EP0375491B1 - Verfahren und Anlage für Wärmebehandlungen wie Einsatzhärten, Karbonitrieren oder Erwärmung vor dem Härten von metallischen Werkstoffen - Google Patents

Verfahren und Anlage für Wärmebehandlungen wie Einsatzhärten, Karbonitrieren oder Erwärmung vor dem Härten von metallischen Werkstoffen Download PDF

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Publication number
EP0375491B1
EP0375491B1 EP89403347A EP89403347A EP0375491B1 EP 0375491 B1 EP0375491 B1 EP 0375491B1 EP 89403347 A EP89403347 A EP 89403347A EP 89403347 A EP89403347 A EP 89403347A EP 0375491 B1 EP0375491 B1 EP 0375491B1
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European Patent Office
Prior art keywords
nitrogen
flow rate
separator
carbonitriding
oxygen content
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.)
Expired - Lifetime
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EP89403347A
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English (en)
French (fr)
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EP0375491A1 (de
Inventor
Alain Combier
Patrice Ollivier
Jean-Marc Viant
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.)
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 AT89403347T priority Critical patent/ATE104361T1/de
Publication of EP0375491A1 publication Critical patent/EP0375491A1/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
    • C23C8/28—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
    • 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
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • 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
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/76—Adjusting the composition of the atmosphere

Definitions

  • the present invention relates to thermal treatments for carburizing, carbonitriding and heating before quenching steels intended to ensure surface hardening of metal parts.
  • a typical example of a carburizing atmosphere composition is given below: nitrogen (N2) 40% carbon monoxide (CO) 19% carbon dioxide (CO2) 0.3% hydrogen (H2) 35% methane (CH4) 1% water vapor (H2O) 0.6% oxygen (WHERE) traces
  • the raw nitrogen produced is therefore impure, because it contains a little oxygen and traces of water.
  • the generator extraction factor flow of nitrogen produced / flow of treated air
  • its production capacity which is obviously to the detriment of the cost price of the gas treated.
  • a “PSA” type generator usually exhibits the following performances as a function of the oxygen content in the gas produced.
  • the residual oxygen is transformed into CO, H2O and CO2.
  • the additional hydrocarbon makes it possible in particular to maintain a low H2O and CO2 content, despite the presence of oxygen in the nitrogen, provided that the oxygen content is not too high. If this is not the case, an additional hydrocarbon content qualified as excessive must be injected, since it can cause soot formation, heterogeneous carburizing, drops in the CO content. Ultimately, obtaining a high potential carbon in the atmosphere may be impossible, which is obviously contrary to good treatment.
  • the maximum oxygen content compatible with the majority of the treatment cycles provided for in case hardening, carbonitriding and heating before quenching of steels is of the order of 2% in nitrogen.
  • the residual H enO and CO2 contents can be contained at low values, generally less than 0.6% for H2O and 0.3% for CO2.
  • the atmosphere formed inside the furnace diffuses into the refractory bricks and at the bricks / atmosphere interface, a balance is reached when the furnace is in continuous operation, but a significant problem remains during the periods of non-operation of the oven. It is indeed more and more common that the heat treatment workshop undergoes interruptions of operation of relatively long durations, for example during the weekend rest. In this case, the treatment atmosphere is of course no longer injected into the oven, not only for reasons of economy but also of safety, since this atmosphere is potentially explosive (high hydrogen and CO content) and toxic (high CO level). In addition, the oven temperature is often lowered somewhat.
  • the nitrogen used comes from a cryogenic source, the residual oxygen content in the oven and in the refractory bricks remains very low, and the restart of the oven in production, the so-called reconditioning period, is then very short, generally 15 minutes to a few hours, depending in particular on the oven temperature, but the cost is also important.
  • the reconditioning of the oven can take considerably more time, thus penalizing the productivity of the installation. Indeed, it will not only be necessary to purge the interior atmosphere of the oven, but also the atmosphere contained in the refractory bricks, a particularly long operation, because these bricks behaving like sponges, it is difficult to diffuse gas there. In addition, the purge is conventionally done from the treatment atmosphere injected again into the oven. This contains in particular a high hydrogen content.
  • This gas which consists of a very "small” molecule diffuses very quickly, so that the hydrogen transforms the oxygen contained in the refractory bricks into water vapor, so that the water vapor content thus produced reaches 4%.
  • This 4% water vapor content is incompatible with the subsequent treatment which requires values of less than 0.6%. We must therefore chemically destroy or purge this water vapor. Purging water vapor is always a difficult operation because this polar molecule has the property of being very easily adsorbed on the surface of solids.
  • refractory bricks by their porosity, have a very large specific surface.
  • the object of the present invention is to propose a method and an installation making it possible to optimize the costs of use while greatly reducing the investment costs.
  • the process of heat treatment of carburizing, carbonitriding or heating before quenching of metal parts of the kind in which an auxiliary gas mixture based on nitrogen, methanol, if necessary ammonia is used, to constitute a treatment atmosphere in an unmuffled oven, the nitrogen being crude nitrogen resulting from the separation of air by an adsorption or permeation separator, providing in nominal operation a nominal flow of nitrogen having a content oxygen residual of the order of 2%, and where a resumption of treatment, after a significant interruption phase, is preceded by a purge by injecting nitrogen into the oven, is characterized in that purge nitrogen is supplied, at a flow rate much lower than the nominal flow rate, by the separator, set at a lower extraction rate, such that the residual oxygen content in the purge nitrogen flow rate is between 0.1 and 0.3 %.
  • the process according to the invention has the double merit of requiring no other source of gas for purging and of ensuring this purging under economic conditions that are the least detrimental to the operating efficiency of the cementation, carbonitriding, or heating before quenching.
  • the invention also relates to an installation for heat treatment of carburizing, carbonitriding or heating before quenching of metal parts, of the type comprising a treatment furnace which is not reeved, at least two sources of constituents in the fluid state of production of an atmosphere carburizing or carbonitriding heat treatment, among which, for the nitrogen component, a nitrogen separator from the air by adsorption or selective permeation, characterized in that it comprises means for adjusting the extraction rate of l production nitrogen supplied by the separator on at least two levels, namely a high level with residual oxygen content of the order of 2% and a low level with residual oxygen content of between 0.1 and 0.3%.
  • a single buffer tank may be sufficient, but then it should be possible to purge it for approximately the time necessary for the generator to change from normal nitrogen quality to purge nitrogen quality.
  • the excess of compressed air compared to the normal step is either vented, with no energy saving effect, or the compressor vacuum device switches on at regular intervals, resulting in significant energy savings.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Metallurgy (AREA)
  • Mechanical Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)
  • Furnace Details (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Muffle Furnaces And Rotary Kilns (AREA)
  • Resistance Heating (AREA)
  • Meat, Egg Or Seafood Products (AREA)

Claims (7)

  1. Verfahren zur Wärmebehandlung von metallischen Werkstoffen, wie Einsatzhärten, Karbonitrieren oder Erwärmen vor dem Härten (Abschrecken), bei dem ein Gasgemisch auf der Basis von Stickstoff, Methanol, vorkommendenfalls Ammoniak, zugeführt wird, um eine Behandlungsatmosphäre in einem Ofen ohne Muffeln zu erzeugen, wobei der Stickstoff roher Stickstoff ist, der aus der Luftzerlegung durch einen Adsorptionsoder Permeationsabscheider stammt, welcher im Nominalbetrieb einen nominalen Stickstoffstrom mit einem Sauerstoffrestgehalt in der Größenordnung von 2% bereitstellt, und bei dem einer Wiederaufnahme der Behandlung nach einer längeren Unterbrechungsphase ein Durchspülen durch Einleiten von Stickstoff in den Ofen vorausgeht, dadurch gekennzeichnet, daß der Spülstickstoff mit einem Strom, der deutlich niedriger ist als der nominale Strom, von dem Abscheider bereitgestellt wird, der auf eine niedrigere Entnahmerate derart eingestellt wird, daß der Sauerstoffrestgehalt in dem Spülstickstoffstrom 0,1 bis 0,3% beträgt.
  2. Anlage zur Wärmebehandlung von metallischen Werkstoffen, wie Einsatzhärten, Karbonitrieren oder Erwärmen vor dem Härten (Abschrecken), mit einem Behandlungsofen ohne Muffeln, mit mindestens zwei Quellen, die Bestandteile in flüssigem Zustand zur Herstellung einer Atmosphäre für Wärmebehandlungen wie Einsatzhärten oder Karbonitrieren liefern, von denen die den Bestandteil Stickstoff liefernde Quelle ein Abscheider (1) von Stickstoff aus Luft durch selektive Adsorption oder Permeation ist, dadurch gekennzeichnet, daß sie Einrichtungen (2, 8) zur Einstellung der Entnahmerate des von dem Abscheider gelieferten hergestellten Stickstoffs auf mindestens zwei Werte umfaßt, nämlich einen hohen Wert mit einem Sauerstoffrestgehalt in der Größenordnung von 2% und einen niedrigen Wert mit einem Sauerstoffrestgehalt von 0,1 bis 0,3%.
  3. Anlage nach Anspruch 2, dadurch gekennzeichnet, daß sie stromab von dem Abscheider (1) parallel geschaltet mindestens einen ersten (6) und einen zweiten Pufferbehälter (9) zur Speicherung von Stickstoffmengen mit unterschiedlichem Sauerstoffgehalt umfaßt.
  4. Anlage nach Anspruch 3, dadurch gekennzeichnet, daß der Abscheider (1) in eine Produktionsleitung mündet, die aufeinanderfolgend einen ersten Durchflußbegrenzer (2), einen über ein 3-Wege-Ventil parallelgeschalteten zweiten Durchflußbegrenzer (8) und den ersten Pufferbehälter (6) umfaßt.
  5. Anlage nach Anspruch 4, dadurch gekennzeichnet, daß der zweite Behälter (9) über 3-Wege-Ventile (5) und (7) parallel zu dem ersten Behälter (6) angeordnet ist.
  6. Anlage nach Anspruch 4 oder 5, dadurch gekennzeichnet, daß die Produktionsleitung einen Durchflußmesser (4) umfaßt, der stromauf von den Behältern (6) und (9) angeordnet ist.
  7. Anlage nach einem der Ansprüche 4 bis 6, dadurch gekennzeichnet, daß sie eine Vorrichtung zur Stickstoffversorgung im Notfall und/oder für den Spitzenbedarf umfaßt, die einen Speicherbehälter (10) für flüssigen Stickstoff, einen Verdampfer (11) und einen Entspanner (12) aufweist und stromauf von dem ersten Behälter (6) in die Produktionsleitung mündet.
EP89403347A 1988-12-20 1989-12-04 Verfahren und Anlage für Wärmebehandlungen wie Einsatzhärten, Karbonitrieren oder Erwärmung vor dem Härten von metallischen Werkstoffen Expired - Lifetime EP0375491B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT89403347T ATE104361T1 (de) 1988-12-20 1989-12-04 Verfahren und anlage fuer waermebehandlungen wie einsatzhaerten, karbonitrieren oder erwaermung vor dem haerten von metallischen werkstoffen.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8816792A FR2640646B1 (fr) 1988-12-20 1988-12-20 Procede et installation de traitement thermique de cementation, carbonitruration ou chauffage avant trempe de pieces metalliques
FR8816792 1988-12-20

Publications (2)

Publication Number Publication Date
EP0375491A1 EP0375491A1 (de) 1990-06-27
EP0375491B1 true EP0375491B1 (de) 1994-04-13

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ID=9373150

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EP89403347A Expired - Lifetime EP0375491B1 (de) 1988-12-20 1989-12-04 Verfahren und Anlage für Wärmebehandlungen wie Einsatzhärten, Karbonitrieren oder Erwärmung vor dem Härten von metallischen Werkstoffen

Country Status (11)

Country Link
US (1) US5045126A (de)
EP (1) EP0375491B1 (de)
JP (1) JPH02217459A (de)
AT (1) ATE104361T1 (de)
AU (1) AU625618B2 (de)
CA (1) CA2005823C (de)
DE (1) DE68914624T2 (de)
ES (1) ES2050834T3 (de)
FR (1) FR2640646B1 (de)
PT (1) PT92615B (de)
ZA (1) ZA899627B (de)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5298090A (en) * 1992-12-22 1994-03-29 Air Products And Chemicals, Inc. Atmospheres for heat treating non-ferrous metals and alloys
US5348592A (en) * 1993-02-01 1994-09-20 Air Products And Chemicals, Inc. Method of producing nitrogen-hydrogen atmospheres for metals processing
DE4400391A1 (de) * 1994-01-08 1995-07-13 Messer Griesheim Gmbh Verfahren zur Vermeidung von Randoxidation beim Aufkohlen von Stählen
NZ314334A (en) * 1996-04-19 1997-09-22 Boc Group Inc Method of heat treating a metal with nitrogen rich gas preheated and then having oxygen-reactive gas added
CN104060265A (zh) * 2014-06-18 2014-09-24 滁州市艾德模具设备有限公司 热作模具耐高温处理工艺
CN110257761B (zh) * 2019-06-14 2021-08-20 武汉汇九厨具科技有限公司 一种无涂层耐磨防锈不粘铁锅及其制造工艺
CN112501544A (zh) * 2020-08-27 2021-03-16 苏州新豪轴承股份有限公司 轴承零件加工工艺

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2450878A1 (fr) * 1979-03-05 1980-10-03 Air Liquide Installation generatrice d'une atmosphere de traitement thermique des metaux
US4805881A (en) * 1987-05-28 1989-02-21 Gas Research Institute Internal gas generator for heat treating furnace

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
"Stealing nitrogen from the air", W. C. Quantz, Advanced Materials and Processes, vol. 134, no. 3, septembre 1988, p. 100-107. *

Also Published As

Publication number Publication date
EP0375491A1 (de) 1990-06-27
US5045126A (en) 1991-09-03
ES2050834T3 (es) 1994-06-01
CA2005823A1 (fr) 1990-06-20
ATE104361T1 (de) 1994-04-15
AU4713389A (en) 1990-06-28
AU625618B2 (en) 1992-07-16
ZA899627B (en) 1990-09-26
PT92615A (pt) 1990-06-29
PT92615B (pt) 1995-09-12
DE68914624D1 (de) 1994-05-19
DE68914624T2 (de) 1994-07-21
FR2640646B1 (fr) 1993-02-05
CA2005823C (fr) 1994-12-13
FR2640646A1 (fr) 1990-06-22
JPH02217459A (ja) 1990-08-30

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