With Working At Or Below 120c Or Unspecified Cold Working Patents (Class 148/603)
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Patent number: 6171416Abstract: At least both ends of a sheet bar in the length direction, which is obtained by roughly rolling a steel slab including 0.1 wt % or less of C, 0.5 wt % or less of Si, 1.0 wt % or less of Mn, 0.1 wt % or less of P, 0.05 wt % or less of S, 0.20 wt % or less of Al, and 0.015 wt % or less of N, are heated so that the temperature at both ends of the sheet bar in the length direction is 15° C. or more higher than the temperature of the remainder of the sheet bar. The rolling finish temperature is Ar3+20° C. to Ar3+100° C. in both end portions of the sheet bar in the length direction, and Ar3+10° C. to Ar3+60° C. in the remainder, and the rolling finish temperature in the both end portions in the length direction is 10° C. or more higher than that of the remainder, so that a steel strip after cold rolling and annealing has r values within ±0.3 of the average r value, and &Dgr;r within ±0.Type: GrantFiled: October 26, 1999Date of Patent: January 9, 2001Assignee: Kawasaki Steel CorporationInventors: Makoto Aratani, Yukio Kobata, Hideo Kuguminato, Akio Tosaka, Masatoshi Aratani, Susumu Okada
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Patent number: 6171413Abstract: A soft cold-rolled steel sheet contains: 0.06 wt. % or less C, 0.1 wt. % or less Si, 0.5 wt. % or less Mn, 0.03 wt. % or less P, 0.03 wt. % or less S, 0.006 wt. % or less N, 0.009 wt. % or less B and the balance being Fe. The method comprises the steps of: continuously casting a steel to produce a slab; hot-rolling the slab to form a hot-rolled steel sheet; cold-rolling the hot-rolled steel sheet to produce a cold-rolled steel sheet; and continuously annealing the cold-rolled steel sheet.Type: GrantFiled: July 16, 1998Date of Patent: January 9, 2001Assignee: NKK CorporationInventors: Yoshimasa Funakawa, Toru Inazumi, Hiroshi Sawada, Naoki Matsui, Jun Taniai, Kenichi Mitsuzuka
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Patent number: 6162308Abstract: A method for producing a cold-rolled steel sheet or strip with good formability, especially stretch formability, for making pressings with a high buckling resistance from a steel comprising (in % by mass): 0.01 to 0.08% C, 0.10 to 0.80% Mn, maximum 0.15% Si, 0.015 to 0.08% Al, a maximum 0.005% N, 0.01 to 0.04% Ti and/or Nb, whose contents exceeding the quantity necessary for stoichiometric binding of the nitrogen, ranges from 0.003 to 0.015% Ti or 0.0015 to 0.008% Nb, and a maximum 0.15% in total of one or several elements from the group copper, vanadium, nickel, the remainder being iron, including unavoidable impurities, including a maximum 0.08% P and a maximum 0.02% S, comprises preheating the cast slab to a temperature exceeding 1050.degree. C., hot-rolling at a final temperature ranging from over the Ar.sub.3 temperature to 950.degree. C., coiling the hot-rolled strip at a temperature ranging from 550 to 750.degree. C.Type: GrantFiled: October 27, 1998Date of Patent: December 19, 2000Assignee: Thyssen Stahl AGInventors: Ilse Heckelmann, Ullrich Heidtmann, Rolf Bode
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Patent number: 6143100Abstract: A bake hardenable cold-rolled steel sheet and a method for producing the steel sheet are provided, wherein the steel sheet includes carbon in a range of about 0.003-0.1 wt. %, with the amount of carbon in solution being about 3-30 ppm, and the steel is substantially free of Ti, Nb, and V, which are otherwise commonly employed in producing low-carbon bake hardenable cold-rolled steel. The method includes a two stage batch or box anneal, a first stage of which is an intercritical batch anneal at a temperature between the A.sub.1 and A.sub.3 temperatures, and a second, subcritical batch anneal at a temperature below the A.sub.1 temperature and above 900.degree. F., with a slow controlled cooling from the intercritical temperature to the subcritical temperature, and from the subcritical temperature to ambient temperature.Type: GrantFiled: September 29, 1998Date of Patent: November 7, 2000Assignee: National Steel CorporationInventor: Weiping Sun
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Patent number: 6117253Abstract: The present invention is related to the cold rolled steel sheet for making a shadow mask of a cathode ray tube of a color Braun tube for selecting colors and a manufacturing method therefor. Objects of the present invention are to enable production of a cold rolled steel sheet by one-step cold rolling and low-temperature annealing rather than by the conventional two-step cold rolling and decarburization annealing, and to provide a cold rolled steel sheet for a shadow mask and the manufacturing method therefor having better etchability and formability which are required for the material for a shadow mask than those of the conventional cold rolled steel sheets. The manufacturing method of the cold rolled steel sheet of the present invention is comprised of the steps of homogenizing the aluminum killed steel, which is composed in weight % of less than 0.002% of C, 0.20-0.45% of Mn, 0.015-0.020% of S, less than 0.02% of P, less than 0.01% of Si, 0.01-0.03% of Cr, 0.01-0.02% of Al, 0.0010-0.Type: GrantFiled: December 18, 1998Date of Patent: September 12, 2000Assignee: Pohang Iron & Steel Co., Ltd.Inventors: Ki Soo Kim, Hyun Gyu Hwang, Eel Young Kim, Chin Kwan Chang, Oh Joon Kwon
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Patent number: 6110299Abstract: A steel sheet for double-rolled tubes has excellent formability, and excellent strength and toughness after forming and heat treatment of a tube because of suppressed coarsening of the ferrite grain size and a method for making the same comprises: hot finish-rolling of a steel material containing C: 0.0005-0.020 wt %, and one or two of Nb: 0.003-0.040 wt %, and Ti: 0.005-0.060 wt % at a final temperature of 1,000-850.degree. C., coiling at 750.degree. C. or less, cold rolling, continuous annealing at 650.degree. C.-850.degree. C. for 20 seconds or less, and second cold-rolling at a rolling reduction rate of 20% or less, so that at least one of Nb and Ti is present in a solid solution state in an amount of 0.005 wt % or more, and the crystal grain size in the ferrite structure is in the range of 5 to 10 .mu.m.Type: GrantFiled: June 24, 1998Date of Patent: August 29, 2000Assignee: Kawasaki Steel CorporationInventors: Akio Tosaka, Kaneharu Okuda, Masatoshi Aratani
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Patent number: 6099665Abstract: This invention aims at producing a cold rolled thin sheet having excellent surface quality from a cast strip of a Cr--Ni type stainless steel cast strip by a thin casting method. The production method of the invention comprises the steps of continuously casting a Cr--Ni type stainless steel to a cast strip having a thickness of not greater than 10 mm by using a continuous casting machine the cast mold wall surface of which moves in synchronism with the cast strip; hot rolling the resulting cast strip at a temperature within the range of 900 to 1,200.degree. C. at a reduction ratio of 10 to 50%; carrying out, subsequently, heat-treatment at a temperature within the range of 1,200 to 900.degree. C. for at least 5 seconds; coiling the hot rolled cast strip at a temperature not higher than 600.degree. C.; descaling the rolled cast strip; cold rolling the cast strip; conducting annealing, pickling or bright annealing; and conducting skin pass rolling, whenever necessary.Type: GrantFiled: October 10, 1996Date of Patent: August 8, 2000Assignee: Nippon Steel CorporationInventors: Shin-ichi Teraoka, Toshiyuki Suehiro, Eiichiro Ishimaru, Tetsurou Takeshita, Shunji Shoda, Takashi Arai, Hideki Oka, Yoshikatsu Nohara
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Patent number: 6063214Abstract: A method of producing a steel sheet useful for making cans. The method steps include hot-rolling a slab consisting of about 0.0005 to 0.01 wt % C, about 0.001 to 0.04 wt % N (the total of C and N is at least about 0.008 wt %), about 0.05 to 2.0 wt % Mn, about 0.005 wt % or less Al, about 0.01 wt % or less O at a finish rolling temperature within a temperature range of about the Ar.sub.3 point to about 950.degree. C., coiling the rolled material at a temperature range of about 400 to 600.degree. C., cold rolling the material, continuously annealing the material at a temperature higher than the recrystallization temperature, and then temper-rolling the material. The steel sheet exhibits good workability during can making and which can be formed into a can having high strength.Type: GrantFiled: August 8, 1994Date of Patent: May 16, 2000Assignee: Kawasaki Steel CorporationInventors: Chikako Fujinaga, Akio Tosaka, Toshiyuki Kato, Kaku Sato, Hideo Kuguminato, Yoshihiro Okawa
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Patent number: 6051085Abstract: The carbon content in molten steel is adjusted to be a value not lower than 0.001%, and a thin steel strip is made from this molten steel using a twin drum type continuous casting apparatus by means of direct casting. The thus obtained slab is given a reduction of not lower than 10%. The coagulated steel strip is cooled to a temperature not higher than the temperature determined by a function of the carbon content, cooling speed and ratio of reduction of in-line. After that, the steel strip is reheated and then cooled again to a temperature not higher than the temperature determined by the function of the carbon content. Then the cooled steel strip is coiled. In the above process, a metallic sheet, the surface of which is smooth and the metallic structure of which is fine, can be produced.Type: GrantFiled: September 23, 1997Date of Patent: April 18, 2000Assignee: Nippon Steel CorporationInventors: Shigenori Tanaka, Satoshi Akamatsu
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Patent number: 6027581Abstract: Cold rolled steel sheet with excellent deep drawability and excellent anti-aging properties, and manufacturing method. The cold rolled steel sheet comprises about C: above 0.015 to 0.150 wt %, Si: 1.0 wt % or less, Mn: 0.01 to 1.50 wt %, P: 0.10 wt % or less, S: 0.003 to 0.050 wt %, Al: 0.001 to below 0.010 wt %, N: 0.0001 to 0.0050 wt %, Ti: 0.001 wt % or more and Ti(wt %)/[1.5.times.S(wt %)+3.4.times.N(wt %)].ltoreq.about 1.0 and B: about 0.0001 to 0.0050 wt %, during annealing, grain growth is improved; Ti is added to form a nitride and a sulfide to avoid precipitation of fine TiC; B is added to precipitate Boron precipitates (Fe.sub.2 B, Fex(C,B)y) in a cooling the hot rolled steel sheet and in cooling step during annealing after cold rolling; a spherical cementite is precipitated and grown in which the Boron series precipitate is a precipitation site.Type: GrantFiled: September 23, 1997Date of Patent: February 22, 2000Assignee: Kawasaki Steel CorporationInventors: Kazunori Osawa, Masahiko Morita, Osamu Furukimi, Takashi Obara
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Patent number: 5997664Abstract: Method for producing a galvannealed steel sheet wherein a slab consisting essentially of C in an amount of 0.004 wt. % or less, N in an amount of 0.004 wt. % or less, Ti in an amount of 0.01 to 0.15 wt %, Si in an amount of 0.05 wt. % or less, Mn in an amount up to 2.5 wt. %, P in an amount up to 0.1 wt. %, S in an amount of 0.015 wt. % or less, sol. Al in an amount of 0.02 to 0.1 wt. % and the balance being Fe, is soaked for at least 30 minutes at a specified temperature (range). The soaked slab is hot rolled to produce a hot-rolled steel sheet which is coiled at a temperature of 500 to 700.degree. C. The coiled hot-rolled steel sheet is cold rolled at a reduction ratio of 60% or more to produce a cold-rolled steel sheet which is annealed at a temperature of from recrystallization temperature to Ac3 transformation temperature. Galvanizing the annealed cold-rolled steel sheet and then galvannealing at a temperature of 450 to 600.degree. C.Type: GrantFiled: June 6, 1997Date of Patent: December 7, 1999Assignee: NKK CorporationInventors: Kenji Tahara, Junichi Inagaki, Toyofumi Watanabe, Masaaki Yamashita
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Patent number: 5954896Abstract: According to the present invention, an ultra low carbon steel with Nb, Ti, or Nb-Ti added thereto is used as a material, and (% S as MnS)/(total S content) is regulated to not more than 0.2 with (% C as carbosulfide)/(total C content) being regulating to not more than 0.7, thereby efficiently precipitating carbosulfide in a .gamma. temperature region during hot rolling and thus reducing the amount of C in solid solution to ensure the homogeneity of the material over the whole length of a coil and to markedly improve the workability.Type: GrantFiled: October 18, 1996Date of Patent: September 21, 1999Assignee: Nippon Steel CorporationInventors: Kazuo Koyama, Masayoshi Suehiro, Naoki Yoshinaga, Natsuko Hashimoto
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Patent number: 5922149Abstract: A method for making steel wires, wherein an elongate shaped wire is produced by rolling or drawing steel consisting of 0.05-0.5% C, 0.4-1.5% Mn, 0-2.5% Cr, 0.1-0.6% Si, 0-1% Mo, no more than 0.25% Ni, and no more than 0.02% S and P, and a first heat treatment is performed on the shaped wire, including at least one step of quenching under predetermined conditions to achieve an HRC hardness of at least 32, a predominately martensitic and bainitic steel structure and a small amount of ferrite. A shaped wire and a flexible tube for conveying an H.sub.2 S-containing effluent are disclosed.Type: GrantFiled: November 4, 1997Date of Patent: July 13, 1999Assignees: Institut Francais du Petrole, CoflexipInventors: Jose Mallen Herrero, Fran.cedilla.ois Ropital, Andre Sugier
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Patent number: 5906690Abstract: A method of producing cold-rolled, high-strength steel strip with good plasticity and isotropic properties out of steel comprising no more than 0.08% carbon, no more than 10% silicon, no more than 1.8% manganese, between 0.010 and 0.10% phosphorus, no more than 0.02% sulfur, no more than 0.08% aluminum and no more than 0.008% nitrogen by weight plus one or more of the elements titanium, vanadium, niobium, and zirconium, the remainder being iron, by hot rolling, cold rolling, and recrystallization annealing; followed by temper rolling. The steel contains either three times as much titanium or six times as much niobium or zirconium as nitrogen.Type: GrantFiled: December 4, 1996Date of Patent: May 25, 1999Assignee: Fried. Krupp AG Hoesch-KruppInventors: Bernhard Engl, Klaus-Dieter Horn, Gunter Stich
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Patent number: 5855696Abstract: The cold rolled steel sheet or galvanized steel sheet comprises by weight C: 0.0001 to 0.0026%, Si: not more than 1.2%, Mn: 0.03 to 3.0%, P: 0.015 to 0.15%, S: 0.0010 to 0.020%, Al: 0.005 to 0.1%, N: 0.0005 to 0.0080% and B: 0.0003 to 0.0030% with the balance consisting of Fe and unavoidable impurities. A process for producing the above steel sheet is also provided which comprises the steps of: performing hot roll finishing of a slab having the above chemical composition at the Ar.sub.3 transformation point or above; preferably, then cooling the hot rolled strip, within 1.5 sec after the completion of the hot rolling, to 750.degree. C. at a rate of not less than 50.degree. C./sec; coiling the strip in the temperature range of from room temperature to 750.degree. C.; cold rolling the coiled strip a reduction ratio of not less than 70%; subjecting the cold rolled strip to continuous annealing at 600.degree. to 900.degree. C.Type: GrantFiled: March 19, 1997Date of Patent: January 5, 1999Assignee: Nippon Steel CorporationInventors: Makoto Tezuka, Kohsaku Ushioda, Shiro Fujii, Atsushi Itami, Yasuharu Sakuma, Tatsuo Yokoi
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Patent number: 5846343Abstract: A cold rolled steel sheet including about 0.001 weight percent or less of carbon (C), about 0.1 weight percent or less of silicon (Si), about 0.3 weight percent or less of manganese (Mn), about 0.05 weight percent or less of phosphorus (P), about 0.003 weight percent or less of sulfur (S), about 0.1 weight percent or less of aluminum (Al), about 0.002 weight percent or less of nitrogen (N), about 0.005 to 0.02 weight percent of titanium (Ti), about 0.001 to 0.01 weight percent of niobium (Nb), and the balance iron and incidental impurities. The total weight percent of carbon, sulfur, and nitrogen is about 0.004 weight percent or less. The content of titanium, carbon, sulfur and nitrogen satisfies the equation: about 4.times.(C wt %).ltoreq.(Ti wt %)-48/14(N wt %)-48/32(S wt %).ltoreq.about 12.times.(C wt %). The method of the invention includes uniformly heating a steel slab having a composition as described above at a temperature T(K) satisfying the following equation:T(K).times.(C wt %+S wt %).ltoreq.Type: GrantFiled: March 14, 1996Date of Patent: December 8, 1998Assignee: Kawasaki Steel CorporationInventors: Eiko Yasuhara, Kei Sakata, Toshiyuki Kato
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Patent number: 5759307Abstract: A method of producing a cold-rolled strip from a stainless, ferretic or austenitic high-grade steel or a titanium alloy, wherein the strip which has been wound into a coil and has been manufactured by a hot-rolling or casting process is subjected in one pass to the steps of unwinding the coil, mechanically descaling the strip if required, subsequently chemically and/or electrochemically first or black pickling of the strip, then cold-rolling the strip to finished dimensions, degreasing the strip as required, annealing the strip, finish-pickling the strip and, if necessary, passivating, dressing and stretcher-leveling the strip. The pickling step is carried out in a pickling solution which contains hydrochloric acid, sulfuric acid and/or nitric acid.Type: GrantFiled: August 30, 1996Date of Patent: June 2, 1998Assignees: Keramchemie GmbH, BWG Bergwerk- und Walzwerk Maschinenbau GmbHInventors: Heinz Berger, Rolf Noe, Frank Barhold, Jorg Neumann, Andreas Noe, Ralf Waldmann, Bodo Block
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Patent number: 5759306Abstract: A method is provided for making a steel sheet suitable as a can material. The method includesa step for hot rolling a steel slab to a strip having a thickness of less than about 1.2 mm,a step for coiling the strip into a coil at a temperature range between about 600.degree. and 750.degree. C.,a step for pickling the coil with an acid, anda step for cold rolling the coil at a rolling reduction rate of about 50 to 90 percent, wherein the steel slab containsabout 0.0020 weight percent or less of carbon,about 0.020 weight percent or less of silicon,about 0.50 weight percent or less of manganese,about 0.020 weight percent or less of phosphorus,about 0.010 weight percent or less of sulfur,about 0.150 weight percent or less of aluminum,about 0.0050 weight percent or less of nitrogen, andthe balance iron and incidental impurities.A steel sheet suitable as a can material is also provided by this method.Type: GrantFiled: March 11, 1996Date of Patent: June 2, 1998Assignee: Kawasaki Steel CorporationInventors: Akio Tosaka, Kaneharu Okuda, Toshiyuki Kato, Hideo Kuguminato
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Patent number: 5738738Abstract: A method for manufacturing a cold rolled steel plate used for enamel applications such as tableware, construction panel, external plate material of microwave oven and gas range, and bathtub, in which an excellent enamel adherence between an enamel layer and a raw steel plate is increased and a formability required for the production of complicated shape is greatly improved and to provide a method for manufacturing a high processing cold rolled steel plate being excellent in enamel adherence. The invention is, in a method for manufacturing an enamel coating cold rolled steel plate by utilizing aluminum killed steel, a method for manufacturing a high processing cold rolled steel plate being excellent in enamel close adhering property in which an aluminum killed steel, in which C: less than 0.01%, Mn: 0.1-0.4%, S: 0.03-0.09%, Ti: 0.04-0.1% and N: less than 0.01% by weight % are contained, and an atomic ratio defined by Ti/(C+N+0.4S) is adjusted to 1.0-2.Type: GrantFiled: August 19, 1996Date of Patent: April 14, 1998Assignees: Pohang Iron & Steel Co., Ltd., Research Institute of Industrial Science & TechnologyInventors: Jeong Bong Yoon, Sung Ju Kim
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Patent number: 5725697Abstract: A method of manufacturing a cold-rolled can steel sheet having less planar anisotropy and achieving good workability. Rough-rolling is first performed on a continuously-cast slab. The slab has a composition essentially consisting of: C: 0.004 wt % or lower; Mn: 0.05-0.5 wt %; P: 0.02 wt % or lower; Al: 0.005-0.07 wt %; N: 0.004 wt % or lower; and Nb: 0.001-0.018 wt %, the rest being Fe and unavoidable impurities. A resultant sheet bar is then subjected to hot rolling which is completed at a finishing rolling temperature at an Ar.sub.3 transformation point or higher. The resultant sheet bar is coiled at a temperature range from 450.degree.-700.degree. C. Subsequently, the resultant sheet bar undergoes primary cold rolling before continuous annealing, which is performed at a recrystallization temperature or higher, and secondary cold rolling. The primary and secondary cold rolling are respectively performed at reduction ratios satisfying the following conditions of:88%.gtoreq.CR.sub.1 %+0.36.times.CR.sub.2 .Type: GrantFiled: December 21, 1994Date of Patent: March 10, 1998Assignee: Kawasaki Steel CorporationInventors: Chikako Fujinaga, Akio Tosaka, Toshiyuki Kato, Kaku Sato, Hideo Kuguminato
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Patent number: 5690757Abstract: Method for the continuous manufacture of steel strip in which steel strip is fed into an annealing furnace at a certain feed-in rate and drawn out of the furnace at a rate higher than the feed-in rate while subjecting the steel strip to a pulling force in the annealing furnace at a temperature above the recrystallization temperature of the steel in the region of 1000.degree. to 1250.degree. C. This results in the introduction of a permanent stretch of the steel strip corresponding to the difference between the feed-out and feed-in rates as well as a reduction in the cross-section of the strip corresponding to the elongation and a reduction of the strip thickness and strip width.Type: GrantFiled: September 14, 1994Date of Patent: November 25, 1997Assignee: Avesta SheffieldInventor: Sten Ljungars
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Patent number: 5690755Abstract: The present invention provides a cold-rolled steel sheet and a hot-dip galvanized steel sheet having good bake hardenability, non-aging properties at room temperature and good formability and a process for producing the same. An extra low carbon steel or an extra low carbon steel containing at least one element selected from Ti and Nb is annealed at a temperature of not lower than the AC.sub.3 transformation point to bring the structure after annealing to a structure of low-temperature transformation products. This makes it possible to provide a steel sheet that has a combination of high paint-bake hardenability and non-aging properties at room temperature and is excellent also in formability in respect of average r value (deep drawability) and elongation (punch stretchability). In particular, with respect to paint-bake hardenability, a BH property on a high level up to about 10 kgf/mm.sup.Type: GrantFiled: September 11, 1996Date of Patent: November 25, 1997Assignee: Nippon Steel CorporationInventors: Naoki Yoshinaga, Kohsaku Ushioda, Osamu Akisue, Yoshikazu Matsumura, Kunio Nishimura
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Patent number: 5669992Abstract: A bumper beam for vehicles is formed from cold-rolled sheet steel having an initial tensile strength of approximately 70 ksi. The steel sheet is roll formed in a desired cross-section and swept into a curvature corresponding to the vehicle requirements before the steel sheet is heat treated by induction heat and quenched to provide a bumper beam having a tensile strength from 100 ksi up to approximately 260 ksi.Type: GrantFiled: January 30, 1996Date of Patent: September 23, 1997Inventors: Brand Bronsema, Jeffrey A. Anderson, John J. Kary
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Patent number: 5656102Abstract: Rolled articles such as hot rolled or cold rolled and annealed sheet and/or strip include effective amounts of vanadium in low carbon steels to produce an improved bake hardenable product especially adapted for automotive use. The use of vanadium in the alloy steel chemistry controls bake hardenability, permits solution annealing at lower temperatures in its manufacturing sequence and specifies a composition range which is more easily cast within desired limits and causes less variation in final mechanical properties. Controlling the vanadium to carbon ratio to maintain a value of about 10 or greater also improves aging resistance.Type: GrantFiled: February 27, 1996Date of Patent: August 12, 1997Assignee: Bethlehem Steel CorporationInventors: Keith A. Taylor, John G. Speer
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Patent number: 5656103Abstract: A non-heat treated, high tensile strength, highly formable steel strap that may be applied in a tensioned loop about packaged articles with a strapping machine. The strap is fabricated from a steel comprising approximately, 0.20 to 0.25 percent carbon, 0.30 to 0.60 percent manganese, 0.04 percent maximum phosphorus, 0.05 percent maximum sulfur, an aluminum in an amount sufficient for full aluminum kill, 0.10 percent maximum silicon, and a boron to free nitrogen ratio of approximately between 1.07 to 1.43. The steel is coiled at a coiling temperature of approximately 1100 degrees Fahrenheit to reduce self-annealing that occurs during air cooling after coiling. The coiled steel is then reduced approximately 80 percent by cold rolling to increase tensile strength before it is fabricated into steel strap which may be protected with a zinc coating.Type: GrantFiled: October 31, 1996Date of Patent: August 12, 1997Assignee: Illinois Tool Works Inc.Inventor: Philip M. Roberts
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Patent number: 5618355Abstract: A high-strength steel sheet suitable for deep drawing, characterized by comprising 0.04 to 0.25 mass % of C and 0.3 to 3.0 mass %, in total, of at least one of Si and Al, the steel sheet having multiple phases structure comprising ferrite as a main phase (a phase having the highest volume fraction), not less than 3 vol. % of austenite, and bainite and martensite; said steel satisfying a requirement that a value obtained by dividing volume fraction of Vg (vol. %) of austenite before working by the content of C (mass %) contained in the whole steel, Vg/C, is 40 to 140, a requirement that Vp (volume fraction of austenite at the time of plane strain tensile deformation)/Vs (volume fraction of austenite at the time of shrink flanging deformation) is not more than 0.Type: GrantFiled: December 12, 1995Date of Patent: April 8, 1997Assignee: Nippon Steel CorporationInventors: Kazuo Koyama, Matsuo Usuda, Manabu Takahashi, Yasuharu Sakuma, Shunji Hiwatashi, Kaoru Kawasaki
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Patent number: 5587027Abstract: A method for manufacturing a canning steel sheet with non-aging property and superior workability uses, as a starting material, an ultra-low-carbon steel slab composed of from 0.0015% to 0.0100% by weight C, up to 0.20% by weight Si, from 0.10% to 1.20% by weight Mn, from 0.02% to 0.10% by weight Al, from 0.005% to 0.040% by weight P, up to 0.015% by weight S, up to 0.005% by weight N, and balance iron and unavoidable impurities. The manufacturing method includes hot rolling the steel, cold rolling the steel at a reduction ratio not less than 70% after pickling, and recrystallization annealing the steel by using a continuous annealing furnace in an atmosphere having a hydrogen content not less than 3% and a dew point not lower than -20.degree. C. at a temperature not lower than 730.degree. C. so that the content of remained C in the steel is kept less than 0.0015% by weight. At least one element selected from Nb, Ti and B may be added in predetermined amounts to the above composition.Type: GrantFiled: February 15, 1995Date of Patent: December 24, 1996Assignee: Kawasaki Steel CorporationInventors: Akio Tosaka, Chikako Fujinaga, Toshiyuki Kato, Kaku Sato, Hideo Kuguminato
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Patent number: 5582658Abstract: A high strength steel sheet adapted for press forming and method producing the same. The steel sheet containing by weight C: 0.01-0.1%, Si: 0.1-1.2%, Mn: not more than 3.0%, Ti:a value of (Ti%-1.5S%-3.43N%)/C% being 4-12, B: 0.0005-0.005%, Al: not more than 0.1%, P: not more than 0.1%, S: not more than 0.02%, N: not more than 0.05%. The method for producing the steel sheet wherein a steel slab containing the above mentioned component composition is heated and hot rolled in a temperature range of 1100-1280.degree. C. to provide a hot rolled sheet. The hot rolled sheet may be is subjected to cold rolling and annealing to provide a cold rolled sheet.Type: GrantFiled: December 13, 1995Date of Patent: December 10, 1996Assignee: Kawasaki Steel CorporationInventors: Susumu Masui, Kei Sakata, Fusao Togashi, Masahiko Morita, Toshiyuki Kato
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Patent number: 5558727Abstract: A high strength steel sheet for automobiles which exhibits excellent press-formability strength against impact resistance at a high strain rate is hot rolled under specific conditions, or is cold rolled from hot rolled sheet which is prepared under conventional conditions, with the cold rolled steel being annealed under specific conditions. The steel sheet comprises 0.010-0.10 wt % of C, not greater than 1.50 wt % of Si, 0.50-3.00 wt % of Mn, not greater than 0.010 wt % of S and 0.01-0.1 wt % of Al, and one kind or two kinds selected from 0.05-0.15 wt % of P and 0.5-1.5 wt % of Cr, and the balance being Fe and inevitable impurities and having a structure mainly composed of 2-30 vol % of martensite phase and a ferrite phase containing a solution C not greater than 0.0010 wt %.Type: GrantFiled: February 23, 1995Date of Patent: September 24, 1996Assignee: Kawasaki Steel CorporationInventors: Kazuya Miura, Shusaku Takagi, Takaaki Hira, Toshiyuki Kato, Nobutaka Kurosawa
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Patent number: 5558726Abstract: This invention aims at obtaining a cold steel sheet having excellent cold formability irrespective of a high N content in order to re-utilize a scrap steel generated from scraps. A steel sheet comprising not greater than 0.1% of C, 60 to 150 ppm of N, not greater than 0.4% of Mn satisfying the relation Mn/S.gtoreq.7, not greater than 0.030% of S, not greater than 0.1% of Al and not greater than 0.08% of Ti satisfying the relation N (%)--Ti/3.42 (%).ltoreq.0.007, wherein the size of TiN in the weight at least 1/2 of the total TiN weight is 0.05 to 10 .mu.m, is obtained. When production is made by continuous annealing, Ti is added so as to satisfy the relation N (%)--Ti/3.42 (%).ltoreq.0.004% and furthermore, high temperature winding is effected in hot rolling or B is added.When production is made by box annealing, the Ti content is adjusted so as to satisfy the relation 0.002%.ltoreq.N (%)--Ti/3.42 (%).ltoreq.0.Type: GrantFiled: June 14, 1995Date of Patent: September 24, 1996Assignees: Nippon Steel Corporation, Japan Casting & Forging CorporationInventors: Hisayoshi Yatoh, Yasuhiko Yamashita, Takashi Harabuchi, Seinosuke Yano
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Patent number: 5542994Abstract: A method of producing a high-formable, high-strength cold-rolled steel sheet from a steel slab comprising a steel with very low carbon content, one or both of Ti and Nb as a composition for forming a carbide or a nitride, and B in the range satisfying the following expression:0.001 A.ltoreq.B (wt %).ltoreq.0.003 Awherein A is a parameter determined approximately by the following expression with reference to the relation:A=P (wt %)+0.2 Mn (wt %)+0.8 Si (wt %)-0.2, subjecting the steel to a hot rolling so as to finish at a temperature between about Ar.sub.3 transformation temperature and about Ar.sub.3 transformation temperature +100 C.degree.. Thereafter, the steel is successively subjected to coiling, cold-rolling and, then, continuous annealing at temperatures between Ac.sub.1 transformation temperature +5 C.degree. and Ac.sub.1 transformation temperature +50 C.degree., and not lower than 860 C.degree..Type: GrantFiled: December 23, 1994Date of Patent: August 6, 1996Assignee: Kawasaki Steel CorporationInventors: Kazuhiro Seto, Kaneharu Okuda, Kei Sakata, Toshiyuki Kato, Takashi Ono
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Patent number: 5534089Abstract: A method of manufacturing a small planar anisotropic high-strength can steel plate. Hot-rolling is first performed on a steel slab at an Ar.sub.3 transformation point or higher to obtain hot rolled steel strip. The slab has a composition which essentially consists of and which satisfies the conditions of: C.ltoreq.0.004%, Si.ltoreq.0.02%, Mn=0.5%-3%, P.ltoreq.0.02%, Al=0.02%-0.05%, 0.008%.ltoreq.N.ltoreq.0.024%, and the rest being Fe and unavoidable impurities, wherein the conditions have the relationship of:Al%/N%>2. Then, the resultant strip is cooled at a cooling rate of 10.degree. C./s or higher so as to reach a temperature of 650.degree. C. or lower. The resultant strip is further coiled at a temperature in a range of from 550.degree. C. to 400.degree. C. Cold-rolling is performed on the resultant strip at a reduction ratio of 82% or higher preceded by removing a scale to obtain cold rolled steel strip.Type: GrantFiled: December 20, 1994Date of Patent: July 9, 1996Assignee: Kawasaki Steel CorporationInventors: Chikako Fujinaga, Akio Tosaka, Toshiyuki Kato, Kaku Sato
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Patent number: 5531839Abstract: A continuously annealed cold-rolled steel sheet excellent in balance between deep drawability and resistance to secondary-work embrittlement, which consists essentially of: under 0.0030 wt. % carbon, up to 0.05 wt. % silicon, from 0.05 to 0.20 wt. % manganese, up to 0.02 wt. % phosphorus, up to 0.15 wt. % sulfur, from 0.025 to 0.06 wt. % soluble aluminum, up to 0.0030 wt. % nitrogen, from 0.02 to 0.10 wt. % titanium, from 0.0003 to 0.0010 wt. % boron, and the balance being iron and incidental impurities, where a value of an index (X) representing a content rate of titanium to boron, as calculated by specific formulae, is of from 9.2 to 11.2. The above-mentioned continuously annealed cold-rolled steel sheet is manufactured by: carrying out a finishing-rolling in a hot-rolling of a steel slab having the above-mentioned chemical composition so that a reduction rate distribution function (Y) as expressed by another specific formula is satisfied; completing the finishing-rolling at a temperature of from 880.Type: GrantFiled: March 28, 1995Date of Patent: July 2, 1996Assignee: NKK CorporationInventors: Yoshihiro Hosoya, Masaya Morita, Seishi Tsuyama
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Patent number: 5486241Abstract: The present invention provides a non-aging at room temperature ferritic single-phase cold-rolled steel sheet or hot-dip galvanized steel sheet for deep drawing and having excellent fabrication embrittlement resistance and paint-bake hardenability, by heating a slab comprising, in terms of % by weight, 0.0001 to 0.0015% of C, not more than 1.2% of Si, 0.03 to 3.0% of Mn, 0.01 to 0.15% of P, 0.0010 to 0.020% of S, 0.005 to 0.1% of Al, 0.0001 to 0.0080% of N and 0.0001 to 0.0030% of B and optionally 0.1 to 3% of Cr with the balance consisting of Fe and unavoidable impurities, hot-rolling the heated slab at a finishing temperature of not lower than (Ar.sub.3 --100).degree. C., cooling the hot-rolled coil within 1 sec after the hot rolling at a rate of not less than 50.degree. C./sec from the finishing temperature to a temperature in the range of from 600.degree. to 750.degree. C.Type: GrantFiled: June 29, 1994Date of Patent: January 23, 1996Assignee: Nippon Steel CorporationInventors: Kohsaku Ushioda, Naoki Yoshinaga, Yoshikazu Matsumura, Osamu Akisue, Kunio Nishimura, Hidekuni Murakami
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Patent number: 5470403Abstract: The present invention provides a cold rolled steel sheet and a hot dip zinc-coated cold rolled steel sheet excellent in paint bake hardenability, non-aging properties and formability, and a process for producing the same. In the present invention, an extremely low carbon steel or extremely low carbon steel containing at least one element selected from the group consisting of Ti and Nb is used as a base steel, and Mn and Cr are positively added thereto, whereby the resultant steel has a mixed structure after annealing. Accordingly, there can be obtained a steel sheet having both a high paint bake hardenability and non-aging properties, and being excellent in formability such as an average r-value (deep drawability). With regard to the paint bake hardenability, the present invention may provide a cold rolled steel sheet and a hot dip zinc-coated cold rolled steel sheet to which paint bake hardening may be optionally imparted in an amount as large as about 10 kgf/mm.sup.Type: GrantFiled: February 18, 1994Date of Patent: November 28, 1995Assignee: Nippon Steel CorporationInventors: Naoki Yoshinaga, Kohsaku Ushioda, Osamu Akisue, Kunio Nishimura
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Patent number: 5460665Abstract: A method of manufacturing a cold rolled steel sheet includes the steps of preparing, as a material, a steel whose composition consists of C: 0.004 wt % or less, Si: 0.10 wt % or less, Mn: 0.50 wt % or less, Ti: between 0.01 wt % and 0.10 wt %, Nb: between 0.003 wt % and 0.03 wt %, B: between 0.001 wt % and 0.004 wt %, Al: between 0.03 wt % and 0.10 wt %, P: 0.025 wt % or less, S: 0.01 wt % or less, N: 0.006 wt % or less; performing a hot rolling on the material steel under the conditions of a finishing temperature between 800.degree. C. and 900.degree. C.; coiling the material at a temperature lower than 650.degree. C.; performing a cold rolling; performing a continuous annealing at a temperature between 830.degree. C. and Ac.sub.3 transformation point; and performing a skin pass rolling.Type: GrantFiled: October 11, 1994Date of Patent: October 24, 1995Assignee: Kawasaki Steel CorporationInventors: Eiko Yasuhara, Kei Sakata, Susumu Satoh, Toshiyuki Kato
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Patent number: 5454887Abstract: A process for manufacturing a medium-carbon steel plate having a graphitization of 50% or more with improved formability and weldability is disclosed, the process comprises the steps of:hot rolling a steel with a finishing temperature of 700.degree.-900.degree. C., the alloy composition of the steel consisting essentially of, by weight %:C: 0.20-0.70%,Si: more than 0.20 but not more than 2.00%,Mn: 0.05-0.50%, P: not more than 0.020%,S: not more than 0.010%, sol. Al: 0.01-1.00%,B: 0.0003-0.0050%, N: 0.002-0.010%,B/N: 0.2-0.8,Cu: 0-1.00%, Ni: 0-2.00%, Ca: 0-0.010%, andFe and incidental impurities: balance,cooling the resulting hot-rolled steel plate at a cooling rate of 5.degree.-50.degree. C./s,coiling the steel plate at a temperature of 400.degree.-650.degree. C., andoptionally, cold rolling the hot-rolled steel plate with a reduction in thickness of 20-85%, andannealing the cold-rolled steel plate at a temperature of 600.degree.- Ac.sub.1 for 1 hour or longer.Type: GrantFiled: July 23, 1993Date of Patent: October 3, 1995Assignee: Sumitomo Metal Industries, Ltd.Inventor: Kiyoshi Fukui
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Patent number: 5405463Abstract: Deep drawability and aging resistibility as required are imparted to cold rolled steel sheet by controlling the amount of C, starting temperatures of rapid cooling and cooling rate in a proposed continuous annealing process.Type: GrantFiled: September 20, 1993Date of Patent: April 11, 1995Assignee: Nippon Kokan Kabushiki KaishaInventors: Takayoshi Shimomura, Osamu Nozoe, Masataka Sakoh
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Patent number: 5360676Abstract: A raw plated steel sheet for can comprises recrystallized particles containing approximately C<0,004%, Si<0.03%, Mn:0.05-0.6%, P<0.02%, S<0.02%, N<0.01%, Al:0.005-0.1%, Nb:0,001-0.1%, B:0.0001-0.005% in weight. The maximum diameter of a particle is less than about 30 .mu.m, and an area ratio of particles ranging about 5-25 .mu.m being more than about 50%. Such a steel sheet has excellent processing characteristics and good uniformity in product quality.Type: GrantFiled: April 6, 1993Date of Patent: November 1, 1994Assignee: Kawasaki Steel CorporationInventors: Hideo Kuguminato, Toshikatsu Kato, Chikako Fujinaga, Kyoko Hamahara
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Patent number: 5328528Abstract: The primary object of the present invention is to provide a cold-rolled steel sheet with properties of high-strength, high-ductility, and a process for manufacturing it. The constituents of the cold-rolled steel sheet comprise: 0.08%-0.25% carbon by weight, 0.03%-2.0% silicon by weight, 0.6%-1.8% manganese by weight, 0.01%-0.10% niobium by weight, 0.01%-0.08% aluminium by weight, with the rest being substantially iron and unnoticed impurities. The process for manufacturing cold-rolled steel sheets of the present invention by using the molten steel material as described above includes the following steps:(a) preparing steel ingots by continuous casting the molten steel;(b) hot rolling the steel ingots into hot-rolled bands;(c) coiling the hot-rolled bands at a temperature below 600.degree. C.;(d) after cold-rolling, forming steel sheets from the hot-rolled bands and soaking the steel sheets at a temperature in the two-phase range (equal to AC1+10.degree. C.-AC3-10.degree. C. shown in FIG.Type: GrantFiled: March 16, 1993Date of Patent: July 12, 1994Assignee: China Steel CorporationInventor: Huang-Chuan Chen
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Patent number: 5290370Abstract: A high-tension steel sheet suitable for deep drawing and having superior surface treatment characteristics is made of a steel consisting essentially of, by weight: 0.001 to 0.05% of C; not more than 1.0% of Si; not more than 2.5% of Mn; 0.05 to 1.0% of Mo; one or both of 0.001 to 0.2% of Nb and not more than 0.3% of Ti, wherein Ti*%+(48/93)Nb%.gtoreq.(48/12)C% in which Ti*%=Ti%-(48/32) S%-(48/14)N%, wherein, when Ti*%<0, Ti*% is regarded as being 0; 0.0005 to 0.01% of B; 0.01 to 0.10% of Al; not more than 0.15% of P; not more than 0.010% of S; not more than 0.006% of N; Si, Mn and P meeting the condition of 0.2<(Si%+10P%)/Mn%<3.3; and the balance substantially Fe and incidental impurities. This steel sheet is produced by a process which includes: hot-rolling the steel slab to obtain a hot rolled steel strip at a final hot-rolling temperature not lower than the Ar.sub.3 transformation temperature; coiling the steel strip at a temperature not lower than 300.degree. C. but not higher than 615.degree. C.Type: GrantFiled: August 17, 1992Date of Patent: March 1, 1994Assignee: Kawasaki Steel CorporationInventors: Susumu Okada, Susumu Masui, Susumu Satoh, Kei Sakata, Masahiko Morita, Toshiyuki Kato
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Patent number: 5232524Abstract: The steel having improved deep-drawing properties is characterized in that it contains carbon in a proportion of less than 0.015%, manganese in a proportion of from 0.15 to 0.25%, sulfur in a proportion of less than 0.012% and aluminum in a proportion of less than 0.04%.This steel is intended for the production of thin sheet metal intended for deep-drawing, in accordance with a process comprising, in particular, the following operations:production, in a converter, of a steel having the above composition;hot-rolling entirely in the austenitic region;winding at a temperature higher than 650.degree. C.;continuous annealing, after cold-rolling, at a temperature below 700.degree. C.Type: GrantFiled: June 26, 1992Date of Patent: August 3, 1993Assignee: SollacInventors: Daniel Lafontaine, Georges Van Hoeck, Patrick Zimmer
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Patent number: 5228932Abstract: An Fe-Cr-Al alloy having excellent oxidation resistance and high temperature brittleness resistance comprises:Cr: 10 to 28 wt. %,Al: 1 to 10 wt. %, andB : 0.0003 to 0.010 wt. %,andLa: 0.01 to 0.20 wt. % andZr: 0.01 to 1.0 wt. %,while within the scope of Equation (1)0.1.ltoreq.[wt. % of Zr]/[wt. % of La].ltoreq.20 (1)and wherein elements of impurities are limited as follows:C: 0.05 wt. % or less,N: 0.02 wt. % or less,Si: 0.5 wt. % or less,Mn: 1.0 wt. % or lessTi: less than 0.05 wt. %and the balance consisting of Fe and incidental impurities.Type: GrantFiled: May 27, 1992Date of Patent: July 20, 1993Assignee: Kawasaki Steel CorporationInventors: Hiroshi Shimizu, Sadao Hasuno
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Patent number: 5188681Abstract: A process for manufacturing a thin sheet of a Cr-Ni-base stainless steel having an excellent surface quality and material quality, which comprises casting a cast strip having a thickness of 6 mm or less from a Cr-Ni-base stainless steel including 18% Cr-8% Ni steel by a continuous casting wherein a casting mold is moved synchronously with the cast strip, and subjecting the cast strip to cold rolling to form a thin sheet product, wherein the cast strip immediately after the casting is coiled at a temperature of 800.degree. to 1200.degree. C. and subjected to cold rolling and final annealing to form a thin sheet product.Type: GrantFiled: September 12, 1991Date of Patent: February 23, 1993Assignee: Nippon Steel CorporationInventors: Shinichi Teraoka, Masanori Ueda, Toshiyuki Suehiro
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Patent number: 5156694Abstract: A formable thin steel sheet such as hot rolled sheet, cold rolled sheet or surface treated sheet comprises not more than 0.003 wt % of C, not more than 1.0 wt % of Si, not more than 1.0 wt % of Mn, not more than 0.15 wt % of P, not more than 0.020 wt % of S, not more than 0.0045 wt % of O, not more than 0.0020 wt % of N, not more than 0.15 wt % of Al provided that a ratio of Al/N is not less than 30, and the balance being Fe and inevitable impurities, and has not only improved formability for press forming, deep drawing or the like but also improved fatigue resistance as a welded joint.Type: GrantFiled: May 7, 1991Date of Patent: October 20, 1992Assignee: Kawasaki Steel CorporationInventors: Yoshio Yamazaki, Susumu Okada, Susumu Satoh, Toshiyuki Kato, Hideo Abe, Keiji Nishimura
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Patent number: 5137584Abstract: Cold rolled, recrystallization annealed, high strength steel for porcelain enameling. The steel consists essentially of at least 0.005 wt. % niobium, at least 0.02 wt. % carbon, at least 0.10 wt. % manganese, at least 0.01 wt. % aluminum, nitrogen as an impurity, the ratio of acid sol. aluminum to total nitrogen being at least 2:1, all percentages by weight and the balance being iron and unavoidable impurities, whereby the annealed steel has a yield strength of at least 21 kg/mm.sup.2 after being strained at least 8% and when heated to at least 815.degree. C. The steel is produced by hot rolling a slab to a sheet having a finishing temperature at least A.sub.r3, coiling the hot rolled sheet at a temperature at least 677.degree. C. to precipitate residual nitrogen as aluminum nitride, removing scale from the hot rolled sheet, cold rolling the descaled sheet, annealing the cold rolled sheet without decarburization at a temperature less than 721.degree. C.Type: GrantFiled: July 5, 1991Date of Patent: August 11, 1992Assignee: Armco Steel Company, L.P.Inventor: Rodney J. Jesseman
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Patent number: 5123971Abstract: A cold reduced, non-aging, aluminum killed steel characterized by an elongated grain structure and having an r.sub.m value at least 1.8 produced from a slab having a reduced hot rolling temperature. A slab consisting essentially of .ltoreq.0.08% carbon, .ltoreq.0.1% acid sol. aluminum, .ltoreq.0.2% manganese, all percentages by weight, the balance iron and unavoidable impurities, is hot rolled to a sheet from a temperature less than 1260.degree. C. Preferably, the slab is continuously cast from a melt consisting essentially of 0.03-0.08% acid sol. aluminum, 0.003-0.007% total nitrogen, <0.20% manganese, wherein % acid sol. aluminum.times.% total nitrogen is within the range of 1.times.10.sup.-4 to 5.times.10.sup.-4 and is hot rolled from a temperature of 1093.degree.-1175.degree. C. The hot rolled sheet is descaled, cold reduced, batch annealed and temper rolled. Preferably, the cold reduced sheet is annealed in the range of 538.degree.-649.degree. C.Type: GrantFiled: June 25, 1991Date of Patent: June 23, 1992Assignee: Armco Steel Company, L.P.Inventor: Rollin E. Hook