EP0045984A1 - Procédé pour la fabrication de pièces en un alliage résistant aux températures élevées - Google Patents

Procédé pour la fabrication de pièces en un alliage résistant aux températures élevées Download PDF

Info

Publication number
EP0045984A1
EP0045984A1 EP81200670A EP81200670A EP0045984A1 EP 0045984 A1 EP0045984 A1 EP 0045984A1 EP 81200670 A EP81200670 A EP 81200670A EP 81200670 A EP81200670 A EP 81200670A EP 0045984 A1 EP0045984 A1 EP 0045984A1
Authority
EP
European Patent Office
Prior art keywords
deformation
values
primary material
epsilon
final
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
EP81200670A
Other languages
German (de)
English (en)
Other versions
EP0045984B1 (fr
Inventor
Gernot Dr. Dipl.-Ing. Gessinger
Robert Dr. Dipl.-Ing. Singer
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.)
BBC Brown Boveri AG Switzerland
Original Assignee
BBC Brown Boveri AG Switzerland
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 BBC Brown Boveri AG Switzerland filed Critical BBC Brown Boveri AG Switzerland
Priority to AT81200670T priority Critical patent/ATE6674T1/de
Publication of EP0045984A1 publication Critical patent/EP0045984A1/fr
Application granted granted Critical
Publication of EP0045984B1 publication Critical patent/EP0045984B1/fr
Expired legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/10—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of nickel or cobalt or alloys based thereon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/24—After-treatment of workpieces or articles
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
    • C22C32/001—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with only oxides
    • C22C32/0015—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with only oxides with only single oxides as main non-metallic constituents
    • C22C32/0026—Matrix based on Ni, Co, Cr or alloys thereof

Definitions

  • the invention relates to a method for producing a workpiece according to the preamble of claim 1.
  • Oxide dispersion-hardened alloys in particular those of the nickel-based type, are generally produced by powder metallurgical methods, the technology of mechanical alloying of the powder particles being widely used. In order to achieve the highest possible creep resistance at high temperatures, such alloys must have a coarse-grained structure in the ready-to-use workpiece.
  • the methods of mechanical alloying and the question of the associated further processing of the oxide dispersion-hardened materials are known (for example JPMorse and JSBenjamin, "Mechanical Alloying", New Trends in Materials Processing, pp. 165-199, in particular pp. 177-185, American Society for Metals, seminar October 19/20, 1974).
  • the primary material obtained in a first compression step (powder compaction) must be subjected to further shaping operations. Since both the material and the p dec anungs knew such Legie rations are very high, this shaping can only be carried out economically by forming. At the end of all processes there is always a heat treatment which serves to convert the finished workpiece into the coarse-grained structure which is best suited for high-temperature operation.
  • the setting options for the coarse grain are known to depend on the available driving forces, the number of bacteria and other physical parameters. It is not indifferent in which way the primary material was created. The latter can be done, for example, by extrusion at high or low temperature or by hot isostatic pressing of the mechanically alloyed, encapsulated powder. Mechanical alloying generally causes a state of maximum possible deformation, that is to say strain hardening driven to the saturation limit, which occurs in the subsequent thermomechanical deformation steps is more or less broken down. Practice shows that there is an optimal deformation state of the primary material for the subsequent formation of coarse grains ("normal").
  • the primary material is insufficiently deformed ("underworked"), ie if it has too little work hardening and therefore too little energy for the subsequent recrystallization, the latter is incomplete (mixture of non-recrystallized fine grain with little coarse grain) or is completely absent.
  • the primary material is excessively deformed ("overworked"), ie if it has an excess of energy for later recrystallization, this takes place completely, but, due to the high number of crystallization nuclei, only leads to a relatively fine-grained structure. The latter cannot be converted into coarse grain by any additional heat treatment.
  • the invention is based on the object of specifying a production method for oxide-hardened, heat-resistant workpieces which, regardless of the selected compression step and the resulting state of deformation of the structure of the primary material produced in this way, guarantees a coarse-grained end product which can be used in operation.
  • Fig. 1 the flow diagram of the basic method is shown in block form. It is generally assumed that metallic powders, which may be in the form of elements and / or master alloys, and metal oxide powders as dispersoids.
  • the powders are very fine-grained, the particle size varies between a few and about 60 p, the metal oxide powder mostly even finer (below 1 p).
  • the mixing and mechanical alloying of the powders is generally carried out in a protective gas atmosphere in the attritor.
  • the powder particles are alloyed to homogeneity and mixed with the dispersoid.
  • the cold working is driven to the saturation limit, which is reflected in the high hardness, which can reach up to 700 Vickers units.
  • the mechanically alloyed powder is filled into a ductile metal container, usually soft steel, under vacuum and encapsulated (sealed, sealed can or capsule on all sides).
  • the encapsulated powder is thermally compressed to 100% of the theoretical density.
  • the product is an easily deformable, ultra-fine-grained raw material, which forms the starting material for the further shaping of the workpiece.
  • thermoforming step a raw material is formed which is insufficiently or excessively deformed with respect to the later recrystallization ("underworked”, "normal”, “overworked”).
  • targeted forming final shaping
  • Relevant parameters are temperature, deformation speed and the deformation to be achieved or still necessary in the last forming step, which can be expressed, for example, as a change in cross-section.
  • a finished workpiece is created, which is characterized by coarse grain annealing can be converted into the operationally appropriate end product.
  • pairs of values can be specified for the subsequent forming into the finished workpiece, which two parameters fulfill the prerequisite for the subsequent coarse grain formation.
  • the other parameter, the degree of deformation is expediently determined by the absolute value of the natural logarithm of the cross-sectional ratio of the workpiece. Of course, you can also start from the change in length and then convert it to the cross-sectional ratio.
  • FIG. 2 shows the flow diagram of the process steps for insufficiently deformed starting material.
  • a powder mixture was mechanically alloyed and encapsulated in a soft steel can.
  • the final alloy had the following composition:
  • the subsequent hot compression step consisted of extrusion at a temperature of 1075 ° C.
  • the fine-grained primary material produced in this way had an average sub-grain size of 0.3 ⁇ .
  • the workpiece was subjected to coarse grain annealing at a temperature of 1220 ° C for 1 h. An average grain size of over 100 ⁇ was found. In general, given these conditions, coarse grain can be understood to mean that grain size which means coarsening by at least a factor of 100 compared to the fine-grained starting material.
  • FIG. 3 shows the flow diagram of the process steps for optimally deformed primary material.
  • the starting position corresponded to the exemplary embodiment explained in FIG. 2.
  • the same alloy was used and the same first process steps were used.
  • the extrusion was carried out under similar conditions, but at a temperature of 960 ° C.
  • the reduction ratio also gave an ⁇ of 3.
  • the fine-grained raw material had a sub-grain size of 0.2 ⁇ . In accordance with the reduction of work hardening, this material was in the optimal state of deformation ("normal").
  • the average subgrain size of these materials generally ranges from 0.15 ⁇ to 0.25 ju.
  • FIG. 4 shows the flow diagram of the process steps for excessively deformed starting material.
  • a powder mixture was mechanically alloyed and encapsulated in a soft steel can.
  • the final alloy had the following composition:
  • thermoforming step to compress the encapsulated powder to 100% of the theoretical density consisted in hot isostatic pressing at a temperature of 950 ° C. for 4 hours under a pressure of 135 MPa.
  • the height of the original cylindrical body of 200 mm was reduced to 150 mm.
  • the corresponding E was found to be 0.3.
  • the fine-grained primary material produced in this way had an average sub-grain size of 0.14 ⁇ . Due to the lower degradation of the work hardening of the powder, this material was considered excessive deformed ("overworked").
  • the subgrain size of such materials is usually ⁇ 0.15 ⁇ .
  • the workpiece was subjected to coarse grain annealing at a temperature of 1220 ° C for 1 h. An average grain size of over 60F was found, which clearly means coarse grain in this case.
  • FIG. 5 shows a diagram of the experimentally determined deformation conditions in order to achieve coarse grain for the finished workpiece in the event that insufficiently deformed starting material ("underworked") is assumed.
  • the deformation conditions are shown as pairs of values for the deformation speed and the degree of deformation.
  • Each intersection of an abscissa value with an ordinate value represents a specific state that characterizes the deformation condition, but not a functional relationship between the deformation speed and the degree of deformation. If the intersection falls within the hatched area, the conditions for the success of subsequent coarse grain annealing on the finished workpiece are met. If the intersection falls outside the hatched area, coarse grain formation can no longer be expected. Either the recrystallization is then at least partially absent, or a fine-grained structure that is undesirable for operation is formed.
  • the diagram shows that to achieve coarse grain, the rate of deformation is rather narrow Limits have to be that an optimal value exists regardless of the degree of deformation and that the latter must not fall below a certain minimum.
  • the value for should be between 16.5 and 20, optimally around 18 (dash-dotted horizontal), while should be.
  • the favorable area in the diagram is open parallel to the abscissa, which means that there is no upper limit to the degree of deformation.
  • FIG. 6 is a diagram of the experimentally determined deformation conditions to achieve coarse grain for the finished workpiece in the event that optimally deformed starting material ("normal") is assumed.
  • the hatched area again represents the totality of the intersection points of an abscissa and ordinate value, for which the coarse grain formation is guaranteed on the occasion of the subsequent annealing.
  • the diagram shows that whenever larger deformations of the workpiece corresponding to E> 1.0 are necessary, the rate of deformation must be kept within narrow limits, which is the value for between 15.5 and 20, optimally around 18.
  • the value for 6, on the other hand, is not limited, so it can be as small as desired, in the limit case it can also be zero (no further transformation possible or desirable in practice).
  • Correspondingly in the area of low degrees of deformation for the final shaping is the range for the rate of deformation expanded and reached for
  • FIG. 7 shows a diagram of the experimentally determined deformation conditions in order to achieve coarseness for the finished workpiece in the event that excessively deformed starting material ("overworked") is assumed.
  • the hatched area defined above approaches the ordinate, but does not quite reach it.
  • the permissible value for approximately between 14 and 18, for higher degrees of deformation accordingly between 16 and 20, optimal again at around 18. Otherwise there is a correspondingly low deformation range for example a linear relationship with the mean of the logarithm of the rate of deformation.
  • the degree of deformation 8 must reach at least 0.1.
  • the primary material can be produced in a conventional manner by hot isostatic pressing or by extrusion.
  • the process is generally applicable to the alloy type specified in the examples and related dispersion-hardened austenitic superalloys suitable for precipitation hardening.
  • the working conditions to be observed for the further shaping of a workpiece from a dispersion-hardened nickel alloy were defined as pairs of values of deformation rate / degree of deformation in order to once again achieve a coarse-grained structure which is optimal for operation at high temperatures and clearly represented in diagrams.
  • the process ensures, regardless of the ultra-fine-grained raw material and its degree of work hardening, that coarse grain is obtained in the end product.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Metallurgy (AREA)
  • Materials Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Powder Metallurgy (AREA)
  • Forging (AREA)
  • Press Drives And Press Lines (AREA)
EP81200670A 1980-08-08 1981-06-16 Procédé pour la fabrication de pièces en un alliage résistant aux températures élevées Expired EP0045984B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT81200670T ATE6674T1 (de) 1980-08-08 1981-06-16 Verfahren zur herstellung eines werkstueckes aus einer warmfesten legierung.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH6027/80 1980-08-08
CH602780 1980-08-08

Publications (2)

Publication Number Publication Date
EP0045984A1 true EP0045984A1 (fr) 1982-02-17
EP0045984B1 EP0045984B1 (fr) 1984-03-14

Family

ID=4303031

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81200670A Expired EP0045984B1 (fr) 1980-08-08 1981-06-16 Procédé pour la fabrication de pièces en un alliage résistant aux températures élevées

Country Status (4)

Country Link
EP (1) EP0045984B1 (fr)
JP (1) JPS5754237A (fr)
AT (1) ATE6674T1 (fr)
DE (1) DE3162643D1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0074679A1 (fr) * 1981-09-03 1983-03-23 BBC Aktiengesellschaft Brown, Boveri & Cie. Procédé pour la fabrication d'ébauches en un alliage résistant à la chaleur
EP0087183A1 (fr) * 1982-02-18 1983-08-31 BBC Aktiengesellschaft Brown, Boveri & Cie. Procédé pour la fabrication d'une pièce à grains fins comme produit fini à partir d'un alliage austénitique à base de nickel résistant à la chaleur
EP0274631A1 (fr) * 1986-12-19 1988-07-20 BBC Brown Boveri AG Procédé pour augmenter la ductilité à température ambiante d'une pièce en superalliage à base de nickel durci par dispersion d'oxyde et formée de grains basaltiques grossiers orientés longitudinalement
EP0398121A1 (fr) * 1989-05-16 1990-11-22 Asea Brown Boveri Ag Procédé de fabrication de grains basaltiques grossiers orientés longitudinalement dans un superalliage à base de nickel durci par dispersion d'oxyde

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60131943A (ja) * 1983-12-19 1985-07-13 Sumitomo Electric Ind Ltd 分散粒子強化耐熱耐摩耗アルミニウム合金粉末

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2133186A1 (de) * 1970-07-06 1972-02-10 Int Nickel Ltd Verfahren zum Formen und Waermebehandeln von Pulvern
DE2303802A1 (de) * 1972-01-31 1973-08-16 Int Nickel Ltd Verfahren zur waermebehandlung einer dispersionsverfestigten, hitzebestaendigen knetlegierung
DE2353971A1 (de) * 1972-10-30 1974-05-22 Int Nickel Ltd Aushaertbare dispersionsverfestigte nickel-chrom-legierung
DE2552285A1 (de) * 1975-10-20 1977-04-21 Bbc Brown Boveri & Cie Verfahren zur pulvermetallurgischen herstellung eines werkstuecks aus einer hochwarmfesten legierung

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3909309A (en) * 1973-09-11 1975-09-30 Int Nickel Co Post working of mechanically alloyed products

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2133186A1 (de) * 1970-07-06 1972-02-10 Int Nickel Ltd Verfahren zum Formen und Waermebehandeln von Pulvern
DE2303802A1 (de) * 1972-01-31 1973-08-16 Int Nickel Ltd Verfahren zur waermebehandlung einer dispersionsverfestigten, hitzebestaendigen knetlegierung
FR2170100A1 (fr) * 1972-01-31 1973-09-14 Int Nickel Ltd
DE2353971A1 (de) * 1972-10-30 1974-05-22 Int Nickel Ltd Aushaertbare dispersionsverfestigte nickel-chrom-legierung
DE2552285A1 (de) * 1975-10-20 1977-04-21 Bbc Brown Boveri & Cie Verfahren zur pulvermetallurgischen herstellung eines werkstuecks aus einer hochwarmfesten legierung
FR2328538A1 (fr) * 1975-10-20 1977-05-20 Bbc Brown Boveri & Cie Procede de realisation d'une piece en alliage resistant a des temperatures tres elevees par metallurgie des poudres

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0074679A1 (fr) * 1981-09-03 1983-03-23 BBC Aktiengesellschaft Brown, Boveri & Cie. Procédé pour la fabrication d'ébauches en un alliage résistant à la chaleur
EP0087183A1 (fr) * 1982-02-18 1983-08-31 BBC Aktiengesellschaft Brown, Boveri & Cie. Procédé pour la fabrication d'une pièce à grains fins comme produit fini à partir d'un alliage austénitique à base de nickel résistant à la chaleur
EP0274631A1 (fr) * 1986-12-19 1988-07-20 BBC Brown Boveri AG Procédé pour augmenter la ductilité à température ambiante d'une pièce en superalliage à base de nickel durci par dispersion d'oxyde et formée de grains basaltiques grossiers orientés longitudinalement
EP0398121A1 (fr) * 1989-05-16 1990-11-22 Asea Brown Boveri Ag Procédé de fabrication de grains basaltiques grossiers orientés longitudinalement dans un superalliage à base de nickel durci par dispersion d'oxyde

Also Published As

Publication number Publication date
DE3162643D1 (en) 1984-04-19
EP0045984B1 (fr) 1984-03-14
ATE6674T1 (de) 1984-03-15
JPS5754237A (fr) 1982-03-31

Similar Documents

Publication Publication Date Title
DE69915797T2 (de) Verfahren zur herstellung dichter teile durch uniaxiales pressen agglomerierter kugelförmiger metallpulver.
EP0513407B1 (fr) Procédé de fabrication d' une aube de turbine
DE69935891T2 (de) Verfahren zur Herstellung eines Motorhubventils
DE3445767C2 (fr)
EP0369543B1 (fr) Charge creuse avec revêtement métallique, dispositif et procédé pour sa fabrication
DE2542094A1 (de) Metallpulver, verfahren zur behandlung losen metallpulvers und verfahren zur herstellung eines verdichteten presslings
DE4025408A1 (de) Verfahren zum entwickeln einer verbesserten textur in titanlegierungen sowie damit erhaltene gegenstaende
DE2856082C2 (de) Verfahren zum Herstellen von wärmerückstellbaren Gegenständen aus Kupfer-Zink-Aluminium-Legierungen
EP3372700B1 (fr) Procédé de fabrication d'éléments structuraux en tial forgés
AT411027B (de) Vorrichtung und verfahren zur herstellung feinkristalliner werkstoffe
DE1283547B (de) Verfahren zum Erhoehen der Zugfestigkeit, Dehngrenze und Zeitstandfestigkeit und zurStabilisierung der Kornorientierung von dispersionsgehaerteten Legierungen
EP0035601B1 (fr) Procédé de fabrication d'un alliage-mémoire
EP0574708A1 (fr) Elément pour température élevée, en particulier aube de turbine et procédé de fabrication de cet élément
EP0396185B1 (fr) Procédé pour la préparation d'outils semi-finis résistant au fluage en métal réfractaire
DE1558805C3 (de) Verfahren zur Herstellung von verformten Werkstücken aus dispersionsverstärkten Metallen oder Legierungen
DE2200670B2 (fr)
EP0045984B1 (fr) Procédé pour la fabrication de pièces en un alliage résistant aux températures élevées
DE2443187C2 (de) Verfahren zum Herstellen von Flachwalzprodukten aus mechanisch legierten Pulvern
DE2362650C3 (de) Verfahren zur Verbesserung der Wannverformbarkeit von Zerstäubungspulvern
DE4318827A1 (de) Schwermetallegierung und Verfahren zu ihrer Herstellung
DE2522073A1 (de) Blech aus einer legierung
DE60220773T2 (de) Verfahren zur herstellung eines sinterprodukts
EP0356718B1 (fr) Procédé pour former par extrusion et modification des propriétés mécaniques des produits semi finis en alliages à partir de poudres métalliques qui ont une résistance augmentée à la chaleur
EP0074679B1 (fr) Procédé pour la fabrication d'ébauches en un alliage résistant à la chaleur
DE1920466A1 (de) Verfahren zum Verfestigen von Werkstuecken

Legal Events

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

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Designated state(s): AT BE CH DE FR GB SE

17P Request for examination filed

Effective date: 19820528

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Designated state(s): AT BE CH DE FR GB LI SE

REF Corresponds to:

Ref document number: 6674

Country of ref document: AT

Date of ref document: 19840315

Kind code of ref document: T

REF Corresponds to:

Ref document number: 3162643

Country of ref document: DE

Date of ref document: 19840419

ET Fr: translation filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: CH

Payment date: 19840724

Year of fee payment: 4

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
GBPC Gb: european patent ceased through non-payment of renewal fee
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: AT

Payment date: 19860527

Year of fee payment: 6

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: AT

Effective date: 19890616

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LI

Effective date: 19890630

Ref country code: CH

Effective date: 19890630

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19900822

Year of fee payment: 10

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19910515

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 19910517

Year of fee payment: 11

Ref country code: BE

Payment date: 19910517

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 19910521

Year of fee payment: 11

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Effective date: 19920401

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Effective date: 19920616

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Effective date: 19920617

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: BE

Effective date: 19920630

BERE Be: lapsed

Owner name: BBC A.G. BROWN BOVERI & CIE

Effective date: 19920630

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 19920616

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Effective date: 19930226

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

EUG Se: european patent has lapsed

Ref document number: 81200670.8

Effective date: 19930109