EP0043742B1 - Method of gas-chromizing steels - Google Patents
Method of gas-chromizing steels Download PDFInfo
- Publication number
- EP0043742B1 EP0043742B1 EP81400804A EP81400804A EP0043742B1 EP 0043742 B1 EP0043742 B1 EP 0043742B1 EP 81400804 A EP81400804 A EP 81400804A EP 81400804 A EP81400804 A EP 81400804A EP 0043742 B1 EP0043742 B1 EP 0043742B1
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- EP
- European Patent Office
- Prior art keywords
- steels
- case
- hardening agent
- carbon content
- gas
- 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.)
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 26
- 239000010959 steel Substances 0.000 title claims abstract description 26
- 238000000034 method Methods 0.000 title claims abstract description 11
- 238000005254 chromizing Methods 0.000 title claims 5
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 37
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 23
- 229910000604 Ferrochrome Inorganic materials 0.000 claims abstract description 12
- 238000011282 treatment Methods 0.000 claims abstract description 10
- 239000011651 chromium Substances 0.000 claims description 36
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 23
- 229910052804 chromium Inorganic materials 0.000 claims description 22
- 229910052757 nitrogen Inorganic materials 0.000 claims description 22
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 20
- 239000010410 layer Substances 0.000 claims description 13
- 239000007789 gas Substances 0.000 claims description 11
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 10
- 150000004820 halides Chemical class 0.000 claims description 10
- 239000003795 chemical substances by application Substances 0.000 claims description 9
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 claims description 8
- 238000005121 nitriding Methods 0.000 claims description 6
- 235000019270 ammonium chloride Nutrition 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 5
- 239000000843 powder Substances 0.000 claims description 5
- 229910001629 magnesium chloride Inorganic materials 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 4
- 239000011230 binding agent Substances 0.000 claims description 3
- 239000001257 hydrogen Substances 0.000 claims description 3
- 229910052739 hydrogen Inorganic materials 0.000 claims description 3
- 238000010791 quenching Methods 0.000 claims description 3
- 230000000171 quenching effect Effects 0.000 claims description 3
- 238000005496 tempering Methods 0.000 claims description 3
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 claims description 2
- 239000002344 surface layer Substances 0.000 claims description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 claims 1
- 239000000395 magnesium oxide Substances 0.000 claims 1
- 239000004568 cement Substances 0.000 abstract description 7
- 230000007797 corrosion Effects 0.000 description 5
- 238000005260 corrosion Methods 0.000 description 5
- 239000000758 substrate Substances 0.000 description 4
- 230000003746 surface roughness Effects 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 238000007747 plating Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 2
- 229910021555 Chromium Chloride Inorganic materials 0.000 description 2
- 101100258315 Neurospora crassa (strain ATCC 24698 / 74-OR23-1A / CBS 708.71 / DSM 1257 / FGSC 987) crc-1 gene Proteins 0.000 description 2
- VGIPUQAQWWHEMC-UHFFFAOYSA-N [V].[Mo].[Cr] Chemical compound [V].[Mo].[Cr] VGIPUQAQWWHEMC-UHFFFAOYSA-N 0.000 description 2
- 230000003416 augmentation Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- QSWDMMVNRMROPK-UHFFFAOYSA-K chromium(3+) trichloride Chemical compound [Cl-].[Cl-].[Cl-].[Cr+3] QSWDMMVNRMROPK-UHFFFAOYSA-K 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000005755 formation reaction Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- -1 chromium nitrides Chemical class 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 229910001337 iron nitride Inorganic materials 0.000 description 1
- 230000002045 lasting effect Effects 0.000 description 1
- 229910001635 magnesium fluoride Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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
Definitions
- the present invention relates to an improvement in chromium plating by gas of steels with more than 0.2% carbon, more especially structural steels and tool steels.
- the coatings consist essentially of chromium carbonitride Cr 2 (C, N), of which the very high chromium content (Cr between 75 and 85%) , the high level of hardness, between 2000 and 2500 Vickers (under 50 grams) and the hexagonal structure with the base plane of the mesh directed parallel to the surface of the substrate, make it a particularly interesting compound for all problems where l 'We are looking for good resistance to corrosion, friction and wear.
- the aim of the present invention is to produce single-phase layers of Cr 2 (C, N) by reducing the surface supply of chromium.
- the subject of the invention is an improvement to the gas chromium-plating process for steels with more than 0.2% carbon, consisting of the three successive treatments according to document EP-A-0 010 484, namely: ionic nitriding of a surface layer of thickness between 100 and 350 micrometers, carried out in an atmosphere constituted by 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; gas chromization, lasting between 5 and 30 hours, and carried out at temperatures between 850 ° and 1100 ° C; a heat treatment comprising an oil quenching of the chromized part followed by tempering at a temperature between 600 ° and 650 ° C, for a duration between 30 minutes and 10 hours; this improvement relating to a gas chromization treatment using a powdered cement based on halide and ferro-chromium at
- the halide of the cement consists of a powder of chloride of ammonium, at a concentration between 0.5% and 1.5% in said cement.
- the halide of the cement consists of a powder of magnesium chloride or fluoride d 'ammonium, at a concentration between 0.5% and 1.5% in said cement.
- the main improvement introduced by the present invention with respect to the prior patent consists in using only ferro-chromium whose carbon content is between 1% and 3%, and is preferably close to 2% .
- This presence of ferro-chromium carbon makes it possible to obtain, in gas chromization, a perfectly single-phase layer of chromium carbonitrides Cr 2 (C, N), and to avoid the formation of carbides M zs C e (M denoting a metal such as iron (Fe), chromium (Cr), nickel (Ni), etc.).
- a secondary improvement according to the present invention compared to the previous patent consists, for steels with a carbon content of between 0.20% and 0.35%, while preserving ammonium chloride as halide, to use it at a slightly increased concentration, between 0.5% and 1.5%, instead of 0.4% to 1%.
- Another improvement according to the present invention with respect to the prior patent consists, for steels with a carbon content greater than 0.35%, of replacing the ammonium chloride either with magnesium chloride or with ammonium fluoride, which are more stable halides than ammonium chloride.
- the first example relates to a chromium-molybdenum-vanadium steel, of the 32 CDV 13 type, therefore with 0.32% carbon.
- This steel underwent the first sequence of ionic nitriding under the conditions defined above and more precisely between 520 and 530 ° C, for 30 hours, under a partial nitrogen pressure of between 10 and 50 Pascals, the working pressure being between 250 and 800 Pascals. Under these conditions, the average nitrogen content of the steel between 50 and 200 micrometers deep reaches 2.1% and the nitrided layer does not contain iron nitrides or chromium nitrides.
- the second example relates to a chromium-molybdenum-vanadium steel of type 40 CDV 12, therefore with 0.40% carbon.
- This steel underwent the first sequence of ionic nitriding under the conditions which were specified during the description of the first example.
- the 40 CDV 12 steel sample thus nitrided is introduced into a case hardening box where the second phase of the treatment will take place, which is a gas chromization.
- the cementing agent consists of 99% ferrochrome with 65/70% chromium and 2% carbon with an average particle size of around 2.7 mm (range: 0.5 and 4 mm), and 1% of magnesium chloride, which, when the temperature rises, will decompose to give the active vapor of chromium chloride CrC1 2 .
- the enclosure is brought to an average temperature of 950 ° C for a period of 15 hours and the subsequent heat treatment of the steel part is carried out immediately after the chromization phase.
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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)
- Treatment Of Steel In Its Molten State (AREA)
- Heat Treatment Of Sheet Steel (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
Description
La présente invention concerne un perfectionnement à la chromisation par voie gazeuse des aciers à plus de 0,2% de carbone, plus spécialement les aciers de construction et les aciers à outils.The present invention relates to an improvement in chromium plating by gas of steels with more than 0.2% carbon, more especially structural steels and tool steels.
Dans le document EP-A-0 010 484, la demanderesse a décrit un procédé de chromisation en trois temps successifs, constitués de préférence ainsi:
- 1. Une nitruration ionique, à une température comprise entre 450 et 650°C, utilisant une atmosphère réactive d'azote et d'hydrogène sous une pression partielle d'azote au plus égale à 150 Pascals et sous une pression gazeuse totale comprise entre 200 et 1000 Pascals.
- 2. Une chromisation à une température comprise entre 850° et 1100° C avec un cément constitué par du ferrochrome avec une teneur en chrome allant de 50 à 75% et dont la granulométrie est comprise entre 0,5 et 4 mm, sans liant alumineux ni magnésien, mélangé à un halogénure.
- 3. Un traitement thermique comprenant une trempe à l'huile et un revenu entre 600° et 650°C selon le niveau de résistance demandé pour le substrat.
- 1. An ionic nitriding, at a temperature between 450 and 650 ° C, using a reactive atmosphere of nitrogen and hydrogen under a partial pressure of nitrogen at most equal to 150 Pascals and under a total gas pressure between 200 and 1000 Pascals.
- 2. Chromium plating at a temperature between 850 ° and 1100 ° C with a cement consisting of ferrochrome with a chromium content ranging from 50 to 75% and whose particle size is between 0.5 and 4 mm, without aluminous binder nor magnesian, mixed with a halide.
- 3. A heat treatment including oil quenching and tempering between 600 ° and 650 ° C depending on the level of resistance required for the substrate.
Il est ainsi possible d'augmenter sensiblement l'épaisseur des couches chromisées de haute dureté dans le cas des aciers alliés ayant plus de 0,2% de carbone. En effet, grâce à cette innovation, il est possible de réaliser des couches d'épaisseur égale à 50 micromètres alors que dans le meilleur des cas, la chromisation classique permet d'atteindre 20 micromètres. D'autre part, l'innovation selon le brevet antérieur intéresse également la structure des couches:
- - dans la chromisation classique, les revêtements sont constitués de deux types de carbures: M23C6, plus riche en chrome, vers la surface, et M7C3, plus pauvre en chrome, vers le substrat métallique.
- - in conventional chromization, the coatings consist 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 metallic substrate.
A la suite du traitement en trois stades faisant l'objet du brevet principal, les revêtements sont constitués essentiellement par le carbonitrure de chrome Cr2 (C, N), dont la très forte teneur en chrome (Cr compris entre 75 et 85%), le niveau élevé de dureté, compris entre 2000 et 2500 Vickers (sous 50 grammes) et la structure hexagonale avec le plan de base de la maille dirigé parallèlement à la surface du substrat, en font un composé particulièrement intéressant pour tous les problèmes où l'on recherche une bonne résistance à la fois à la corrosion, au frottement et à l'usure.Following the three-stage treatment which is the subject of the main patent, the coatings consist essentially of chromium carbonitride Cr 2 (C, N), of which the very high chromium content (Cr between 75 and 85%) , the high level of hardness, between 2000 and 2500 Vickers (under 50 grams) and the hexagonal structure with the base plane of the mesh directed parallel to the surface of the substrate, make it a particularly interesting compound for all problems where l 'We are looking for good resistance to corrosion, friction and wear.
Toutefois, dans les conditions opératoires décrites dans le brevet antérieur, l'obtention de couches monophasées de Cr2 (C, N) peut être délicate dans certains cas en raison de l'apport trop important de chrome en surface par rapport au flux d'azote provenant du substrat qui a subi la première phase de nitruration ionique. Il en résulte que sur les joints des formations basaltiques de Cr2 (C, N) se forme localement le carbure M23C6, et la présence dans le revêtement de ce deuxième composé a plusieurs inconvénients:
- - augmentation sensible de la rugosité superficielle,
- - augmentation du risque d'amorçage de fissures à l'interface entre les deux constituants M23C6 et Cr2 (C, N), d'où possibilité d'écaillage et de corrosion localisée.
- - significant increase in surface roughness,
- - increased risk of crack initiation at the interface between the two constituents M 23 C 6 and Cr 2 (C, N), hence the possibility of chipping and localized corrosion.
Le but de la présente invention est la réalisation de couches monophasées de Cr2 (C, N) par une réduction de l'apport superficiel de chrome.The aim of the present invention is to produce single-phase layers of Cr 2 (C, N) by reducing the surface supply of chromium.
A cet effet, l'invention a pour objet un perfectionnement au procédé de chromisation par voie gazeuse des aciers à plus de 0,2% de carbone, constitué des trois traitements successifs selon le document EP-A-0 010 484, à savoir: une nitruration ionique d'une couche superficielle d'épaisseur comprise entre 100 et 350 micromètres, réalisée dans une atmosphère constituée par un mélange d'azote et d'hydrogène, à une température comprise entre 450° C et 650° C, pendant une durée comprise entre 5 et 40 heures, de façon à obtenir entre 1,5% et 2,5% d'azote dans la couche nitrurée; une chromisation gazeuse, d'une durée comprise entre 5 et 30 heures, et réalisée à des températures comprises entre 850° et 1100°C; un traitement thermique comprenant une trempe à l'huile de la pièce chromisée suivie d'un revenu à une température comprise entre 600° et 650° C, d'une durée comprise entre 30 minutes et 10 heures; ce perfectionnement se rapportant à un traitement de chromisation gazeuse utilisant un cément pulvérulent à base d'halogénure et de ferro-chrome à 50%/75% de chrome, avec une granulométrie comprise entre 0,5 millimètre et 4 millimètres, sans liant alumineux ni magnésien, et étant caractérisé en ce que l'on choisit un ferro-chrome dont la teneur en carbone est comprise entre 1 % et 3%, et est de préférence voisine de 2%To this end, the subject of the invention is an improvement to the gas chromium-plating process for steels with more than 0.2% carbon, consisting of the three successive treatments according to document EP-A-0 010 484, namely: ionic nitriding of a surface layer of thickness between 100 and 350 micrometers, carried out in an atmosphere constituted by 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; gas chromization, lasting between 5 and 30 hours, and carried out at temperatures between 850 ° and 1100 ° C; a heat treatment comprising an oil quenching of the chromized part followed by tempering at a temperature between 600 ° and 650 ° C, for a duration between 30 minutes and 10 hours; this improvement relating to a gas chromization treatment using a powdered cement based on halide and ferro-chromium at 50% / 75% chromium, with a particle size between 0.5 millimeter and 4 millimeters, without aluminous binder or magnesian, and being characterized in that a ferro-chromium is chosen whose carbon content is between 1% and 3%, and is preferably close to 2%
Suivant une caractéristique particulière de l'invention, qui ne s'applique qu'aux aciers dont la teneur en carbone est comprise entre 0,20% et 0,35%, l'halogénure du cément est constitué par une poudre de chlorure d'ammonium, à une concentration comprise entre 0,5% et 1,5% dans ledit cément.According to a particular characteristic of the invention, which only applies to steels whose carbon content is between 0.20% and 0.35%, the halide of the cement consists of a powder of chloride of ammonium, at a concentration between 0.5% and 1.5% in said cement.
Suivant une autre caractéristique particulière de l'invention, qui ne s'applique qu'aux aciers dont la teneur en carbone est supérieure à 0,35%, l'halogénure du cément est constitué par une poudre de chlorure de magnésium ou de fluorure d'ammonium, à une concentration comprise entre 0,5% et 1,5% dans ledit cément.According to another particular characteristic of the invention, which only applies to steels whose carbon content is greater than 0.35%, the halide of the cement consists of a powder of magnesium chloride or fluoride d 'ammonium, at a concentration between 0.5% and 1.5% in said cement.
Comme on le comprend, le pefectionnement principal introduit par la présente invention par rapport au brevet antérieur consiste à n'utiliser que des ferro-chromes dont la teneur en carbone est comprise entre 1% et 3%, et est de préférence voisine de 2%. Cette présence du carbone du ferro-chrome permet d'obtenir en chromisation gazeuse une couche parfaitement monophasée de carbonitrures de chrome Cr2 (C, N), et d'éviter la formation de carbures MzsCe (M désignant un métal tel que le fer (Fe), le chrome (Cr), le nickel (Ni), etc.).As will be understood, the main improvement introduced by the present invention with respect to the prior patent consists in using only ferro-chromium whose carbon content is between 1% and 3%, and is preferably close to 2% . This presence of ferro-chromium carbon makes it possible to obtain, in gas chromization, a perfectly single-phase layer of chromium carbonitrides Cr 2 (C, N), and to avoid the formation of carbides M zs C e (M denoting a metal such as iron (Fe), chromium (Cr), nickel (Ni), etc.).
Un perfectionnement secondaire selon la présente invention par rapport au brevet antérieur consiste, pour les aciers à teneur en carbone comprise entre 0,20% et 0,35%, tout en conservant comme halogénure le chlorure d'ammonium, à l'utiliser à une concentration un peu accrue, comprise entre 0,5% et 1,5%, au lieu de 0,4% à 1 %.A secondary improvement according to the present invention compared to the previous patent consists, for steels with a carbon content of between 0.20% and 0.35%, while preserving ammonium chloride as halide, to use it at a slightly increased concentration, between 0.5% and 1.5%, instead of 0.4% to 1%.
Un autre perfectionnement selon la présente invention par rapport au brevet antérieur consiste, pour les aciers à teneur en carbone supérieure à 0,35%, à remplacer le chlorure d'ammonium soit par du chlorure de magnésium, soit par du fluorure d'ammonium, qui sont des halogénures plus stables que le chlorure d'ammonium.Another improvement according to the present invention with respect to the prior patent consists, for steels with a carbon content greater than 0.35%, of replacing the ammonium chloride either with magnesium chloride or with ammonium fluoride, which are more stable halides than ammonium chloride.
Pour bient faire comprendre l'intérêt de l'invention selon la présente invention, en vue de réaliser des couches monophasées de Cr2 (C, N), voici deux exemples relatifs à deux aciers qui, par leur teneur en carbone, se situent de part et d'autre de la limite de 0,35% précédemment définie.To clearly understand the advantage of the invention according to the present invention, with a view to producing single-phase layers of Cr 2 (C, N), here are two examples relating to two steels which, by their carbon content, are of on either side of the 0.35% limit previously defined.
Le premier exemple est relatif à un acier au chrome-molybdène-vanadium,du type 32 CDV 13, donc à 0,32% de carbone. Cet acier a subi la première séquence de nitruration ionique dans les conditions précédemment défines et plus précisément entre 520 et 530° C, pendant 30 heures, sous une pression partielle d'azote comprise entre 10 et 50 Pascals, la pression de travail étant comprise entre 250 et 800 Pascals. Dans ces conditions, la teneur moyenne en azote de l'acier entre 50 et 200 micromètres de profondeur atteint 2,1% et la couche nitrurée ne contient pas de nitrures de fer ni de nitrures de chrome.The first example relates to a chromium-molybdenum-vanadium steel, of the 32 CDV 13 type, therefore with 0.32% carbon. This steel underwent the first sequence of ionic nitriding under the conditions defined above and more precisely between 520 and 530 ° C, for 30 hours, under a partial nitrogen pressure of between 10 and 50 Pascals, the working pressure being between 250 and 800 Pascals. Under these conditions, the average nitrogen content of the steel between 50 and 200 micrometers deep reaches 2.1% and the nitrided layer does not contain iron nitrides or chromium nitrides.
L'échantillon d'acier 32 CDV 13 ainsi nitruré est introduit dans une caisse de cémentation où va se faire la deuxième phase du traitement, qui est une chromisation gazeuse. L'agent de cémentation est constitué par 99% de ferro- chrome à 65/70% de chrome et 2% de carbone, dont la granulométrie moyenne est voisine de 2,7 mm (extrêmes: 0,5 et 4 mm), et par 1% de chlorure d'ammonium, qui, lors de la montée en température, va se décomposer pour donner la vapeur active de chlorure de chrome CrC12. L'enceinte est portée à une température moyenne de 950° C pendant une durée de 15 heures, et le traitement thermique ultérieur de la pièce d'acier est effectué immédiatement après la phase de chromisation. Dans ces conditions, on obtient une couche parfaitement monophasée de carbonitrures de chrome Cr2 (C, N) dont l'épaisseur est voisine de 50 micromètres. Les caractéristiques de cette couche sont les suivantes:
- - dureté voisine de 2500 Hv dans l'échelle Vickers sous une charge de 50 grammes,
- - composition chimique très homogène sur toute son épaisseur avec: 77% Cr, 10% Fe, 10% N2 et 3% C,
- - structure basaltique avec le plan des basaltes dirigé parallèlement au plan de base de la maille hexagonale,
- - très bonne rugosité superficielle avec un RT inférieur à 4 micromètres (le RT est un paramètre qui caractérise la rugosité superficielle d'une surface par la distance qui sépare les plus hauts reliefs des creux les plus profinds notés sur l'enregistrement),
- - absence de défauts ou de porosités entre les basaltes de Cr2 (C, N).
- - hardness close to 2500 Hv in the Vickers scale under a load of 50 grams,
- - very homogeneous chemical composition over its entire thickness with: 77% Cr, 10% Fe, 10% N 2 and 3% C,
- - basalt structure with the basalt plane directed parallel to the base plane of the hexagonal mesh,
- - very good surface roughness with an RT less than 4 micrometers (the RT is a parameter which characterizes the surface roughness of a surface by the distance which separates the highest reliefs from the deepest depressions noted on the recording),
- - absence of defects or porosities between the basalts of Cr 2 (C, N).
Une telle structure est évidemment très favorable pour tous les problèmes où l'on recherche à la fois:
- - une bonne résistance à la corrosion (donnée par la teneur en chrome et l'absence de défauts superficiels),
- - une bonne résistance au frottement et à l'usure (donnée par la dureté du composé, sa structure cristallographique et la rugosité superficielle).
- - good resistance to corrosion (given by the chromium content and the absence of surface defects),
- - good resistance to friction and wear (given by the hardness of the compound, its crystallographic structure and the surface roughness).
Le deuxième exemple est relatif à un acier au chrome-molybdène-vanadium du type 40 CDV 12, donc à 0,40% de carbone. Cet acier a subi la première séquence de nitruration ionique dans les conditions qui ont été précisées lors de la description du premier exemple.The second example relates to a chromium-molybdenum-vanadium steel of type 40 CDV 12, therefore with 0.40% carbon. This steel underwent the first sequence of ionic nitriding under the conditions which were specified during the description of the first example.
L'échantillon d'acier 40 CDV 12 ainsi nitruré est introduit dans une caisse de cémentation où va se faire la deuxième phase du traitement, qui est une chromisation gazeuse. L'agent de cémentation est constitué par 99% de ferrochrome à 65/70% de chrome et 2% de carbone dont la granulométrie moyenne est voisine de 2,7 mm (extrêmes: 0,5 et 4 mm), et 1% de chlorure de magnésium, qui, lors de la montée en température, va se décomposer pour donner la vapeur active de chlorure de chrome CrC12.The 40 CDV 12 steel sample thus nitrided is introduced into a case hardening box where the second phase of the treatment will take place, which is a gas chromization. The cementing agent consists of 99% ferrochrome with 65/70% chromium and 2% carbon with an average particle size of around 2.7 mm (range: 0.5 and 4 mm), and 1% of magnesium chloride, which, when the temperature rises, will decompose to give the active vapor of chromium chloride CrC1 2 .
L'enceinte est portée à une température moyenne de 950°C pendant une durée de 15 heures et le traitement thermique ultérieur de la pièce d'acier est effectué immédiatement après la phase de chromisation.The enclosure is brought to an average temperature of 950 ° C for a period of 15 hours and the subsequent heat treatment of the steel part is carried out immediately after the chromization phase.
Dans ces conditions, on obtient une couche parfaitement monophasée de carbonitrures de chrome Cr2 (C, N) dont l'épaisseur est voisine de 40 micromètres et dont les caractéristiques sont les mêmes que celles qui ont été décrites dans le premier exemple.Under these conditions, a perfectly single-phase layer of chromium carbonitrides Cr 2 (C, N) is obtained, the thickness of which is close to 40 micrometers and the characteristics of which are the same as those which were described in the first example.
Il est bien entendu que l'on peut, sans sortir du cadre de l'invention, imaginer des variantes et perfectionnements de détails, de même qu'envisager l'emploi de moyens équivalents.It is understood that it is possible, without departing from the scope of the invention, to imagine variants and refinements of details, as well as to envisage the use of equivalent means.
Claims (5)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT81400804T ATE6675T1 (en) | 1980-05-29 | 1981-05-21 | METHOD OF INCHROMING STEEL VIA THE GAS PHASE. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR8011950A FR2483468A2 (en) | 1980-05-29 | 1980-05-29 | IMPROVEMENT IN THE CHROMIZATION OF STEELS BY GAS |
FR8011950 | 1980-05-29 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0043742A1 EP0043742A1 (en) | 1982-01-13 |
EP0043742B1 true EP0043742B1 (en) | 1984-03-14 |
Family
ID=9242474
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP81400804A Expired EP0043742B1 (en) | 1980-05-29 | 1981-05-21 | Method of gas-chromizing steels |
Country Status (7)
Country | Link |
---|---|
US (1) | US4357182A (en) |
EP (1) | EP0043742B1 (en) |
JP (1) | JPS5719373A (en) |
AT (1) | ATE6675T1 (en) |
DE (1) | DE3162611D1 (en) |
FR (1) | FR2483468A2 (en) |
ZA (1) | ZA812835B (en) |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS61291962A (en) * | 1985-06-17 | 1986-12-22 | Toyota Central Res & Dev Lab Inc | Surface treatment of iron alloy material |
AU582000B2 (en) * | 1985-06-17 | 1989-03-09 | Toyota Chuo Kenkyusho K.K. | Treating the surface of iron alloy materials |
GB2204327B (en) * | 1987-05-01 | 1991-07-31 | Nii Tekh Avtomobil Promy | Deposition of diffusion carbide coatings on iron-carbon alloy articles |
JPH0248397A (en) * | 1988-08-09 | 1990-02-19 | Kayaba Ind Co Ltd | Autobalance type lifting gear |
US6162513A (en) * | 1996-04-19 | 2000-12-19 | Korea Institute Of Science And Technology | Method for modifying metal surface |
US6209481B1 (en) | 1996-08-30 | 2001-04-03 | University Of Maryland Baltimore County | Sequential ion implantation and deposition (SIID) system |
JP4488840B2 (en) * | 2004-08-30 | 2010-06-23 | 本田技研工業株式会社 | Method for forming hard nitride layer, and roller chain and silent chain obtained by this method |
DE102011119087B3 (en) | 2011-11-22 | 2013-03-14 | Märkisches Werk GmbH | Method for producing a chromium protective layer and its use |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR1001856A (en) * | 1949-12-08 | 1952-02-28 | Diffusion Alloys Ltd | High quality tool manufacturing process |
US3190772A (en) * | 1960-02-10 | 1965-06-22 | Berghaus Bernhard | Method of hardening work in an electric glow discharge |
US3249456A (en) * | 1962-11-09 | 1966-05-03 | Union Carbide Corp | Diffusion coating process |
US3282746A (en) * | 1963-11-18 | 1966-11-01 | Formsprag Co | Method of hardening wear surfaces and product |
CH519588A (en) * | 1970-02-13 | 1972-02-29 | Berghaus Elektrophysik Anst | Process for processing a workpiece by means of a glow discharge and apparatus for performing the process |
JPS5120017B2 (en) * | 1971-11-16 | 1976-06-22 | ||
JPS552721A (en) * | 1978-06-19 | 1980-01-10 | Toyota Central Res & Dev Lab Inc | Surface-treating method for iron alloy material |
FR2439824A1 (en) * | 1978-10-25 | 1980-05-23 | Creusot Loire | IMPROVEMENT IN CHROMIZING STEELS BY GASEOUS WAY |
-
1980
- 1980-05-29 FR FR8011950A patent/FR2483468A2/en active Granted
-
1981
- 1981-04-29 US US06/258,822 patent/US4357182A/en not_active Expired - Lifetime
- 1981-04-29 ZA ZA00812835A patent/ZA812835B/en unknown
- 1981-05-21 AT AT81400804T patent/ATE6675T1/en not_active IP Right Cessation
- 1981-05-21 EP EP81400804A patent/EP0043742B1/en not_active Expired
- 1981-05-21 DE DE8181400804T patent/DE3162611D1/en not_active Expired
- 1981-05-26 JP JP7995881A patent/JPS5719373A/en active Granted
Also Published As
Publication number | Publication date |
---|---|
JPS6145700B2 (en) | 1986-10-09 |
ZA812835B (en) | 1982-04-28 |
ATE6675T1 (en) | 1984-03-15 |
US4357182A (en) | 1982-11-02 |
EP0043742A1 (en) | 1982-01-13 |
FR2483468B2 (en) | 1982-07-16 |
DE3162611D1 (en) | 1984-04-19 |
JPS5719373A (en) | 1982-02-01 |
FR2483468A2 (en) | 1981-12-04 |
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