EP0096602A1 - Verfahren zur Wärmebehandlung von metallischen Werkstücken durch Aufkohlung - Google Patents

Verfahren zur Wärmebehandlung von metallischen Werkstücken durch Aufkohlung Download PDF

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Publication number
EP0096602A1
EP0096602A1 EP83400935A EP83400935A EP0096602A1 EP 0096602 A1 EP0096602 A1 EP 0096602A1 EP 83400935 A EP83400935 A EP 83400935A EP 83400935 A EP83400935 A EP 83400935A EP 0096602 A1 EP0096602 A1 EP 0096602A1
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EP
European Patent Office
Prior art keywords
atmosphere
phase
nitrogen
carbon potential
during
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Granted
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EP83400935A
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English (en)
French (fr)
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EP0096602B1 (de
Inventor
Michel Kostelitz
Phillippe Queille
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Air Liquide SA
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Original Assignee
Air Liquide SA
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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Application filed by Air Liquide SA, LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude filed Critical Air Liquide SA
Priority to AT83400935T priority Critical patent/ATE16118T1/de
Publication of EP0096602A1 publication Critical patent/EP0096602A1/de
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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

Definitions

  • the subject of the present invention is a method of heat treatment of metal parts, in particular steel parts, by carburetion.
  • the atmospheres generally used contain approximately 20% C0, 40% H 2 , 40% N 2 , and very small amounts of carbon dioxide and water vapor. These atmospheres are obtained either from so-called endothermic generators, or synthetically from a gas-gas or gas-alcohol mixture; the most common of these synthetic mixtures is nitrogen-methanol: in fact, at the treatment temperatures used, methanol decomposes according to the reaction CH 3 OH ⁇ CO + 2H 2 and it is possible to obtain a gaseous mixture having the composition given ci -above.
  • the carburetion process is carried out as follows: the carbon monoxide present in the treatment atmosphere reacts according to the relationship: 2CO ⁇ CO 2 + C (1) and there is then transfer of the carbon atoms to the metal.
  • the hydrogen present in the atmosphere also participates in carburetion from the point of view of the speed of the process because it reacts with carbon monoxide according to the reaction: CO + H 2 ⁇ C + H 2 O (2).
  • a hydrocarbon such as methane is injected into the furnace, in addition to the mixture intended to form the C0, H2, N 2 species.
  • propane, or butane in each of said zones and the flow rate of this hydrocarbon is adjusted as a function of the CO 2 content of the atmosphere.
  • the CO 2 content of the atmosphere is monitored and the injection rate of the hydrocarbon is adjusted accordingly as a function of the desired carbon potential.
  • This regulation can also be carried out by monitoring the H 2 O or O 2 content in the atmosphere.
  • the carbon potential ranges of the atmospheres used are conventional carbon potential ranges, ie from 0.7% to 1.1% and in any event less than 1.1%, and that the carbon potential difference between the two phases is small (0.2%).
  • the subject of the invention is a method of heat treatment of metal parts by carburetion which makes it possible to obtain a surface hardening and a carburetted depth of the treated parts satisfactory with a shorter treatment time.
  • the process according to the invention consists in placing the parts to be treated in an oven and in maintaining them, in a carbon enrichment atmosphere comprising in particular carbon monoxide, hydrogen and nitrogen, said treatment comprising a first phase carried out at a temperature of 850 ° C to 1050 ° C followed by a second phase carried out at a temperature of 700 ° C to 950 ° C (preferably 800 ° C to 950 ° C).
  • an atmosphere is used containing approximately 20% to 50% by volume of CO and approximately 40% to 75% by volume of H 2 and having a high carbon potential very close to the limit value leading to soot deposits, ie a carbon potential of approximately 1.1% to 1.6% by weight, and, during the second phase, to have a carbon potential significantly lower than that of the first phase , an increase in the nitrogen content of said atmosphere is increased from 2 to 30 times so that the difference in carbon potential between each of said phases is at least about 0.5% by weight.
  • the concentration of nitrogen in said atmosphere is approximately at most 40% by volume, and during the second phase, said concentration is about 30% to 80% by volume.
  • the applicant sought to increase the carbon potential during the first phase to accelerate the carbon enrichment of the part.
  • Figure 1 represents the theoretical evolution of the carbon potential in a constant temperature oven (without taking into account the influence of the tightness of the oven and the nature of its internal wall), under an initial atmosphere based on of C0, H 2 and N 2 , when high nitrogen flow rates are injected into this furnace.
  • These curves show that effectively a dilution of the treatment atmosphere with nitrogen during the diffusion phase, as developed by the applicant, makes it possible to obtain a very rapid reduction in the carbon potential.
  • an atmosphere with high carbon potential can be used during the first phase, even using an atmosphere rich in fuel species, and sufficiently reduce the carbon potential during the second phase.
  • the treatment atmosphere is formed by introducing into the oven a mixture of nitrogen and methanol (the methanol being sprayed by the stream of nitrogen gas) in such proportions that the desired percentages of CO and H 2 are obtained.
  • the treatment atmosphere can also be formed by introducing an endothermic gas into the oven.
  • a gaseous hydrocarbon such as methane, propane or butane is also introduced in a small percentage (from 0.5% to 5%) relative to the whole of the mixture introduced.
  • gaseous ammonia in a proportion of 0.1% to 10% by volume relative to the whole of the gaseous mixture introduced; there is then carbonitriding.
  • This variant embodiment provides additional surface hardening of the treated parts.
  • the quantity of ammonia introduced into the furnace is chosen according to the steel treated and the degree of nitriding desired.
  • a treatment is carried out in accordance with the invention on steel parts of grade 18CD4 in an oven of the "batch" type shown diagrammatically in FIG. 2 attached.
  • This oven 1 consists of a metal enclosure coated internally with a refractory lining. It has a treatment zone 2 provided with a loading door 3 for the parts to be treated and an airlock 4 provided with a tank 5 for quenching in oil and an outlet door 6 for the treated parts. The treatment zone 2 and the airlock 4 are separated by an interior door 7. The parts to be treated are placed in a basket 8 resting on the bottom of the treatment zone 2. A turbine 9, the function of which is to continuously brew the atmosphere of the oven is placed at a distance above the basket 8.
  • the oven is heated to a temperature of 920 ° C. and then a nitrogen-methanol mixture is introduced into it in proportions such that the atmosphere formed in the oven contains in main species approximately 10% N 2 , 30% CO and 60% H 2 .
  • the parts to be treated are placed in the treatment zone 2, we wait until the temperature rises to 920 ° C and the carbon potential of the atmosphere reaches 1.3% and we maintain the parts in this atmosphere for 2 hours 25 min. During this phase, the rate of C0 2 in the atmosphere is 0.20%.
  • the second phase is then carried out at 860 ° C., increasing the quantity of nitrogen injected into the treatment zone 2 so that the atmosphere formed in the enclosure contains in cash main about 70% N 2 , 10% CO and 20% H 2 and that the carbon potential is 0.7%, and the parts are kept in this atmosphere for 45 min.
  • the CO 2 level in the atmosphere is 0.095%.
  • a small percentage of methane is injected into zone 2 of the furnace (0.5 to 5% relative to the total amount of gaseous mixture introduced) and the injection rate of said methane is adjusted to adjust the carbon potential at the expected value.
  • a treatment is carried out using an atmosphere rich in fuel species having exactly the same composition as that of the first phase of the treatment according to the invention described in Example 1 above, but without modify the nitrogen injection during the second phase, that is to say at constant atmosphere; this comparative treatment is carried out in the same furnace and on 18CD4 steel parts identical to those of Example 1.
  • the first phase is therefore carried out at a temperature of 920 ° C. with an atmosphere whose concentration in main species is 10% N 2 30% CO and 60% H 2 , and with injection of a small quantity of methane and adjustment of the injection rate of said methane to adjust the value of the carbon potential to 1%; the CO 2 level in the atmosphere is 0.28%; the parts are kept in this atmosphere for three hours.
  • the second phase is then carried out at 86 ° C., with the same atmosphere as above, for 1 hour, by adjusting the carbon potential to 0.8%; the rate of C0 2 in the atmosphere is 0.72%.
  • a treatment is carried out in accordance with the invention on steel parts of grade 18CD2, in a continuous pushing oven, shown diagrammatically in FIG. 3 attached.
  • This oven 21 comprises an entry airlock 22 provided with a loading door 23 for the parts to be treated, a carburizing zone 24, a diffusion zone 25, and an exit airlock 26 provided with an exit door 27 of the parts processed.
  • the entry airlock 22, the cementation zone 24, the diffusion zone 25 and the exit airlock 26 are separated from each other by internal doors 28.
  • the parts to be treated are arranged in baskets 29 which move on the bottom of the furnace 21.
  • the carburizing zone 24 has two parts A and B: in part A, the parts to be treated are brought to temperature, and in part B the carburizing itself.
  • Turbines 30, the function of which is to continuously stir the atmosphere of the furnace, are placed at a distance above the baskets 29, in part B of the cementation zone 24 and in the diffusion zone 25.
  • Reservoirs 'nitrogen, methanol and methane, symbolized respectively at 31, 32 and 33, are connected via conduits 34, 35 and 36, provided with valves 37, 38 and 39, to a conduit 40 which opens into part B of the cementation zone 24.
  • the treatment gas mixture is evacuated by burning by means of a flare 44. The treated parts are then cooled in an oil bath (not shown in the figure).
  • the carburizing zone 24 is brought to a temperature of 900 ° C.
  • a nitrogen-methanol mixture is injected into this zone in proportions such that the atmosphere formed in said zone contains approximately 10% N 2 , 30% CO and 60% H 2 in main species, as well as a small amount of methane (0 , 5% to 5% relative to the total amount of the gaseous mixture introduced) so as to obtain a CO 2 level of 0.27%, which corresponds to a carbon potential of 1.2%.
  • Part B of the carburizing zone 24 can contain five baskets.
  • Diffusion zone 25 is at 860 ° C. In this zone only nitrogen is injected (fuel species such as CO and H 2 coming directly from the cementation zone), in an amount such as the atmosphere in this zone diffusion contains about 10% CO, and 20% H 2 .
  • the CO 2 rate in the atmosphere is 0.115%, which corresponds to a carbon potential of 0.6%.
  • the diffusion zone 25 can contain two baskets.
  • the baskets containing the parts to be treated are introduced into the oven every 11 minutes 15 seconds; the pieces therefore remain approximately 56 minutes 15 seconds in the cementation zone and 22 minutes 30 seconds in the diffusion zone.
  • a treatment is carried out using an atmosphere rich in fuel species, similarly composition of N 2 , CO and H (10% N 2 , 30% CO and 60% H 2 ) than the atmosphere used in the carburizing zone during the treatment according to the invention in Example 2 above; but, in this comparative treatment, the atmosphere is the same as in the carburizing zone and in the diffusion zone.
  • the treated parts and the temperatures of the cementation and diffusion zones are the same as those of Example 2.
  • the C0 2 rate of the atmosphere is 0.37% in the cementation zone, which corresponds to a carbon potential of 0.9%; and the CO 2 content of the atmosphere in the diffusion zone is 0.85%, which corresponds to a carbon potential of 0.7%. It is not possible to envisage a greater variation in the CO 2 rate between the two zones, therefore a higher carbon potential in the first zone, because there is no modification of the global atmosphere.
  • the baskets containing the parts to be treated are introduced into the oven every 15 minutes; the pieces therefore remain for 1 hour 15 minutes in the cementation zone and 30 minutes in the diffusion zone.

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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)
  • Automobile Manufacture Line, Endless Track Vehicle, Trailer (AREA)
EP83400935A 1982-05-28 1983-05-09 Verfahren zur Wärmebehandlung von metallischen Werkstücken durch Aufkohlung Expired EP0096602B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT83400935T ATE16118T1 (de) 1982-05-28 1983-05-09 Verfahren zur waermebehandlung von metallischen werkstuecken durch aufkohlung.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8209328A FR2527641A1 (fr) 1982-05-28 1982-05-28 Procede de traitement thermique de pieces metalliques par carburation
FR8209328 1982-05-28

Publications (2)

Publication Number Publication Date
EP0096602A1 true EP0096602A1 (de) 1983-12-21
EP0096602B1 EP0096602B1 (de) 1985-10-16

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ID=9274434

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US (1) US4519853A (de)
EP (1) EP0096602B1 (de)
JP (1) JPH064906B2 (de)
AT (1) ATE16118T1 (de)
AU (1) AU560555B2 (de)
CA (1) CA1208528A (de)
DE (1) DE3361023D1 (de)
FR (1) FR2527641A1 (de)
ZA (1) ZA833445B (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2586258A1 (fr) * 1985-08-14 1987-02-20 Air Liquide Procede pour la cementation rapide et homogene d'une charge dans un four
FR2607231A1 (fr) * 1986-11-26 1988-05-27 Ipsen Ind Int Gmbh Installation de traitement thermique de pieces metalliques sous atmosphere carburante
FR2712898A1 (fr) * 1993-11-24 1995-06-02 Linde Ag Procédé de cémentation gazeuse.

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2586259B1 (fr) * 1985-08-14 1987-10-30 Air Liquide Procede de cementation rapide dans un four continu
JPH0232682Y2 (de) * 1987-05-27 1990-09-04
DE3718240C1 (de) * 1987-05-30 1988-01-14 Ewald Schwing Verfahren zur Waermebehandlung von metallischen Werkstuecken in einer gasdurchstroemten Wirbelschicht
EP0439614A1 (de) * 1989-08-18 1991-08-07 Vsesojuzny Nauchno-Issledovatelsky Proektno-Konstruktorsky I Tekhnologichesky Inst. Elektrotermicheskogo Oborudovania Vniieto Gasgemisch für wärmechemisches behandeln von metallen und legierungen und verfahren zur herstellung
JPH05148612A (ja) * 1991-11-25 1993-06-15 Nippon Piston Ring Co Ltd ピストンリングの製造方法
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
FR2777910B1 (fr) * 1998-04-27 2000-08-25 Air Liquide Procede de regulation du potentiel carbone d'une atmosphere de traitement thermique et procede de traitement thermique mettant en oeuvre une telle regulation
US6287393B1 (en) * 1999-09-03 2001-09-11 Air Products And Chemicals, Inc. Process for producing carburizing atmospheres
US6969430B2 (en) * 2002-06-05 2005-11-29 Praxair Technology, Inc. Process and apparatus for producing atmosphere for high productivity carburizing
US20030226620A1 (en) * 2002-06-05 2003-12-11 Van Den Sype Jaak Stefaan Process and apparatus for producing amtospheres for high productivity carburizing
DE10347312B3 (de) * 2003-10-08 2005-04-14 Air Liquide Deutschland Gmbh Verfahren zur Wärmebehandlung von Eisenwerkstoffen
JP6773411B2 (ja) * 2015-12-08 2020-10-21 日本エア・リキード合同会社 浸炭システム及び表面硬化鋼材の製造方法
CN112301308A (zh) * 2020-11-03 2021-02-02 江苏丰东热处理及表面改性工程技术研究有限公司 碳氮共渗热处理方法及其制得的合金零件

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US2955062A (en) * 1952-02-27 1960-10-04 Midland Ross Corp Method for carburizing in a continuous furnace
US3128323A (en) * 1960-07-11 1964-04-07 Leeds & Northrup Co Measurement and control of constituent potentials
USRE26935E (en) * 1968-06-26 1970-08-18 Carburizino method and apparatus
FR2342352A1 (fr) * 1976-02-27 1977-09-23 Ipsen Ind Int Gmbh Procede de cementation gazeuse de pieces metalliques
FR2442281A1 (fr) * 1978-11-27 1980-06-20 Komatsu Mfg Co Ltd Procede pour cementer les aciers
EP0031034A1 (de) * 1979-12-20 1981-07-01 Maag-Zahnräder und -Maschinen Aktiengesellschaft Verfahren zum regelbaren Aufkohlen oder Erwärmen in Schutzgas von Werkstücken aus Stahl
US4306918A (en) * 1980-04-22 1981-12-22 Air Products And Chemicals, Inc. Process for carburizing ferrous metals
GB2092183A (en) * 1981-01-14 1982-08-11 Holcroft & Co Method of controlling furnace atmospheres

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FR2446322A2 (fr) * 1979-01-15 1980-08-08 Air Liquide Procede de traitement thermique de l'acier et de controle dudit traitement
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2955062A (en) * 1952-02-27 1960-10-04 Midland Ross Corp Method for carburizing in a continuous furnace
US3128323A (en) * 1960-07-11 1964-04-07 Leeds & Northrup Co Measurement and control of constituent potentials
USRE26935E (en) * 1968-06-26 1970-08-18 Carburizino method and apparatus
FR2342352A1 (fr) * 1976-02-27 1977-09-23 Ipsen Ind Int Gmbh Procede de cementation gazeuse de pieces metalliques
FR2442281A1 (fr) * 1978-11-27 1980-06-20 Komatsu Mfg Co Ltd Procede pour cementer les aciers
EP0031034A1 (de) * 1979-12-20 1981-07-01 Maag-Zahnräder und -Maschinen Aktiengesellschaft Verfahren zum regelbaren Aufkohlen oder Erwärmen in Schutzgas von Werkstücken aus Stahl
US4306918A (en) * 1980-04-22 1981-12-22 Air Products And Chemicals, Inc. Process for carburizing ferrous metals
GB2092183A (en) * 1981-01-14 1982-08-11 Holcroft & Co Method of controlling furnace atmospheres

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2586258A1 (fr) * 1985-08-14 1987-02-20 Air Liquide Procede pour la cementation rapide et homogene d'une charge dans un four
EP0213011A1 (de) * 1985-08-14 1987-03-04 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Verfahren zur schnellen und homogenen Aufkohlung von Werkstücken in einem Ofen
US4744839A (en) * 1985-08-14 1988-05-17 L'air Liquide Process for a rapid and homogeneous carburization of a charge in a furnace
FR2607231A1 (fr) * 1986-11-26 1988-05-27 Ipsen Ind Int Gmbh Installation de traitement thermique de pieces metalliques sous atmosphere carburante
BE1002059A4 (fr) * 1986-11-26 1990-06-12 Ipsen Ind Internat Ges Mit Bes Installation de traitement thermique de pieces metalliques dans une atmosphere de cementation par le carbone.
FR2712898A1 (fr) * 1993-11-24 1995-06-02 Linde Ag Procédé de cémentation gazeuse.

Also Published As

Publication number Publication date
AU560555B2 (en) 1987-04-09
JPS58213870A (ja) 1983-12-12
JPH064906B2 (ja) 1994-01-19
US4519853B1 (de) 1987-12-29
ATE16118T1 (de) 1985-11-15
AU1489083A (en) 1983-12-01
FR2527641B1 (de) 1985-02-22
US4519853A (en) 1985-05-28
CA1208528A (fr) 1986-07-29
EP0096602B1 (de) 1985-10-16
ZA833445B (en) 1984-02-29
DE3361023D1 (en) 1985-11-21
FR2527641A1 (fr) 1983-12-02

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