Austenitic Phase Structure Patents (Class 148/611)
  • Publication number: 20140041766
    Abstract: The invention relates to a method for manufacturing a ferritic-austenitic stainless steel having good formability, good weldability and high elongation. The stainless steel containing the sum of carbon and nitrogen C+N in the range 0.17-0.295 in weight % in which sum C+N a lower carbon content to avoid sensitisation during welding is compensated by an increased nitrogen content to maintain formability is heat treated so that the microstructure of the stainless steel contains 45-75% austenite in the heat treated condition, the remaining microstructure being ferrite, and the measured Md30 temperature of the stainless steel is adjusted between 0 and 50° C. in order to utilize the transformation induced plasticity (TRIP) for improving the formability of the stainless steel.
    Type: Application
    Filed: April 18, 2012
    Publication date: February 13, 2014
    Applicant: OUTOKUMPU OYJ
    Inventors: James Oliver, Jan Y. Jonsson, Juho Talonen, Rachel Petersson, Jan-Olof Andersson
  • Patent number: 8506729
    Abstract: An austenitic stainless steel hot-rolled steel material can be provided which has sea-water resistance and strength superior to conventional steel. Low-temperature toughness can be maintained, which is preferable in a structural member of speedy craft. The steel material can include an austenitic stainless steel hot-rolled steel material which excels in the properties of corrosion resistance, proof stress, and low-temperature toughness. In such austenitic stainless steel hot-rolling steel material, e.g., PI [=Cr+3.3(Mo+0.5W)+16N] ranges from 35 to 40, ? cal [=2.9 (Cr+0.3Si+Mo+0.5W)?2.6 (Ni+0.3Mn+0.25Cu+35C+20N)?18] ranges from ?6 to +2, and a 0.2% proof stress at room temperature is not less than 550 MPa, Charpy impact value measured using a V-notch test piece at ?40° C. is not less than 100 J/cm2, and the pitting potential measured in a deaerated aqueous solution of 10% NaCl at 50° C. (Vc?100) is not less than 500 mV (as it relates to saturated Ag/AgCl).
    Type: Grant
    Filed: January 13, 2012
    Date of Patent: August 13, 2013
    Assignee: Nippon Steel & Sumikin Stainless Steel Corporation
    Inventors: Yuusuke Oikawa, Shinji Tsuge, Shigeo Fukumoto, Kazuhiro Suetsugu, Ryo Matsuhashi, Hiroshige Inoue
  • Patent number: 8317944
    Abstract: One or more embodiments relates to a high-temperature, titanium alloyed, 9 Cr-1 Mo steel exhibiting improved creep strength and oxidation resistance at service temperatures up to 650° C. The 9 Cr-1 Mo steel has a tempered martensite microstructure and is comprised of both large (0.5-3 ?m) primary titanium carbides and small (5-50 nm) secondary titanium carbides in a ratio of. from about 1:1.5 to about 1.5:1. The 9 Cr-1 Mo steel may be fabricated using exemplary austenizing, rapid cooling, and tempering steps without subsequent hot working requirements. The 9 Cr-1 Mo steel exhibits improvements in total mass gain, yield strength, and time-to-rupture over ASTM P91 and ASTM P92 at the temperature and time conditions examined.
    Type: Grant
    Filed: October 26, 2011
    Date of Patent: November 27, 2012
    Assignee: U.S. Department of Energy
    Inventors: Paul D. Jablonski, David Alman, Omer Dogan, Gordon Holcomb, Christopher Cowen
  • Patent number: 8268101
    Abstract: The invention relates to an austenitic stainless steel strip having an elastic limit Rp0.2 which is greater than or equal to 600 MPa, a breaking load Rm which is greater than or equal to 800 MPa, an elongation A80 which is greater than or equal to 40% and a bright surface finish of the bright annealed type. The invention also relates to a method for the continuous production of said austenitic stainless steel strip.
    Type: Grant
    Filed: April 6, 2006
    Date of Patent: September 18, 2012
    Assignee: Aperam Stainless France
    Inventors: Francois Conrad, Christian Proudhon, Patrick Borgna
  • Patent number: 8246767
    Abstract: The invention relates to a composition and heat treatment for a high-temperature, titanium alloyed, 9 Cr-1 Mo steel exhibiting improved creep strength and oxidation resistance at service temperatures up to 650° C. The novel combination of composition and heat treatment produces a heat treated material containing both large primary titanium carbides and small secondary titanium carbides. The primary titanium carbides contribute to creep strength while the secondary titanium carbides act to maintain a higher level of chromium in the finished steel for increased oxidation resistance, and strengthen the steel by impeding the movement of dislocations through the crystal structure. The heat treated material provides improved performance at comparable cost to commonly used high-temperature steels such as ASTM P91 and ASTM P92, and requires heat treatment consisting solely of austenization, rapid cooling, tempering, and final cooling, avoiding the need for any hot-working in the austenite temperature range.
    Type: Grant
    Filed: September 12, 2008
    Date of Patent: August 21, 2012
    Assignee: The United States of America, as represented by the United States Department of Energy
    Inventors: Paul D. Jablonski, David Alman, Omer Dogan, Gordon Holcomb, Christopher Cowen
  • Patent number: 8226780
    Abstract: This ferrite-austenite stainless steel sheet includes: in terms of mass %, C: 0.1% or less; Cr: 17 to 25%; Si: 1% or less; Mn: 3.7% or less; Ni: 0.6 to 3%; Cu: 0.1 to 3%; and N: 0.06% or more and less than 0.15%, with the remainder being Fe and inevitable impurities, wherein the steel sheet has a two-phase structure consisting of a ferrite phase and an austenite phase, a volume fraction of the austenite phase is in a range of 15 to 70%, and in a sheet plane (ND) of a center of a sheet thickness, grains of the ferrite phase having a crystal orientation satisfying ND//{111}±10° and grains of the ferrite phase having a crystal orientation satisfying ND//{101}±10° are present in a total content of 10% by area or more.
    Type: Grant
    Filed: January 30, 2009
    Date of Patent: July 24, 2012
    Assignees: Nippon Steel, Sumikin Stainless Steel Corporation
    Inventors: Masaharu Hatano, Akihiko Takahashi, Eiichiro Ishimaru, Ken Kimura
  • Patent number: 8172959
    Abstract: There are provided an austenitic stainless steel having high stress corrosion crack resistance, characterized by containing, in percent by weight, 0.030% or less C, 0.1% or less Si, 2.0% or less Mn, 0.03% or less P, 0.002% or less S, 11 to 26% Ni, 17 to 30% Cr, 3% or less Mo, and 0.01% or less N, the balance substantially being Fe and unavoidable impurities; a manufacturing method for an austenitic stainless steel, characterized in that a billet consisting of the said austenitic stainless steel is subjected to solution heat treatment at a temperature of 1000 to 1150° C.; and a pipe and a in-furnace structure for a nuclear reactor to which the said austenitic stainless steel is applied.
    Type: Grant
    Filed: January 13, 2005
    Date of Patent: May 8, 2012
    Assignees: Mitsubishi Heavy Industries, Ltd., The Tokyo Electric Power Company, Inc.
    Inventors: Yasuhiro Sakaguchi, Toshihiko Iwamura, Hiroshi Kanasaki, Hidehito Mimaki, Masaki Taneike, Shunichi Suzuki, Kenrou Takamori, Suguru Ooki, Naoki Anahara, Naoki Hiranuma, Toshio Yonezawa
  • Publication number: 20120080124
    Abstract: The invention provides an alloy steel having the following composition: Ni 5-14 wt %; Cr 4-16 wt %; Co 7-14 wt %; Mo 1-5 wt %; W 0-5 wt %; Ti 0-0.8 wt %; Al 0.1-3 wt %; the balance being Fe save for incidental impurities. This provides an ultra-high strength corrosion resistant steel with good toughness, which does not significantly creep at temperatures up to 450° C. The high quantity of alloying to elements, particularly chromium, also gives the alloy good corrosion resistance. The alloy is particularly suitable for main shafts of gas turbine engines.
    Type: Application
    Filed: September 14, 2011
    Publication date: April 5, 2012
    Applicant: ROLLS-ROYCE PLC
    Inventors: Andrew T.W. BARROW, Harshad K.D.H. BHADESHIA, Martin J. RAWSON, Paul O. HILL
  • Publication number: 20120000579
    Abstract: An ultra-high strength stainless steel alloy with enhanced toughness includes in % by weight: 0 to 0.06% carbon (C); 12.0 to 18% chromium (Cr); 16.5 to 31.0% cobalt (Co); 0 to 8% molybdenum (Mo); 0.5 to 5.0% nickel (Ni); 0 to 0.5% titanium (Ti); 0 to 1.0% niobium (Nb); 0 to 0.5% vanadium (V); 0 to 16% tungsten (W); balance iron (Fe) and incidental deoxidizers and impurities. The heat treating method includes the steps of austenitizing at least once followed by quenching, tempering and sub-zero cooling to obtain no more than about 6-8% retained austenite in the finished alloy.
    Type: Application
    Filed: September 7, 2011
    Publication date: January 5, 2012
    Applicant: CARNEGIE MELLON UNIVERSITY
    Inventor: Warren M. Garrison, JR.
  • Publication number: 20120000580
    Abstract: A corrosion-resistant austenitic steel is claimed which, in each case relative to 100 mass percent, contains 20 to 32% manganese, 10 to 15% chromium, a total of 0.5 to 1.3% carbon and nitrogen, wherein the ratio of carbon to nitrogen is 0.5 to 1.5, the remainder being iron and melt-related impurities. The claimed steel can be produced and processed at normal pressure and has TWIP properties. It is in particular suited for producing structural components in constructs, such as in the automotive industry.
    Type: Application
    Filed: March 3, 2010
    Publication date: January 5, 2012
    Applicant: MAX-PLANCK-INSTITUT FUER EISENFORSCHUNG GMBH
    Inventors: Sebastian Weber, Lais Mujica Roncery
  • Patent number: 7914630
    Abstract: The subject of the invention is a process for the continuous manufacture of an austenitic stainless steel strip having a dull surface appearance, consisting in subjecting an austenitic stainless steel strip to a heat treatment in a bright annealing furnace inside which an inert or reducing flushing gas circulates, which gas has a dew point above ?15° C., and then in pickling the strip using a suitable acid pickling solution.
    Type: Grant
    Filed: March 9, 2005
    Date of Patent: March 29, 2011
    Assignee: Ugine & Alz France
    Inventors: Arnaud Dessis, Henri Giraud, Caroline Dhondt
  • Publication number: 20100294402
    Abstract: This stainless steel sheet includes, in terms of mass %, C: 0.001 to 0.1%, N: 0.01 to 0.15%, Si: 0.01 to 2%, Mn: 0.1 to 10%, P: 0.05% or less, S: 0.01% or less, Ni: 0.5 to 5%, Cr: 10 to 25%, and Cu: 0.5 to 5%, with a remainder being Fe and unavoidable impurities, and contains a ferrite phase as a main phase and 10% or more of an austenite phase, wherein a work-hardening rate in a strain range of up to 30% is 1000 MPa or more which is measured by a static tensile testing and a difference between static and dynamic stresses which occur when 10% of deformation is caused is 150 MPa or more. This method for producing a stainless steel includes annealing a cold-rolled steel sheet under conditions where a holding temperature is set to be in a range of 950 to 1150° C. and a cooling rate until 400° C. is set to be in a range of 3° C./sec or higher.
    Type: Application
    Filed: January 22, 2009
    Publication date: November 25, 2010
    Inventors: Junichi Hamada, Haruhiko Kajimura, Eiichiro Ishimaru
  • Patent number: 7708841
    Abstract: An austenitic, substantially ferrite-free steel alloy and a process for producing components therefrom. This Abstract is not intended to define the invention disclosed in the specification, nor intended to limit the scope of the invention in any way.
    Type: Grant
    Filed: December 2, 2004
    Date of Patent: May 4, 2010
    Assignees: Boehler Edelstahl GmbH & Co KG, Schoeller-Bleckmann Oilfield Technology GmbH
    Inventors: Gabriele Saller, Herbert Aigner, Josef Bernauer, Raimund Huber
  • Publication number: 20100012232
    Abstract: Disclosed are corrosion resistant, non-magnetic austenitic stainless steels containing alloying elements molybdenum, nickel, and copper and further containing small quantities of an additional element selected from the group consisting of a rare-earth element, calcium, cobalt, iridium, osmium, rhenium, rhodium, ruthenium, silver, and a combination thereof.
    Type: Application
    Filed: July 9, 2009
    Publication date: January 21, 2010
    Applicant: BAKER HUGHES INCORPORATED
    Inventor: Hendrik John
  • Publication number: 20090081068
    Abstract: An ultra-high strength stainless steel alloy with enhanced toughness includes in % by weight: 0 to 0.06% carbon (C); 12.0 to 18% chromium (Cr); 16.5 to 31.0% cobalt (Co); 0 to 8% molybdenum (Mo); 0.5 to 5.0% nickel (Ni); 0 to 0.5% titanium (Ti); 0 to 1.0% niobium (Nb); 0 to 0.5% vanadium (V); 0 to 16% tungsten (W); balance iron (Fe) and incidental deoxidizers and impurities. The heat treating method includes the steps of austenitizing at least once followed by quenching, tempering and sub-zero cooling to obtain no more than about 6-8% retained austenite in the finished alloy.
    Type: Application
    Filed: June 18, 2008
    Publication date: March 26, 2009
    Applicant: CARNEGIE MELLON UNIVERSITY
    Inventor: Warren M. Garrison, JR.
  • Publication number: 20090022617
    Abstract: A low-nickel austenitic stainless steel is provided which comprises by weight: ?0.08% C, 4.0˜5.0% Mn, 0.7˜1.0% Si, 3.5˜4.5% Ni, 16.0˜18.0% Cr, 3.0˜3.50% Cu, ?0.045% S, ?0.030% P, impurity elements in the total amount of ?0.2%, and Fe as the balance. This low-nickel austenitic stainless steel has decreased nickel content, but retains excellent mechanical properties and corrosion resistance property. Therefore, the cost for producing the stainless steel can be reduced remarkably. The method for producing the low-nickel austenitic stainless steel is also provided.
    Type: Application
    Filed: October 5, 2007
    Publication date: January 22, 2009
    Inventor: Hyunku Kim
  • Patent number: 6893727
    Abstract: This invention relates to a stainless steel gasket having markedly improved strength and fatigue properties due to precipitation strengthening. Its composition comprises C: at most 0.03%, Si: at most 1.0%, Mn: at most 2%, Cr: 16.0%-18.0%, Ni: 6.0%-8.0%, N: at most 0.25%, if necessary Nb: at most 0.30%, and a remainder of Fe and unavoidable impurities. After cold rolling, final annealing is carried out, and after a structure is formed of recrystallized grains with an average grain diameter of at most 5 ?m having an area ratio of 50-100% and an unrecrystallized portion having an area ratio of 0-50%, a metal gasket is formed by steps including temper rolling with a reduction of at least 30% to make the area ratio of a strain induced martensite phase at least 40%, and forming and heat treatment at 200-350° C.
    Type: Grant
    Filed: October 24, 2003
    Date of Patent: May 17, 2005
    Assignees: Sumitomo Metal Industries, Ltd., Honda Giken Kogyo Kabushiki Kaisha
    Inventors: Kazuhiko Adachi, Seishi Ishiyama, Kenichi Goshokubo, Takashi Katsurai
  • Patent number: 6475310
    Abstract: A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800° C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800° C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700° C.
    Type: Grant
    Filed: October 10, 2000
    Date of Patent: November 5, 2002
    Assignee: The United States of America as represented by the United States Department of Energy
    Inventors: John S. Dunning, David E. Alman
  • Patent number: 6406570
    Abstract: An elastic component for a precision measuring instrument is made from an austenitic metal alloy containing less than two percent ferrite, less than two percent martensite, and more than eleven percent chromium. The crystalline texture has a nano-structure with blocked dislocations. The manufacturing process includes cold hardening followed by thermal aging between 200° C. and 700° C. The benefits are low anelasticity, freedom from creep and hysteresis, resistance to corrosion, and a low magnetic permeability. Examples are load cells used in analytical, motion-guiding mechanisms, coupling elements and pivoting elements.
    Type: Grant
    Filed: August 7, 2000
    Date of Patent: June 18, 2002
    Assignee: Mettler-Toledo, GmbH
    Inventor: Jean-Maurice Tellenbach
  • Patent number: 6338762
    Abstract: An austenitic stainless steel for use in engine gaskets having a high fatigue strength and resistance to settlement and method of manufacture thereof. The austenitic stainless steel is prepared by cold rolling at least 40%, annealing at a temperature of 700° C. to 900° C. followed by temper rolling with a reduction of at least 40%. The metal structure obtained by annealing is a recovered unrecrystallized structure or a mixed structure of a recovered unrecrystallized structure and a recrystallized structure. The austenitic stainless steel includes at most 0.03% C, at most 1.0% Si, at most 2.0% Mn, 16.0% to 18.0% Cr, 6.0% to 8.0% Ni and up to 0.20% N.
    Type: Grant
    Filed: May 3, 2000
    Date of Patent: January 15, 2002
    Assignee: Sumitomo Metal Industries, Ltd.
    Inventors: Naoto Sato, Kazuhiko Adachi, Kenichi Goshokubo, Takashi Katsurai, Shigeki Muroga
  • Patent number: 6149744
    Abstract: Method of making a hot-rolled steel sheet having superior surface appearance, free of surface patterns and uneven glossiness from an austenitic stainless steel slab containing about 0.03 percent by weight or more of Cu, about 0.03 percent by weight or more of V, and about 0.01 percent by weight or more of Mo under any of the following conditions: (A) pickling in a nitric-hydrofluoric acid solution containing about 20 to 100 g/l of nitric acid and about 100 to 300 g/l of hydrofluoric acid; (B) controlling nitric-hydrofluoric acid content in response to the iron ion content in the solution; (C) a preliminary pickling step prior to finishing pickling; (D) grinding about 2 .mu.m or more of the surface after preliminary pickling and prior to finishing pickling; (E) causing counterflow with a relative flow rate of 0.5 to 5.
    Type: Grant
    Filed: October 23, 1998
    Date of Patent: November 21, 2000
    Assignee: Kawasaki Steel Corporation
    Inventors: Kunio Fukuda, Takumi Ujiro, Masaaki Kohno, Susumu Satoh, Masahiro Yoshioka, Shinji Yamazaki
  • Patent number: 6132525
    Abstract: Austenitic steel intended for use in radiation areas of nuclear reactors is largely resistant to irradiation-induced stress corrosion cracking if its silicon, phosphorus and sulfur contents are reduced in relation to standard commercial steel quantities and its grain structure has finely dispersed carbide precipitation, particularly of niobium carbide. The finely dispersed distribution can be induced in that larger niobium precipitation takes place at annealing temperatures between 1100 and 1150.degree. C., and carbide is precipitated through the corresponding annealing at temperatures of approximately 750.degree. C.
    Type: Grant
    Filed: March 7, 1997
    Date of Patent: October 17, 2000
    Assignee: Electric Power Research Institute, Inc.
    Inventors: Dietrich Alter, Peter Dewes, Friedrich Garzarolli, Roland Hahn, J. Lawrence Nelson
  • Patent number: 6129795
    Abstract: A method is provided for improving the microstructure of nickel and iron-based precipitation strengthened superalloys used in high temperature applications by increasing the frequency of "special", low-.SIGMA. CSL grain boundaries to levels in excess of 50%. Processing entails applying specific thermomechanical processing sequences to precipitation hardenable alloys comprising a series of cold deformation and recrystallization-annealing steps performed within specific limits of deformation, temperature, and annealing time. Materials produced by this process exhibit significantly improved resistance to high temperature degradation (eg. creep, hot corrosion, etc.), enhanced weldability, and high cycle fatigue resistance.
    Type: Grant
    Filed: August 3, 1998
    Date of Patent: October 10, 2000
    Assignee: Integran Technologies Inc.
    Inventors: Edward M. Lehockey, Gino Palumbo, Peter Keng-Yu Lin, David L. Limoges
  • Patent number: 6060180
    Abstract: The present invention provides a highly corrosion-resistant alloy used as a boiler tube in equipment the energy source of which is obtained by burning fossil fuel or waste, a steel tube for which the alloy is used, and a process for producing the steel tube. The alloy comprises up to 0.05% of C, 1.0 to 2.6% of Si, 0.02 to 1.0% of Mn, 20.0 to 28.0% of Cr, 18.0 to 30.0% of Ni, up to 4.0% of Mo, up to 0.05% of Al, 0.05 to 0.30% of N and the balance Fe and unavoidable impurities. Furthermore, the present invention also provides a multilayer steel tube having the alloy as a liner material and a standardized boiler tube as a base layer material, and a process for producing the multilayer steel tube.
    Type: Grant
    Filed: November 2, 1997
    Date of Patent: May 9, 2000
    Assignee: Nippon Steel Corporation
    Inventors: Tetsuo Ishitsuka, Koichi Nose
  • Patent number: 5980662
    Abstract: Methods are provided for annealing coils of austenitic stainless steels through the use of a batch annealing process. The preferred methods involved selecting compositions of austenitic stainless steel alloys having a sufficiently low weight percentage of carbon so that annealing of the austenitic stainless steel occurs without intergranular carbide precipitation at a temperature of less than about 1700.degree. F., which is well below the normal annealing temperature for austenitic stainless steels. The lower annealing temperatures allow for annealing in conventional batch annealing furnaces. The content of carbon in T-201L stainless steel was kept at less than 0.030 weight percent and the steel was successfully annealed at temperatures within a range of about 1650.degree. F. to about 1700.degree. F. The carbon content of T-304L stainless steel was kept at less than 0.015 weight percent and the steel was successfully annealed at temperatures within a range of about 1550.degree. F. to about 1700.degree. F.
    Type: Grant
    Filed: April 22, 1997
    Date of Patent: November 9, 1999
    Assignee: Allegheny Ludlum Corporation
    Inventors: Yeong-U Kim, Lewis L. Kish, Nazmi Toker
  • Patent number: 5976275
    Abstract: The present invention aims at providing structural materials having a resistance to degradation by neutron irradiation, causing no SCC in an environment of light-water reactors even after subjecting the materials to neutron irradiation of approximately at least 1.times.10.sup.22 n/cm.sup.2 (E>1 MeV), and having thermal expansion coefficients approximately similar to that of structural materials. The high nickel austenitic stainless steels of the present invention having a resistance to degradation by neutron irradiation can be produced by subjecting stainless steels having compositions (by weight %) of 0.005 to 0.08% of carbon, at most 0.3% of Mn, at most 0.2% of (Si+P+S), 25 to 40% of Ni, 25 to 40% of Cr, at most 3% of Mo or at most 5% of (Mo+W), at most 0.3% of Nb+Ta, at most 0.3% of Ti, at most 0.001% of B and the balance of Fe to a solution-annealing treatment at a temperature of 1000 to 1150.degree. C.
    Type: Grant
    Filed: June 5, 1997
    Date of Patent: November 2, 1999
    Assignee: Mitsubishi Jukogyo Kabushiki Kaisha
    Inventors: Toshio Yonezawa, Toshihiko Iwamura, Hiroshi Kanasaki, Koji Fujimoto, Shizuo Nakada, Kazuhide Ajiki, Mitsuhiro Nakamura
  • Patent number: 5858135
    Abstract: A method for producing strip cast, austenitic stainless steel strip comprises providing a strip cast strip having an initial microstructure including a detrimental amount of delta ferrite and a detrimental amount of dendritic structure is provided. The strip may have a composition comprising the following ingredients: 0.4 wt. % max. carbon, 5-38 wt. % nickel, and 15-28 wt. % chromium. The strip is subjected to a cold rolling step prior to any annealing step. Upon subsequent annealing, (a) the amount of delta ferrite in the strip is reduced to substantially below the detrimental amount of delta ferrite that was in the strip prior to cold rolling and (b) the amount of dendritic structure in the strip is reduced to below the detrimental amount of dendritic structure that was in the strip prior to cold rolling. By employing the method of the present invention, an austenitic stainless steel strip having a high quality surface is produced.
    Type: Grant
    Filed: July 29, 1997
    Date of Patent: January 12, 1999
    Assignee: Inland Steel Company
    Inventors: Zofia E. Niemczura, Kenneth E. Blazek
  • Patent number: 5824264
    Abstract: A high-temperature austenitic stainless steel having improved weldability is disclosed. The steel consists essentially, by weight, of:C: 0.05%-0.15%, Si: less than 1.0%, Mn: 2.0% or less,P: 0.04% or less, S: 0.01% or less, Cr: 20%-30%,Ni: 10%-15%, N: 0.10%-0.30%,B: 0.0010%-0.01%,one or two of La and Ce: 0.01%-0.10% in total,Al: 0.01%-0.20%, anda balance of Fe and incidental impurities, wherein the contents of N and Al satisfy the following inequality:% N+2.times.% Al.ltoreq.0.500%and the value for Ni balance (Ni bal.) of the steel calculated by the following formula is in the range of from -1.0% to +3.0%:Ni bal. (%)=% Ni+0.5.times.% Mn+30.times.(% C+% N)-1.1.times.(% Cr+1.5.times.% Si)+8.2.
    Type: Grant
    Filed: July 25, 1996
    Date of Patent: October 20, 1998
    Assignee: Sumitomo Metal Industries, Ltd.
    Inventors: Hideki Uno, Yoshitaka Nishiyama, Yoshiatsu Sawaragi, Nobuo Otsuka, Kazuhiro Ogawa, Toshiro Anraku
  • Patent number: 5817193
    Abstract: In the fabrication of components from a face centered cubic alloy, wherein the alloy is cold worked and annealed, the cold working is carried out in a number of separate steps, each step being followed by an annealing step. The resultant product has a grain size not exceeding 30 microns, a "special" grain boundary fraction not less than 60%, and major crystallographic texture intensities all being less than twice that of random values. The product has a greatly enhanced resistance to intergranular degradation and stress corrosion cracking, and possesses highly isotropic bulk properties.
    Type: Grant
    Filed: January 17, 1997
    Date of Patent: October 6, 1998
    Inventor: Gino Palumbo
  • Patent number: 5284535
    Abstract: A method of manufacturing an austenitic stainless steel sheet having reduced minute surface concavities and convexties ropings and gloss unevenness and a manufacturing system for carrying out the same are provided. The method comprises (a) a casting process of casting a molten austenitic (.gamma.) stainless steel into a thin cast plate by a twin-roll thin plate casting method employing a pair of cooled rolls disposed opposite to each other, (b) a cooling process of cooling the cast thin plate in a single phase state of the .gamma. phase, (c) a cast plate in a dual phase state of the .delta. and .gamma. phase or a single phase state of the .delta. phase and then cooling the thin cast plate to restore the single phase state of the .gamma. phase, and (d) a cold-rolling process of cold-rolling the heat-treated thin cast plate.
    Type: Grant
    Filed: August 19, 1991
    Date of Patent: February 8, 1994
    Assignee: Nippon Steel Corporation
    Inventors: Yoshiyuki Ueshima, Kenichi Miyazawa, Toshiaki Mizoguchi, Masayuki Abe
  • Patent number: 5269856
    Abstract: A high strength steel belt having an excellent flatness and a duplex structure of austenite and martensite has been prepared by a process which comprises providing a cold rolled or cold rolled and annealed strip of a martensitic structure from low carbon martensitic stainless steel containing from 10 to 17% by weight of Cr and having a carbon content of not exceeding 0.15% by weight, connecting ends of the strip or ends of a plate cut from said strip to provide an endless belt, causing the endless belt to circularly move between rolls under tension and to pass through a heating furnace where the belt is heated to a temperature within a range from (As point of the steel+30.degree. C.) to Af point of the steel and not higher than 900.degree. C. so that a part of the martensitic phase may be changed to a reversed austenitic phase and a desired surface flatness may be obtained after cooling.
    Type: Grant
    Filed: November 13, 1992
    Date of Patent: December 14, 1993
    Assignee: Nisshin Steel Co., Ltd.
    Inventors: Takashi Igawa, Yoshihiro Uematsu, Toshihiko Takemoto
  • Patent number: 5252149
    Abstract: An erosion and corrosion resistant ferrochromium alloy comprising the following composition, in wt. %, 34-50 chromium, 1.5-2.5 carbon, up to 5 manganese, up to 5 silicon, up to 5 molybdenum, up to 10 nickel, up to 5 copper, up to 1% of each of one or more micro-alloying elements selected from the group consisting of titanium, zirconium, niobium, boron, vanadium and tungsten, and balance, iron and incidental impurities.The alloy has a microstructure comprising eutectic chromium carbides in a matrix comprising one or more of ferrite, retained austenite and martensite, as herein defined. Optionally, the microstructure further comprises one of primary chromium carbides, primary ferrite or primary austenite in the matrix.
    Type: Grant
    Filed: February 10, 1993
    Date of Patent: October 12, 1993
    Assignee: Warman International Ltd.
    Inventor: Kevin F. Dolman
  • Patent number: 5180450
    Abstract: A high strength, low alloy, low to medium carbon structural steel is provided of the Fe/Cr/C type, said steel characterized by the presence of a small but effective amount of each of Cu and Ni sufficient to enhance the mechanical stability of retained austenite formed following quenching of said steel from its austentizing temperature. Preferably the steel also includes small but effective amounts a Al, Ti and Nb suficient to provide a fine grained microstructure.
    Type: Grant
    Filed: June 5, 1990
    Date of Patent: January 19, 1993
    Assignee: Ferrous Wheel Group Inc.
    Inventor: Banagaru V. N. Rao
  • Patent number: 5171384
    Abstract: A high strength steel strip excellent in shape having a duplex structure of austenite and martensite has been prepared by a process which comprises providing a cold rolled or cold rolled and annealed strip of a martensitic structure from low carbon martensitic stainless steel containing from 10 to 17% by weight of Cr and having a carbon content of not exceeding 0.15% by weight, causing the strip to continuously pass through a continuous heat treatment furnace under tension where the strip is heated to temperatures within the range from (the As point of the steel+30.degree. C.) to the Af point of the steel and not higher than 900.degree. C.
    Type: Grant
    Filed: October 9, 1991
    Date of Patent: December 15, 1992
    Assignee: Nisshin Steel Co., Ltd.
    Inventors: Takashi Igawa, Yoshihiro Uematsu, Toshihiko Takemoto
  • Patent number: 4804445
    Abstract: A surface layer which is composed of the carbonitride of molybdenum is formed on an article made of iron or an iron alloy by heating the article in the presence of a material containing molybdenum and a treating agent. The treating agent may be composed of at least one of the cyandides and cyanates of alkali metals and alkaline earth metals. The layer adhering closely to the article can be formed efficiently at a temperature which is so low that virtually no thermal strain may develop in the article.
    Type: Grant
    Filed: November 20, 1987
    Date of Patent: February 14, 1989
    Assignee: Kabushiki Kaisha Toyota Chuo Kenkyusho
    Inventors: Yukio Ohta, Shigeo Moriyama, Akira Sato, Tohru Arai, Hironori Fujita, Yoshihiko Sugimoto
  • Patent number: 4671824
    Abstract: Process for producing zirconium oxide blue-black coatings on zirconium alloy substrates by treating said alloys with molten salts containing small amounts of oxidizing compounds. The molten salts are sodium cyanide and combinations of sodium chloride and potassium chloride.
    Type: Grant
    Filed: December 18, 1985
    Date of Patent: June 9, 1987
    Assignee: Teledyne Industries, Inc.
    Inventor: John C. Haygarth
  • Patent number: 4655852
    Abstract: A steel article which is made of carbon or low alloy steel, with a prescribed chemical composition, is heat treated so that its yield strength is increased to a minimum of 60,000 psi and is subsequently dipped or spray covered with aluminum and then heated to interdiffuse aluminum metal and the iron in the steel matrix, thereby forming a new intermetallic layer which is an integral part of the steel article and which is essentially an aluminum-iron alloy, all in a manner which does not lower the yield strength of the steel below 60,000 psi. In the preferred form of the invention, a steel article is austenitized above its critical temperature for about 15 minutes or more and is subsequently rapidly cooled to below 600.degree. F. to transform the austenite structure to a much stronger martensitic structure and is then reheated to below 1341.degree. F. to temper the martensite.
    Type: Grant
    Filed: August 16, 1985
    Date of Patent: April 7, 1987
    Inventor: Anthony T. Rallis
  • Patent number: 4654237
    Abstract: A process for chemical and thermal treatment of steel workpieces accompanied by the formation thereon of a coating includes diffusive precipitation onto the base metal of the workpiece of an intermetallic compound from a melt of a low-melting-point metal, such as sodium or lithium, at a temperature of from 720.degree. to 820.degree. C. for a duration of time necessary for obtaining a coating layer of required thickness.
    Type: Grant
    Filed: September 6, 1985
    Date of Patent: March 31, 1987
    Assignees: Fiziko Mekhanichesky Institut Imeni Karpenko, Institut Metallurgii Imeni Baikova Akademii Nauk SSR
    Inventors: Evgeny M. Savitsky, Mikhail S. Goikhman, Petr M. Khudyk, Valery V. Chepkasov, Valentin V. Sulyagin, Viktoria P. Polyakova, Viktor F. Shatinsky, Nelli B. Gorina, Evgeny M. Rudkovsky
  • Patent number: 4624895
    Abstract: A low-titanium alloy steel foil having a cold rolled metallic aluminum hot-dip coated surface which is adapted for growing a thick surface coating of spine-like whiskers of aluminum oxide suitable for retaining a coating of a metallic catalyst, which is formable at room temperature without annealing, and which exhibits good resistance to oxidation at temperatures up to 1149.degree. C. (2100.degree. F.).
    Type: Grant
    Filed: June 4, 1984
    Date of Patent: November 25, 1986
    Assignee: Inland Steel Company
    Inventor: Richard A. Nickola
  • Patent number: 4608092
    Abstract: A process for improving the corrosion resistance of ferrous metal parts also subject to heat and chemical treatment following nitriding in association or not with carburizing and/or sulfurizing essentially comprises immersing the parts in a known bath of molten salts to which is added a sufficient quantity of a halogenophosphate having formula:M.sub.2 (PO.sub.3 X).sub.min which X and is fluorine and M is a metal of subgroup Ia, IIa or IIb of the periodic table of elements, having the valency m. The preferred halogenophosphate is sodium, potassium, calcium or zinc monofluorophosphate. The molten salt bath may be of the oxidizing type, comprising for example, 65% by weight KOH, 25% NaNO.sub.3, 10% Na.sub.2 CO.sub.3, or of the neutral type, for example a eutectic mixture of 50% BaCl.sub.2, 30% CaCl.sub.2, 20% NaCl. The halogenophosphate may be added in proportions of 0.1 to 20 g per kilogram of salt bath.
    Type: Grant
    Filed: March 19, 1985
    Date of Patent: August 26, 1986
    Assignee: Centre Stephanois de Recherches Mecaniques Hydromecanique et Frottement
    Inventors: Yves Tremoureux, Jean-Luc Reynaud
  • Patent number: 4536224
    Abstract: There is described a salt bath based on an alkali and/or alkaline earth metal halide with which there can be produced without the use of current adherent and wear resistant boride coatings on metallic workpieces. This bath contains gaseous boron monofluoride or a compound from which there is formed intermediately boron monofluoride. Advantageous there is used a salt bath containing 30-60% BaCl.sub.2, 10-25% NaCl, 1-20% boron oxide or borate, 10-30% NaF, and 1-15% B.sub.4 C.
    Type: Grant
    Filed: July 12, 1984
    Date of Patent: August 20, 1985
    Assignee: Degussa Aktiengesellschaft
    Inventors: Hans-Hermann Beyer, Ulrich Baudis, Peter Biberbach, Wolfgang Weber
  • Patent number: 4534794
    Abstract: A salt system having a reduced rate of corrosion comprises a salt selected from the group consisting of KNO.sub.3,NaNO.sub.3 and mixtures thereof, and a minor amount of a corrosion inhibitor selected from the group consisting of Li.sub.2 O, Na.sub.2 O, CuO, Mgo, NiO, CaO, Al.sub.2 O.sub.3, Cr.sub.2 O.sub.3, SiO.sub.2, Mn.sub.3 O.sub.4, Ti.sub.2 O.sub.3, Y.sub.2 O.sub.3, Na.sub.2 CrO.sub.4, Na.sub.2 Cr.sub.2 O.sub.7, K.sub.2 CrO.sub.4, K.sub.2 Cr.sub.2 O.sub.7, and mixtures thereof.
    Type: Grant
    Filed: May 14, 1981
    Date of Patent: August 13, 1985
    Assignee: Rockwell International Corporation
    Inventors: Robert J. Walter, Bernard J. Gerik
  • Patent number: 4453987
    Abstract: A method for producing an edged tool which has an excellent cutting ability and durability, which comprises immersing an edged-tool material in a molten-salt bath containing a carbide-forming element, such as a Va Group element, titanium, chromium or manganese, to form a carbide layer on the surface of the edged-tool material; heating the edged-tool material to a temperature not lower than the austenite-transformation temperature of the material in a non-oxidizing gas atmosphere for a predetermined period of time; and rapidly cooling the heated material to harden it. According to the improved method of the present invention, the edged tool (having an excellent cutting ability and durability) is produced without grinding the formed carbide layer on the surface thereof.
    Type: Grant
    Filed: April 6, 1982
    Date of Patent: June 12, 1984
    Assignee: Kabushiki Kaisha Toyota Chuo Kenkyusho
    Inventors: Tohru Arai, Yoshihiko Sugimoto
  • Patent number: 4448611
    Abstract: To improve the corrosion resistance of ferrous metal parts containing free r combined sulphur on the surface, the parts are immersed in a bath of molten oxidizing salts at between 350.degree. C. and 450.degree. C., the bath typically having a composition by weight of 60% of potassium hydroxide, 30% of sodium nitrate and 10% of sodium carbonate. Between 0.5% and 15% of oxygen-containing salts, the normal oxidation-reduction potential of which is less than or equal to -1 volt, relative to the hydrogen electrode, such as alkali metal dichromates, permanganates, peroxycarbonates, iodates and periodates, are added to the bath, and an oxygen-containing gas is blown into the bath with an oxygen flow of between 1.5 and 7.5 liters/hour per 100 kg of bath. The molten salts of the bath are filtered continuously through an iron gauze filter cartridge in a furnace, the molten salts being transported into the filter cartridge by entrainment of the salts in a pipe by bubbles of air blown in through the pipe.
    Type: Grant
    Filed: April 25, 1983
    Date of Patent: May 15, 1984
    Assignee: Centre Stephanois de Recherches Mecaniques Hydromecanique et Frottement
    Inventors: Bernard Grellet, Jean-Pierre Emmanuel, Bernard Sipp
  • Patent number: 4440581
    Abstract: Vanadium carbide layers are produced on iron and iron alloys having a content of at least 0.1 weight % carbon by treating the workpiece at 800.degree. to 1100.degree. C. in a salt bath which contains 1-30 weight % of vanadium or ferrovanadium powder. The salt bath consists of alkaline earth and/or alkali metal halide.
    Type: Grant
    Filed: June 29, 1981
    Date of Patent: April 3, 1984
    Assignee: Degussa Aktiengesellschaft
    Inventors: Ulrich Baudis, Peter Biberbach, Wolfgang Weber
  • Patent number: 4436560
    Abstract: A process for manufacturing a boride dispersed copper alloy by preparing a metallic material having a surface portion comprising at least one of Al, As, Cd, Co, Cr, Fe, Mg, Mo, Nb, Pt, Ta, W and Zr, and copper or an alloy thereof, and diffusing boron into the surface portion. The resulting material includes fine boride particles uniformly dispersed in the surface portion and is useful as a material for electrical contacts or sliding parts due to its high wear, adhesion and arc resistance and high electrical conductivity.
    Type: Grant
    Filed: June 11, 1982
    Date of Patent: March 13, 1984
    Assignees: Kabushiki Kaisha Toyota Chuo Kenkyusho, Kabushiki Kaisha Tokai Rika Denki Seisakusho
    Inventors: Hironori Fujita, Tohru Arai, Jiro Mizuno
  • Patent number: 4436559
    Abstract: A process for manufacturing a boride dispersion copper alloy by preparing a metallic material having a surface portion comprising at least one of beryllium, gallium, manganese, nickel, palladium, silicon and vanadium, and copper or an alloy thereof, and diffusing boron into the surface portion. The resulting material includes fine boride particles uniformly dispersed in the surface portion and is useful as a material for electrical contacts or sliding parts due to its high resistance to adhesion, wear and arc, and excellent electrical conductivity and sliding properties.
    Type: Grant
    Filed: June 11, 1982
    Date of Patent: March 13, 1984
    Assignee: Kabushiki Kaisha Toyota Chuo Kenkyusho
    Inventors: Hironori Fujita, Tohru Arai
  • Patent number: 4419853
    Abstract: A composition and method for treating the surface of a metal structure adapted to be used for such purposes as a cornerbead and to have a cementitious material such as a joint compound applied to the surface thereto, the compound and composition and method resulting in the improvement of the adhesion between the surface of the metal structure and the cementitious compound applied thereto, which comprises preparing a composition such as that comprising a forming lubricant for processing the metal structure and a minor proportion of a polyfunctional aziridine incorporated therein. The presence of the aziridine enhances the adhesion properties between the surface of the metal and the cementitious compound even when less highly processed metals and less expensive compounds are utilized.
    Type: Grant
    Filed: September 24, 1981
    Date of Patent: December 13, 1983
    Assignee: United States Gypsum Company
    Inventors: Friedrich Failmezger, Geronimo E. Lat
  • Patent number: 4400222
    Abstract: A method for treating surfaces is provided, in which a material to be treated, such as iron, iron alloys or the like is immersed in a molten bath prepared by adding 5 to 50 weight % of a metal cementing agent consisting of one or more selected from the group consisting of a Group Va element, a substance containing the Group Va element, a Group VIa element and a substance containing the Group VIa element to a salt bath agent consisting of a neutral salt containing 5 to 30 mol % of a borate admixed therewith, to form the carbide of the Group Va element or Group VIa element or the composite carbide of these elements on the surfaces of the material. To the molten bath there may be optionally added 1 to 10 weight % of an adjuvant consisting of one or more selected from the group consisting of the oxysalts of the Groups IVa, Va and VIa elements and/or 1 to 10 weight % of a metal or an alloy thereof selected from the group consisting of a Group IVa metal and an alloy thereof.
    Type: Grant
    Filed: June 16, 1981
    Date of Patent: August 23, 1983
    Assignee: Hitachi Metals, Ltd.
    Inventor: Norimasa Uchida
  • Patent number: 4400224
    Abstract: A method for forming a carbide layer on the surface of a carbon-containing ferrous alloy article or a cemented carbide article in a molten treating bath. The bath is prepared by introducing 5 to 20% by weight of alumina into molten boric acid or borate bath and a carbide-forming element dissolved therein. By employing the treating bath of this invention, the life of the bath can be remarkably improved, and no sintered substance of undissolved carbide-forming element is produced in the treating bath. Further, it is possible to reduce markedly the corrosion of the article and of the vessel holding the bath.
    Type: Grant
    Filed: April 2, 1982
    Date of Patent: August 23, 1983
    Assignee: Kabushiki Kaisha Toyota Chuo Kenkyusho
    Inventors: Tohru Arai, Hironori Fujita, Yasuo Takada