EP2773787B1 - Method for low-pressure carbonitriding using a reduced temperature gradient in an initial nitridation phase - Google Patents
Method for low-pressure carbonitriding using a reduced temperature gradient in an initial nitridation phase Download PDFInfo
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- EP2773787B1 EP2773787B1 EP12769125.1A EP12769125A EP2773787B1 EP 2773787 B1 EP2773787 B1 EP 2773787B1 EP 12769125 A EP12769125 A EP 12769125A EP 2773787 B1 EP2773787 B1 EP 2773787B1
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- temperature
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- 238000000034 method Methods 0.000 title claims description 19
- 238000005256 carbonitriding Methods 0.000 title claims description 10
- 238000005121 nitriding Methods 0.000 claims description 51
- 238000010791 quenching Methods 0.000 claims description 11
- 230000000171 quenching effect Effects 0.000 claims description 10
- 229910000831 Steel Inorganic materials 0.000 claims description 8
- 239000010959 steel Substances 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 230000007423 decrease Effects 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 claims 5
- 238000005255 carburizing Methods 0.000 description 7
- 238000009792 diffusion process Methods 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
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Classifications
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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
- C23C8/28—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 more than one element being applied in one step
- C23C8/30—Carbo-nitriding
- C23C8/32—Carbo-nitriding of ferrous surfaces
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- 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
-
- 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
- C23C8/02—Pretreatment of the material to be coated
-
- 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
- C23C8/34—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 more than one element being applied in more than one step
-
- 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
- C23C8/80—After-treatment
Definitions
- the present invention relates to a low pressure carbonitriding process for steel parts, including, but not limited to, parts used in the manufacture of motor vehicles.
- the invention also applies to parts used in the manufacture of agricultural machinery, machine tool, or parts in the aeronautical field.
- the document DE 10 2010 028 165 A1 discloses a carbonitriding process wherein an initial nitriding phase is performed after the rise and stabilization of the process temperature.
- the object of the invention is to improve the process of the aforementioned document, that is to say to improve the quality of the parts obtained, preferably with a reduction of the treatment time.
- the invention proposes a method for the low-pressure carbonitriding of steel parts according to claim 1.
- the parts are maintained longer in a temperature range favorable to good nitriding.
- the initial nitriding phase comprises a temperature step.
- the initial nitriding phase is carried out under optimal temperature conditions, so that it is possible to shorten or to eliminate one of the nitriding steps subsequent to the carburizing temperature, and thus to reduce the total time of treatment.
- the initial nitriding phase is immediately followed by a first cementation step.
- the total elimination of the temperature equalization phase makes it possible to lengthen the initial nitriding phase in an optimum temperature range for nitriding.
- the process comprises a final nitriding step accompanied by a temperature drop immediately before quenching.
- the final nitriding step comprises a temperature step.
- the final nitriding step is also carried out in an optimum temperature range, so that the quality of the treatment is improved.
- the method according to the invention comprises a first step of temperature rise comprising a first phase M of simple temperature rise, illustrated by a line in continuous line, from the ambient temperature to a point at a temperature of 700 ° C. , denoted Ni1 in the figure.
- the simple temperature rise phase is carried out up to a temperature of between 700 ° C. and 750 ° C., and has a duration of between 10 minutes and 90 minutes. That is, the simple temperature rise is carried out with a temperature gradient of between 8 ° C / min and 75 ° C / min.
- the process then comprises an initial nitriding phase Ni with continuation of the temperature rise step up to a temperature of 940 ° C. in the example illustrated.
- the temperature of 940 ° C corresponds to a compromise between a temperature of 860 ° C which allows a treatment of better quality and a temperature of 1000 ° C which allows for faster processing.
- the rise in temperature continues smoothly but with a temperature gradient of between 3.5 ° C / min and 16 ° C / min less than the temperature gradient during the simple temperature rise.
- the duration of the initial nitriding phase is between 15 minutes and 45 minutes, depending on the amount of nitrogen that it is desired to set in this initial step and the composition of the steel to be treated.
- the initial nitriding phase comprises injection phases of a nitriding gas such as alternating ammonia with diffusion phases.
- the rise in temperature continues with the same temperature gradient as during the simple rise in temperature to a point at a temperature of between 750 ° C. and 850 ° C., here 800 ° C. noted Ni2 on the figure 2 .
- the temperature is then maintained according to a plateau until a moment noted Ni3 on the figure 2 from which a high temperature rise is performed to reach the carburizing temperature.
- the temperature of the bearing is chosen in a manner known per se to perform the initial nitriding phase under optimal conditions given the composition of the parts to be treated. Note in this connection that because of the bearing, the final temperature rise can be carried out very rapidly, for example 80 ° C / min at 100 ° C / min without subjecting the parts to unacceptable constraints.
- the rise in temperature continues from the point Ni1 with a lower temperature gradient than in the first embodiment, preferably within a range of 2 ° C / min at 8 ° C / min, up to a Ni4 moment, corresponding here to a temperature of 850 ° C, from which a high temperature rise is performed to reach the carburizing temperature, according to a gradient similar to that of the second embodiment.
- the process then comprises n alternating cementation phases with nitriding phases.
- the carburizing and nitriding steps comprise alternating treatment gas injection phases with diffusion phases not shown in the figures.
- the diagram has been interrupted between the nitriding step N1 and the last cementation step Cn.
- the process comprises a final nitriding step Nn accompanied by a descent of temperature immediately before T quenching.
- the temperature is lowered continuously to a temperature within the optimum temperature range for all nitriding. in remaining high enough to allow effective quenching.
- the final temperature before quenching is 840 ° C.
- satisfactory results are obtained for a final temperature before quenching between 900 ° C. and 800 ° C. It has been found that this limited descent of temperature decreases the stress on the parts during quenching.
- the final nitriding step has a duration of preferably between 15 minutes and 60 minutes, which corresponds to a temperature gradient of between 10 ° C./min and 1 ° C./min.
- the final nitriding step preferably comprises alternating nitriding gas injection phases with diffusion phases.
- the descent of temperature is first of all carried out in a strong way, with a gradient as strong as possible without generating undue stresses in the steel, up to the optimum nitriding temperature for the steel being treated, noted Nn1 in the figure, here 840 ° C, then the temperature is maintained at a plateau until the beginning of quenching.
- the method according to the invention can be implemented by combining any of the embodiments of the initial nitriding phase with any of the embodiments of the final nitriding phase, or even terminate the cycle. treatment in conventional manner, that is to say with a quench performed directly from the carburizing temperature.
- the temperature of the workpieces has time to equalize so that it is possible to eliminate the equalization step provided in the aforementioned document. If this is necessary, for example because of a particular configuration of the parts to be treated, it may however provide a temperature equalization step of reduced duration between the initial nitriding phase and the first cementation step.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
- Heat Treatment Of Articles (AREA)
Description
La présente invention concerne un procédé de carbonitruration basse pression de pièces en acier, notamment bien que non exclusivement, des pièces entrant dans la fabrication de véhicules automobiles. En particulier l'invention s'applique également à des pièces entrant dans la fabrication de machines agricoles, de machine-outil, ou à des pièces dans le domaine aéronautique.The present invention relates to a low pressure carbonitriding process for steel parts, including, but not limited to, parts used in the manufacture of motor vehicles. In particular the invention also applies to parts used in the manufacture of agricultural machinery, machine tool, or parts in the aeronautical field.
On connaît du document
Le document
Le but de l'invention est d'améliorer le procédé du document précité, c'est-à-dire d'améliorer la qualité des pièces obtenues, de préférence avec une réduction du temps de traitement.The object of the invention is to improve the process of the aforementioned document, that is to say to improve the quality of the parts obtained, preferably with a reduction of the treatment time.
En vue de la réalisation de ce but, on propose selon l'invention un procédé de carbonitruration basse pression de pièces en acier conforme à la revendication 1.With a view to achieving this object, the invention proposes a method for the low-pressure carbonitriding of steel parts according to claim 1.
Ainsi, les pièces sont maintenues plus longtemps dans une plage de températures favorables à une bonne nitruration.Thus, the parts are maintained longer in a temperature range favorable to good nitriding.
Selon une version avantageuse de l'invention, la phase de nitruration initiale comporte un palier de température.According to an advantageous version of the invention, the initial nitriding phase comprises a temperature step.
Ainsi, la phase de nitruration initiale est effectuée dans des conditions optimales de température, de sorte qu'il est possible de raccourcir ou de supprimer l'une des étapes de nitruration ultérieure à la température de cémentation, et de réduire ainsi le temps total de traitement.Thus, the initial nitriding phase is carried out under optimal temperature conditions, so that it is possible to shorten or to eliminate one of the nitriding steps subsequent to the carburizing temperature, and thus to reduce the total time of treatment.
Selon un autre aspect avantageux de l'invention, la phase de nitruration initiale est immédiatement suivie d'une première étape de cémentation. Ainsi, la suppression totale de la phase d'égalisation en température permet d'allonger la phase de nitruration initiale dans une plage de température optimale pour la nitruration.According to another advantageous aspect of the invention, the initial nitriding phase is immediately followed by a first cementation step. Thus, the total elimination of the temperature equalization phase makes it possible to lengthen the initial nitriding phase in an optimum temperature range for nitriding.
Selon l'invention, le procédé comporte une étape de nitruration finale accompagnée d'une descente de température immédiatement avant la trempe. De préférence l'étape de nitruration finale comporte un palier de température. Ainsi l'étape de nitruration finale est également effectuée dans une plage de température optimale, de sorte que la qualité du traitement est améliorée.According to the invention, the process comprises a final nitriding step accompanied by a temperature drop immediately before quenching. Preferably, the final nitriding step comprises a temperature step. Thus the final nitriding step is also carried out in an optimum temperature range, so that the quality of the treatment is improved.
D'autres caractéristiques et avantages de l'invention apparaîtront à la lecture de la description qui suit de différents modes de mise en oeuvre particuliers non limitatifs du procédé de carbonitruration basse pression selon l'invention, en référence aux 3 figures annexées qui sont des diagrammes schématiques illustrant les différentes étapes du procédé selon l'invention selon différents modes de réalisation.Other features and advantages of the invention will become apparent on reading the following description of various nonlimiting particular embodiments of the low pressure carbonitriding process according to the invention, with reference to the 3 appended figures which are diagrams. schematics illustrating the various steps of the method according to the invention according to different embodiments.
En référence à la
Le procédé comporte ensuite une phase de nitruration initiale Ni avec poursuite de l'étape de montée en température jusqu'à une température de 940°C dans l'exemple illustré. En pratique la température de 940°C correspond à un compromis entre une température de 860°C qui permet de réaliser un traitement de meilleure qualité et une température de 1000°C qui permet de réaliser un traitement plus rapide.The process then comprises an initial nitriding phase Ni with continuation of the temperature rise step up to a temperature of 940 ° C. in the example illustrated. In practice the temperature of 940 ° C corresponds to a compromise between a temperature of 860 ° C which allows a treatment of better quality and a temperature of 1000 ° C which allows for faster processing.
Dans l'exemple de réalisation de la
De façon connue en soi la phase de nitruration initiale comporte des phases d'injection d'un gaz nitrurant tel que de l'ammoniac alternées avec des phases de diffusion.In a manner known per se, the initial nitriding phase comprises injection phases of a nitriding gas such as alternating ammonia with diffusion phases.
Selon un deuxième mode de réalisation de la phase de nitruration initiale, illustré par la
Selon un troisième mode de réalisation de la phase de nitruration initiale, illustré à l'aide de la
Quel que soit le mode de réalisation utilisé pour la phase de nitruration initiale, le procédé comporte ensuite n phases de cémentation alternées avec des phases de nitruration. De façon connue en soi les étapes de cémentation et de nitruration comprennent des phases d'injection d'un gaz de traitement alternées avec des phases de diffusion non représentées sur les figures. Sur la figure, le diagramme a été interrompu entre l'étape de nitruration N1 et la dernière étape de cémentation Cn. À l'issue de cette dernière étape de cémentation Cn, le procédé comporte une étape de nitruration finale Nn accompagnée d'une descente de température immédiatement avant la trempe T.Whatever the embodiment used for the initial nitriding phase, the process then comprises n alternating cementation phases with nitriding phases. In a manner known per se, the carburizing and nitriding steps comprise alternating treatment gas injection phases with diffusion phases not shown in the figures. In the figure, the diagram has been interrupted between the nitriding step N1 and the last cementation step Cn. At the end of this last cementation step Cn, the process comprises a final nitriding step Nn accompanied by a descent of temperature immediately before T quenching.
Selon un premier mode de réalisation de la dernière étape de nitruration Nn, illustré par un trait en tirets courts sur la figure, la descente de température est effectuée de façon continue jusqu'à une température comprise dans la plage de température optimale pour la nitruration tout en restant suffisamment élevée pour permettre une trempe efficace. Dans l'exemple illustré la température finale avant la trempe est de 840°C. En pratique des résultats satisfaisants sont obtenus pour une température finale avant la trempe comprise entre 900°C et 800°C. Il a été constaté que cette descente limitée de température diminue la contrainte sur les pièces lors de la trempe.According to a first embodiment of the last nitriding step Nn, illustrated by a dashed line in the figure, the temperature is lowered continuously to a temperature within the optimum temperature range for all nitriding. in remaining high enough to allow effective quenching. In the example illustrated, the final temperature before quenching is 840 ° C. In practice, satisfactory results are obtained for a final temperature before quenching between 900 ° C. and 800 ° C. It has been found that this limited descent of temperature decreases the stress on the parts during quenching.
L'étape de nitruration finale à une durée de préférence comprise entre 15 mn et 60 mn, ce qui correspond à un gradient de température compris entre 10°C/mn et 1°C/mn. Comme pour la phase de nitruration initiale, l'étape de nitruration finale comporte de préférence des phases d'injection d'un gaz nitrurant alternées avec des phases de diffusion.The final nitriding step has a duration of preferably between 15 minutes and 60 minutes, which corresponds to a temperature gradient of between 10 ° C./min and 1 ° C./min. As for the initial nitriding phase, the final nitriding step preferably comprises alternating nitriding gas injection phases with diffusion phases.
Selon un second mode de réalisation de la dernière étape de nitruration Nn, illustré à la
En pratique le procédé selon l'invention peut être mis en oeuvre en combinant l'un quelconque des modes de réalisation de la phase de nitruration initiale avec l'un quelconque des modes de réalisation de la phase de nitruration finale, voire même terminer le cycle de traitement de façon conventionnelle, c'est-à-dire avec une trempe effectuée directement à partir de la température de cémentation.In practice, the method according to the invention can be implemented by combining any of the embodiments of the initial nitriding phase with any of the embodiments of the final nitriding phase, or even terminate the cycle. treatment in conventional manner, that is to say with a quench performed directly from the carburizing temperature.
On remarquera qu'en raison de l'efficacité accrue des phases de nitruration selon l'invention il est possible de remplacer au moins une étape de nitruration comprise entre deux étapes de cémentation par une étape de diffusion simple. Une telle étape est plus courte qu'une étape de nitruration de sorte que la durée totale du traitement est raccourcie.It will be noted that because of the increased efficiency of the nitriding phases according to the invention it is possible to replace at least one nitriding step between two carburizing steps by a simple diffusion step. Such a step is shorter than a nitriding step so that the total duration of the treatment is shortened.
Bien entendu l'invention n'est pas limitée au mode de mise en oeuvre décrit et on peut y apporter des variantes de réalisation sans sortir du cadre de l'invention telle que définie par les revendications. En particulier, bien que l'invention ait été décrite en relation avec une phase de nitruration initiale commençant dans une plage de températures de 700°C à 750°C, on peut prévoir de commencer celle-ci seulement lorsque les pièces ont atteint une température optimale de nitruration.Naturally, the invention is not limited to the embodiment described and variants can be implemented without departing from the scope. of the invention as defined by the claims. In particular, although the invention has been described in connection with an initial nitriding phase beginning in a temperature range of 700 ° C to 750 ° C, it can be expected to start it only when the parts have reached a temperature optimal nitriding.
En raison du gradient de température réduit pendant la phase de nitruration initiale, il a été expérimenté que la température des pièces à traiter a le temps de s'égaliser de sorte qu'il est possible de supprimer l'étape d'égalisation prévue dans le document précité. Si cela est nécessaire, par exemple en raison d'une configuration particulière des pièces à traiter, on peut toutefois prévoir une étape d'égalisation de température de durée réduite entre la phase de nitruration initiale et la première étape de cémentation.Due to the reduced temperature gradient during the initial nitriding phase, it has been experimented that the temperature of the workpieces has time to equalize so that it is possible to eliminate the equalization step provided in the aforementioned document. If this is necessary, for example because of a particular configuration of the parts to be treated, it may however provide a temperature equalization step of reduced duration between the initial nitriding phase and the first cementation step.
Claims (4)
- A method for low-pressure carbonitriding of steel parts, in particular parts used in the manufacture of motor vehicles, comprising alternate steps of cementation (Cl-Cn) and of nitriding (Nl-Nn) at constant temperature, preceded by a heating step including a simple heating phase (M) followed by an initial nitriding phase (N1) with continuation of the heating, and followed by a quenching step (T), characterized in that during the initial nitriding phase (N1) the heating is carried out with a reduced temperature gradient comprised between 3.5°C/mn and 16°C/mn relative to the simple heating phase (M) which is carried out with a temperature gradient comprised between 8°C/mn and 70°C/mn, in that the initial nitriding phase (N1) is realized from a temperature comprised between 700°C and 750°C, and up to a temperature comprised between 860°C and 1000°C and in that it comprises a final nitriding step (Nn) accompanied by a decrease in temperature immediately before the quenching (T), the drop in temperature being carried out down to a temperature comprised between 900°C and 800°C and with a temperature gradient comprised between 10°C/mn and 1°C/mn.
- The low-pressure carbonitriding method according to Claim 1, characterized in that the initial nitriding phase (Ni) comprises a temperature stage (Ni2-Ni3).
- The low-pressure carbonitriding method according to Claim 1, characterized in that the initial nitriding phase (N1) is immediately followed by a first cementation step (C1).
- The low-pressure carbonitriding method according to Claim 1, characterized in that the final nitriding step comprises a temperature stage (Nn1).
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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FR1159877A FR2981948B1 (en) | 2011-10-31 | 2011-10-31 | LOW PRESSURE CARBONITRURATION PROCESS WITH REDUCED GRADIENT TEMPERATURE IN AN INITIAL NITRIDATION PHASE |
PCT/EP2012/069889 WO2013064336A1 (en) | 2011-10-31 | 2012-10-08 | Method for low-pressure carbonitriding using a reduced temperature gradient in an initial nitridation phase |
Publications (2)
Publication Number | Publication Date |
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EP2773787A1 EP2773787A1 (en) | 2014-09-10 |
EP2773787B1 true EP2773787B1 (en) | 2018-07-04 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP12769125.1A Active EP2773787B1 (en) | 2011-10-31 | 2012-10-08 | Method for low-pressure carbonitriding using a reduced temperature gradient in an initial nitridation phase |
Country Status (10)
Country | Link |
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US (1) | US9708704B2 (en) |
EP (1) | EP2773787B1 (en) |
JP (1) | JP6189850B2 (en) |
KR (1) | KR101945004B1 (en) |
CN (1) | CN103946412B (en) |
BR (1) | BR112014010315A2 (en) |
FR (1) | FR2981948B1 (en) |
IN (1) | IN2014CN03952A (en) |
MX (1) | MX360731B (en) |
WO (1) | WO2013064336A1 (en) |
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Publication number | Priority date | Publication date | Assignee | Title |
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FR1159877A (en) | 1956-10-17 | 1958-07-03 | Quick release adjustable strap buckle | |
JPH02294461A (en) * | 1989-05-09 | 1990-12-05 | Mazda Motor Corp | Carburizing treating method for steel member |
US5273585A (en) | 1990-03-27 | 1993-12-28 | Mazda Motor Corporation | Heat-treating apparatus |
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FR2884523B1 (en) | 2005-04-19 | 2008-01-11 | Const Mecaniques Sa Et | LOW PRESSURE CARBONITRUTING PROCESS AND FURNACE |
JP5295813B2 (en) * | 2009-02-17 | 2013-09-18 | Dowaサーモテック株式会社 | Method for nitriding iron group alloys |
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2012
- 2012-10-08 WO PCT/EP2012/069889 patent/WO2013064336A1/en active Application Filing
- 2012-10-08 US US14/354,358 patent/US9708704B2/en active Active
- 2012-10-08 MX MX2014005220A patent/MX360731B/en active IP Right Grant
- 2012-10-08 BR BR112014010315A patent/BR112014010315A2/en active Search and Examination
- 2012-10-08 EP EP12769125.1A patent/EP2773787B1/en active Active
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- 2012-10-08 KR KR1020147015025A patent/KR101945004B1/en active IP Right Grant
- 2012-10-08 JP JP2014539274A patent/JP6189850B2/en active Active
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FR2981948B1 (en) | 2014-01-03 |
IN2014CN03952A (en) | 2015-10-23 |
US20150101710A1 (en) | 2015-04-16 |
JP6189850B2 (en) | 2017-08-30 |
CN103946412A (en) | 2014-07-23 |
US9708704B2 (en) | 2017-07-18 |
CN103946412B (en) | 2016-10-05 |
KR101945004B1 (en) | 2019-02-01 |
EP2773787A1 (en) | 2014-09-10 |
WO2013064336A1 (en) | 2013-05-10 |
JP2014532809A (en) | 2014-12-08 |
FR2981948A1 (en) | 2013-05-03 |
MX360731B (en) | 2018-11-14 |
BR112014010315A2 (en) | 2017-05-02 |
MX2014005220A (en) | 2015-03-05 |
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