EP0172776A1 - Verfahren zur Verbesserung der Schmiedbarkeit eines rostfreien austenoferritischen Stahles - Google Patents

Verfahren zur Verbesserung der Schmiedbarkeit eines rostfreien austenoferritischen Stahles Download PDF

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Publication number
EP0172776A1
EP0172776A1 EP85420132A EP85420132A EP0172776A1 EP 0172776 A1 EP0172776 A1 EP 0172776A1 EP 85420132 A EP85420132 A EP 85420132A EP 85420132 A EP85420132 A EP 85420132A EP 0172776 A1 EP0172776 A1 EP 0172776A1
Authority
EP
European Patent Office
Prior art keywords
steel
forgeability
hyper
improving
hot
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.)
Granted
Application number
EP85420132A
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English (en)
French (fr)
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EP0172776B1 (de
Inventor
Marc Henry
Bernard Heritier
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.)
Ugine Aciers
Ugine Savoie SA
Original Assignee
Ugine Aciers
Ugine Savoie SA
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 Ugine Aciers, Ugine Savoie SA filed Critical Ugine Aciers
Priority to AT85420132T priority Critical patent/ATE32356T1/de
Publication of EP0172776A1 publication Critical patent/EP0172776A1/de
Application granted granted Critical
Publication of EP0172776B1 publication Critical patent/EP0172776B1/de
Expired 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
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • 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

Definitions

  • the present invention relates to a method for improving the forgeability of a so-called "duplex" austenoferritic stainless steel.
  • This resistance to corrosion under stress is generally linked to the presence of a ferritic phase most often occupying between 30 and 70% of the volume of "duplex" stainless steel in the hyper-quenched state.
  • the Applicant has studied the possibility of improving this forgeability by a modification of composition which does not alter the essential qualities of the products obtained, in particular their mechanical characteristics R and E 0.2 in the hyper-soaked state.
  • the process of the invention applies to a steel preferably having (% by weight):
  • the content of Si is preferably comprised between, 8 and 2.3% and the Mo content is itself preferably between 1.5 and 3% and more preferably between 2 and 3%, this limitation to 3% instead of 3.5% having for reason Mo's contribution to the formation of weakening phases.
  • the Si content is preferably between 2.3 and 2.7% and the products obtained then have, at the hyper quenched state and possibly upright and work hardened, an elastic limit E 0.2> 560 MPa (these products are either bars of diameter or thickness between 20 and 100 mm, used for various uses for their mechanical characteristics and their resistance to corrosion Either hyper-soaked and possibly hardened wire rod, with a diameter or thickness between 5 and 20 mm, or else hyper-hardened and possibly hardened sheet metal, with a thickness between 0.5 and 10 mm.
  • test flows were made in a laboratory HF oven.
  • the analyzes are shown in Table 1.
  • the square ingots of 100x100 mm cross section coming from these flows were preheated between 1250 and 1300 ° C and forged in several passes with intermediate reheating in 15 mm octagons.
  • Test pieces machined in these octagons were then subjected to conventional forgeability tests. After rapid reheating to 1350 ° C or 1325 ° C and holding for one minute at this temperature, then cooling if necessary to the test temperature, the test pieces underwent hot tensile tests at temperatures staggered between 1350 or 1325 ° C and 950 or 900 ° C.
  • the transition to 3.14% Si results in a much less rapid decrease in forgeability with temperature.
  • the curve (23) corresponding to 1.9% Si has in its central part of rapid decay (temperature range 1100 to 1200 ° C) a slope similar to that of the central part of the curve (50) (which, for its part, corresponds to 1150 to 1250 * C approximately).
  • the rapidly decreasing part has a markedly lower slope: of the order of 1% by 4 ° C, instead of 1% by 1.5 at 2 ° C for the curve (50).
  • the forgeability is greatly improved between 1050 and 1150'C.
  • the hot transformer will thus have the maximum of the following comparative working temperature intervals, corresponding to ⁇ > 50%:
  • E 0.2 and R increase very markedly with Si%.
  • the approximate average trend lines "E 0.2" and “R” have similar slopes ( Figure 2), and from Si 2% E 0.2 is clearly greater than 560 MPa while R is greater than 800 MPa , whatever the hyper quenching temperature used (Table III).
  • An elastic limit E 0.2 of 560 MPa, substantially equivalent to 80,000 psi, is imposed in particular for tubes of "grade N-80" according to the specification of API (American Petroleum Institute) and for ancillary equipment.
  • the steel of the invention with Si preferably; 2% allows this condition to be satisfied without wrinkling after overheating.
  • the notation "traces” corresponds to the start of the sigma phase in an amount less than or equal to 1% of the volume, and in FIG. 3 the curves plotted by interpolation correspond to 1 to 2% of the sigma phase. .
  • the sigma phase must be absent due to the cooling conditions after overheating.
  • the notation "yes” on the Table means that the sigma phase has been observed in an amount greater than approximately 1%.
  • the steel according to the invention intended for the manufacture of blanks ⁇ 100 to 250 mm, blanks which on cooling after hot working cross the interval 800 to 950 ° C in a fairly long time, has a content of If preferably between 1.8 and 2.3% and a Mo content preferably limited to 3% maximum.
  • this steel When the steel is intended for the manufacture of bars of diameter or thickness less than 100 mm, or of hyper-soaked and possibly hardened wire rod of diameter or thickness between 5 and 20 mm, or of hyper-tempered and possibly hardened sheets of thickness included between 0.5, this steel has an Si content preferably of at least 2.3% for its mechanical properties in the hyper quenched state and optionally upright and work hardened (E 0.2 ⁇ 560 MPa) and limited to 2, 7% to reduce the risk of embrittlement.
EP85420132A 1984-07-20 1985-07-18 Verfahren zur Verbesserung der Schmiedbarkeit eines rostfreien austenoferritischen Stahles Expired EP0172776B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT85420132T ATE32356T1 (de) 1984-07-20 1985-07-18 Verfahren zur verbesserung der schmiedbarkeit eines rostfreien austenoferritischen stahles.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8412028A FR2567911A1 (fr) 1984-07-20 1984-07-20 Acier inoxydable austenoferritique " duplex " et produits corroyes correspondants
FR8412028 1984-07-20

Publications (2)

Publication Number Publication Date
EP0172776A1 true EP0172776A1 (de) 1986-02-26
EP0172776B1 EP0172776B1 (de) 1988-02-03

Family

ID=9306592

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85420132A Expired EP0172776B1 (de) 1984-07-20 1985-07-18 Verfahren zur Verbesserung der Schmiedbarkeit eines rostfreien austenoferritischen Stahles

Country Status (5)

Country Link
EP (1) EP0172776B1 (de)
AT (1) ATE32356T1 (de)
DE (1) DE3561554D1 (de)
ES (1) ES8703940A1 (de)
FR (1) FR2567911A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2663923A1 (fr) * 1990-06-29 1992-01-03 Corning France Hublots frettes et procede pour leur fabrication.

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2919639B1 (fr) * 2007-07-30 2009-11-13 Ugitech Fil crante pour armature de structure en beton, en acier inoxydable duplex.
RU2522914C1 (ru) * 2013-02-27 2014-07-20 Федеральное государственное автономное образовательное учреждение высшего профессионального образования "Уральский федеральный университет имени первого Президента России Б.Н. Ельцина" Аустенитно-ферритная сталь с высокой прочностью

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE891399C (de) * 1940-06-20 1953-09-28 Eisen & Stahlind Ag Austenitische Stahllegierungen fuer Gegenstaende, die bei ihrer Herstellung oder im Betrieb einer Erwaermung ausgesetzt werden
US2839392A (en) * 1955-07-28 1958-06-17 Du Pont Corrosion resistant alloy
FR1572641A (de) * 1967-06-19 1969-06-27
FR2045584A1 (de) * 1969-06-03 1971-03-05 Ugine Kuhlmann

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE891399C (de) * 1940-06-20 1953-09-28 Eisen & Stahlind Ag Austenitische Stahllegierungen fuer Gegenstaende, die bei ihrer Herstellung oder im Betrieb einer Erwaermung ausgesetzt werden
US2839392A (en) * 1955-07-28 1958-06-17 Du Pont Corrosion resistant alloy
FR1572641A (de) * 1967-06-19 1969-06-27
FR2045584A1 (de) * 1969-06-03 1971-03-05 Ugine Kuhlmann

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2663923A1 (fr) * 1990-06-29 1992-01-03 Corning France Hublots frettes et procede pour leur fabrication.

Also Published As

Publication number Publication date
EP0172776B1 (de) 1988-02-03
FR2567911A1 (fr) 1986-01-24
ATE32356T1 (de) 1988-02-15
ES8703940A1 (es) 1987-03-01
ES545391A0 (es) 1987-03-01
DE3561554D1 (en) 1988-03-10

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