EP0107489A1 - Rostfreier Stahl - Google Patents

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Publication number
EP0107489A1
EP0107489A1 EP83306395A EP83306395A EP0107489A1 EP 0107489 A1 EP0107489 A1 EP 0107489A1 EP 83306395 A EP83306395 A EP 83306395A EP 83306395 A EP83306395 A EP 83306395A EP 0107489 A1 EP0107489 A1 EP 0107489A1
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EP
European Patent Office
Prior art keywords
alloy
stainless steel
alloys
austenite
nitrogen
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP83306395A
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English (en)
French (fr)
Inventor
Kevan John Gradwell
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mather and Platt Ltd
Original Assignee
Mather and Platt Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mather and Platt Ltd filed Critical Mather and Platt Ltd
Publication of EP0107489A1 publication Critical patent/EP0107489A1/de
Withdrawn legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N

Definitions

  • the present invention relates to stainless steel alloys.
  • Duplex stainless steel alloys of the ferritic austenitic type have been developed over recent years for their combination of mechanical properties, high resistance to localized corrosion and their resistance to stress corrosion cracking in a seawater environment. Such steels are described for example in U.K. Patent No. 1,158,614 and U.S. Patent No. 3,065,119 and are available under the designations CD4MCu and Ferralium.
  • a typical composition of such an alloy is as follows:
  • compositional levels of the elements promoting either austenite or ferrite in the microstructure are controlled to produce a structure which is balanced and which contains a minimum of 65% austenite.
  • This microstructural control provides an alloy which has a good combination of toughness and corrosion resistance in thick section castings when adopting air cooling from solution heat treatment temperatures.
  • austenite levels of 65% and above result in an overall reduction in tensile strength since the latter is sensitive to changes in the austenite/ferrite balance.
  • Nitrogen is used in amounts up to 0.5% in austenitic stainless steels of the A.I.S.I. 200 series to impart high strength levels.
  • solubility of nitrogen in the conventional duplex 25 Cr/5Ni steels reaches a maximum of approximately 0.2% (J.F. Elliot et al Thermochemistry for Steelmaking, Vol II, Adison and Wesley Publishers, 1963).
  • the inclusion of amounts of nitrogen in excess of 0.2% in the conventional duplex 25Cr/5Ni steels results in severe gassing problems in castings.
  • said alloy having a duplex microstructure of austenite and ferrite.
  • the alloy is of the following composition
  • the alloy has a microstructure comprising at least 60% and more preferably at least 65% austenite
  • N 2 0.15 - 0.3 % N 2 in the alloy provides an increase in tensile and proof stresses as well as in localised corrosion performance. Amounts of nitrogen less than 0.15% do not give the required properties for the alloy whereas amounts greater than 0.3% cannot be obtained due to its limited solubility. Amounts of manganese less than 3.5% do not give the required N 2 solubility whereas amounts greater than 5.0 % lead to excessive formation of sigma phase.
  • the alloy may be prepared from a melt containing the various components in the required amount by casting of the melt and subsequent heat treatment in the manner known for the production of duplex alloys of the austenite ferrite type.
  • the nitrogen for the alloy may be provided by high nitrogen ferrochrome.
  • the alloy with above 60% austenite content has a tensile strength of 650 MPa or less and a 0.2% Proof Strength of 490 MPa or less.
  • ferritic austenitic alloys which contained nominally 25% Cr, 6-7% Ni, 2% Mo, 0.05% N 29 amounts of manganese from 1 to 15%, and a balance of iron plus unavoidable impurities.
  • Fig. 2 illustrates this formation of sigma phase and is a Time Temperature Transformation curve showing the rate of sigma phase formation in a conventional duplex base alloy (nominally 25Cr/5Ni) (curve A), an alloy containing 3% Mn (curve B), and one containing 5% Mn (curve C).
  • Curve A a conventional duplex base alloy
  • Curve B an alloy containing 3% Mn
  • curve C a continuous cooling path typical of the cooling rate 'seen' at the centre of a 6" diameter billet.
  • Fig. 2 also shows the TTT curve showing rate of formation of sigma phase in Uranus 50, a typical duplex stainless steel alloy with a 50/50 austenite/ferrite microstructure.
  • duplex alloys (nominally 25Cr/5Ni) were prepared.
  • One series of alloys contained a nominal 1% Mn and the other contained 4.5% Mn.
  • the alloys of each series were prepared with nitrogen levels of between 0.2 and 0.35%.
  • Fig. 3 is a graph showing the relationship of increasing manganese content on the critical crevice and pitting temperatures in artificial seawater of two nominally 25Cr/5Ni duplex alloys, one containing 0.1% N 2 and the other 0.23% N 2 .
  • the solid curves represent pitting temperatures and the dashed lines represent crevice temperatures.
  • the alloy with the higher nitrogen content has the higher values of critical pitting tmmperature and critical crevice temperature; the alloy with 0.23% nitrogen maintains a critical pitting temperature of over 60°C up to a manganese addition of 5% and also shows a rise in critical crevice temperature for manganese additions of 3 to 4%.
  • Fig. 4 is a graph showing the relationship of increasing levels of nitrogen on the pitting and crevice temperatures of a series of duplex alloys (nominally 25Cr/5Ni) containing 4.5% Mn. The alloys were subjected to cyclic anodic polarisation measurement in artificial seawater to determine their localised corrosion performance.
  • the alloy may include copper in an amount up to 1% by weight. If greater than 0.5% by weight of copper is added, the active dissolution rate of a duplex alloy in boiling hydrochloric acid and the crevice corrosion loss in a chloride solution is also decreased.
  • Tungsten upto 1% by weight increases the immunity potentials to crevice corrosion of a duplex alloy in high temperature chloride solutions above which crevice corrosive starts.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
EP83306395A 1982-10-23 1983-10-21 Rostfreier Stahl Withdrawn EP0107489A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8230332 1982-10-23
GB8230332 1982-10-23

Publications (1)

Publication Number Publication Date
EP0107489A1 true EP0107489A1 (de) 1984-05-02

Family

ID=10533811

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83306395A Withdrawn EP0107489A1 (de) 1982-10-23 1983-10-21 Rostfreier Stahl

Country Status (2)

Country Link
EP (1) EP0107489A1 (de)
GB (1) GB2128632A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1985005129A1 (en) * 1984-04-27 1985-11-21 Bonar Langley Alloys Limited High chromium duplex stainless steel
EP0455625A1 (de) * 1990-05-03 1991-11-06 BÖHLER Edelstahl GmbH Hochfeste korrosionsbeständige Duplexlegierung
EP2684973A1 (de) * 2011-03-09 2014-01-15 Nippon Steel & Sumikin Stainless Steel Corporation Zweiphasiger edelstahl mit hervorragender schweissnaht-korrosionsbeständigkeit
US9862168B2 (en) 2011-01-27 2018-01-09 Nippon Steel & Sumikin Stainless Steel Corporation Alloying element-saving hot rolled duplex stainless steel material, clad steel plate having duplex stainless steel as cladding material therefor, and production method for same

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2229065A (en) * 1938-12-14 1941-01-21 Electro Metallurg Co Austenitic alloy steel and article made therefrom
DE1214005B (de) * 1965-02-03 1966-04-07 Suedwestfalen Ag Stahlwerke Bauteile aus austenitischen Staehlen
FR1444807A (fr) * 1965-05-24 1966-07-08 Loire Atel Forges Perfectionnements apportés aux aciers inoxydables austénitiques présentant une grande résistance au fluage
FR2007566A1 (de) * 1968-04-30 1970-01-09 Armco Steel Corp
FR2045584A1 (de) * 1969-06-03 1971-03-05 Ugine Kuhlmann
DE2457089A1 (de) * 1973-12-10 1975-06-12 Schoeller Bleckmann Stahlwerke Austenitisch-ferritischer chromnickel-stickstoff-stahl
EP0060577A1 (de) * 1981-03-16 1982-09-22 BBC Brown Boveri AG Turbinenschaufelwerkstoff hoher Festigkeit gegen Korrosionsermüdung, Verfahren zu dessen Herstellung und seine Verwendung

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3306736A (en) * 1963-08-30 1967-02-28 Crucible Steel Co America Austenitic stainless steel
GB1158614A (en) * 1967-03-16 1969-07-16 Langley Alloys Ltd Improvement in Stainless Steels
ATA285473A (de) * 1972-04-24 1976-09-15 Bofors Ab Austenitisch-ferritischer, nichtrostender stahl mit hoher festigkeit und guter korrosionsbestandigkeit
GB1456634A (en) * 1972-09-13 1976-11-24 Langley Alloys Ltd High strength stainless steel having a high resistance to corro sive and abrasive wear in corrosive environments particularly chloride environments
JPS5424364B2 (de) * 1973-05-04 1979-08-21
DE2616599B2 (de) * 1976-04-13 1981-03-26 Mannesmann AG, 40213 Düsseldorf Verwendung eines hochlegierten Stahles zum Herstelen von hochfesten, gegen Sauergaskorrosion beständigen Gegenständen

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2229065A (en) * 1938-12-14 1941-01-21 Electro Metallurg Co Austenitic alloy steel and article made therefrom
DE1214005B (de) * 1965-02-03 1966-04-07 Suedwestfalen Ag Stahlwerke Bauteile aus austenitischen Staehlen
FR1444807A (fr) * 1965-05-24 1966-07-08 Loire Atel Forges Perfectionnements apportés aux aciers inoxydables austénitiques présentant une grande résistance au fluage
FR2007566A1 (de) * 1968-04-30 1970-01-09 Armco Steel Corp
FR2045584A1 (de) * 1969-06-03 1971-03-05 Ugine Kuhlmann
DE2457089A1 (de) * 1973-12-10 1975-06-12 Schoeller Bleckmann Stahlwerke Austenitisch-ferritischer chromnickel-stickstoff-stahl
EP0060577A1 (de) * 1981-03-16 1982-09-22 BBC Brown Boveri AG Turbinenschaufelwerkstoff hoher Festigkeit gegen Korrosionsermüdung, Verfahren zu dessen Herstellung und seine Verwendung

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1985005129A1 (en) * 1984-04-27 1985-11-21 Bonar Langley Alloys Limited High chromium duplex stainless steel
US4657606A (en) * 1984-04-27 1987-04-14 Bonar Langley Alloys Limited High chromium duplex stainless steel
EP0455625A1 (de) * 1990-05-03 1991-11-06 BÖHLER Edelstahl GmbH Hochfeste korrosionsbeständige Duplexlegierung
US9862168B2 (en) 2011-01-27 2018-01-09 Nippon Steel & Sumikin Stainless Steel Corporation Alloying element-saving hot rolled duplex stainless steel material, clad steel plate having duplex stainless steel as cladding material therefor, and production method for same
EP2684973A1 (de) * 2011-03-09 2014-01-15 Nippon Steel & Sumikin Stainless Steel Corporation Zweiphasiger edelstahl mit hervorragender schweissnaht-korrosionsbeständigkeit
EP2684973A4 (de) * 2011-03-09 2015-04-15 Nippon Steel & Sumikin Sst Zweiphasiger edelstahl mit hervorragender schweissnaht-korrosionsbeständigkeit
US9365914B2 (en) 2011-03-09 2016-06-14 Nippon Steel & Sumikin Stainless Steel Corporation Duplex stainless steel superior in corrosion resistance of weld

Also Published As

Publication number Publication date
GB8328210D0 (en) 1983-12-21
GB2128632A (en) 1984-05-02

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Inventor name: GRADWELL, KEVAN JOHN