EP0018263B1 - Verfahren zum Verchromen von Stahlgegenständen und mit einem Chromdiffusionsüberzug versehene Stahlgegenstände - Google Patents

Verfahren zum Verchromen von Stahlgegenständen und mit einem Chromdiffusionsüberzug versehene Stahlgegenstände Download PDF

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Publication number
EP0018263B1
EP0018263B1 EP80400451A EP80400451A EP0018263B1 EP 0018263 B1 EP0018263 B1 EP 0018263B1 EP 80400451 A EP80400451 A EP 80400451A EP 80400451 A EP80400451 A EP 80400451A EP 0018263 B1 EP0018263 B1 EP 0018263B1
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EP
European Patent Office
Prior art keywords
nitrogen
steel
layer
steel piece
chromium
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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
EP80400451A
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English (en)
French (fr)
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EP0018263A1 (de
Inventor
André Robert Faure
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Atto Confirmatorio E Ricognitivo Di Licenza Esclus
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Aubert and Duval SA
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Priority to AT80400451T priority Critical patent/ATE3883T1/de
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Publication of EP0018263B1 publication Critical patent/EP0018263B1/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
    • 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
    • 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
    • C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
    • C23C10/02—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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12535—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] with additional, spatially distinct nonmetal component
    • Y10T428/12576—Boride, carbide or nitride component
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771—Transition metal-base component
    • Y10T428/12806—Refractory [Group IVB, VB, or VIB] metal-base component
    • Y10T428/12826—Group VIB metal-base component
    • Y10T428/12847—Cr-base component
    • Y10T428/12854—Next to Co-, Fe-, or Ni-base component

Definitions

  • the present invention relates to a method for chromizing steel parts, of the type according to which chromium is diffused in order to obtain a surface layer of chromium and according to which the chromium contribution is obtained by decomposition in the gas phase d halides, the decomposition of the halide and the diffusion of chromium in the steel being carried out simultaneously by heating the parts to temperatures not exceeding 1300 ° C, in the halide atmosphere, the operation of actual chromization being preceded by a surface nitrogen addition operation.
  • the actual chromization is known, for example, from the work of Doctor GAL-MICHE and from the French patents ONERA n ° 1 012 401 and their two additions 60 539 and 60686.
  • the object of the present invention is to propose a hard chromization process of the aforementioned type and making it possible to produce steel parts having a hard chromized surface layer comprising carbo-nitrides, a layer having a thickness greater than at least 20 ⁇ m, preferably 30 ⁇ m, and a fine grain undercoat with little or no decarburization.
  • This object is achieved by the fact that prior to the actual chromizing operation, the introduction of nitrogen into the surface layer of the steel part is made so that the nitrogen surface layer has a content greater than 0 , 8% nitrogen over a depth or thickness at least equal to 0.5 mm.
  • the surface introduction of nitrogen is carried out by heating the part to be treated at a temperature between 400 and 800 ° C and in any case at a temperature below the lower critical point of the treated steel, and during the times between 12 and 150 hours in a nitrogen generating medium which, by way of example may consist of molten nitrous salts, ammonia or nitrogen gases, ionized or not.
  • the invention obtains after the actual chromizing operation of the hard chromized layers comprising carbonitrides instead of separate carbides and / or separate nitrides, these layers being of a thickness greater than at least 20 ⁇ m and having a high resistance to wear.
  • the presence of nitrogen in the surface layers of the steel parts makes it possible to achieve a different balance of the chromium and carbon elements with respect to the base steel during the chromization reaction, this different balance thus allowing to obtain much deeper chromized surface layers without producing significantly decarburized undercoats and without enlarging the grain as an undercoat.
  • nitrogenous surface layers previously containing more than 0.8% nitrogen over a depth at least equal to 0.5 mm.
  • nitrogenous surface layers are prepared having a nitrogen content of between 1 and 2% over a depth of 0.5 to 1.0 mm.
  • Such satisfactory nitrogenous layers can be obtained by treatment cycles in an ammonia atmosphere of 24 hours at 700 ° C. or 90 hours at 560 ° C.
  • the chromium halide atmosphere conforms to the already known technique
  • the temperature and holding time parameters can be conformed to the already known technique, but they can also be modified according to the prior introduction of nitrogen; compared to what they would be on the same steel not "activated in accordance with the present invention.
  • the chromization temperatures can be reduced in order to limit the magnification of the grains of the undercoat.
  • the steel parts may preferably undergo a regenerative heat treatment in order to reduce the grain sizes and improve the resilience of the base steel.
  • the comparison drawing shows the comparison of the chromized layers obtained on the same steel grade 32 CDV 13 (AFNOR) by known chromization techniques without or with prior activation by nitrogen and in the three cases followed by a heat treatment of grain regeneration by heating under vacuum, quenching and tempering.
  • AFNOR chromization technique
  • FIG. 1 is a micro-hardness diagram showing for the steel grade 32 CDV 13 (AFNOR) three examples of chromized steel parts and, FIGS. 2 to 4 show microphotos of the surface layer and of the adjacent undercoat of these three examples of chrome-plated steel parts, the enlargement factor in all three cases being 200.
  • AFNOR steel grade 32 CDV 13
  • FIGS. 2 to 4 show microphotos of the surface layer and of the adjacent undercoat of these three examples of chrome-plated steel parts, the enlargement factor in all three cases being 200.
  • the curve has a solid line represents the hardness of a piece of steel in Vickers degrees as a function of the depth of the level considered.
  • This piece of steel, the transverse structure of which is illustrated in FIG. 2 has not been subjected to prior activation by nitrogen, but only a chromium-plating operation of 12 hours at 940 ° C.
  • the chromized surface layer 1 has a depth or thickness of 12 ⁇ m and has a Vickers hardness greater than 1,500 points and reaching more than 1,800 points.
  • a sub-layer 2 whose Vickers hardness decreases rapidly to a minimum value of 260 and then slowly rises to Vickers hardness at the heart of the steel part, hardness which is of the order of 350 and is reached at a depth of 77 ⁇ m.
  • this sublayer or decarburization zone 2 is of the order of 65 ⁇ m which is more than 5 times the thickness of the chromized surface layer 1 and the minimum hardness of the sublayer 2 is only about 3/4 of the Vickers hardness at the heart of the steel part.
  • the decrease in the hardness of the underlay compared to that of the core of the steel part clearly shows the extent of the decarburized zone and the harmful influence of the inevitable carbon pumping during the known chromization operation. It is also noted from FIG. 2 that the size of the grain in the sub-layer is significant (Afnor index 4).
  • Curve b of FIG. 1 shows the hardness of a piece of steel of the same aforementioned grade without activation with nitrogen, subjected to a chromization operation also for 12 hours, but at a higher temperature, namely 980 ° C.
  • This increase in temperature brings the depth of the chromized surface layer 1 to 16 ⁇ m, but on the other hand the corresponding structure illustrated in FIG. 3 shows an even larger and unfavorable grain size (Afnor index 3) than that of the structure shown. in FIG.
  • the microdurethane diagram shows at the bottom of curve b between a depth of 16 ⁇ m and 85 ⁇ m (sublayer 2) an even deeper and more intense decarburization zone (minimum Vickers hardness 240 points) than that of the example of curve a and of FIG. 2.
  • the Vickers hardness of the underlay 2 is of the order of 2/3 of the Vickers hardness at the heart of the steel piece and the layer 2 with its decarburized zone has a thickness at least four times greater than that of the chromized surface layer 1.
  • Curve c of FIG. 1 corresponds to a piece of steel having undergone prior activation by the surface introduction of nitrogen in accordance with the present invention (treatment cycle of 90 hours at 560 ° C.).
  • This curve c in FIG. 1 shows the Vickers hardness of a piece of steel of the same grade as the previous examples, but is obtained after the same chromization cycle as the example of curve a, that is 12 hours at 940 ° C.
  • the chromized layer 1 has a depth of 50 wm.
  • the structure illustrated in FIG. 4 also shows the fineness of the grain obtained in the sub-layer 2 over a depth of 1 mm and the diagram of microduretures (FIG. 1) shows for the curve c a much less thick decarburization zone (20 to 30 Jlm) and less intense (minimum Vickers hardness around 330 points) than in the two previous examples.
  • the thickness of the decarburized zone is very small, is less than that of the chromized layer 1 and is only approximately equal to half that of said chromized layer 1.
  • the hardness of the decarburized zone of the underlayer 2 it is at least equal to about 95% of the hardness of the core of the steel piece.
  • the loss of hardness in the underlay with respect to the base steel at the heart of the steel part is less than 25 Vickers points and affects a weakly decarburized zone with a thickness of less than 25 ⁇ m.
  • carbon-containing steel intended for hard chromium plating has a surface layer containing at least 0.8% nitrogen over a depth greater than 0.5 mm. It has been found that to the extent that the nitrogen content of the surface layer before chromization exceeds 0.8% over a depth of 0.5 mm, there is found after said chromization in the sublayer a residual nitrogen content greater than 0.4% over a depth greater than 0.5 mm, this nitrogen content preventing significant decarburization and significant enlargement of the grain of the undercoat.
  • the nitrogen content of the surface layer of the steel is, before chromization, greater than 0.8% over a depth greater than 0.5 mm, after said chromization is found in the chromized surface layer the presence of chromium carbonitrides with a nitrogen content greater than 2%.
  • the invention relates not only to the new hard chromizing process, but also to the pieces of steel chromized according to the present process and having a hard chromized surface layer with a depth at least equal to 20 ⁇ m and having a Vickers hardness at least equal. at 1,200 points.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Heat Treatment Of Steel (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)

Claims (8)

1. Verfahren zum Inchromieren von Stahlstücken, bei welchem zur Erzielung einer Chrom-Oberflächenschicht Chrom in die Oberfläche von Stahlstücken diffundieren gelassen wird und bei welchem die Zufuhr von Chrom durch Zersetzung von Chromhalogeniden in der Gasphase erzielt wird, wobei die Halogenidzersetzung und die Chromdiffusion in den Stahl unter Erhitzen der Stücke auf Temperaturen von höchstens 1 300 °C in Halogenidatmosphäre gleichzeitig durchgeführt werden, wobei dem eigentlichen Inchromierverfahren ein Verfahren zur oberflächlichen Zufuhr von Stickstoff vorangeht, dadurch gekennzeichnet, daß die Einbringung von Stickstoff in die Oberflächenschicht des Stahlstücks derart durchgeführt wird, daß die mit Stickstoff behandelte Oberflächenschicht über eine Tiefe bzw. Dicke von zumindest 0,5 mm einen Stickstoffgehalt von mehr als 0,8 % aufweist, daß diese Einbringung von Stickstoff in die Oberfläche durch Erhitzen des zu behandelnden Stahlstücks auf eine Temperatur zwischen 400 °C und 800 °C und auf jeden Fall auf eine Temperatur, die unter dem unteren kritischen Punkt des behandelten Stahlstücks liegt, in einem stickstofferzeugenden Milieu durchgeführt wird und daß die Dauer des Zyklus der Einbringung von Stickstoff zwischen 12 und 150 Stunden beträgt.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Einbringung von Stickstoff . in die Oberfläche des Stahlstücks unmittelbar vom eigentlichen Inchromierverfahren gefolgt wird.
3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß nach dem Zyklus der Einbringung von Stickstoff in die Oberfläche das mit Stickstoff behandelte Stahlstück abkühlen gelassen wird, bevor es dem eigentlichen Inchromierverfahren unterzogen wird.
4. Stahlstück mit einer inchromierten Oberflächenschicht einer Härte von zumindest 1 200 Vickers, einer Stärke von zumindest 20 µm, die Carbonitride aufweist, sowie mit einer darunter befindlichen Schicht, welche eine an die inchromierte Schicht angrenzende entkohlte Zone darstellt und eine niedrigere Härte als jene des Kerns des Stahlstücks aufweist, dadurch gekennzeichnet, daß die Dicke der entkohlten Zone geringer ist als jene der inchromierten Oberflächenschicht, und daß die Erniedrigung der Härte in der entkohlten Zone der darunter befindlichen Schicht gegenüber der Härte des Stahls im Kern des Stücks weniger als 25 Vickers-Punkte beträgt.
5. Stahlstück nach Anspruch 4, dadurch gekennzeichnet, daß die entkohlte Zone eine Tiefe bzw. Dicke von weniger als 30 µm aufweist.
6. Stahlstück nach einem der Ansprüche-4 und 5, dadurch gekennzeichnet, daß die darunter befindliche Schicht über eine Dicke bzw. Tiefe von zumindest 0,5 mm feines Korn mit einem Afnor-Index von gleich oder höher als 6 aufweist.
7. Stahlstück nach einem der Ansprüche 4 bis 6, dadurch gekennzeichnet, daß der Gehalt der darunter befindlichen Schicht an Reststickstoff mehr als 0,4 % beträgt.
8. Stahlstück nach Anspruch 7, dadurch gekennzeichnet, daß die darunter befindliche Schicht über eine Dicke bzw. Tiefe von mehr als 0,5 mm Reststickstoff aufweist.
EP80400451A 1979-04-20 1980-04-03 Verfahren zum Verchromen von Stahlgegenständen und mit einem Chromdiffusionsüberzug versehene Stahlgegenstände Expired EP0018263B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT80400451T ATE3883T1 (de) 1979-04-20 1980-04-03 Verfahren zum verchromen von stahlgegenstaenden und mit einem chromdiffusionsueberzug versehene stahlgegenstaende.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7910094A FR2454471A1 (fr) 1979-04-20 1979-04-20 Procede de chromisation de pieces metalliques telles que des pieces d'acier et pieces metalliques chromisees
FR7910094 1979-04-20

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EP0018263A1 EP0018263A1 (de) 1980-10-29
EP0018263B1 true EP0018263B1 (de) 1983-06-22

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EP (1) EP0018263B1 (de)
AT (1) ATE3883T1 (de)
DE (1) DE3063830D1 (de)
FR (1) FR2454471A1 (de)

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US4578319A (en) * 1984-05-08 1986-03-25 Toyo Kohan Co., Ltd. Surface treated steel sheet having an excellent weldability and its production method
US4765847A (en) * 1985-06-17 1988-08-23 Kabushiki Kaisha Toyota Chuo Kenkyusho Method of treating the surface of iron alloy materials
JP2584217B2 (ja) * 1986-11-18 1997-02-26 株式会社豊田中央研究所 表面処理方法
US5123972A (en) * 1990-04-30 1992-06-23 Dana Corporation Hardened insert and brake shoe for backstopping clutch
SA05260056B1 (ar) 1991-03-08 2008-03-26 شيفرون فيليبس كيميكال كمبني ال بي جهاز لمعالجة الهيدروكربون hydrocarbon
US5575902A (en) * 1994-01-04 1996-11-19 Chevron Chemical Company Cracking processes
US6258256B1 (en) 1994-01-04 2001-07-10 Chevron Phillips Chemical Company Lp Cracking processes
US6274113B1 (en) 1994-01-04 2001-08-14 Chevron Phillips Chemical Company Lp Increasing production in hydrocarbon conversion processes
US6419986B1 (en) 1997-01-10 2002-07-16 Chevron Phillips Chemical Company Ip Method for removing reactive metal from a reactor system
US6197125B1 (en) * 1999-12-13 2001-03-06 Mcdermott Technology, Inc. Modification of diffusion coating grain structure by nitriding
JP4977700B2 (ja) * 2005-07-21 2012-07-18 ハード テクノロジーズ プロプライエタリー リミテッド 金属物の複合表面処理
CN115058684B (zh) * 2022-06-29 2024-02-09 中国航发动力股份有限公司 一种高碳工具钢铬硬化层的制备方法

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US2437249A (en) * 1946-04-17 1948-03-09 Nitralloy Corp Method of nitriding
FR1012401A (fr) * 1949-08-05 1952-07-09 Onera (Off Nat Aerospatiale) Perfectionnements apportés aux procédés de formation d'alliages superficiels de diffusion, notamment de chrome
FR60539E (fr) * 1949-12-06 1954-11-09 Nat D Etudes & De Rech S Aeron Perfectionnements apportés aux procédés de formation d'alliages superficiels de diffusion, notamment de chrome
FR60686E (fr) * 1950-06-27 1954-11-22 Onera (Off Nat Aerospatiale) Perfectionnements apportés aux procédés de formation d'alliages superficiels de diffusion, notamment de chrome
US3256818A (en) * 1955-11-26 1966-06-21 Berghaus Bernhard Method of reducing barrel wear
US3152007A (en) * 1961-04-13 1964-10-06 Diamond Alkali Co Process for chromizing ferrous metal objects
US3205153A (en) * 1962-05-21 1965-09-07 Chandler Evans Inc Process and product of chrome plating nitrided steel
US3222212A (en) * 1962-11-29 1965-12-07 Alloy Surfaces Co Inc Process for chromizing
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FR1410647A (fr) * 1964-10-05 1965-09-10 Formsprag Co Procédé de durcissement des surfaces frottantes et nouveaux produits industriels obtenus
US3414428A (en) * 1964-10-20 1968-12-03 Allied Chem Chromizing compositions and methods and continuous production of chromium halides for chromizing
FR95448E (fr) * 1967-06-27 1970-11-06 Ct Stephanois De Rech Mecaniqu Traitement de surface pour pieces mécaniques.
FR1555534A (de) * 1967-06-27 1969-01-31
FR2031373A1 (en) * 1969-02-17 1970-11-20 Petignat Maurice Surface-hardening of oxidn resistant austen - itic steel parts
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FR2439824A1 (fr) * 1978-10-25 1980-05-23 Creusot Loire Perfectionnement dans la chromisation des aciers par voie gazeuse

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FR2454471A1 (fr) 1980-11-14
ATE3883T1 (de) 1983-07-15
DE3063830D1 (en) 1983-07-28
EP0018263A1 (de) 1980-10-29
US4481264A (en) 1984-11-06
FR2454471B1 (de) 1983-12-23

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