EP0049530A1 - Procédé et dispositif pour carburer des pièces en acier - Google Patents

Procédé et dispositif pour carburer des pièces en acier Download PDF

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Publication number
EP0049530A1
EP0049530A1 EP81108034A EP81108034A EP0049530A1 EP 0049530 A1 EP0049530 A1 EP 0049530A1 EP 81108034 A EP81108034 A EP 81108034A EP 81108034 A EP81108034 A EP 81108034A EP 0049530 A1 EP0049530 A1 EP 0049530A1
Authority
EP
European Patent Office
Prior art keywords
carbon
workpieces
gas mixture
annealing furnace
soot
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
EP81108034A
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German (de)
English (en)
Other versions
EP0049530B1 (fr
Inventor
Karlheinz Längerich
Rüdiger Dr. Conrad
Wolfgang Dr. Danzer
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.)
Linde GmbH
Original Assignee
Linde GmbH
Xaver Fendt and Co
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 Linde GmbH, Xaver Fendt and Co filed Critical Linde GmbH
Publication of EP0049530A1 publication Critical patent/EP0049530A1/fr
Application granted granted Critical
Publication of EP0049530B1 publication Critical patent/EP0049530B1/fr
Expired legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/20—Carburising
    • C23C8/22—Carburising of ferrous surfaces
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases

Definitions

  • the invention relates to a method and a device for carburizing metallic workpieces, in which the workpieces are brought to a high temperature in an annealing furnace, exposed to the action of a carbon-containing gas mixture and hardened.
  • gas carburizing and carbonitriding are becoming increasingly important.
  • the processes are carried out in closed annealing furnaces, which allow a controlled atmosphere to be set and maintained at a certain reaction temperature.
  • the main problem with the gas carburizing process is the transfer of carbon from the gas atmosphere to the material, e.g. Steel, to be carried out in a controlled manner in order to achieve reproducible carburizing results on workpieces of different basic carbon content, different alloys and in particular different shapes.
  • a carburizing gas atmosphere from a gas mixture of the three components nitrogen, coal Introduce hydrogen and oxygen dispenser into the furnace chamber (DE-OS 24 50 879 and DE-OS 28 18 558).
  • hydrocarbons paraffin or paraffinic hydrocarbons, methane, ethane, propane, butane or natural gas with a proportion of 7.5 to 38 grams of carbon.
  • Oxygen, air, carbon dioxide, carbon monoxide, water vapor or mixtures thereof serve as oxygen donors.
  • the gas components are fed to the furnace separately or in mixtures.
  • the measurement and control of the gas atmosphere takes place via a dew point, infrared (C0 2 ) or oxygen measurement.
  • the carburizing process is divided into two or three intervals in which the carburizing agent is fed into the furnace (interval carbons). The intervals are separated in time by two or three phases in which no carbonizing agent is fed into the furnace. During the carbonization intervals, the carbon potential in the furnace rises sharply and soot is formed. In the subsequent phase, in which air is fed into the furnace instead of carbon dioxide, the carbon potential drops again to zero. Edge oxidations cannot be avoided with this procedure. However, if the proportion of carburizing agent in the gas mixture is reduced in order to avoid excessive soot formation, the carburizing time increases considerably.
  • the invention is therefore based on the object of a method for the uniform carburizing of workpieces that are more reliable, faster and therefore more economical.
  • This object is achieved in that one or more of the carbon-containing gas components of the gas mixture are added in a pulsating manner during its action on the surface of the workpieces.
  • the invention is based on the knowledge that a large carbon potential gradient between the workpiece surface and the core itself comes to the fore as an additional driving diffusion force from the beginning of carburization.
  • the carbon-containing gas components of the gas mixture are added in a pulsating manner. This means that the carbon content of the gas mixture is raised to a certain level in various phases during the carburization, these phases being separated by time intervals in which the carbon content is not changed by the addition of carbon-containing gas components, and the carbon content of the gas mixture consequently decreases.
  • the gas mixture has at least atmospheric pressure and rises rapidly during the intermittent addition of a carbon-containing gas component.
  • This pressure increase is particularly pronounced when hydrocarbons with two or more carbon atoms are introduced into the furnace, since each of their molecules breaks down into several gas molecules with a corresponding pressure increase.
  • the pressure of the gas atmosphere fluctuates in the same rhythm in which the pulsating addition of the carbon-containing gas components takes place ("breathing" of the gas atmosphere).
  • the main advantage of this process is that the glow time is reduced by up to 60% compared to the endogas process, while the duration of carburization takes place under glow time and understanding diffusion. Large hardening depths are also achieved.
  • a uniform carburization is achieved, which leads to the workpieces being free of soot and edge oxidation.
  • the process is significantly more reliable, because of the low H 2 content, the risk of explosion is lower and the furnaces can be gassed safely during idle and at the weekend.
  • the addition period is 2 to 200 seconds, preferably 15 to 60 seconds, while the duration of the diffusion phase is 10 to 500 seconds, preferably 50 to 200 seconds.
  • the methane and / or the soot content in the gas mixture is measured, the measured variables are fed to a control unit and the addition of one or more of the hydrocarbons by the control unit after comparison of the values of the methane and / or soot content with a setpoint set in each case.
  • the setpoints are selected so that over-carbonization, ie, soot formation, does not take place.
  • the surface of the metallic workpieces therefore always remains soot-free. Rather, the carbon potential is kept almost constant at a value, the working line, around which the carbon potential fluctuates.
  • the carbon potential rises briefly during the pulsed addition of hydrocarbons and falls below the almost constant mean value given during the subsequent diffusion phase.
  • material potential never drops to zero. It is crucial here that the working line of the process is at a high carbon potential above the classic soot limit, without producing soot, since the stay in the soot area is only very short. This fact has proven to be an essential feature of the method according to the invention, on which the high carburizing rate can be attributed.
  • the method according to the invention can also be used for carbonitriding the workpieces.
  • ammonia is added pulsating to the gas mixture while it is acting on the surface of the workpieces.
  • An annealing furnace for carrying out the method according to the invention essentially has a device for supplying and discharging gases into and from the annealing furnace and an associated control device.
  • the control device is advantageously connected to a soot sensor and a gas analyzer for determining the methane content in the gas mixture, the control unit responding to the difference between measured value signals and a setpoint signal for the soot and / or methane content that can be set in one or two setpoint transmitters Valve for the addition of hydrocarbons is connected.
  • the device for supplying the carbon-containing gas components opens into the interior of the annealing furnace in the lower region and in the immediate vicinity of the carburized workpieces located in the annealing furnace.
  • An annealing furnace 1 is connected via a line 2 to a control unit consisting of a soot sensor 3, a gas analyzer 4 and a controller 5.
  • the gas components nitrogen, carbon dioxide, hydrocarbon, and which come directly from storage bottles, are fed via valves 7, 8 and 9 and a feed 6 into the annealing furnace, which is connected to an outflow line 10 for the exhaust gases.
  • Valve 7, which regulates the supply of nitrogen, is open for driving in and heating up the batch in the furnace chamber, while valve 8 (carbon dioxide) and valve 9 (hydrocarbon, for example propane) are closed.
  • valves 7 and 8 are open and also valve 9 for a short time, for example 20 seconds.
  • the gas mixture passed into the furnace chamber accordingly consists of inert nitrogen, CO 2 and propane.
  • the propane is unstable at the high temperatures and breaks down into radicals, some of which are highly reactive, which cause rapid oversaturation of the workpiece surface with carbon. Because of the resulting significant carbon potential gradient between the workpiece surface and the core, this potential gradient comes to the fore as an additional driving diffusion force from the beginning of the carbonization.
  • both methane and soot are generated in the gas mixture.
  • a part of this gas mixture is drawn off via line 2 and the soot content in the soot sensor and the methane content in the gas analyzer 4, for example an infrared analyzer, are measured.
  • the controller 5 the output values of these two measuring devices are compared with predetermined target values, and if these target values are exceeded, the valve 9 is closed via a relay 11, i.e. the supply of e.g. Interrupted propane.
  • the addition period for the propane is, for example, 20 seconds.
  • the controller 5 opens the valve 9 again via the relay 11 and a new cycle begins.
  • valves 8 and 9 close and the charge is lowered to the hardening temperature.
  • a double spur gear made of 20 Mn CrS, module 5 is sketched in the detail in FIG. 3.
  • the broad dashed line outside the body edges marks the surface hardened area, the narrow dashed line its position and its course.
  • the course of the hardened surface layer requires the determination of the measuring points, which are designated M1 and M2, for the hardening depth.
  • a production batch having a surface area of about 11 m 2 and a weight of 500 kg is at a temperature Glühtem e-p 130 min of 945 ° C in a Aichelin multipurpose chamber furnace. Carburized long. The addition period for propane is approximately 20 seconds and the duration of the diffusion phase is approximately 60 seconds.
  • Figure 4 shows the hardness curve on a double spur gear (material 16 Mn Cr5) from this batch.
  • the surface hardness in HV according to DIN 6773 is plotted against the hardening depth in mm.
  • Curve 1 relates to measuring point 1 and curve 2 to measuring point 2.
  • the workpiece is free of carbides and residual austenite, the carburized steel is martensite. It can clearly be seen that there is constant surface hardening down to a hardening depth of approx. 0.45 mm. However, this then decreases with the hardening depth, due to the shape of the workpiece at measuring point M1 more slowly than at measuring point M2.
  • a specified surface hardness of 610 HV (solid line) corresponds to a hardening depth of 0.83 mm at measuring point M1 and 0.68 mm at measuring point M2. This means that the indentation in the workpiece is sufficiently hardened to avoid deformation.
  • Example 2 Analogous to Example 1, with the difference that the annealing temperature is 960 ° C., the annealing time is 30 minutes, and the addition period for Propane on average 90 seconds and the diffusion time is approximately 200 seconds.
  • Figure 5 shows the hardness curve.
  • a surface hardness of 610 HV corresponds to a hardening depth of 0.45 mm at measuring point M1 and 0.36 mm at measuring point M2. So after a short time (30 min) a considerable hardening depth was reached.
  • FIG. 6 shows the course of the case hardening depth at a limit hardness of 610 HV1 as a function of the annealing time at different annealing temperatures.
  • the almost linear course of the curve from a hardening depth of approx. 0.45 mm is noteworthy.
  • Curves for annealing temperatures between 930 ° C and 960 ° C lie between the two curves shown. The results of 60 tests under production conditions are incorporated into the curve.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
  • Pressure Welding/Diffusion-Bonding (AREA)
  • Forging (AREA)
EP81108034A 1980-10-08 1981-10-07 Procédé et dispositif pour carburer des pièces en acier Expired EP0049530B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3038078 1980-10-08
DE19803038078 DE3038078A1 (de) 1980-10-08 1980-10-08 Verfahren und vorrichtung zum aufkohlen metallischer werkstuecke

Publications (2)

Publication Number Publication Date
EP0049530A1 true EP0049530A1 (fr) 1982-04-14
EP0049530B1 EP0049530B1 (fr) 1985-06-05

Family

ID=6113949

Family Applications (1)

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EP81108034A Expired EP0049530B1 (fr) 1980-10-08 1981-10-07 Procédé et dispositif pour carburer des pièces en acier

Country Status (11)

Country Link
US (1) US4472209A (fr)
EP (1) EP0049530B1 (fr)
AT (1) AT369792B (fr)
AU (1) AU543782B2 (fr)
BR (1) BR8102150A (fr)
DE (2) DE3038078A1 (fr)
DK (1) DK433181A (fr)
ES (1) ES505891A0 (fr)
GR (2) GR75086B (fr)
NO (1) NO813283L (fr)
ZA (1) ZA812500B (fr)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0080124A3 (en) * 1981-11-20 1984-08-22 Linde Aktiengesellschaft Process for case hardening metallic articles
EP0156378A3 (en) * 1984-03-29 1986-03-26 Joachim Dr.-Ing. Wunning Method and apparatus for carburizing steel with a gas
DE3507527A1 (de) * 1984-11-20 1986-05-22 Ewald 4133 Neukirchen-Vluyn Schwing Verfahren und anlage zum aufkohlen eines werkstueckes aus stahl
DE3707003A1 (de) * 1987-03-05 1988-09-15 Ewald Schwing Verfahren zum aufkohlen eines werkstueckes aus stahl
FR2678287A1 (fr) * 1991-06-26 1992-12-31 Etudes Const Mecaniques Procede et four de cementation a basse pression.
EP0532386A1 (fr) * 1991-09-13 1993-03-17 Innovatique S.A. Procédé et dispositif de cémentation d'un acier dans une atmosphère à basse pression
WO2003097893A1 (fr) * 2002-05-15 2003-11-27 Linde Aktiengesellschaft Procede et dispositif de traitement thermique de pieces metalliques
WO2012048669A1 (fr) 2010-10-11 2012-04-19 Ipsen International Gmbh Procédé et dispositif de carburation et carbonitruration de matériaux métalliques
US8828150B2 (en) 2007-10-01 2014-09-09 Robert Bosch Gmbh Method for carburizing workpieces and its application
EP2541176A3 (fr) * 2005-11-23 2014-09-24 Surface Combustion, Inc. Système de distribution de fluide d'un four atmosphérique pour le traitement de surface d' articles métalliques

Families Citing this family (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4632707A (en) * 1985-04-09 1986-12-30 Air Products And Chemicals, Inc. Protective atmosphere process for annealing and/or hardening ferrous metals
KR910004557B1 (ko) * 1986-08-12 1991-07-06 미쯔비시지도오샤 고오교오 가부시기가이샤 가스침탄방법 및 장치
US4776901A (en) * 1987-03-30 1988-10-11 Teledyne Industries, Inc. Nitrocarburizing and nitriding process for hardening ferrous surfaces
DE3714283C1 (de) * 1987-04-29 1988-11-24 Ipsen Ind Internat Gmbh Verfahren zur Gasaufkohlung von Stahl
US4989840A (en) * 1989-11-08 1991-02-05 Union Carbide Canada Limited Controlling high humidity atmospheres in furnace main body
CH681186A5 (fr) * 1989-11-09 1993-01-29 Battelle Memorial Institute
US5133813A (en) * 1990-07-03 1992-07-28 Tokyo Heat Treating Company Ltd. Gas-carburizing process and apparatus
DE4221958C1 (de) * 1992-07-02 1993-11-18 Mannesmann Ag Verfahren zum Herstellen eines Zahnradelementes einer Ritzelwelle
IT1272670B (it) * 1993-09-24 1997-06-26 Lindberg Ind Srl Metodo e dispositivo per la formazione e l'erogazione controllata di un'atmosfera gassosa ad almeno due componenti ed applicazione di impianti di trattamento termico o di combustibile
RU2048601C1 (ru) * 1993-12-20 1995-11-20 Рыжов Николай Михайлович Способ диагностики процесса химико-термической обработки сталей и сплавов в тлеющем разряде и устройство для его осуществления
FR2821362B1 (fr) * 2001-02-23 2003-06-13 Etudes Const Mecaniques Procede de cementation basse pression
US7468107B2 (en) * 2002-05-01 2008-12-23 General Motors Corporation Carburizing method
DE10232432A1 (de) * 2002-07-17 2004-01-29 Linde Ag Verfahren und Vorrichtung zum Unterdruckaufkohlen
DE10235131A1 (de) * 2002-08-01 2004-02-19 Ipsen International Gmbh Verfahren und Vorrichtung zum Schwärzen von Bauteilen
WO2005038076A1 (fr) * 2003-10-14 2005-04-28 Etudes Et Constructions Mecaniques Procede et four de cementation basse pression
US20080120843A1 (en) * 2006-11-06 2008-05-29 Gm Global Technology Operations, Inc. Method for manufacturing low distortion carburized gears
US8075420B2 (en) * 2009-06-24 2011-12-13 Acushnet Company Hardened golf club head

Citations (3)

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Publication number Priority date Publication date Assignee Title
GB527081A (en) * 1938-03-30 1940-10-02 Renault Louis Improvements in or relating to gaseous cementation
DE2450879A1 (de) * 1973-10-26 1975-04-30 Air Prod Ltd Verfahren zur waermebehandlung von eisenmetallen
DE2818558A1 (de) * 1977-04-27 1978-11-09 Air Prod & Chem Verfahren zur waermebehandlung von eisenmetallen

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US29881A (en) * 1860-09-04 Ghaut-elevator
US2886478A (en) * 1953-06-29 1959-05-12 Honeywell Regulator Co Method and control apparatus for carburizing ferrous objects
US3796615A (en) 1971-06-23 1974-03-12 Hayes Inc C I Method of vacuum carburizing
US4035203A (en) * 1973-12-21 1977-07-12 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Method for the heat-treatment of steel and for the control of said treatment
US4049473A (en) * 1976-03-11 1977-09-20 Airco, Inc. Methods for carburizing steel parts
DE2636273C3 (de) * 1976-08-12 1980-02-07 Ipsen Industries International Gmbh, 4190 Kleve Verfahren zur Regelung eines Aufkohlens von Teilen in einem Vakuumofen
US4152177A (en) * 1977-02-03 1979-05-01 General Motors Corporation Method of gas carburizing

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB527081A (en) * 1938-03-30 1940-10-02 Renault Louis Improvements in or relating to gaseous cementation
DE2450879A1 (de) * 1973-10-26 1975-04-30 Air Prod Ltd Verfahren zur waermebehandlung von eisenmetallen
DE2818558A1 (de) * 1977-04-27 1978-11-09 Air Prod & Chem Verfahren zur waermebehandlung von eisenmetallen

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Harterri Technische Mitteilungen, Band 35, Nr. 6, Juni 1980, seiten 284-288 Munchen, DE. G. BOUTTIER et al.: "Schutzgasatmosphare auf Stickstoff-Basis" (Vorgetragen auf dem 35. Hartereikolloqium vom 3.-5. Oktober 1979 in Wiesbaden) * seite 285.3: "Thermochemische Behandlungen; seite 286, beispiel 9 * *

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0080124A3 (en) * 1981-11-20 1984-08-22 Linde Aktiengesellschaft Process for case hardening metallic articles
EP0156378A3 (en) * 1984-03-29 1986-03-26 Joachim Dr.-Ing. Wunning Method and apparatus for carburizing steel with a gas
DE3507527A1 (de) * 1984-11-20 1986-05-22 Ewald 4133 Neukirchen-Vluyn Schwing Verfahren und anlage zum aufkohlen eines werkstueckes aus stahl
DE3707003A1 (de) * 1987-03-05 1988-09-15 Ewald Schwing Verfahren zum aufkohlen eines werkstueckes aus stahl
FR2678287A1 (fr) * 1991-06-26 1992-12-31 Etudes Const Mecaniques Procede et four de cementation a basse pression.
EP0532386A1 (fr) * 1991-09-13 1993-03-17 Innovatique S.A. Procédé et dispositif de cémentation d'un acier dans une atmosphère à basse pression
FR2681332A1 (fr) * 1991-09-13 1993-03-19 Innovatique Sa Procede et dispositif de cementation d'un acier dans une atmosphere a basse pression.
WO2003097893A1 (fr) * 2002-05-15 2003-11-27 Linde Aktiengesellschaft Procede et dispositif de traitement thermique de pieces metalliques
EP2541176A3 (fr) * 2005-11-23 2014-09-24 Surface Combustion, Inc. Système de distribution de fluide d'un four atmosphérique pour le traitement de surface d' articles métalliques
EP2541177A3 (fr) * 2005-11-23 2014-09-24 Surface Combustion, Inc. Système de distribution de fluide d'un four atmosphérique pour le traitement de surface d' articles métalliques
US8828150B2 (en) 2007-10-01 2014-09-09 Robert Bosch Gmbh Method for carburizing workpieces and its application
WO2012048669A1 (fr) 2010-10-11 2012-04-19 Ipsen International Gmbh Procédé et dispositif de carburation et carbonitruration de matériaux métalliques

Also Published As

Publication number Publication date
GR75375B (fr) 1984-07-13
ZA812500B (en) 1982-04-28
AU6915481A (en) 1982-04-22
ATA539980A (de) 1982-06-15
US4472209A (en) 1984-09-18
NO813283L (no) 1982-04-13
EP0049530B1 (fr) 1985-06-05
GR75086B (fr) 1984-07-13
DE3038078A1 (de) 1982-05-06
AU543782B2 (en) 1985-05-02
DK433181A (da) 1982-04-09
BR8102150A (pt) 1982-08-17
AT369792B (de) 1983-01-25
ES8206658A1 (es) 1982-09-01
ES505891A0 (es) 1982-09-01
DE3170866D1 (en) 1985-07-11

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