EP0662525B1 - Procédé pour empêcher l'oxydation superficielle pendant la carburation des aciers - Google Patents

Procédé pour empêcher l'oxydation superficielle pendant la carburation des aciers Download PDF

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Publication number
EP0662525B1
EP0662525B1 EP94202796A EP94202796A EP0662525B1 EP 0662525 B1 EP0662525 B1 EP 0662525B1 EP 94202796 A EP94202796 A EP 94202796A EP 94202796 A EP94202796 A EP 94202796A EP 0662525 B1 EP0662525 B1 EP 0662525B1
Authority
EP
European Patent Office
Prior art keywords
carbon
gas mixture
hydrogen
carburization
nitrogen
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
Application number
EP94202796A
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German (de)
English (en)
Other versions
EP0662525A1 (fr
Inventor
Hans-Peter Schmidt
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.)
Messer Griesheim GmbH
Original Assignee
Messer Griesheim GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Messer Griesheim GmbH filed Critical Messer Griesheim GmbH
Publication of EP0662525A1 publication Critical patent/EP0662525A1/fr
Application granted granted Critical
Publication of EP0662525B1 publication Critical patent/EP0662525B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • C21D3/00—Diffusion processes for extraction of non-metals; Furnaces therefor
    • C21D3/02—Extraction of non-metals
    • C21D3/06—Extraction of hydrogen
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/20—Carburising
    • C23C8/22—Carburising of ferrous surfaces
    • C—CHEMISTRY; METALLURGY
    • 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 invention relates to a method for avoiding edge oxidation when carburizing steels according to the preamble of claim 1.
  • low carbon steels are annealed in carbon donors at temperatures between 800 and 950 ° C (see for example US-A-4 152 177 or US-A-4 643 402).
  • the surface is enriched with carbon and hardens when quenched.
  • Endogases which contain about 20% CO, 40% H 2 , 40% N 2 are mostly used as carbon donors.
  • the base alloy elements are oxidized in the edge zone of the steels, so that they are no longer present in the subsequent microstructure formation.
  • An undesirable one forms in the edge zone of the steels Structure which has unfavorable properties and requires mechanical removal or blasting of this edge zone in order to achieve the required properties of the steels (workpieces).
  • the released carbon, as well as the adsorbed oxygen, are released from the alloy and diffuse into the steel.
  • the amount of dissolved oxygen is determined by the oxygen activity of the gas phase and the duration of the treatment time and is very much less than the amount of carbon that dissolves.
  • the oxygen solubility in pure iron at 950 ° C. and a C level of 1% by weight carbon using an endogas from methane is approximately 0.0003% by weight oxygen (3 ppm oxygen).
  • the oxygen potential of the carburizing media used is usually so low that there is no oxidation of the iron. Alloying elements present in the steels, however, have a high affinity for oxygen, so that small amounts of dissolved oxygen in the alloy lead to what is known as internal oxidation.
  • Edge oxidation or internal oxidation means oxide precipitates of the above-mentioned metals within a metal grain or along the grain boundaries, which are formed by the diffused dissolved oxygen and are then dispersed in the matrix.
  • the invention has for its object to prevent edge oxidation when carburizing steels.
  • the invention provides a carburizing process with only low investment and operating costs because the annealing can be carried out in conventional industrial furnace systems at atmospheric pressure.
  • the edge oxidation of the steels is avoided by the heat treatment being carried out in gas phases which contain no or only little oxygen-containing molecules.
  • the partial pressure of oxygen in the gas atmosphere does not exceed the formation pressure of the oxides.
  • the gas components hydrogen and hydrocarbons of the gas mixture according to the invention are not oxygen-containing (oxygen-free), so that almost none Partial pressure of oxygen is present.
  • the carbon transfer from the gas phase into the steel during the initial and diffusion phase is large and the required carbon content in the edge of the material (approx. 1% C) sets in relatively quickly.
  • the unstable hydrocarbon (C x H y ) on the alloy surface mainly breaks down into hydrogen, methane and atomic carbon, which quickly diffuses into the material. If propane is used, the decay can take place according to the following reaction equation: C. 3rd H 8th ⁇ 2 CH 4th + C ad
  • the resulting carbon activity in the gas phase is influenced by the amount of hydrocarbon added. Since the gas phase consists mainly of hydrogen, the C level is regulated by the methane / hydrogen ratio that arises.
  • the carburization reaction via methane decay in hydrogen atmospheres is:
  • the hydrogen content and in particular the methane content that is established are continuously analyzed and the hydrocarbon supply is regulated to a desired marginal carbon content on the basis of the actual values recorded.
  • the hydrogen dissolved in the workpiece during the main carburization phase is greatly reduced, so that hydrogen embrittlement can be excluded.
  • the carbon-containing gas mixture is replaced by nitrogen after carburizing and the hydrogen dissolved in the steel is thus broken down.
  • the steel is kept in the nitrogen atmosphere for between 5 and 15 minutes.
  • the steel 16 MnCr 5 (1% Mn; 1% Cr; 0.20% Si) was carburized in an industrial furnace system.
  • the furnace system was formed with endogas at approx. 1,000 ° C before the first carburization.
  • the temperature and thermal voltage of the oxygen probe or the dew point or the CO 2 content were measured and registered, and a clear statement was made about the quality of the furnace formation.
  • the carburizing process was carried out as follows:
  • the furnace gas composition was continuously analyzed for H 2 , CH 4 , CO, CO 2 and H 2 O in both process variants throughout the entire process.
  • the temperature profile was also measured and registered. Carbon and oxygen activity were continuously determined and corrected for their target values.

Landscapes

  • 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)
  • Arc Welding In General (AREA)

Claims (7)

  1. Procédé pour éviter l'oxydation marginale pendant la cémentation par le carbone des aciers avec des éléments d'alliage qui sont présents en faible concentration par action d'un mélange gazeux contenant du carbone à la température de la cémentation par le carbone,
    caractérisé en ce que
    les aciers sous un mélange gazeux d'azote/hydrogène ou avec de l'hydrogène pur sont chauffés à la température de cémentation par le carbone et le mélange gazeux azote/hydrogène ou l'hydrogène pendant la cémentation par le carbone est remplacé par un mélange gazeux contenant du carbone avec une activité d'oxygène plus faible que celle nécessaire pour la formation d'oxyde manganeux (II) ou d'oxyde chromique (III) et le mélange gazeux contenant du carbone fournit du carbone qui diffuse dissout à l'intérieur de l'acier.
  2. Procédé selon la revendication 1,
    caractérisé en ce que
    le mélange gazeux contenant du carbone est un mélange gazeux hydrogène/hydrocarbure, de préférence un mélange gazeux hydrogène/propane.
  3. Procédé selon les revendications 1 ou 2,
    caractérisé en ce que
    vers la fin de la cémentation par le carbone le mélange gazeux contenant du carbone est remplacé par un gaz de craquage azote-méthanol.
  4. Procédé selon une des revendications 1 à 3,
    caractérisé en ce que
    la composition du mélange gazeux ou du gaz de craquage est conçue pendant le chauffage et la cémentation par le carbone et est ajustée en fonction des valeurs réelles de la teneur en carbone par apport d'hydrocarbure à une teneur de carbone marginal désirée.
  5. Procédé selon une des revendications 1 à 4,
    caractérisé en ce que
    le mélange gazeux contenant du carbone ou le gaz de craquage est remplacé après la cémentation par le carbone par de l'azote et de l'hydrogène dissout dans l'acier dégradé est décomposé.
  6. Procédé selon la revendication 4,
    caractérisé en ce que
    l'acier est maintenu entre 5 et 15 minutes dans l'atmosphère d'azote à la température de cémentation par le carbone.
  7. Procédé selon la revendication 4,
    caractérisé en ce que
    l'acier est refroidi dans l'atmosphère d'azote en dessous de la température de cémentation par le carbone.
EP94202796A 1994-01-08 1994-09-27 Procédé pour empêcher l'oxydation superficielle pendant la carburation des aciers Expired - Lifetime EP0662525B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4400391 1994-01-08
DE4400391A DE4400391A1 (de) 1994-01-08 1994-01-08 Verfahren zur Vermeidung von Randoxidation beim Aufkohlen von Stählen

Publications (2)

Publication Number Publication Date
EP0662525A1 EP0662525A1 (fr) 1995-07-12
EP0662525B1 true EP0662525B1 (fr) 1997-06-25

Family

ID=6507609

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94202796A Expired - Lifetime EP0662525B1 (fr) 1994-01-08 1994-09-27 Procédé pour empêcher l'oxydation superficielle pendant la carburation des aciers

Country Status (4)

Country Link
US (1) US5498299A (fr)
EP (1) EP0662525B1 (fr)
AT (1) ATE154832T1 (fr)
DE (2) DE4400391A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10321414A1 (de) * 2003-05-13 2004-12-09 Robert Bosch Gmbh Verfahren zur Wärmebehandlung von metallischen Werkstücken in Kammeröfen

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5795410A (en) * 1997-01-23 1998-08-18 Usx Corporation Control of surface carbides in steel strip
US6612154B1 (en) 1998-12-22 2003-09-02 Furnace Control Corp. Systems and methods for monitoring or controlling the ratio of hydrogen to water vapor in metal heat treating atmospheres
US6591215B1 (en) * 1999-02-18 2003-07-08 Furnace Control Corp. Systems and methods for controlling the activity of carbon in heat treating atmospheres
FR2826376B1 (fr) * 2001-06-25 2003-09-26 Serthel Procede de cementation et de carbonitruration des aciers par l'oxyde de carbone
DE10254846B4 (de) * 2002-11-25 2011-06-16 Robert Bosch Gmbh Verfahren zum Einsatzhärten von Bauteilen aus Warmarbeitsstählen mittels Unterdruckaufkohlung
US20060151334A1 (en) * 2002-12-03 2006-07-13 Jean-Jacque Duruz Method of conditioning iron alloy-based anodes for aluminium electrowinning
US20080149226A1 (en) * 2006-12-26 2008-06-26 Karen Anne Connery Method of optimizing an oxygen free heat treating process
US20080149227A1 (en) * 2006-12-26 2008-06-26 Karen Anne Connery Method for oxygen free carburization in atmospheric pressure furnaces
US20080149225A1 (en) * 2006-12-26 2008-06-26 Karen Anne Connery Method for oxygen free carburization in atmospheric pressure furnaces
US20080187850A1 (en) * 2007-02-06 2008-08-07 Xerox Corporation Tunable electrophotographic imaging member and method of making same
US9109277B2 (en) * 2011-01-10 2015-08-18 Air Products And Chemicals, Inc. Method and apparatus for heat treating a metal
EP3168314A1 (fr) 2015-11-13 2017-05-17 Air Liquide Deutschland GmbH Procédé de traitement thermique de pièces métalliques
AU2017268409B2 (en) 2016-05-20 2021-12-16 Ideapaint, Inc. Dry-erase compositions and methods of making and using thereof

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US4049473A (en) * 1976-03-11 1977-09-20 Airco, Inc. Methods for carburizing steel parts
US4152177A (en) * 1977-02-03 1979-05-01 General Motors Corporation Method of gas carburizing
CH641840A5 (en) * 1977-06-16 1984-03-15 Standardgraph Filler & Fiebig Process for increasing the abrasion resistance of workpieces of stainless steel or nickel metal alloys
US4175986A (en) * 1978-10-19 1979-11-27 Trw Inc. Inert carrier gas heat treating control process
US4935073A (en) * 1981-11-27 1990-06-19 Sri International Process for applying coatings of zirconium and/or titantuim and a less noble metal to metal substrates and for converting the zirconium and/or titanium to an oxide, nitride, carbide, boride or silicide
SU1204642A1 (ru) * 1982-04-09 1986-01-15 Центральное Производственно-Техническое Предприятие По Ремонту,Наладке И Проектированию Энергетических Установок Предприятий Черной Металлургии Способ производства тонкостенных изделий из высокоуглеродистой стали
US4643402A (en) * 1985-07-24 1987-02-17 Mg Industries System for producing a regulated atmosphere for a high-temperature process
FR2586259B1 (fr) * 1985-08-14 1987-10-30 Air Liquide Procede de cementation rapide dans un four continu
FR2640646B1 (fr) * 1988-12-20 1993-02-05 Air Liquide Procede et installation de traitement thermique de cementation, carbonitruration ou chauffage avant trempe de pieces metalliques
SE466755B (sv) * 1989-06-30 1992-03-30 Aga Ab Foerfarande foer uppkolning av staal med reducering av vaetehalten i uppkolningsskiktet
EP0480924A1 (fr) * 1989-07-07 1992-04-22 Aga Aktiebolag Procede de cementation d'elements de paliers a roulement en acier au nickel faiblement allie
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10321414A1 (de) * 2003-05-13 2004-12-09 Robert Bosch Gmbh Verfahren zur Wärmebehandlung von metallischen Werkstücken in Kammeröfen
DE10321414B4 (de) * 2003-05-13 2008-12-18 Robert Bosch Gmbh Verfahren zur Wärmebehandlung von metallischen Werkstücken in Kammeröfen

Also Published As

Publication number Publication date
EP0662525A1 (fr) 1995-07-12
ATE154832T1 (de) 1997-07-15
US5498299A (en) 1996-03-12
DE4400391A1 (de) 1995-07-13
DE59403219D1 (de) 1997-07-31

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