EP0010484B1 - Verbesserung der Inchromierung von Stahl in der Gasphase - Google Patents

Verbesserung der Inchromierung von Stahl in der Gasphase Download PDF

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Publication number
EP0010484B1
EP0010484B1 EP79400724A EP79400724A EP0010484B1 EP 0010484 B1 EP0010484 B1 EP 0010484B1 EP 79400724 A EP79400724 A EP 79400724A EP 79400724 A EP79400724 A EP 79400724A EP 0010484 B1 EP0010484 B1 EP 0010484B1
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EP
European Patent Office
Prior art keywords
nitrogen
steels
chromising
chromium
hours
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
Application number
EP79400724A
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English (en)
French (fr)
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EP0010484A1 (de
Inventor
Robert Leveque
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Creusot Loire SA
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Creusot Loire SA
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Application filed by Creusot Loire SA filed Critical Creusot Loire SA
Priority to AT79400724T priority Critical patent/ATE1529T1/de
Publication of EP0010484A1 publication Critical patent/EP0010484A1/de
Application granted granted Critical
Publication of EP0010484B1 publication Critical patent/EP0010484B1/de
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Classifications

    • 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
    • C23C12/00—Solid state diffusion of at least one non-metal element other than silicon and at least one metal element or silicon into metallic material 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

Definitions

  • the present invention relates to an improvement in chromium-plating by gas of steels with more than 0.2% carbon, more particularly structural steels and tool steels; this improvement makes it possible to significantly increase the thickness of the chromized layer, as well as its toughness.
  • chromization of steels by gas is well known.
  • the formation of chromium-based diffusion alloys on the surface of steels has already been described in numerous invention patents.
  • the transport of chromium to the surface of the material to be treated is carried out by means of halides, which are the only chromium compounds in the vapor state at diffusion temperatures.
  • the passage of chromium in solid solution in the metal is made by exchange between the chromium halide and the iron according to a reaction which, in the case of chlorides, can be written:
  • the reaction must be carried out at high temperature and in the austenitic range, that is to say above 850 ° C. for the usual steels.
  • the surface reaction of carbon and chromium causes on the one hand the formation of a film of chromium carbides, on the other hand a diffusion of carbon towards the area.
  • the surface film consists of two types of carbides, M 23 C 6 , richer in chromium towards the surface and M 7 C 3 , poorer in chromium, towards the metal substrate.
  • M indicates a metal such as der (Fe), chromium (Cr), nickel (Ni), etc ...
  • the surface film has a thickness between 12 and 18 micrometers, and a hardness level between 1200 and 1800 in the Vickers hardness scale. Chromium thus diffuses into steel over a depth generally close to 15 micrometers. In known methods, this depth of chromization never exceeds 20 micrometers.
  • a first solution for increasing the thickness and the toughness of the carbide layers can be constituted by an initial treatment phase consisting of a rapid rise in temperature, in particular in the range 600-900 ° C where usually precipitate carbides M I C 3 in the ferritic structure.
  • an initial treatment phase consisting of a rapid rise in temperature, in particular in the range 600-900 ° C where usually precipitate carbides M I C 3 in the ferritic structure.
  • such a solution would present risks with regard to the initiation of cracking and spalling during heating, in particular for parts of relatively alloyed steels having geometries which are ill-suited to the high stresses of thermal origin which would result from such a cycle of heater.
  • the present invention while applying the principle of chromizing the part in the austenitic phase, avoids the risks mentioned above by first producing a nitrided layer, but without a combination layer, that is to say in such a way that it does not in any way formation of a surface layer of iron and chromium nitrides. Indeed, a surface layer of iron nitrides would remain relatively stable, even at high temperatures, and would constitute a real barrier opposing the diffusion of chromium, this barrier being reinforced by the formation of chromium nitrides linked to an additional contribution. nitrogen.
  • the subject of the present invention is a process for chromizing steels over a depth e greater than 40 micrometers, usable for steels having a carbon content at least equal to 0.2%, in particular for structural steels and for tool steels, consisting of three successive treatments, namely: a nitriding treatment, a gas chromizing treatment and a thermal treatment, and characterized in that the nitriding treatment consists of ionic nitriding of a surface layer with a thickness between 100 and 350 micrometers, produced in an atmosphere consisting of a mixture of nitrogen and hydrogen, at a temperature between 450 ° C and 650 ° C, for a period between 5 and 40 hours , so as to obtain between 1.5% and 2.5% of nitrogen in the nitrided layer, in that the chromization by gas-forming form of chromium carbides, lasting between 5 and 30 hours, is carried out at temperatures between 850 ° C and 1,100 ° C, and in that the heat treatment comprises an oil
  • the ionic nitriding forming the first of the three treatments and carried out under a nitrogen and hydrogen atmosphere is carried out under a partial nitrogen pressure at most equal to 150 Pascals, and under a total gas pressure. between 200 and 1000 Pascals.
  • the chromization forming the second of the three treatments uses a pulverulent mixture based on ferro-chromium and on chloride of ammonium, the latter representing by weight only 0.4% to 1% of the pulverulent mixture, the ferro-chromium powder preferably having a chromium content of between 50% and 75% and a particle size of between 0.5 millimeter and 4 millimeters, without aluminous or magnesium binder.
  • ionic nitriding should be understood to mean a thermochemical treatment of a metal surface by ion bombardment with rarefied gas, performing surface nitriding of the metal part placed in a cathode under an atmosphere. nitrogen and hydrogen at a temperature between 450 ° C and 650 ° C.
  • thermochemical treatments of metal surfaces by ion bombardments, and more particularly nitriding are based on the properties of the electric discharge in rarefied gases, in this case mixtures of nitrogen and hydrogen with possibly hydrocarbons.
  • the reactive gas atmosphere can be chosen independently of the need for its pyrolitic cracking since its activation is obtained by ionization. It is therefore possible to adjust the partial nitrogen pressure so that the phase or phases provided for in the binary iron-nitrogen balance diagram are superficially formed.
  • one of the main advantages of the invention consists, thanks to ionic nitriding, in obtaining a nitrided layer without combination layer, that is to say without iron and chromium nitrides, in a way reliable and repetitive by adjusting the partial pressure of nitrogen as a function of the treatment temperature and the chemical composition of the steel. So, without the risk of cracking, the steel on the surface can quickly pass into the austenitic phase at moderate temperature, because of a nitrogen content of the order of 1.5% to 2.5%.
  • gas chromization can be carried out at greater depth, for example up to 50 micrometers and even more, and with the formation on the surface of a single type of carbonitrides, in Cr 2 (C, N), this which results in a significant increase in the toughness of the coating.
  • a chromium-molybdenum-vanadium steel of the type is treated 35 CDV 12, therefore at 0.35% carbon, in order to obtain a chromization depth of 50 micrometers.
  • the ionic nitriding which constitutes the first of the three successive treatments according to the invention is carried out here in a metal enclosure provided with heat shields and cooled by circulation of water, which enclosure constitutes the anode connected to the ground.
  • the electrical parameters are chosen in such a way that the current increases with the direct voltage produced by the generator and that the sample to be nitrided which constitutes the cathode is covered by the corona corresponding to the abnormal discharge regime. Near the cathode surface, the gaseous ions are formed and accelerated towards the sample and cause it to heat up, which is continued until the temperature chosen to carry out the thermochemical treatment.
  • the temperature regulation is obtained using a thermocouple protected by an alumina sheath and placed in the sample under conditions which prevent arcing.
  • the pressure at which the thermochemical treatment is carried out is generally between 250 and 800 Pascals; a primary pump is sufficient to create the initial vacuum, then to allow the renewal of the nitriding gas near the sample.
  • the nitriding gas mixture is composed of nitrogen and hydrogen.
  • the partial pressures of nitrogen P N for which oh obtains a solid solution of nitrogen in the ferrite network are between 10 and 50 Pascals.
  • the temperature is set on average at 520 ° C and does not deviate from the range between 510 and 530 ° C. Leaving aside the temperature rise and the low pressure setting of the atmosphere, the duration of ion nitriding at good pressure and at the right temperature is 25 hours.
  • the metal piece of CDV 12 steel 35 thus nitrided is then extracted from the ion nitriding furnace and introduced into a case-hardening box which will carry out the second treatment according to the invention, which is gas chromization.
  • the cementing agent used is a powder consisting for 99.5% of ferro-chromium with 60/70% of chromium and for 0.5% of ammonium chloride, without alumina or magnesia.
  • This powder has a particle size between 0.5 and 4 mm, with an average size close to 2.7 mm.
  • This powder is placed at the bottom of the case-hardening box, which has the shape of a vertical cylinder, and it is covered by a partition on which the piece of steel to be chromized is placed.
  • At the upper part of the case-hardening box there is a ferro-chromium reserve in a basket used for the direct regeneration of the active vapor of chromium chloride CrCI 2 . Introduced hydrogen creates a reducing atmosphere.
  • the enclosure is brought to an average temperature of 950 ° C, not deviating from the range 920 ° C-980 ° C, for a period of 20 hours.
  • the ferrous chloride vapors from reaction (1) react on the chromium reserve placed at the top of the body, which regenerates gaseous chromium chloride CrCI 2 which participates in the chromization according to (1).
  • the chromized part undergoes the third treatment according to the invention, that is to say that it is extracted from the case hardening box, it is immediately soaked in oil , then it is introduced into a tempering oven maintained at a temperature of the order of 625 ° C., for 2 hours.
  • the chromized coating thus obtained in the present example according to the invention is to be compared with that of a chromization of known type, not preceded by ionic nitriding.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Claims (3)

1. Verfahren zur Inchromierung von Stählen auf eine Tiefe e von mehr als 40 Mikrometern, das auf Stähle mit einem Kohlenstoffgehalt von mindestens 0,2% anwendbar ist und durch drei aufeinanderfolgende Behandlungsvorgänge gebildet ist, nämlich durch eine Nitrierungs-Behandlung, eine Inchromierungs-Behandlung über die Gasphase und eine Wärme-Behandlung, dudurch gekennzeichnet, daß die Nitrierungs-Behandlung in einer ionischen Nitrierung einer Oberflächen-Schicht in einer Dicke zwischen 100 und 350 Mikrometern besteht, welche in einer Atmosphäre aus einem Gemisch von Stickstoff und Wasserstoff innerhalb eines Temperaturbereiches zwischen 450 und 650°C und eines Zeitraums zwischen 5 und 40 Stunden durchgeführt wird, so daß in der nitrierten Schicht ein Gehalt zwischen 1,5 und 2,5% Stickstoff erhalten wird, daß die Inchromierung über die Gasphase zur Bildung von Chromkarbiden innerhalb eines Zeitraums zwischen 5 und 30 Stunden und eines Temperaturbereichs zwischen 850 und 1100°C durchgeführt wird und daß die Wärmebehandlung eine Öl-Härtung des inchromierten Werkstückes, gefolgt von einer Vergütung bei einer Temperatur innerhalb eines Bereichs zwischen 600 und 650°C, und je nach den Abmessungen des behandelten Werkstücks innerhalb eines Zeitraums zwischen 30 Minuten und 10 Stunden umfaßt.
2. Verfahren zur Inchromierung von Stählen nach Anspruch 1, dadurch gekennzeichnet, daß die ionische Nitrierung, welche den ersten der drei Behandlungsvorgänge darstellt und in einer Atmosphäre aus Stickstoff und Wasserstoff durchgeführt wird, bei einem Stickstoff-Partialdruck von höchstens gleich 150 Pascal und einem Gas-Gesamt druck innerhalb eines Bereichs Zwischen 200 und 1000 Pascal vorgenommen wird.
3. Verfahren zur Inchromierung von Stählen nach einem der Ansprüche 1 und 2, bei welchem die Inchromierung, welche den zweiten der drei Behandlungsvorgänge darstellt, nach der bekannten Zementations-Technik in einer reduzierenden Atmosphäre auf Basis von Wasserstoff Vorgenommen und als Zement eine pulverförmige Mischung auf der Basis von Ferrochrom und Ammoniumchlorid eingesetzt wird, dadurch gekennzeichnet, daß die pulverförmige Mischung zwischen 0,4 und 1% Ammoniumchlorid enthält, daß das Ferrochrompulver einen Chrom-Gehalt im Bereich zwischen 50 und 75% und eine KorngrößenVerteilung im Bereich zwischen 0,5 und 4 mm aufweist und weder ein, Aluminium- noch eine Magnesium-Bindemettel vorhanden ist.
EP79400724A 1978-10-25 1979-10-08 Verbesserung der Inchromierung von Stahl in der Gasphase Expired EP0010484B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT79400724T ATE1529T1 (de) 1978-10-25 1979-10-08 Verbesserung der inchromierung von stahl in der gasphase.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7830308 1978-10-25
FR7830308A FR2439824A1 (fr) 1978-10-25 1978-10-25 Perfectionnement dans la chromisation des aciers par voie gazeuse

Publications (2)

Publication Number Publication Date
EP0010484A1 EP0010484A1 (de) 1980-04-30
EP0010484B1 true EP0010484B1 (de) 1982-09-08

Family

ID=9214133

Family Applications (1)

Application Number Title Priority Date Filing Date
EP79400724A Expired EP0010484B1 (de) 1978-10-25 1979-10-08 Verbesserung der Inchromierung von Stahl in der Gasphase

Country Status (7)

Country Link
US (1) US4242151A (de)
EP (1) EP0010484B1 (de)
JP (1) JPS6035989B2 (de)
AT (1) ATE1529T1 (de)
DE (1) DE2963643D1 (de)
FR (1) FR2439824A1 (de)
ZA (1) ZA795719B (de)

Families Citing this family (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2454471A1 (fr) * 1979-04-20 1980-11-14 Aubert Et Duval Procede de chromisation de pieces metalliques telles que des pieces d'acier et pieces metalliques chromisees
FR2483468A2 (fr) * 1980-05-29 1981-12-04 Creusot Loire Perfectionnement dans la chromisation des aciers par voie gazeuse
US4818351A (en) * 1986-07-30 1989-04-04 Kabushiki Kaisha Toyota Chuo Kenkyusho Method for the surface treatment of an iron or iron alloy article
FR2604188B1 (fr) * 1986-09-18 1992-11-27 Framatome Sa Element tubulaire en acier inoxydable presentant une resistance a l'usure amelioree
GB2204327B (en) * 1987-05-01 1991-07-31 Nii Tekh Avtomobil Promy Deposition of diffusion carbide coatings on iron-carbon alloy articles
US5460875A (en) * 1990-10-04 1995-10-24 Daidousanso Co., Ltd. Hard austenitic stainless steel screw and a method for manufacturing the same
JP3023222B2 (ja) * 1991-08-31 2000-03-21 大同ほくさん株式会社 硬質オーステナイト系ステンレスねじおよびその製法
US5226975A (en) * 1991-03-20 1993-07-13 Cummins Engine Company, Inc. Plasma nitride chromium plated coating method
KR100503497B1 (ko) * 2002-11-25 2005-07-26 한국기계연구원 크롬도금층의 내식성 및 내마모성을 향상시키는 열처리방법
CN1300445C (zh) * 2003-12-26 2007-02-14 东方汽轮机厂 一种汽轮机高温叶片及其热处理工艺
JP4488840B2 (ja) * 2004-08-30 2010-06-23 本田技研工業株式会社 硬質窒化物層の形成方法、並びにこの形成方法により得られたローラーチェーン及びサイレントチェーン
DE102005041080A1 (de) * 2004-08-31 2006-03-16 Tochigi Fuji Sangyo K.K. Reibeingriffsvorrichtung
US9598761B2 (en) 2009-05-26 2017-03-21 The Gillette Company Strengthened razor blade
JP6637231B2 (ja) * 2014-10-07 2020-01-29 エア・ウォーターＮｖ株式会社 金属の表面改質方法および金属製品
WO2020170264A1 (en) * 2019-02-21 2020-08-27 Fluid Controls Private Limited Method of heat treating an article
CN112575333A (zh) * 2020-11-24 2021-03-30 江西铜印象文化创意有限公司 一种铜工艺品除杂式表面热处理工艺

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US1902503A (en) * 1930-05-29 1933-03-21 Gen Electric Process for coating metals
US2046638A (en) * 1932-04-22 1936-07-07 Link Belt Co Process of treating metal
US3256818A (en) * 1955-11-26 1966-06-21 Berghaus Bernhard Method of reducing barrel wear
US3190772A (en) * 1960-02-10 1965-06-22 Berghaus Bernhard Method of hardening work in an electric glow discharge
US3282746A (en) * 1963-11-18 1966-11-01 Formsprag Co Method of hardening wear surfaces and product
FR1410647A (fr) * 1964-10-05 1965-09-10 Formsprag Co Procédé de durcissement des surfaces frottantes et nouveaux produits industriels obtenus
DE1521325C3 (de) * 1966-04-13 1975-06-26 Elektrophysikalische Anstalt Bernhard Berghaus, Vaduz Verfahren zur Gewinnung von verschleißfesten Gleitflächen mit guten Einlaufeigenschaften auf Werkstücken aus Elsen und Stahl
FR95448E (fr) * 1967-06-27 1970-11-06 Ct Stephanois De Rech Mecaniqu Traitement de surface pour pieces mécaniques.
DE1621268B1 (de) * 1967-10-26 1971-06-09 Berghaus Elektrophysik Anst Verfahren und Vorrichtung zur Ionitrierung von Hochlegierten Staehlen
GB1318887A (en) * 1969-10-31 1973-05-31 Lucas Industries Ltd Method of manufacturing high strength extruded steel components
CH519588A (de) * 1970-02-13 1972-02-29 Berghaus Elektrophysik Anst Verfahren zur Bearbeitung eines Werkstückes mittels einer Glimmentladung und Apparatur zur Durchführung des Verfahrens

Also Published As

Publication number Publication date
JPS6035989B2 (ja) 1985-08-17
DE2963643D1 (en) 1982-10-28
ATE1529T1 (de) 1982-09-15
FR2439824A1 (fr) 1980-05-23
ZA795719B (en) 1980-10-29
EP0010484A1 (de) 1980-04-30
US4242151A (en) 1980-12-30
JPS5558366A (en) 1980-05-01
FR2439824B1 (de) 1981-05-08

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