27, 2013
    Publication date: February 5, 2015
    Inventors: Thomas Schulz, Andreas Wedemeier, Michael Pohl, Hans-Joachim Kratz, Matthias Geler, Oliver Meyer
  • Patent number: 8920708
    Abstract: The present invention provides a method of cooling a hot-rolled steel strip which has passed through a finishing rolling, including: cooling the hot-rolled steel strip from a first temperature of not lower than 600° C. and not higher than 650° C. to a second temperature of not higher than 450° C. with cooling water having the water amount density of not lower than 4 m3/m2/min and not higher than 10 m3/m2/min, wherein with respect to the area of the target surface, the area of a portion where a plurality of spray jets of the cooling water directly strikes on the target surface is at least 80%.
    Type: Grant
    Filed: August 14, 2012
    Date of Patent: December 30, 2014
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Yoshihiro Serizawa, Yasuhiro Nishiyama, Shigeru Ogawa, Shinji Ida, Hitoshi Nikaidoh, Isao Yoshii, Noriyuki Hishinuma, Tetsuo Kishimoto, Nobuhiro Takagi
  • Patent number: 8893402
    Abstract: A method for controlling the atmosphere in a protective gas chamber for the continuous treatment of metal strips. A metal strip is guided into and out of the protective gas chamber via locks. At least one lock has at least two sealing elements for the metal strip which runs through it, with the result that a sealed chamber is formed between the two sealing elements. The gas pressure (P2, PD) is measured in the protective gas chamber and in the sealed chamber of the lock and the pressure (PD) in the sealed chamber is regulated, to be precise in such a way that, during operation, the differential pressure between the protective gas chamber and the sealed chamber is kept as far as possible to an optimum value.
    Type: Grant
    Filed: January 30, 2012
    Date of Patent: November 25, 2014
    Assignee: Andritz Technology and Asset Management GmbH
    Inventors: Martin Hamman, Jerome Vallee
  • Publication number: 20140338797
    Abstract: Steel with high strength and good formability is produced with compositions and methods for forming austenitic and martensitic microstructure in the steel. Carbon, manganese, molybdenum, nickel copper and chromium may promote the formation of room temperature stable (or meta-stable) austenite by mechanisms such as lowering transformation temperatures for non-martensitic constituents, and/or increasing the hardenability of steel. Thermal cycles utilizing a rapid cooling below a martensite start temperature followed by reheating may promote formation of room temperature stable austenite by permitting diffusion of carbon into austenite from martensite.
    Type: Application
    Filed: May 16, 2014
    Publication date: November 20, 2014
    Inventors: Grant A. Thomas, Jose Mauro B. Losz
  • Publication number: 20140338798
    Abstract: Steel with high strength and good formability is produced with compositions and methods for forming austenitic and martensitic microstructure in the steel. Carbon, manganese, molybdenum, nickel copper and chromium may promote the formation of room temperature stable (or meta-stable) austenite by mechanisms such as lowering transformation temperatures for non-martensitic constituents, and/or increasing the hardenability of steel. Thermal cycles utilizing a rapid cooling below a martensite start temperature followed by reheating may promote formation of room temperature stable austenite by permitting diffusion of carbon into austenite from martensite.
    Type: Application
    Filed: May 16, 2014
    Publication date: November 20, 2014
    Inventors: Grant A. Thomas, Luis G. Garza-Martinez
  • 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
  • Patent number: 8845831
    Abstract: There is provided a heat treatment method in which high-quality tempering treatment can be performed in a short period of time. In this method, when an object to be treated is tempered after being quenched, the object to be treated is rapidly cooled to a 90% martensite transformation finishing temperature without being cooled to the ordinary temperature after quench heating, and then is subjected to 100% martensite transformation by using a 100° C. liquid, and thereafter, tempering treatment is performed after the whole of the object to be treated is soaked by using the 100° C. liquid.
    Type: Grant
    Filed: February 2, 2009
    Date of Patent: September 30, 2014
    Assignee: Denki Kogyo Co., Ltd.
    Inventors: Seiichi Sawatsubashi, Keiichi Kubo
  • Patent number: 8828153
    Abstract: A high-strength cold-rolled steel sheet providing a product with a good surface condition after press forming, having excellent bake hardenability and anti room temperature aging property, and having a dual phase structure with a tensile strength of at least 340 MPa is provided. A high-strength cold-rolled steel sheet has a structure comprising a main phase which is a ferrite and a secondary phase which is a low temperature transformation product including a martensite and has a hardness distribution of the ferrite phase in an arbitrary cross section having a length of 10 mm in the widthwise 10 direction of the sheet which satisfies the relationship prescribed by (HV(max)?HV(ave))<0.5×(Hv(ave). HV(max) is the maximum Vickers hardness of ferrite grains in a region at a distance of from (?)t to (¼)t in the thickness direction from the surface when the thickness of the high-strength cold-rolled steel sheet is t, and Hv(ave) is the average Vickers hardness of ferrite grains in this region.
    Type: Grant
    Filed: December 8, 2010
    Date of Patent: September 9, 2014
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Jun Haga, Nobusato Kojima
  • Patent number: 8815025
    Abstract: A high strength steel, including about 0.05 to about 0.25% of C, less than about 0.5% of Si, about 0.5 to about 3.0% of Mn, not more than about 0.06% of P, not more than about 0.01% of S, about 0.50 to about 3.0% of Sol. Al, not more than about 0.02% of N, about 0.1 to about 0.8% of Mo, about 0.02 to about 0.40% of Ti, and the balance of iron and unavoidable impurities, wherein the steel has a structure formed of at least three phases including a bainite phase, and a retained austenite phase in addition to a ferrite phase having a composite carbide containing Ti and Mo dispersed and precipitated therein, wherein the total volume of the ferrite phase and the bainite phase is not smaller than 80%, the volume of the bainite phase is about 5% to about 60%, and the volume of the retained austenite phase is about 3 to about 20%.
    Type: Grant
    Filed: November 3, 2006
    Date of Patent: August 26, 2014
    Assignees: JFE Steel Corporation, ThyssenKrupp Steel AG
    Inventors: Takeshi Yokota, Akio Kobayashi, Kazuhiro Seto, Yoshihiro Hosoya, Thomas Heller, Brigitte Hammer, Rolf Bode, Günter Stich
  • Patent number: 8668789
    Abstract: A method for the manufacturing of high strength cold rolled steel sheets includes continuously annealing a cold rolled steel sheet that has a composition containing C: 0.05-0.3% mass, Si: 0.6-3.0% mass, Mn: 1.0-3.0% mass, P: ?0.1% mass, S: ?0.02% mass, Al: 0.01-1% mass, N: ?0.01% mass, and Fe and inevitable impurities: balance, in a manner such that the cold rolled steel sheet is heated in a furnace using an oxidizing burner to a steel sheet temperature of ?700° C., then soak-annealed in a reducing atmosphere furnace at 750-900° C., then cooled so the average cooling rate between 500° C. and 100° C. is ?50° C./s. High-Si cold rolled steel sheets with high strength and good phosphatability while containing Si?0.6% are obtained without controlling conditions so as to increase the dew point in the reducing atmosphere in the soaking furnace or to increase the vapor hydrogen partial pressure ratio.
    Type: Grant
    Filed: July 27, 2010
    Date of Patent: March 11, 2014
    Assignee: JFE Steel Corporation
    Inventors: Junichiro Hirasawa, Naoto Yoshimi, Hiroki Nakamaru, Kohei Hasegawa, Hideyuki Tsurumaru, Keita Yonetsu, Hideyuki Takahashi, Masato Sasaki
  • Patent number: 8656750
    Abstract: A hot forming die that includes a first die and a second die. The first die has a first die structure that is formed of a tool steel. The first die structure has a first die surface and a plurality of first cooling apertures. The first die surface has a complex shape. The first cooling apertures are spaced apart from the die surface by a first predetermined distance. The second die has a second die surface. The first and second die surfaces cooperate to form a die cavity. Related methods for forming a hot forming die and for hot forming a workpiece are also provided.
    Type: Grant
    Filed: June 12, 2012
    Date of Patent: February 25, 2014
    Assignee: Magna International Inc.
    Inventors: Frank A. Horton, Boris Shulkin, Bradford L. Hastilow, Jim Metz, James R. Judkins, Monty Hansen, Seetarama S. Kotagiri, Andreas G. Janssen
  • Publication number: 20140034196
    Abstract: The invention relates to a high strength multi-phase steel for a cold- or hot-rolled steel strip having excellent forming properties, in particular for light vehicle construction, comprising the elements (contents in mass %): C 0.060 to=0.115; Al 0.020 to=0.060; Si 0.100 to=0.500; Mn 1.300 to=2.500; P=0.025; S=0.0100; Cr 0.280 to=0.480; Mo<0.150; Ti=0.005 to=0.050; Nb=0.005 to=0.050; B=0.0005 to=0.0060; N=0.0100; the remainder being iron including the usual elements present in steel and which are not mentioned above.
    Type: Application
    Filed: November 30, 2011
    Publication date: February 6, 2014
    Inventors: Andreas Wedemeier, Thomas Schulz, Michael Pohl, Phillip Wüllner, Jörg Heinecke, Christian Schlegel
  • Patent number: 8634953
    Abstract: The invention relates to a method and equipment for controlling flatness of a stainless steel strip in connection with cooling after annealing in a finishing line.
    Type: Grant
    Filed: June 27, 2008
    Date of Patent: January 21, 2014
    Assignee: Outokumpu OYJ
    Inventor: Stephan Söderlund
  • Patent number: 8591675
    Abstract: The present invention relates to a method for acting on the temperature of a travelling strip (4) by blowing gas or a water/gas mixture, whereby a plurality of jets of gas or a water/gas mixture, extending toward the surface of the strip and arranged in such a way that the impacts (24, 34) of the jets of gas or water/gas mixture on each surface of the strip are distributed at the nodes of a two-dimensional network, are sprayed onto each face of the strip. The impacts (24) of the jets on one face (A) are not opposite the impacts (34) of the jets on the other face (B), and the jets of gas or water/gas mixture come from tubular nozzles (23, 33) which are supplied by at least one distribution chamber (21, 31) and extend at a distance from the distribution chamber in such a way as to leave a free space for the flow of the returning gas or water/gas mixture parallel to the longitudinal direction of the strip and perpendicular to the longitudinal direction of the strip.
    Type: Grant
    Filed: October 21, 2008
    Date of Patent: November 26, 2013
    Assignee: ArcelorMittal France
    Inventors: Jerome Muller, Akli Elias, Thierry Petesch, Ivan Santi, Paul Durighello, Karen Beaujard
  • Patent number: 8535458
    Abstract: A steel sheet contains, on a mass percent basis, 0.03%-0.12% C, 0.5% or less Si, 0.8%-1.8% Mn, 0.030% or less P, 0.01% or less S, 0.005%-0.1% Al, 0.01% or less N, 0.035%-0.100% Ti, and the balance being Fe and incidental impurities and has microstructures with a fraction of polygonal ferrite of 80% or more, the polygonal ferrite having an average grain size of 5 to 10 ?m. The amount of Ti present in a precipitate having a size of less than 20 nm is 70% or more of the value of Ti* calculated using expression (1): Ti*=[Ti]?48×[N]/14??(1) where [Ti] and [N] represent a Ti content (percent by mass) and a N content percent by mass), respectively, of the steel sheet.
    Type: Grant
    Filed: May 11, 2010
    Date of Patent: September 17, 2013
    Assignee: JFE Steel Corporation
    Inventors: Noriaki Kohsaka, Kazuhiro Seto, Reiko Sugihara, Masahide Watabe, Yasushi Tanaka
  • Patent number: 8516867
    Abstract: A manufacturing apparatus comprises a final stand, with standing side members, and a cooling apparatus. The cooling apparatus comprises rows of upper surface cooling nozzles, rows of lower surface cooling nozzles, and an upper surface guide on the upper surface side of the steel sheet. An end portion of the cooling apparatus on a side of the final stand is arranged between the standing side members of the housing. When defining a width of a uniformly cooled region, an average gap distance (Wsw) between the end portion of the width of the uniformly cooled region and the standing side member of the housing; a gravity acceleration rate, an average water volume density of the width of the uniformly cooled region, and a value determined by Wsw and an average distance h between the upper surface guide and the upper surface of the steel sheet, a specific relation is satisfied.
    Type: Grant
    Filed: November 21, 2011
    Date of Patent: August 27, 2013
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Tomofumi Hosho, Yoichi Haraguchi, Kazuaki Kobayashi
  • Patent number: 8465601
    Abstract: A high carbon steel sheet having superior strength and ductility and a method for manufacturing the same comprising: 0.2 to 1.0 wt % carbon (C), 0 to 3.0 wt % silicon (Si), 0 to 3.0 wt % manganese (Mn), 0 to 3.0 wt % chromium (Cr), 0 to 3.0 wt % nickel (Ni), 0 to 0.5 wt % molybdenum (Mo), 0 to 3.0 wt % aluminum (Al), 0 to 0.01 wt % boron (B), 0 to 0.5 wt % titanium (Ti), and the remainder substantially being iron (Fe) and inevitable impurities. The contents of carbon, manganese, chromium, and nickel satisfy the following Equation 1, and the contents of silicon and aluminum satisfy the following Equation 2: (3.0?2.5×C)wt %?(Mn+Cr+Ni/2)?8.5 wt %—(Equation 1) Si+Al>1.0 wt % (Equation 2).
    Type: Grant
    Filed: December 5, 2008
    Date of Patent: June 18, 2013
    Assignee: POSCO
    Inventors: Young-Roc Im, Jae-Kon Lee, Kyoo-Young Lee, Yeong-Woo Jeon, Jae-Hwa Ryu, Kyong-Su Park
  • Publication number: 20130133786
    Abstract: A method for manufacturing a high strength steel sheet includes heating a steel sheet containing at least 0.10 mass % of carbon to either a temperature in an austenite single phase region or a temperature in an (austenite+ferrite) two-phase region; cooling the steel sheet to a cooling stop temperature as a target temperature set within a cooling temperature region ranging from Ms to (Ms?150° C.) to allow a portion of non-transformed austenite to proceed to martensitic transformation; retaining a coldest part in a sheet widthwise direction of the steel sheet at a temperature in a temperature range from the cooling stop temperature as the target temperature to (the cooling stop temperature+15° C.) for 15 seconds to 100 seconds; and heating the sheet to a temperature to temper said martensite, wherein “Ms” represents martensitic transformation start temperature and said cooling temperature region is exclusive of Ms and inclusive of (Ms?150° C.).
    Type: Application
    Filed: February 28, 2011
    Publication date: May 30, 2013
    Applicant: JFE STEEL CORPORATION
    Inventors: Hiroshi Matsuda, Yoshimasa Funakawa, Yasushi Tanaka
  • Patent number: 8425225
    Abstract: Method of reducing the formation of folds on metal strips (1) exposed to rapid heating in continuous heat-treatment lines, in which lines said strips are caused to pass through heating sections (2) comprising successive and separate heating means (5; 5a; 5b; 5c; 5d), wherein the average slope of the increase in temperature of the strip between the inlet and the outlet of a heating means decreases from one heating means to the following heating means.
    Type: Grant
    Filed: April 27, 2007
    Date of Patent: April 23, 2013
    Assignee: Fives Stein
    Inventors: Catherine Pasquinet, Frédéric Marmonier
  • Patent number: 8414716
    Abstract: The present invention provides a method of cooling a hot-rolled steel strip which has passed through a finishing rolling, including: cooling the hot-rolled steel strip from a first temperature of not lower than 600° C. and not higher than 650° C. to a second temperature of not higher than 450° C. with cooling water having the water amount density of not lower than 4 m3/m2/min and not higher than 10 m3/m2/min, wherein with respect to the area of the target surface, the area of a portion where a plurality of spray jets of the cooling water directly strikes on the target surface is at least 80%.
    Type: Grant
    Filed: May 13, 2010
    Date of Patent: April 9, 2013
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Yoshihiro Serizawa, Yasuhiro Nishiyama, Shigeru Ogawa, Shinji Ida, Hitoshi Nikaidoh, Isao Yoshii, Noriyuki Hishinuma, Tetsuo Kishimoto, Nobuhiro Takagi
  • Patent number: 8404062
    Abstract: A cooling device and a cooling method for a hot strip allow uniform and stable cooling of the strip at a high cooling rate when supplying the coolant to the upper surface of the hot strip. The cooling device includes an upper header unit 21 for supplying a rod-like flow to the upper surface of the strip 10. The upper header unit 21 is formed of the first upper header group including plural first upper headers 21a arranged in a conveying direction and a second upper header group including plural second upper headers 21b arranged in the conveying direction. The cooling device is provided with an ON-OFF mechanism 30 to allow each of the upper headers 21a and 21b of the first and the second upper header groups to independently execute the ON-OFF control (start/end injection control) of an injection (feeding) of the rod-like flow.
    Type: Grant
    Filed: January 15, 2008
    Date of Patent: March 26, 2013
    Assignee: JFE Steel Corporation
    Inventors: Satoshi Ueoka, Naoki Nakata, Takashi Kuroki, Nobuo Nishiura
  • Patent number: 8404358
    Abstract: A galvannealed steel sheet includes: a steel sheet; a galvannealed layer; and a Mn—P based oxide film. A Zn—Fe alloy phase in the galvannealed layer is measured by X-ray diffractometry. The value of a diffraction intensity ?(2.59 ?) of ? phase divided by a diffraction intensity ?1(2.13 ?) of ?1 phase is less than or equal to 0.1. The value of a diffraction intensity ?(1.26 ?) of ? phase divided by a diffraction intensity ?1(2.13 ?) of ?1 phase is greater than or equal to 0.1 and less than or equal to 0.4. The Mn—P based oxide film is formed using 5 to 100 mg/m2 of Mn and 3 to 500 mg/m2 of P on a surface of the galvannealed layer.
    Type: Grant
    Filed: July 9, 2009
    Date of Patent: March 26, 2013
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Masao Kurosaki, Jun Maki, Hiroyuki Tanaka, Shintaroh Yamanaka
  • Patent number: 8282747
    Abstract: A cooling method of steel plate able to raise a cooling uniformity in a steel plate conveyance direction comprising, at a front stage part of a cooling apparatus, not spraying while a front end region of steel plate is passing, spraying by successively increasing the cooling water rate from 80 to 95 vol % (Qfront) of a standard water density when the front part region passes so that the amount of cooling water becomes the standard water density when a boundary part of the front part region and a center part region arrives, and continuing spraying by the standard water density while the center part region is passing, then, at a rear stage part of the cooling apparatus, spraying by making the amount of cooling water 80 to 95 vol % of the standard water density while the front end region of the steel plate is passing, successively increasing the amount of cooling water rate from 80 to 95 vol % of the standard water density when the front part region passes so that the amount of cooling water becomes the standard
    Type: Grant
    Filed: July 31, 2007
    Date of Patent: October 9, 2012
    Assignee: Nippon Steel Corporation
    Inventor: Tomoya Oda
  • 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: 8257517
    Abstract: A steel sheet excellent in mechanical strength, workability and thermal stability and suited for use as a raw material in such fields of manufacturing automobiles, household electric appliances and machine structures and of constructing buildings, and a manufacturing method thereof are provided. The steel sheet is a hot-rolled steel sheet of carbon steel or low-alloy steel, the main phase of which is ferrite, and is characterized in that the average ferrite crystal grain diameter D (?m) at the depth of ¼ of the sheet thickness from the steel sheet surface satisfies the relations respectively defined by the formulas (1) and (2) given below and the increase rate X (?m/min) in average ferrite crystal grain diameter at 700° C. at the depth of ¼ of the sheet thickness from the steel sheet surface and said average crystal grain diameter D (?m) satisfy the relation defined by the formula (3) given below: 1.2?D?7??formula (1) D?2.7+5000/(5+350·C+40·Mn)2??formula (2) D·X?0.
    Type: Grant
    Filed: March 14, 2011
    Date of Patent: September 4, 2012
    Assignee: Sumitomo Metal Industries, Ltd.
    Inventors: Toshirou Tomida, Norio Imai, Mitsuru Yoshida, Kaori Kawano, Masayuki Wakita, Tamotsu Toki, Masanori Yasuyama, Hitomi Nishibata
  • Patent number: 8215147
    Abstract: A hot forming die that includes a first die and a second die. The first die has a first die structure that is formed of a tool steel. The first die structure has a first die surface and a plurality of first cooling apertures. The first die surface has a complex shape. The first cooling apertures are spaced apart from the die surface by a first predetermined distance. The second die has a second die surface. The first and second die surfaces cooperate to form a die cavity. Related methods for forming a hot forming die and for hot forming a workpiece are also provided.
    Type: Grant
    Filed: July 12, 2007
    Date of Patent: July 10, 2012
    Assignee: Magna International Inc.
    Inventors: Frank A. Horton, Boris Shulkin, Bradford L. Hastilow, Jim Metz, James R. Judkins, Monty Hansen, Seetarama S. Kotagiri, Andreas G. Janssen
  • Patent number: 8192566
    Abstract: A continuous annealing and pickling process of flat cold-rolled products, such as stainless steel strips, to obtain a high surface quality product at high production rates and with a low environmental impact. It comprises the following steps: heating, up to a temperature comprised in the range 650-1050° C., in an atmosphere with an oxygen content comprised in the range from 0.5 to 12%; heating for a time comprised from 10 to 200 sec up to a temperature comprised in the range from 650 to 1200° C. in presence of oxidizing agents and/or inert agents; cooling down to temperatures comprised in the range from 650° C. to ambient temperature in presence of oxidizing agents and/or inert agents; thermochemical or electrolytic descaling and finally possible pickling and/or passivation, by means of the use of pickling baths consisting of mineral acid solutions.
    Type: Grant
    Filed: November 14, 2007
    Date of Patent: June 5, 2012
    Assignees: Danieli & C. Officine Meccaniche S.p.A., Centro Sviluppo Materiali S.p.A.
    Inventors: Alessandro Dulcetti, Milorad Pavlicevic, Nicoletta Zacchetti, Alessandra Primavera, Stefano Luperi, Luca Lattanzi, Simone Guanin
  • Publication number: 20120067470
    Abstract: The present invention provides a method of cooling a hot-rolled steel strip which has passed through a finishing rolling, including: cooling the hot-rolled steel strip from a first temperature of not lower than 600° C. and not higher than 650° C. to a second temperature of not higher than 450° C. with cooling water having the water amount density of not lower than 4 m3/m2/min and not higher than 10 m3/m2/min, wherein with respect to the area of the target surface, the area of a portion where a plurality of spray jets of the cooling water directly strikes on the target surface is at least 80%.
    Type: Application
    Filed: May 13, 2010
    Publication date: March 22, 2012
    Inventors: Yoshihiro Serizawa, Yasuhiro Nishiyama, Shigeru Ogawa, Shinji Ida, Hitoshi Nikaidoh, Isao Yoshii, Noriyuki Hishinuma, Tetsuo Kishimoto, Nobuhiro Takagi
  • Patent number: 8133333
    Abstract: The present disclosure relates to an iron alloy sheet comprising ?-Fe, and/or ?-Fe phases wherein the alloy has a melting point in the range of 800 to 1500° C., a critical cooling rate of less than 105 K/s and structural units in the range of about 150 nm to 1000 nm.
    Type: Grant
    Filed: October 18, 2007
    Date of Patent: March 13, 2012
    Assignee: The NanoSteel Company, Inc.
    Inventors: Daniel James Branagan, Joseph Buffa, Michael Breitsameter, David Paratore
  • Patent number: 8084143
    Abstract: High yield ratio high-strength thin steel sheet superior in weldability and ductility characterized by: being comprised of steel containing, by mass %, C: over 0.030 to less than 0.10%, Si: 0.30 to 0.80%, Mn: 1.7 to 3.2%, P: 0.001 to 0.02%, S: 0.0001 to 0.006%, Al: 0.060% or less, N: 0.0001 to 0.0070%, containing further Ti: 0.01 to 0.055%, Nb: 0.012 to 0.055%, Mo: 0.07 to 0.55%, B: 0.0005 to 0.0040%, and simultaneously satisfying 1.1 ?14×Ti(%)+20×Nb(%)+3×Mo(%)+300×B(%)?3.7, the balance comprised or iron and unavoidable impurities, and having a yield ratio of 0.64 to less than 0.92, a TS×E11/2 of 3320 or more, an YR×TS×EL1/2 of 2320 or more, and a maximum tensile strength (TS) of 780 MPa or more.
    Type: Grant
    Filed: September 30, 2004
    Date of Patent: December 27, 2011
    Assignee: Nippon Steel Corporation
    Inventors: Naoki Yoshinaga, Shunji Hiwatashi, Yasuharu Sakuma, Atsushi Itami
  • Patent number: 8075711
    Abstract: A hot-rolled high strength steel sheet in which, without using expensive Mo, and by effectively using Ti, which is an expensive element, the amount of precipitation hardening of which is large, both ductility and stretch-flangeability are improved at a tensile strength of 780 MPa or higher, and desirable tensile fatigue properties are exhibited. The hot-rolled high strength steel sheet has a composition including, in percent by mass, C: 0.06% to 0.15%, Si: 1.2% or less, Mn: 0.5% to 1.6%, P: 0.04% or less, S: 0.005% or less, Al: 0.05% or less, and Ti: 0.03% to 0.20%, the balance being Fe and incidental impurities, wherein the steel sheet has a structure in which the volume fraction of ferrite is 50% to 90%, the balance is substantially bainite, the total volume fraction of ferrite and bainite is 95% or more, precipitates containing Ti are precipitated in the ferrite, and the precipitates have an average diameter of 20 nm or less; and 80% or more of the Ti content in the steel is precipitated.
    Type: Grant
    Filed: December 27, 2006
    Date of Patent: December 13, 2011
    Assignee: JFE Steel Corporation
    Inventors: Koichi Nakagawa, Reiko Sugihara, Tetsuo Shimizu, Shusaku Takagi
  • Patent number: 8043447
    Abstract: In a method of manufacturing a high tensile strength thick steel plate, a steel slab contains 0.03-0.055% of C, 3.0-3.5% of Mn, and 0.002-0.10% of Al, the amount of Mo is limited to 0.03% or less, the amount of Si is limited to 0.09% or less, the amount of V is limited to 0.01% or less, the amount of Ti is limited to 0.003% or less, the amount of B is limited to 0.0003% or less, and of which Pcm value representing a weld cracking parameter is fallen within the range of 0.20-0.24% and DI value representing a hardenability index is fallen within the range of 1.00-2.60, is heated to 950-1100° C. The steel slab is subjected to a rolling process with a cumulative draft of 70-90% when a temperature is in a range of 850° C. or more, and then, the steel slab is subjected to a rolling process at 780° C. or higher with a cumulative draft of 10-40% when a temperature is in a range of 780-830° C., and subsequently, accelerated cooling at a cooling rate of 8-80° C./sec is started from 700° C.
    Type: Grant
    Filed: March 31, 2009
    Date of Patent: October 25, 2011
    Assignee: Nippon Steel Corporation
    Inventors: Manabu Hoshino, Masaaki Fujioka, Yoichi Tanaka, Masanori Minagawa
  • Patent number: 7927433
    Abstract: A cold-rolled steel sheet of carbon steel or low-alloy steel comprising C: 0.01 to 0.25% by mass with a ferrite main phase is has an average ferrite crystal grain diameter D (?m) at the depth of ¼ of the sheet thickness from the steel sheet surface satisfying formulas (5,6) and the increase rate X (?m/min) in average ferrite crystal grain diameter at 700° C. at the depth of ¼ of the sheet thickness from the steel sheet surface and D (?m) satisfying formula (3): 1.2?D?9.3??(5) D?5.0?2.0·Cr+5000/(5+350·C+40·Mn)2??(6) D·X?0.1??(3) and, at said ¼ inch depth, the area percentage of ferrite crystal grains the crystal grain diameter d (?m) of which satisfying formula (4) is at least 80%: D/3?d?3D??(4) wherein C, Cr and Mn represent mass % of the respective elements in the steel.
    Type: Grant
    Filed: April 27, 2010
    Date of Patent: April 19, 2011
    Assignee: Sumitomo Metal Industries, Ltd.
    Inventors: Toshirou Tomida, Norio Imai, Mitsuru Yoshida, Kaori Kawano, Masayuki Wakita, Tamotsu Toki, Masanori Yasuyama, Hitomi Nishibata
  • Patent number: 7879164
    Abstract: A steel sheet excellent in mechanical strength, workability and thermal stability and suited for use as a raw material in such fields of manufacturing automobiles, household electric appliances, machine structures, and of constructing buildings, and a manufacturing method thereof is provided. The steel sheet is a hot-rolled steel sheet of a carbon steel or low-alloy steel, the main phase of which is ferrite, and is characterized in that the average ferrite crystal grain diameter D(?m) at the depth of ¼ of the sheet thickness from the steel sheet surface satisfies the relations respectively defined by formulas (1) and (2) given below and the increase rate X (?m/min) in average ferrite crystal grain diameter at 700° C. at the depth of ¼ of the sheet thickness from the steel sheet surface and said average crystal grain diameter D(?m) satisfy the relation defined by the formula (3) given below: 1.2?D?7??formula (1) D?2.7+5000/(5+350·C+40·Mn)2??formula (2) D·X?0.
    Type: Grant
    Filed: April 27, 2010
    Date of Patent: February 1, 2011
    Assignee: Sumitomo Metal Industries, Ltd.
    Inventors: Toshirou Tomida, Norio Imai, Mitsuru Yoshida, Kaori Kawano, Masayuki Wakita, Tamotsu Toki, Masanori Yasuyama, Hitomi Nishibata
  • Patent number: 7857917
    Abstract: The present invention provides a high strength thick steel plate for marine structures superior in weldability and low temperature toughness of the HAZ, which is able to be produced at a low cost without use of a complicated method of production, and a method of production of the same, that is, steel for welded structures excellent in low temperature toughness of the weld heat affected zone and a method of production of the same characterized by casting molten steel containing, by mass %, C: 0.03 to 0.12%, Si: 0.05 to 0.30%, Mn: 1.2 to 3.0%, P: 0.015% or less, S: 0.001 to 0.015%, Cu+Ni: 0.10% or less, Al: 0.001 to 0.050%, Ti: 0.005 to 0.030%, Nb: 0.005 to 0.10%, and N: 0.0025 to 0.0060% by the continuous casting method, making the cooling rate from near the solidification point to 800° C. in the secondary cooling at that time 0.06 to 0.6° C./s, hot rolling the obtained slab, and cooling it from a temperature of 800° C. or more.
    Type: Grant
    Filed: July 21, 2005
    Date of Patent: December 28, 2010
    Assignee: Nippon Steel Corporation
    Inventors: Kazuhiro Fukunaga, Yasushi Mizutani, Rikio Chijiiwa, Yoshiyuki Watanabe
  • Patent number: 7815757
    Abstract: The oxide film thickness of the steel material surface (dH2O+do2) is made to become 15 nm or less where post-treatment after water-cooling is not needed by suitably setting the conditions of the water-cooling start temperature (Ti), water-cooling end temperature (To), steel material thickness (d), concentration of solute oxygen in the cooling water (Do), and cooling rate (CR) in the equation of dH2O+do2=7.98×10?4(Ti?To)dDo+{5.50×10?3(Ti2?To2)?6.51(Ti?To)}/CR.
    Type: Grant
    Filed: April 5, 2006
    Date of Patent: October 19, 2010
    Assignees: Nippon Steel Corporation, Nippon Steel Engineering Co., Ltd.
    Inventors: Hisamoto Wakabayashi, Yasumitu Kondo, Tooru Akashi
  • Publication number: 20100258216
    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: Application
    Filed: March 19, 2008
    Publication date: October 14, 2010
    Applicant: CORUS STAAL BV
    Inventors: Hai Wu, Camile Wilbert Josè Hol, Pieter Jacob Van Popta, Willem Cornelis Verloop
  • Patent number: 7763131
    Abstract: The invention relates to a method of improving the cooling of a blown-gas cooling chamber or of a blown-air cooling section in a line for heat treating steel and/or aluminum, and/or of improving the quality of products for treatment by reducing the vibration generated by the cooling, in which jets of gas or air are projected against each of the faces of the strip traveling through said section or chamber.
    Type: Grant
    Filed: October 12, 2005
    Date of Patent: July 27, 2010
    Assignee: CMI Thermline Services
    Inventors: Michel Boyer, Patrick Dubois