EP0545069A1 - Method of treating steel and refractory metals - Google Patents

Method of treating steel and refractory metals Download PDF

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Publication number
EP0545069A1
EP0545069A1 EP19920118403 EP92118403A EP0545069A1 EP 0545069 A1 EP0545069 A1 EP 0545069A1 EP 19920118403 EP19920118403 EP 19920118403 EP 92118403 A EP92118403 A EP 92118403A EP 0545069 A1 EP0545069 A1 EP 0545069A1
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Prior art keywords
chamber
pressure
temperature
bar
treatment
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German (de)
French (fr)
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EP0545069B1 (en
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Albrecht Dr. Melber
Peter Dr. Minarski
Friedrich Dr. Preisser
Klaus Dr. Zimmermann
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Leybold Durferrit GmbH
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Leybold Durferrit GmbH
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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
    • C23C8/02—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
    • C23C8/80—After-treatment

Definitions

  • the invention relates to a process for the treatment of steels and metals, in particular for the passivation and for the subsequent thermochemical surface treatment or for the thermochemical surface treatment and a subsequent thermochemical aftertreatment in a process chamber under the action of pressure and temperature.
  • thermochemical surface treatment e.g. nitriding, nitro-carburizing or boriding
  • refractory metals e.g. Ti, Zr, Mo, W. Nb, Ta, V
  • the passive layers exist namely mostly made of oxides and form a thin protective skin, which prevent the undisturbed diffusion of non-metals such as N, C, and B during the surface treatment. This completely prevents diffusion, for example, in the case of refractory metals, and in some cases in the case of high-alloy steels, which leads to uneven treatment results.
  • pre-oxidation is carried out to achieve a uniform treatment result. This means that impurities on the surfaces are oxidized and the already existing oxide layer is influenced. In some cases, this can influence the uniformity of the layer formation.
  • the layers produced are very thin and contain ever larger amounts of oxygen.
  • thermochemical surface treatment of metals e.g. carburizing, tempering, annealing, carbonitriding, nitrocarburizing
  • edge oxidation This edge oxidation reduces the fatigue strength, so that the life of edge-oxidized components is reduced.
  • Components that have oxidation after heat treatment are therefore usually post-treated with mechanical processing with the aim of removing the oxidation (e.g. grinding gear wheels).
  • the drop in fatigue strength due to edge oxidation can also be compensated for by means of solidification processes (e.g. shot peening of gear wheels) of the components.
  • thermochemical surface treatment a heat treatment process is carried out in which the intercrystalline oxidation of metals is removed.
  • a first gas or gas mixture from the group N2, H2 or NH3 is let into a process chamber for de-passivation, a pressure greater than 1 bar a and a temperature between 100 ° C and 1,000 ° C independently of one another in the chamber and in a second process step, a second gas or gas mixture from the group of N-, C- or B-containing gases for thermochemical surface treatment is let into a process chamber and a temperature between 100 ° C and 1,000 ° C at a pressure greater than or equal to 1 bar a.
  • the de-passivation of alloyed steels and refractory metals is advantageously carried out by heat treatment in gas mixtures containing, for example, NH3 and / or H2, at temperatures between 100 and 1,000 ° C and pressures greater than 1 bar, whereby the disruptive oxide skin is reduced and the pure metal or the alloy is coated with a thin nitride layer as protection against renewed oxidation.
  • gas mixtures containing, for example, NH3 and / or H2
  • the disruptive oxide skin is reduced and the pure metal or the alloy is coated with a thin nitride layer as protection against renewed oxidation.
  • thermochemical removal of the oxides takes place in gas mixtures containing NH3, H2 and N2, at temperatures between 100 ° C and 1,000 ° C and pressures greater than 1 bar a.
  • the oxides are reduced by reacting with the gas phase and releasing their oxygen atoms or forming nitrides.
  • parts heat-treated in this way can be almost completely deoxidized.
  • Such a heat treatment can be carried out for higher alloyed steels as a replacement for the tempering treatment which is to be carried out anyway, tempering and deoxidizing are then carried out in one step.
  • This method makes it possible to continue to carry out thermochemical treatments with oxidizing gas components and to achieve higher fatigue properties on the components through the subsequent deoxidation. As a result, the use of expensive and complicated mechanical post-treatments can be dispensed with.
  • a refractory metal for example Ti
  • a treatment chamber 1 FIG. 1
  • NH3 is let into the chamber and the passivated titanium is reduced at a pressure of 10 bar a.
  • a gas change takes place in the chamber.
  • NH3 is exchanged for N2 and at a constant temperature the second process step begins, namely the thermochemical treatment.
  • This nitriding process is carried out at 30 bar a process pressure.
  • the treatment time is usually two to four hours and depends on the desired nitride layer thickness.
  • the desired TiN coating is obtained as the end product after the second process step.
  • a second system configuration is also conceivable, which consists of a combination of two different treatment chambers 1 and 2 (FIG. 2). This is used e.g. in the treatment of bulk steels, such as a high-alloy steel X 20 CrMoV 12 1.
  • the steel After the steel has been introduced into the treatment chamber 1, it is heated to 580 ° C and at a pressure of e.g. 10 bar a H2 and / or NH3 is let in.
  • a pressure of e.g. 10 bar a H2 and / or NH3 is let in.
  • the steel used is de-passivated and at the same time provided with a thin nitride layer as protection against further oxidation.
  • the steel which is protected against oxidation, is then brought into a second treatment chamber 2.
  • a material-specific nitriding temperature of 550 ° C is set and at a pressure of 1 bar a a gas mixture of NH3, H2 is let in.
  • a nitrided X 20 CrMo V 12 1 steel is obtained as the end product.
  • carbon-containing gases such as CO2 or CO can be used for coal at temperatures between 800 ° C and 1,000 ° C.
  • thermochemical treatment process for example nitriding
  • a pressure chamber which, as shown in FIG. 1, must be designed, for example, for 30 bar a.
  • 16 MnCr5 steel free of edge oxidation is obtained.

Abstract

Method for treating steels and metals, especially for depassivating and subsequent thermochemical surface treatment in a process chamber (1,2) under the influence of pressure and temperature, wherein, in a first process step, a first gas or gas mixture selected from the group N2, H2 or NH3 is introduced in a process chamber (1) for the purpose of depassivation, a pressure greater than 1 bar absolute and a temperature between 100 DEG C and 1,000 DEG C being settable in the chamber (1), and in a second process step a second gas or gas mixture selected from the group of N-, C- or B-containing gases is introduced into a process chamber (1,2) for the purpose of thermochemical surface treatment, and a temperature between 100 DEG C and 1,000 DEG C at a pressure greater than or equal to 1 bar absolute being settable. <IMAGE>

Description

Die Erfindung betrifft ein Verfahren zur Behandlung von Stählen und Metallen, insbesondere zur Entpassivierung und zur anschließenden thermochemischen Oberflächenbehandlung bzw. zur thermochemischen Oberflächenbehandlung und einer anschließenden thermochemischen Nachbehandlung in einer Prozeßkammer unter Einwirkung von Druck und Temperatur.The invention relates to a process for the treatment of steels and metals, in particular for the passivation and for the subsequent thermochemical surface treatment or for the thermochemical surface treatment and a subsequent thermochemical aftertreatment in a process chamber under the action of pressure and temperature.

Bei der thermochemischen Oberflächenbehandlung (z.B. Nitrieren, Nitrokarburieren oder Borieren) von legierten Stählen und Refraktärmetallen (z.B. Ti, Zr, Mo, W. Nb, Ta, V) kommt es bislang durch die oberflächenbedeckenden Passivschichten auf den Materialien zu folgenden Schwierigkeiten: Die Passivschichten bestehen nämlich meist aus Oxiden und bilden eine dünne Schutzhaut, die das ungestörte Eindiffundieren von Nichtmetallen wie z.B. N, C, und B bei der Oberflächenbehandlung mit Nachteil verhindern. Dadurch wird z.B. bei den Refraktärmetallen eine Eindiffusion völlig, bei hochlegierten Stählen teilweise verhindert, was zu ungleichmäßigen Behandlungsergebnissen führt.
Bei bestimmten Sorten legierter Stähle wird zu Erzielung eines gleichmäßigen Behandlungsergebnisses eine Voroxidation vorgenommen. Damit werden Verunreinigungen an den Oberflächen oxidiert und die bereits bestehende Oxidschicht beeinflußt. Dadurch kann in manchen Fällen Einfluß auf die Gleichmäßigkeit der Schichtausbildung genommen werden. Die erzeugten Schichten sind sehr dünn und enthalten immer größere Mengen Sauerstoff.In thermochemical surface treatment (e.g. nitriding, nitro-carburizing or boriding) of alloyed steels and refractory metals (e.g. Ti, Zr, Mo, W. Nb, Ta, V), the surface-covering passive layers on the materials have so far caused the following difficulties: The passive layers exist namely mostly made of oxides and form a thin protective skin, which prevent the undisturbed diffusion of non-metals such as N, C, and B during the surface treatment. This completely prevents diffusion, for example, in the case of refractory metals, and in some cases in the case of high-alloy steels, which leads to uneven treatment results.
For certain types of alloyed steel, pre-oxidation is carried out to achieve a uniform treatment result. This means that impurities on the surfaces are oxidized and the already existing oxide layer is influenced. In some cases, this can influence the uniformity of the layer formation. The layers produced are very thin and contain ever larger amounts of oxygen.

Bei der thermochemischen Oberflächenbehandlung von Metallen (z.B. Aufkohlen, Vergüten, Glühen, Carbonitrieren, Nitrocarburieren) kommt es weiterhin, bedingt durch die Verwendung sauerstoffhaltiger Prozeßgase zu einer interkristallinen Oxidation der behandelten Bauteile. Da die Oxidation nur an der freien Oberfläche, also am Rand der Bauteile auftritt, wird diese Form der Oxidation auch als Randoxidation bezeichnet. Diese Randoxidation bewirkt eine Herabsetzung der Dauerfestigkeit, so daß die Lebensdauer randoxidierter Bauteile verkleinert wird.In the thermochemical surface treatment of metals (e.g. carburizing, tempering, annealing, carbonitriding, nitrocarburizing), there is an intercrystalline oxidation of the treated components due to the use of oxygen-containing process gases. Since the oxidation only occurs on the free surface, i.e. on the edge of the components, this form of oxidation is also referred to as edge oxidation. This edge oxidation reduces the fatigue strength, so that the life of edge-oxidized components is reduced.

Es sind zur Zeit zwei Wärmebehandlungsverfahren zum Aufkohlen von Werkstücken bekannt, die mit sauerstofffreien Prozeßgasen betrieben werden. Diese Verfahren, Plasmaaufkohlung und Vakuumaufkohlung, konnten bisher jedoch noch keine industrielle Anwendung in nennenswertem Umfang finden.There are currently two heat treatment processes for carburizing workpieces that are operated with oxygen-free process gases. However, these processes, plasma carburizing and vacuum carburizing, have so far not found any significant industrial use.

Bauteile, die nach der Wärmebehandlung Oxidation aufweisen, werden daher meist durch mechanische Bearbeitung nachbehandelt, mit dem Ziel die Oxidation abzutragen (z.B. Schleifen von Zahnrädern). Der Abfall der Dauerfestigkeit durch Randoxidation kann auch durch Verfahren zur Verfestigung (z.B. Kugelstrahlen von Zahnrädern) der Bauteile kompensiert werden.Components that have oxidation after heat treatment are therefore usually post-treated with mechanical processing with the aim of removing the oxidation (e.g. grinding gear wheels). The drop in fatigue strength due to edge oxidation can also be compensated for by means of solidification processes (e.g. shot peening of gear wheels) of the components.

Aufgabe der vorliegenden Erfindung ist es nun einerseits, durch eine Vorbehandlung die Oberflächen der genannten Materialien so zu konditionieren, daß eine störungsfreie Aufnahme von diffusionsfähigen Atomen bei der thermochemischen Wärmebehandlung möglich ist und andererseits ein Verfahren zu entwickeln, das die Randoxidation wärmebehandelter Teile entfernt und die mechanischen Bearbeitung ersetzt.It is an object of the present invention, on the one hand, to condition the surfaces of the materials mentioned so that a trouble-free absorption of diffusible atoms during thermochemical heat treatment is possible, and on the other hand to develop a process which removes the edge oxidation of heat-treated parts and the mechanical ones Processing replaced.

Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß ein Behandlungsverfahren mit mehreren Verfahrensschritten durchgeführt wird, bzw. daß im Anschluß an die thermochemische Oberflächenbehandlung ein Wärmebehandlungsverfahren durchgeführt wird, in dem die interkristalline Oxidation von Metallen entfernt wird.This object is achieved according to the invention in that a treatment process is carried out with several process steps, or in that, following the thermochemical surface treatment, a heat treatment process is carried out in which the intercrystalline oxidation of metals is removed.

In einem ersten Verfahrensschritt wird ein erstes Gas oder Gasgemisch aus der Gruppe N₂, H₂ oder NH₃ zur Entpassivierung in eine Prozeßkammer eingelassen, ein Druck größer 1 bar a und eine Temperatur zwischen 100 °C und 1.000 °C voneinander unabhängig in der Kammer eingestellt und in einem zweiten Verfahrensschritt wird ein zweites Gas- oder Gasgemisch aus der Gruppe N-, C- oder B-haltiger Gase zur thermochemischen Oberflächenbehandlung in eine Prozeßkammer eingelassen und eine Temperatur zwischen 100 °C und 1.000 °C bei einem Druck größer oder gleich 1 bar a eingestellt.In a first process step, a first gas or gas mixture from the group N₂, H₂ or NH₃ is let into a process chamber for de-passivation, a pressure greater than 1 bar a and a temperature between 100 ° C and 1,000 ° C independently of one another in the chamber and in a second process step, a second gas or gas mixture from the group of N-, C- or B-containing gases for thermochemical surface treatment is let into a process chamber and a temperature between 100 ° C and 1,000 ° C at a pressure greater than or equal to 1 bar a.

Die Entpassivierung von legierten Stählen und Refraktärmetallen erfolgt mit Vorteil durch eine Wärmebehandlung in Gasgemischen, die z.B NH₃ und/oder H₂ enthalten, bei Temperaturen zwischen 100 und 1.000 °C und Drücken größer 1 bar, wobei die störende Oxidhaut reduziert wird und das reine Metall bzw. die Legierung als Schutz vor einer erneuten Oxidation mit einer dünnen Nitridschicht überzogen wird. Mit solchermaßen vorbehandelten Teilen können gleichmäßige Behandlungsergebnisse erzielt werden und diese Teile können vorteilhafterweise entweder in der gleichen Anlage weiter behandelt werden oder zur Weiterbehandlung in eine andere Anlage umgesetzt werden, wobei die aufgebrachte dünne Nitridschicht einen Schutz gegen die erneute Oxidation bewirkt. Findet die weitere Behandlung bei höheren Temperaturen statt, z.B. Aufkohlen oder Borieren, so wird die Nitridschicht schnell aufgelöst und stellt kein Hindernis für die eindiffundierenden Elemente dar.The de-passivation of alloyed steels and refractory metals is advantageously carried out by heat treatment in gas mixtures containing, for example, NH₃ and / or H₂, at temperatures between 100 and 1,000 ° C and pressures greater than 1 bar, whereby the disruptive oxide skin is reduced and the pure metal or the alloy is coated with a thin nitride layer as protection against renewed oxidation. With parts pretreated in this way, uniform treatment results can be achieved, and these parts can advantageously either be treated further in the same installation or be converted into a further installation for further treatment, the thin nitride layer applied providing protection against renewed oxidation. If the further treatment takes place at higher temperatures, e.g. Carburizing or boronizing, the nitride layer dissolves quickly and does not represent an obstacle for the diffusing elements.

Die thermochemische Entfernung der Oxide erfolgt in Gasgemischen, die NH₃, H₂ und N₂ enthalten, bei Temperaturen zwischen 100 °C und 1.000 °C und Drücken größer 1 bar a. Die Oxide werden reduziert, indem sie mit der Gasphase reagieren und ihre Sauerstoffatome abgeben oder Nitride bilden. Solchermaßen wärmebehandelte Teile können je nach Zusammensetzung der Oxide nahezu vollkommen desoxidiert werden.The thermochemical removal of the oxides takes place in gas mixtures containing NH₃, H₂ and N₂, at temperatures between 100 ° C and 1,000 ° C and pressures greater than 1 bar a. The oxides are reduced by reacting with the gas phase and releasing their oxygen atoms or forming nitrides. Depending on the composition of the oxides, parts heat-treated in this way can be almost completely deoxidized.

Eine solche Wärmebehandlung kann bei höher legierten Stählen als Ersatz für die ohnehin durchzuführende Anlaßbehandlung durchgeführt werden, Anlassen und Desoxidieren werden dann in einem Schritt durchgeführt. Durch dieses Verfahren ist es möglich, thermochemische Behandlungen mit oxidierenden Gaskomponenten weiter durchzuführen und durch die anschließende Desoxidation höhere Dauerfestigkeitseigenschaften an den Bauteilen zu erzielen. Dadurch kann auf den Einsatz teurer und komplizierter mechanischer Nachbehandlungen verzichtet werden.Such a heat treatment can be carried out for higher alloyed steels as a replacement for the tempering treatment which is to be carried out anyway, tempering and deoxidizing are then carried out in one step. This method makes it possible to continue to carry out thermochemical treatments with oxidizing gas components and to achieve higher fatigue properties on the components through the subsequent deoxidation. As a result, the use of expensive and complicated mechanical post-treatments can be dispensed with.

Weitere Ausführungsmöglichkeiten und Merkmale sind in den Unteransprüchen näher beschrieben und gekennzeichnet.Further design options and features are described and characterized in more detail in the dependent claims.

Die Erfindung läßt die verschiedensten Ausführungsmöglichkeiten zu; einige davon sind in den anhängenden Skizzen beispielhaft dargestellt, und zwar zeigen:

Figur 1
eine Entpassivierung und eine thermochemische Behandlung in einer Behandlungskammer als Prinzipskizze,
Figur 2
eine Entpassivierung und eine thermochemische Behandlung in zwei getrennten Behandlungskammern als Prinzipskizze und
Figur 3
eine thermochemischen Entfernung der Randoxidation als Prinzipskizze.
The invention allows a wide variety of design options; some of these are shown as examples in the attached sketches, which show:
Figure 1
a de-passivation and a thermochemical treatment in a treatment chamber as a schematic diagram,
Figure 2
a de-passivation and a thermochemical treatment in two separate treatment chambers as a schematic and
Figure 3
a thermochemical removal of the edge oxidation as a basic sketch.

In eine Behandlungskammer 1 (Fig. 1) wird ein Refraktärmetall (z.B. Ti) eingebracht und auf 800 °C aufgeheizt. Anschließend wird NH₃ in die Kammer eingelassen und bei einem Druck von 10 bar a wird das passivierte Titan reduziert. Nach diesem ersten Verfahrensschritt der Entpassivierung findet ein Gaswechsel in der Kammer statt. NH₃ wird gegen N₂ ausgetauscht und bei gleichbleibender Temperatur beginnt der zweite Verfahrensschritt, nämlich die thermochemische Behandlung. Dieser Nitriervorgang wird bei 30 bar a Verfahrensdruck durchgeführt. Die Behandlungszeit beträgt üblicherweise zwei bis vier Stunden und ist von der gewünschten Nitrierschichtdicke abhängig. Als Endprodukt erhält man nach dem zweiten Verfahrensschritt die gewünschte TiN-Beschichtung.A refractory metal (for example Ti) is introduced into a treatment chamber 1 (FIG. 1) and heated to 800.degree. Then NH₃ is let into the chamber and the passivated titanium is reduced at a pressure of 10 bar a. After this first process step of the passivation, a gas change takes place in the chamber. NH₃ is exchanged for N₂ and at a constant temperature the second process step begins, namely the thermochemical treatment. This nitriding process is carried out at 30 bar a process pressure. The treatment time is usually two to four hours and depends on the desired nitride layer thickness. The desired TiN coating is obtained as the end product after the second process step.

Es ist auch eine zweite Anlagenkonstellation denkbar, die aus einer Kombination von zwei unterschiedlichen Behandlungskammern 1 und 2 besteht (Fig. 2). Diese findet ihre Anwendung z.B. bei der Behandlung von Massenstählen, wie beispielsweise einem hochlegierten Stahl X 20 CrMoV 12 1.A second system configuration is also conceivable, which consists of a combination of two different treatment chambers 1 and 2 (FIG. 2). This is used e.g. in the treatment of bulk steels, such as a high-alloy steel X 20 CrMoV 12 1.

Nachdem der Stahl in die Behandlungskammer 1 eingebracht ist, wird diese auf 580 °C aufgeheizt und mit einem Druck von z.B. 10 bar a wird H₂ und/oder NH₃ eingelassen. In diesem ersten Verfahrensschritt wird der eingesetzte Stahl entpassiviert und gleichzeitig mit einer dünnen Nitridschicht als Schutz vor weiterer Oxidation versehen.After the steel has been introduced into the treatment chamber 1, it is heated to 580 ° C and at a pressure of e.g. 10 bar a H₂ and / or NH₃ is let in. In this first process step, the steel used is de-passivated and at the same time provided with a thin nitride layer as protection against further oxidation.

Anschließend wird der vor Oxidation geschützte Stahl in eine zweite Behandlungskammer 2 verbracht. Hier wird eine werkstoffspezifische Nitriertemperatur von 550 °C eingestellt und bei einem Druck von 1 bar a ein Gasgemsich aus NH₃, H₂ eingelassen. Nach Abschluß dieses zweiten Behandlungsschrittes erhält man als Endprodukt einen nitrierten X 20 CrMo V 12 1- Stahl. Statt stickstoffhaltiger Gase können zum Kohlen auch kohlenstoffhaltige Gase wie CO₂ oder CO bei bei Temperaturen zwischen 800 °C und 1.000 °C eingesetzt werden.The steel, which is protected against oxidation, is then brought into a second treatment chamber 2. Here a material-specific nitriding temperature of 550 ° C is set and at a pressure of 1 bar a a gas mixture of NH₃, H₂ is let in. After completion of this second treatment step, a nitrided X 20 CrMo V 12 1 steel is obtained as the end product. Instead of nitrogen-containing gases, carbon-containing gases such as CO₂ or CO can be used for coal at temperatures between 800 ° C and 1,000 ° C.

Ein wesentlicher Vorteil einer zweiteiligen Behandlungsanlage nach Figur 2 gegenüber einer Anlage nach Figur 1 ist, daß der eigentliche thermochemische Behandlungsvorgang, beispielsweise das Nitrieren in einer konventionellen Nitrieranlage unter Atmosphärendruck durchgeführt werden kann. Somit entfällt die Notwendigkeit eine Druckkammer einzusetzen, die wie in Figur 1 dargestellt, beispielsweise für 30 bar a ausgelegt sein muß.An essential advantage of a two-part treatment plant according to FIG. 2 compared to a plant according to FIG. 1 is that the actual thermochemical treatment process, for example nitriding, can be carried out in a conventional nitriding plant under atmospheric pressure. This eliminates the need to use a pressure chamber which, as shown in FIG. 1, must be designed, for example, for 30 bar a.

In Figur 3 wird ein einsatzgehärteter Stahl 16 MnCr5 mit 10 µm Randoxidation in eine Prozeßkammer 1 eingebracht und auf eine Prozeßtemperatur ζ = 200 °C erwärmt. In die Kammer wird nun ein Gasgemisch aus NH₃ und N₂ mit einem Druck p=20 bar a eingelassen. Nach Abschluß dieses Prozesses erhält man einen randoxidationsfreien Stahl 16 MnCr5.In FIG. 3, a case-hardened steel 16 MnCr5 with 10 μm edge oxidation is introduced into a process chamber 1 and heated to a process temperature ζ = 200 ° C. A gas mixture of NH₃ and N₂ with a pressure p = 20 bar a is now let into the chamber. Upon completion of this process, 16 MnCr5 steel free of edge oxidation is obtained.

BezugszeichenlisteReference symbol list

11
ProzeßkammerProcess chamber
22nd
ProzeßkammerProcess chamber
PP
Druckprint
ζζ
Temperaturtemperature

Claims (13)

Verfahren zur Behandlung von legierten Stählen und Refraktärmetallen, insbesondere zur Entpassivierung und zur anschließenden thermochemischen Oberflächenbehandlung in einer Prozeßkammer (1,2) unter Einwirkung von Druck und Temperatur, dadurch gekennzeichnet, daß in einem ersten Verfahrensschritt ein erstes Gas oder Gasgemisch aus der Grupp N₂, H₂ oder NH₃ zur Entpassivierung in eine Prozeßkammer (1) eingelassen wird, ein Druck größer 1 bar a und eine Temperatur zwischen 100 °C und 1.000 °C voneinander unabhängig in der Kammer (1) einstellbar sind und daß in einem zweiten Verfahrensschritt ein zweites Gas oder Gasgemisch aus der Grupp N-, C- oder B-haltiger Gase zur thermochemischen Oberflächenbehandlung in eine Prozeßkammer (1,2) eingelassenwird und eine Temperatur zwischen 100 °C und 1.000 °C bei einem Druck größer und gleich 1 bar a einstellbar sind.Process for the treatment of alloyed steels and refractory metals, in particular for the passivation and subsequent thermochemical surface treatment in a process chamber (1, 2) under the action of pressure and temperature, characterized in that in a first process step a first gas or gas mixture from the group N₂, H₂ or NH₃ for passivation in a process chamber (1) is admitted, a pressure greater than 1 bar a and a temperature between 100 ° C and 1,000 ° C independently of one another in the chamber (1) and that in a second process step, a second gas or gas mixture from the group containing N, C or B-containing gases for thermochemical surface treatment in a process chamber (1,2) and a temperature between 100 ° C and 1,000 ° C at a pressure greater than and equal to 1 bar a can be set. Verfahren nach Anspruch 1, dadurch gekennzeichnet , daß in dem ersten Verfahrensschritt ein Druck von typischerweise 10 bar a eingestellt ist.A method according to claim 1, characterized in that a pressure of typically 10 bar a is set in the first process step. Verfahren nach den Ansprüchen 1 oder 2, dadurch gekennzeichnet , daß in dem zweiten Verfahrensschritt in der Kammer (1) ein Druck von typischerweise 30 bar a eingestellt ist.Process according to claims 1 or 2, characterized in that in the second process step a pressure of typically 30 bar a is set in the chamber (1). Vorrichtung zur Durchführung eines Verfahrens nach den Ansprüchen 1, 2 oder 3, dadurch gekennzeichnet , daß der erste und der zweite Verfahrensschritt in ein und derselben Prozeßkammer (1) durchgeführt werden.Device for carrying out a method according to claims 1, 2 or 3, characterized in that that the first and second process steps are carried out in one and the same process chamber (1). Vorrichtung nach den Ansprüchen 1, 2 oder 3, dadurch gekennzeichnet , daß der erste Verfahrensschritt in einer ersten Prozeßkammer (1) und der zweite Verfahrensschritt in einer zweiten Prozeßkammer (2) durchgeführt werden.Device according to claims 1, 2 or 3, characterized in that the first process step is carried out in a first process chamber (1) and the second process step in a second process chamber (2). Vorrichtung nach Anspruch 5, dadurch gekennzeichnet , daß die erste Prozeßkammer (1) für einen Druck größer 1 bar a ausgelegt ist.Apparatus according to claim 5, characterized in that the first process chamber (1) is designed for a pressure greater than 1 bar a. Vorrichtung nach Anspruch 5, dadurch gekennzeichnet , daß die zweite Prozeßkammer (2) für Atmosphärendruck ausgelegt ist.Apparatus according to claim 5, characterized in that the second process chamber (2) is designed for atmospheric pressure. Verfahren zur Behandlung von Stählen und Metallen in einer Prozeßkammer (1) unter Einwirkung von Druck und Temperatur mit einem ersten Verfahrensschritt, in dem eine thermochemische Oberflächenbehandlung, beispielsweise das Einsatzhärten, durchgeführt wird, dadurch gekennzeichnet , daß in einem zweiten Verfahrensschritt zur thermochemischen Entfernung der Randoxidation ein Gas oder Gasgemisch aus der Gruppe N₂, H₂ oder NH₃ in eine Prozeßkammer (1) eingelassen wird und ein Druck größer 1 bar a und eine Temperatur zwischen 100 °C und 1.000 °C voneinander unabhängig in der Kammer (1) einstellbar sind.Process for the treatment of steels and metals in a process chamber (1) under the action of pressure and temperature with a first process step in which a thermochemical surface treatment, for example case hardening, is carried out, characterized in that in a second process step for the thermochemical removal of the edge oxidation a gas or gas mixture from the group N₂, H₂ or NH₃ is admitted into a process chamber (1) and a pressure greater than 1 bar a and a temperature between 100 ° C and 1,000 ° C can be adjusted independently in the chamber (1). Verfahren nach Anspruch 8, dadurch gekennzeichnet , daß Bauteile aus unlegierten oder niedriglegierten Stählen behandelt werden.Method according to claim 8, characterized in that components made of unalloyed or low-alloyed steels are treated. Verfahren nach Anspruch 8, dadurch gekennzeichnet , daß Bauteile aus höherlegierten Stählen behandelt werden.Method according to claim 8, characterized in that components made of higher-alloy steels are treated. Verfahren nach Anspruch 10, dadurch gekennzeichnet , daß gleichzeitig mit der thermochemischen Entfernung der Randoxidation ein Wärmebehandlungsverfahren, beispielsweise das Anlassen von Stählen durchgeführt wird.Method according to Claim 10, characterized in that a heat treatment process, for example the tempering of steels, is carried out simultaneously with the thermochemical removal of the edge oxidation. Verfahren nach einem oder mehreren der Ansprüche 8 bis 11, dadurch gekennzeichnet , daß der Prozeßdruck während des Verfahrens zur thermochemischen Entfernung der Randoxidation typischerweise 20 bar a beträgt.Method according to one or more of claims 8 to 11, characterized in that the process pressure during the process for the thermochemical removal of the edge oxidation is typically 20 bar a. Verfahren nach Anspruch 12, dadurch gekennzeichnet , daß die Prozeßtemperatur typischerweise kleiner oder gleich der Anlaßtemperatur des zu behandelnden Stahls ist.A method according to claim 12, characterized in that the process temperature is typically less than or equal to the tempering temperature of the steel to be treated.
EP92118403A 1991-12-04 1992-10-27 Method of treating steel and refractory metals Expired - Lifetime EP0545069B1 (en)

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Application Number Priority Date Filing Date Title
DE4139975 1991-12-04
DE4139975A DE4139975C2 (en) 1991-12-04 1991-12-04 Process for the treatment of alloyed steels and refractory metals and application of the process
DE4208848A DE4208848C2 (en) 1991-12-04 1992-03-19 Process for the thermochemical after-treatment of steels and metals
DE4208848 1992-03-19

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EP0545069B1 EP0545069B1 (en) 1995-12-06

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FR2719057A1 (en) * 1994-04-22 1995-10-27 Innovatique Sa Method of nitriding metallic surfaces
WO1995029269A1 (en) * 1994-04-22 1995-11-02 Innovatique S.A. Method of low pressure nitriding a metal workpiece and oven for carrying out said method
WO2003027349A2 (en) * 2001-09-25 2003-04-03 Robert Bosch Gmbh Method for heat-treating work pieces made of temperature-resistant steels
WO2004040033A1 (en) * 2002-10-31 2004-05-13 Seco/Warwick Sp. Z O.O. Method for under-pressure carburizing of steel workpieces
EP2430210B1 (en) * 2009-05-11 2018-01-24 Robert Bosch GmbH Method for carbonitriding

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FR2719057A1 (en) * 1994-04-22 1995-10-27 Innovatique Sa Method of nitriding metallic surfaces
WO1995029269A1 (en) * 1994-04-22 1995-11-02 Innovatique S.A. Method of low pressure nitriding a metal workpiece and oven for carrying out said method
WO2003027349A2 (en) * 2001-09-25 2003-04-03 Robert Bosch Gmbh Method for heat-treating work pieces made of temperature-resistant steels
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WO2004040033A1 (en) * 2002-10-31 2004-05-13 Seco/Warwick Sp. Z O.O. Method for under-pressure carburizing of steel workpieces
EP2430210B1 (en) * 2009-05-11 2018-01-24 Robert Bosch GmbH Method for carbonitriding

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EP0545069B1 (en) 1995-12-06
ATE131216T1 (en) 1995-12-15
DE4208848C2 (en) 2001-08-30
DE59204598D1 (en) 1996-01-18
JPH0665631A (en) 1994-03-08
DE4208848A1 (en) 1993-09-23
ES2080416T3 (en) 1996-02-01

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