EP1865081A1 - Process of continuous colouring of a stainless steel or nickel-based containing chromium substrate and installation of implementation of the process - Google Patents

Process of continuous colouring of a stainless steel or nickel-based containing chromium substrate and installation of implementation of the process Download PDF

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Publication number
EP1865081A1
EP1865081A1 EP06291130A EP06291130A EP1865081A1 EP 1865081 A1 EP1865081 A1 EP 1865081A1 EP 06291130 A EP06291130 A EP 06291130A EP 06291130 A EP06291130 A EP 06291130A EP 1865081 A1 EP1865081 A1 EP 1865081A1
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Prior art keywords
substrate
stainless steel
chromium
heating zone
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EP06291130A
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German (de)
French (fr)
Inventor
Marc Mantel
Eric Chauveau
Christophe Vachey
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Ugitech SA
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Ugitech SA
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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
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/48—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 not containing phosphates, hexavalent chromium compounds, fluorides or complex fluorides, molybdates, tungstates, vanadates or oxalates
    • C23C22/50—Treatment of iron or alloys based thereon
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/56—Continuous furnaces for strip or wire
    • 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
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
    • C23C22/08—Orthophosphates
    • 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
    • C23C8/10—Oxidising
    • 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
    • C23C8/80—After-treatment

Definitions

  • the present invention relates to a continuous dyeing process for a stainless steel or nickel base alloy substrate containing chromium.
  • Stainless steels have corrosion resistance properties, and are now widely used in the building market for decorative applications (facades, roofs, furniture etc .). For these applications, there is a market demand to have colored products while maintaining the metallic appearance of the surface. Products with good cleanability, good resistance to UV aging and good fire resistance are also sought.
  • Physical deposits include sputter deposition, an alternative vacuum deposition process. From a target, subjected to the action of an ionic bombardment of energetic particles, the atoms of the material to be colored are deposited on a material carrier. The ions are obtained by a glow discharge between two electrodes.
  • Chemical deposits consist of converting the surface of the metal into a stable oxide by immersion in an aqueous solution containing chromium (Cr 6+ ) salts.
  • the metal is oxidized under anodic polarization.
  • a current generator and a cell adapted to the type of sample are used so as to obtain a good distribution of the current lines.
  • the stainless steel sample is placed in anode, the cathode consists of a lead plate.
  • the object of the present invention is therefore to overcome the disadvantages of the processes of the prior art by providing a method of staining substrates of stainless steel or chromium-containing nickel base alloy, which has improved productivity, stable coloring , matt or glossy, retaining a metallic appearance and which further has a corrosion resistance equivalent to the uncolored base metal.
  • a method is also sought that makes it possible to obtain a colored surface that is not very sensitive to fingerprints and scratches, having the most homogeneous coloration possible, as well as good cleanability, good resistance to UV and fire.
  • a first object of the present invention is constituted by a method of continuously dyeing a substrate made of stainless steel or chromium-containing nickel base alloy, according to which said substrate is passed through a heating zone set to a set temperature between 800 and 1500 ° C, in order to obtain a surface oxidized layer having a thickness of less than 200 nm and a ratio between the chromium and iron contents greater than 0.02 in said oxidized layer, and then said substrate is cooled to a temperature of less than or equal to 70 ° C.
  • a third object of the invention is constituted by a substrate made of stainless steel or chromium-containing nickel base alloy, comprising a surface-oxidized layer having a thickness of less than 200 nm and a ratio between the chromium and iron contents greater than 0.02 in said oxidized layer.
  • the high temperature of the furnace makes it possible to diffuse the chromium of the base metal towards the surface and thus to improve the resistance to corrosion by increasing the ratio Cr / Fe of the oxide film.
  • XPS photoelectron spectroscopy
  • the method according to the invention has the essential advantage of allowing continuous operation. It applies perfectly to a wire or a profile, but also to a coil of strips of cold rolled material, or even to a bar.
  • yarn will be referred to when the substrate has a diameter of less than 32 mm and is wound into a reel and bar when the product will have a diameter greater than 2 mm with a finished length less than or equal to 12 m.
  • austenitic stainless steels such as type 304, 304L, 306, 316 and 316L steels.
  • the optional first step of the process according to the invention consists in improving the homogeneity of the surface of the substrate even before it is colored.
  • the inventors have indeed found that the brightness and the shade of the final color are influenced by the homogeneity of the surface state. It is therefore advantageous to integrate a surface preparation of the substrate to be colored. However, it is quite possible to carry out this operation prior to the implementation of the method according to the invention, on a separate line.
  • a cold plastic deformation operation such as drawing or cold rolling with a reduction rate greater than 4% or else a preparation of the surface condition by abrasion, shot blasting, sandblasting, annealing stripping or any other method to control and homogenize the surface condition.
  • the heating zone is preferably a furnace comprising an enclosure and electrical resistances, but it is also possible to form the desired oxide film with a combustion furnace or by other heating systems that do not necessarily require enclosures. scrolling, like induction heating.
  • the passage furnace preferentially used for coloring the substrate by oxidation is set to operate at a set temperature of between 800 and 1500 ° C., and preferably between 800 and 1300 ° C.
  • the setting of the oven temperature is a function of the speed of the line and the color that is to be obtained.
  • the line speed which depends on the length of the furnace, the operating temperature and the desired color is preferably greater than 1 m / min and more preferably greater than or equal to 10 m / min.
  • the method according to the invention makes it possible to obtain different colors by playing on the one hand on the temperature of the furnace and on the other hand on the running speed of the wire.
  • a series of tests were carried out on a laboratory cyclic oven (see FIG. 1), comprising a 610 mm heating zone by treating 304L type stainless steel wires.
  • FIG. 2 shows a number of additional tests in which the residence times in the oven at fixed temperature have been varied. We see that by playing on this time, we can get the full range of colorations.
  • the atmosphere used in the oven may be oxidizing or inert.
  • an oxidizing atmosphere it will be possible in particular to use air in order to maintain the highest possible line speed and to have good productivity.
  • inert gases such as nitrogen, hydrogen or a nitrogen / hydrogen mixture.
  • the dew point will preferably be controlled in a range of -20 ° C to + 30 ° C depending on the target color and the speed of the line.
  • a cooling system is provided to bring the temperature of the substrate to a value less than or equal to 70 ° C.
  • an anti-corrosion treatment of the substrate according to the invention is carried out after coloring and cooling.
  • This treatment consists in placing the substrate in contact with an aqueous solution of mineral acid until the oxidized layer formed during the coloration is partially dissolved, followed by rinsing with water.
  • the anti-corrosion treatment greatly improves the resistance to pitting corrosion in a chloride medium. This gives a pitting corrosion resistance close to that of the base metal.
  • mineral acids such as nitric acid or preferably phosphoric acid
  • the anti-corrosion treatment is preferably carried out at ambient temperature, but it is especially possible to work between 20 and 70 ° C., in particular if it is desired to increase the speed of the line and therefore the productivity of the coloring process.
  • the maximum temperature of use of the solutions will also depend on the nature of the acids used as well as their concentrations. The optimal parameters of this treatment have been defined using different tests.
  • Tests were carried out on 316 type austenitic stainless steel wires, which had previously been colored at an oven temperature of 920 ° C to 930 ° C, with an oven residence time of 32 seconds.
  • the bath used for the anti-corrosion treatment contained an aqueous nitric acid solution at 20% by volume and at a temperature of 60 ° C.
  • the tests were carried out on 316 type austenitic stainless steel wire, which had previously been colored at an oven temperature between 920 ° C and 930 ° C, with a residence time in the oven of 32s.
  • the samples were immersed in an acid bath for 30 seconds. Since nitric acid can pose health and environmental problems, the effectiveness of phosphoric acid has also been tested.
  • a cold plastic deformation treatment of the substrate which has just been cooled is carried out so as to obtain a degree of deformation of between 5 and 15%.
  • this operation may consist of a skin-pass (cold-rolled wire and strip), stretching (bars) or even profiling.
  • the present inventors have indeed found that this operation made it possible to improve, and surprisingly, various properties of the surface of the treated substrate, such as sensitivity to fingerprints, sensitivity to scratching, and corrosion resistance. . In addition, the homogeneity of the coloration and the corrosion resistance is also improved.
  • the tests for evaluating the homogeneity of the coloration were carried out on threads identical to those used for the fingerprint sensitivity test. The evaluation is performed visually by an operator.
  • this variant of the process according to the invention improves the homogeneity of the coloration, in particular when the oxidation temperature exceeds 900 ° C.
  • Corrosion resistance was measured by the pitting potential measured against a saturated calomel electrode on AISI 316L grade in 0.02M NaCl solution at 23 ° C. The results are collated in Table 8. ⁇ u> Table 8 Pitting potential measurements ⁇ / u> Potential for puncture NaCl 0.02M 23 ° C 316L naked 658 mV Colored 316L 900 ° C 253 mV Colored 316L 900 ° C + Skin Pass 5% 602 mV
  • the contact angle of the yarn according to the invention is significantly increased compared to that which has not been subjected to the process according to the invention, which means that the surface of this yarn has an improved hydrophobicity, which makes it easier to clean and less reactive to contamination.

Abstract

The process for continuous coloring of a stainless steel or nickel-based alloy containing chromium substrate, comprises unwinding the substrate in a heating zone at a reference temperature of 800-1500[deg] C to obtain an oxidized surface layer. A thickness of the oxidized surface layer is less than 200 nm. A ratio between a content of chromium and iron is higher than 0.02 in the oxidized layer. The substrate is cooled at = 70[deg] C. A substrate surface preparation is carried out before an introduction of substrate into the heating zone for homogenizing the substrate. The process for continuous coloring of a stainless steel or nickel-based alloy containing chromium substrate, comprises unwinding the substrate in a heating zone at a reference temperature of 800-1500[deg] C to obtain an oxidized surface layer. A thickness of the oxidized surface layer is less than 200 nm. A ratio between a content of chromium and iron is higher than 0.02 in the oxidized layer. The substrate is cooled at = 70[deg] C. A substrate surface preparation is carried out before an introduction of substrate into the heating zone for homogenizing the substrate. After cooling, the substrate is contacted with an aqueous solution of phosphoric acid and then rinsed with water. After coloring, the substrate is subjected to a cold plastic deformation (known as skin pass) to obtain a deformation rate of 5-15%. The substrate having a stainless steel wire has a diameter lower than 32 mm, and the substrate having a stainless steel bar has a diameter higher than 2 mm and a length = 12 m. An operation of cold plastic deformation of the stainless steel- wire and bar is a wire drawing operation. The substrate is unwinded in the heating zone through a passage in an enclosure under an inert atmosphere. Independent claims are included for: (1) an installation for manufacturing a stainless steel or nickel-based alloy containing chromium substrate; and (2) a stainless steel or nickel-based alloy containing chromium substrate.

Description

La présente invention concerne un procédé de coloration en continu d'un substrat en acier inoxydable ou en alliage base nickel contenant du chrome.The present invention relates to a continuous dyeing process for a stainless steel or nickel base alloy substrate containing chromium.

Les aciers inoxydables ont des propriétés de résistance à la corrosion, et sont aujourd'hui largement utilisés dans le marché du bâtiment pour des applications décoratives (façades, toitures, mobiliers etc....). Pour ces applications, il existe une demande du marché d'avoir des produits colorés tout en conservant l'aspect métallique de la surface. On recherche également des produits présentant une bonne nettoyabilité, une bonne résistance au vieillissement par UV et une bonne résistance au feu.Stainless steels have corrosion resistance properties, and are now widely used in the building market for decorative applications (facades, roofs, furniture etc ....). For these applications, there is a market demand to have colored products while maintaining the metallic appearance of the surface. Products with good cleanability, good resistance to UV aging and good fire resistance are also sought.

Afin de colorer en surface un substrat métallique, on connaît deux types de procédés :

  • les procédés générant des couches d'oxydes incolores très minces (10 à 200 nm) donnant une coloration par interférences lumineuses et
  • les procédés générant des couches d'oxydes colorés épaisses (quelques micromètres) ou des couches de revêtements colorés (émaux, peinture, revêtements organiques).
In order to surface color a metal substrate, two types of processes are known:
  • processes generating very thin colorless oxide layers (10 to 200 nm) giving a coloration by light interferences and
  • processes generating layers of thick colored oxides (a few micrometers) or layers of colored coatings (enamels, paint, organic coatings).

Dans le premier type de procédés, on trouve en particulier les dépôts physiques, les procédés chimiques ou électrochimiques et les procédés thermiques.In the first type of process, there are in particular physical deposits, chemical or electrochemical processes and thermal processes.

Les dépôts physiques recouvrent notamment les dépôts par pulvérisation cathodique, variante des procédés de dépôt sous vide. À partir d'une cible, soumise à l'action d'un bombardement ionique de particules énergétiques, on dépose, sur un porte-matériau, les atomes du matériau à colorer. Les ions sont obtenus par une décharge luminescente entre deux électrodes.Physical deposits include sputter deposition, an alternative vacuum deposition process. From a target, subjected to the action of an ionic bombardment of energetic particles, the atoms of the material to be colored are deposited on a material carrier. The ions are obtained by a glow discharge between two electrodes.

L'inconvénient majeur de ce procédé est sa mise en oeuvre industrielle qui nécessite des moyens relativement lourds, des vitesses parfois lentes pour un processus en continu ; facteurs qui rendent ce procédé peu productif.The major disadvantage of this method is its industrial implementation which requires relatively heavy means, sometimes slow speeds for a continuous process; factors that make this process unproductive.

Les dépôts par voie chimique consistent à convertir la surface du métal en un oxyde stable, par immersion dans une solution aqueuse contenant des sels de chrome (Cr6+).Chemical deposits consist of converting the surface of the metal into a stable oxide by immersion in an aqueous solution containing chromium (Cr 6+ ) salts.

Dans les procédés électrochimiques, le métal est oxydé sous polarisation anodique. On utilise un générateur de courant et une cellule adaptée au type d'échantillon de manière à obtenir une bonne répartition des lignes de courant. L'échantillon d'acier inoxydable est placé en anode, la cathode est constituée d'une plaque de plomb.In electrochemical processes, the metal is oxidized under anodic polarization. A current generator and a cell adapted to the type of sample are used so as to obtain a good distribution of the current lines. The stainless steel sample is placed in anode, the cathode consists of a lead plate.

La qualité des produits obtenus par ces procédés chimiques et électrochimiques est généralement bonne, mais ils posent deux problèmes majeurs qui sont :

  • le fait que les bains utilisés contiennent des chromates (Cr hexavalent) toxiques tant pour la santé humaine que pour l'environnement et
  • les temps d'immersion de plusieurs minutes nécessaires à l'obtention de la coloration, qui les rendent incompatibles avec un procédé en continu.
The quality of the products obtained by these chemical and electrochemical processes is generally good, but they pose two major problems which are:
  • the fact that the baths used contain chromates (hexavalent Cr) toxic to both human health and the environment, and
  • immersion times of several minutes required to obtain the color, which make them incompatible with a continuous process.

On connaît enfin les procédés thermiques, dans lesquels le métal est porté à une température déterminée pendant une durée donnée. La couche d'oxydes formée de quelques dizaines de nanomètres conduit à des couleurs d'interférence. Ce phénomène est bien connu mais on cherche généralement à l'éviter plutôt qu'à le provoquer, car les films formés par oxydation dégradent la résistance à la corrosion des nuances traitées.Thermal processes are known in which the metal is heated to a predetermined temperature for a given period of time. The oxide layer formed by a few tens of nanometers leads to interference colors. This phenomenon is well known but it is generally sought to avoid it rather than to provoke it, since the films formed by oxidation degrade the corrosion resistance of the treated shades.

Dans le second type de procédés, on citera plus particulièrement l'application de peinture. Celle-ci est considérée, à juste titre, comme inutile sur un acier inoxydable ou un alliage base nickel contenant du chrome, du fait de l'excellente tenue à la corrosion atmosphérique de ces nuances. En outre, l'aspect obtenu n'est plus métallique, la peinture dissimulant totalement la surface du substrat. Enfin, ces revêtements résistent mal aux UV et au feu.In the second type of process, mention will be made more particularly of the application of paint. This is rightly considered as useless on a stainless steel or a nickel base alloy containing chromium, because of the excellent resistance to atmospheric corrosion of these grades. In addition, the appearance obtained is no longer metallic, the paint completely concealing the surface of the substrate. Finally, these coatings are poorly resistant to UV and fire.

Le but de la présente invention est donc de remédier aux inconvénients des procédés de l'art antérieur en mettant à disposition un procédé de coloration de substrats en acier inoxydable ou en alliage base nickel contenant du chrome, qui présente une productivité améliorée, une coloration stable, mate ou brillante, conservant un aspect métallique et qui présente en outre une résistance à la corrosion équivalente au métal de base non coloré. On recherche également un procédé permettant d'obtenir une surface colorée peu sensible aux traces de doigts et aux rayures, présentant une coloration la plus homogène possible, ainsi qu'une bonne nettoyabilité, une bonne résistance aux UV et au feu.The object of the present invention is therefore to overcome the disadvantages of the processes of the prior art by providing a method of staining substrates of stainless steel or chromium-containing nickel base alloy, which has improved productivity, stable coloring , matt or glossy, retaining a metallic appearance and which further has a corrosion resistance equivalent to the uncolored base metal. A method is also sought that makes it possible to obtain a colored surface that is not very sensitive to fingerprints and scratches, having the most homogeneous coloration possible, as well as good cleanability, good resistance to UV and fire.

A cet effet, un premier objet de la présente invention est constitué par un procédé de coloration en continu d'un substrat en acier inoxydable ou en alliage base nickel contenant du chrome, selon lequel on fait défiler ledit substrat dans une zone de chauffage réglée à une température de consigne comprise entre 800 et 1500°C, afin d'obtenir une couche oxydée en surface présentant une épaisseur inférieure à 200 nm et un rapport entre les teneurs en chrome et en fer supérieur à 0,02 dans ladite couche oxydée, puis on refroidit ledit substrat à une température inférieure ou égale à 70°C.For this purpose, a first object of the present invention is constituted by a method of continuously dyeing a substrate made of stainless steel or chromium-containing nickel base alloy, according to which said substrate is passed through a heating zone set to a set temperature between 800 and 1500 ° C, in order to obtain a surface oxidized layer having a thickness of less than 200 nm and a ratio between the chromium and iron contents greater than 0.02 in said oxidized layer, and then said substrate is cooled to a temperature of less than or equal to 70 ° C.

Le procédé selon l'invention peut également comprendre différentes caractéristiques, prises seules ou en combinaison :

  • avant d'introduire le substrat dans ladite zone de chauffage, on effectue une préparation de surface du substrat pour homogénéiser ladite surface,
  • après avoir été refroidi, ledit substrat est mis en contact avec une solution aqueuse d'acide minéral, puis rincé à l'eau,
  • l'acide minéral est l'acide phosphorique,
  • après avoir été coloré, ledit substrat est soumis à une déformation plastique à froid (dite skin pass) permettant d'obtenir un taux de déformation compris entre 5 et 15%,
  • le substrat est un fil d'acier inoxydable choisi parmi un acier inoxydable austénitique, un acier inoxydable ferritique, un acier inoxydable martensitique et un acier inoxydable duplex et présentant un diamètre inférieur à 32 mm, que l'on bobine à l'issue du procédé,
  • l'opération de déformation plastique à froid dudit fil est une opération de tréfilage,
  • le substrat est une barre d'acier inoxydable choisi parmi un acier inoxydable austénitique, un acier inoxydable ferritique, un acier inoxydable martensitique et un acier inoxydable duplex et présentant un diamètre supérieur à 2 mm et une longueur inférieure ou égale à 12 m,
  • l'opération de déformation plastique à froid de ladite barre est une opération d'étirage,
  • le substrat défile dans ladite zone de chauffage par passage dans une enceinte dans laquelle règne une atmosphère inerte.
The method according to the invention may also comprise different characteristics, taken alone or in combination:
  • before introducing the substrate into said heating zone, a surface preparation of the substrate is carried out in order to homogenize said surface,
  • after being cooled, said substrate is brought into contact with an aqueous solution of mineral acid, then rinsed with water,
  • the mineral acid is phosphoric acid,
  • after having been colored, said substrate is subjected to a cold plastic deformation (called skin pass) making it possible to obtain a degree of deformation comprised between 5 and 15%,
  • the substrate is a stainless steel wire selected from austenitic stainless steel, a ferritic stainless steel, a martensitic stainless steel and a duplex stainless steel and having a diameter of less than 32 mm, which is reeled at the end of the process ,
  • the cold plastic deformation operation of said wire is a drawing operation,
  • the substrate is a stainless steel bar selected from austenitic stainless steel, a ferritic stainless steel, a martensitic stainless steel and a duplex stainless steel and having a diameter greater than 2 mm and a length less than or equal to 12 m,
  • the cold plastic deformation operation of said bar is a drawing operation,
  • the substrate passes through said heating zone by passing through an enclosure in which an inert atmosphere prevails.

Un second objet de l'invention est constitué par une installation pour la mise en oeuvre du procédé selon l'invention, comprenant :

  • des moyens de défilement dudit substrat,
  • des moyens de chauffage dudit substrat, comprenant des moyens de réglage de la température de consigne et
  • des moyens de refroidissement dudit substrat jusqu'à une température inférieure à 70°C.
A second object of the invention is constituted by an installation for implementing the method according to the invention, comprising:
  • means for scrolling said substrate,
  • means for heating said substrate, comprising means for adjusting the set temperature and
  • means for cooling said substrate to a temperature below 70 ° C.

L'installation selon l'invention peut également comprendre les variantes suivantes, prises isolément ou en combinaison :

  • l'installation peut comprendre en outre des moyens permettant d'homogénéiser la surface dudit substrat, lesdits moyens étant placés en amont desdits moyens de chauffage,
  • l'installation peut comprendre en outre des moyens de mise en contact dudit substrat avec une solution aqueuse d'acide minéral, ainsi que des moyens de rinçage du dit substrat,
  • l'installation peut comprendre en outre des moyens de déformation plastique à froid dudit substrat, placés en aval desdits moyens de chauffage.
The installation according to the invention may also comprise the following variants, taken separately or in combination:
  • the installation may furthermore comprise means making it possible to homogenize the surface of said substrate, said means being placed upstream of said heating means,
  • the installation may further comprise means for bringing said substrate into contact with an aqueous solution of mineral acid, as well as means for rinsing said substrate,
  • the installation may further comprise cold plastic deformation means of said substrate, placed downstream of said heating means.

Un troisième objet de l'invention est constitué par un substrat en acier inoxydable ou en alliage base nickel contenant du chrome, comprenant une couche oxydée en surface présentant une épaisseur inférieure à 200 nm et un rapport entre les teneurs en chrome et en fer supérieur à 0,02 dans ladite couche oxydée.A third object of the invention is constituted by a substrate made of stainless steel or chromium-containing nickel base alloy, comprising a surface-oxidized layer having a thickness of less than 200 nm and a ratio between the chromium and iron contents greater than 0.02 in said oxidized layer.

Le substrat selon l'invention peut également comprendre les variantes suivantes, prises isolément ou en combinaison :

  • le substrat a en outre subi une déformation plastique à froid avec un taux de déformation compris entre 5 et 15%, ladite déformation ayant eu lieu après oxydation de la surface,
  • le substrat est sous forme d'une bobine d'un fil d'acier inoxydable présentant un diamètre inférieur à 32 mm, ledit acier étant choisi parmi un acier inoxydable austénitique, un acier inoxydable ferritique, un acier inoxydable martensitique et un acier inoxydable duplex,
  • le substrat est sous forme d'une barre d'acier inoxydable présentant un diamètre supérieur à 2 mm et une longueur inférieure ou égale à 12 m, ledit acier étant choisi parmi un acier inoxydable austénitique, un acier inoxydable ferritique, un acier inoxydable martensitique et un acier inoxydable duplex.
The substrate according to the invention may also comprise the following variants, taken alone or in combination:
  • the substrate has also undergone a cold plastic deformation with a strain rate of between 5 and 15%, said deformation having occurred after oxidation of the surface,
  • the substrate is in the form of a coil of a stainless steel wire having a diameter of less than 32 mm, said steel being selected from austenitic stainless steel, a ferritic stainless steel, a martensitic stainless steel and a duplex stainless steel,
  • the substrate is in the form of a stainless steel bar having a diameter greater than 2 mm and a length less than or equal to 12 m, said steel being chosen from an austenitic stainless steel, a ferritic stainless steel, a martensitic stainless steel and a duplex stainless steel.

Comme on l'a vu précédemment, des procédés de coloration par oxydation thermique existent déjà mais ne permettent pas d'obtenir des produits avec une résistance à la corrosion suffisante. Les présents inventeurs ont constaté qu'en suivant les paramètres du procédé selon l'invention, la température élevée du four permet de faire diffuser le chrome du métal de base vers la surface et d'améliorer ainsi la résistance à la corrosion en augmentant le rapport Cr/Fe du film d'oxyde.As has been seen previously, thermal oxidation dyeing methods already exist but do not make it possible to obtain products with sufficient corrosion resistance. The present inventors have found that by following the parameters of the process according to the invention, the high temperature of the furnace makes it possible to diffuse the chromium of the base metal towards the surface and thus to improve the resistance to corrosion by increasing the ratio Cr / Fe of the oxide film.

En effet, des examens XPS (spectroscopie de photoélectrons) ont révélé la présence de chrome dans le film coloré obtenu pour les traitements thermiques compris entre 800°C et 1500°C. Le rapport Cr/Fe est de l'ordre de 0,1 pour des échantillons produits à 900°C pendant 30s et de 0,56 pour les échantillons produits à 800°C pendant 60s. L'effet sur la résistance à la corrosion démarre pour un rapport Cr/Fe de 0,02 environ.Indeed, XPS (photoelectron spectroscopy) examinations revealed the presence of chromium in the colored film obtained for the treatments temperatures between 800 ° C and 1500 ° C. The Cr / Fe ratio is in the order of 0.1 for samples produced at 900 ° C for 30s and 0.56 for samples produced at 800 ° C for 60s. The effect on corrosion resistance starts at a Cr / Fe ratio of about 0.02.

D'autres caractéristiques et avantages de l'invention apparaîtront à la lecture de la description qui va suivre, donnée uniquement à titre d'exemple et non à titre limitatif.Other features and advantages of the invention will appear on reading the description which follows, given solely by way of example and not by way of limitation.

Le procédé selon l'invention présente l'avantage essentiel de permettre d'opérer en continu. Il s'applique parfaitement à un fil ou à un profil, mais aussi à une bobine de bandes de matériau laminé à froid, ou bien encore à une barre. Dans le cadre de la présente invention, on parlera de fil lorsque le substrat présentera un diamètre inférieur à 32 mm et est enroulé en bobine et de barre lorsque le produit présentera un diamètre supérieur à 2 mm avec une longueur finie inférieure ou égale à 12m.The method according to the invention has the essential advantage of allowing continuous operation. It applies perfectly to a wire or a profile, but also to a coil of strips of cold rolled material, or even to a bar. In the context of the present invention, yarn will be referred to when the substrate has a diameter of less than 32 mm and is wound into a reel and bar when the product will have a diameter greater than 2 mm with a finished length less than or equal to 12 m.

Il s'applique aux substrats en acier inoxydable ou en alliage base nickel contenant du chrome. On citera plus particulièrement les aciers inoxydables austénitiques tels que les aciers de type 304, 304L, 306, 316 et 316L.It is applicable to stainless steel or nickel base alloy substrates containing chromium. More particularly, mention may be made of austenitic stainless steels such as type 304, 304L, 306, 316 and 316L steels.

La première étape, facultative, du procédé selon l'invention consiste à améliorer l'homogénéité de la surface du substrat avant même qu'il ne soit coloré. Les inventeurs ont en effet constaté que la brillance et la nuance de la couleur finale sont influencées par l'homogénéité de l'état de surface. Il est donc avantageux d'intégrer une préparation de surface du substrat à colorer. Il est cependant tout à fait possible de procéder à cette opération préalablement à la mise en oeuvre du procédé selon l'invention, sur une ligne distincte.The optional first step of the process according to the invention consists in improving the homogeneity of the surface of the substrate even before it is colored. The inventors have indeed found that the brightness and the shade of the final color are influenced by the homogeneity of the surface state. It is therefore advantageous to integrate a surface preparation of the substrate to be colored. However, it is quite possible to carry out this operation prior to the implementation of the method according to the invention, on a separate line.

Pour améliorer l'homogénéité et contrôler l'état de surface du substrat de départ, on peut effectuer une opération de déformation plastique à froid comme le tréfilage ou le laminage à froid avec un taux de réduction supérieur à 4% ou bien encore une préparation de l'état de surface par abrasion, grenaillage, sablage, recuit décapage ou tout autre procédé permettant de contrôler et d'homogénéiser l'état de surface.To improve the homogeneity and to control the surface condition of the starting substrate, it is possible to carry out a cold plastic deformation operation such as drawing or cold rolling with a reduction rate greater than 4% or else a preparation of the surface condition by abrasion, shot blasting, sandblasting, annealing stripping or any other method to control and homogenize the surface condition.

Lorsque l'on pratique un tréfilage ou laminage, il est ensuite nécessaire de nettoyer le substrat avant son entrée dans la zone de chauffage où va avoir lieu la coloration.When drawing or rolling, it is then necessary to clean the substrate before entering the heating zone where the coloring will take place.

La zone de chauffage est de préférence un four comportant une enceinte et des résistances électriques, mais il est possible également de former le film d'oxydes souhaité avec un four à combustion ou par d'autres systèmes de chauffage ne nécessitant pas obligatoirement d'enceinte de défilement, comme le chauffage par induction.The heating zone is preferably a furnace comprising an enclosure and electrical resistances, but it is also possible to form the desired oxide film with a combustion furnace or by other heating systems that do not necessarily require enclosures. scrolling, like induction heating.

Le four à passage utilisé préférentiellement pour colorer le substrat par oxydation est réglé pour fonctionner à une température de consigne comprise entre 800 et 1500°C, et de préférence comprise entre 800 et 1300°C. Comme on le verra plus loin, le réglage de la température du four est fonction de la vitesse de la ligne ainsi que de la couleur que l'on veut obtenir. La vitesse de ligne qui dépend de la longueur du four, de la température de fonctionnement et de la couleur désirée est de préférence supérieure à 1 m/min et de façon plus particulièrement préférée supérieure ou égale à 10m/min.The passage furnace preferentially used for coloring the substrate by oxidation is set to operate at a set temperature of between 800 and 1500 ° C., and preferably between 800 and 1300 ° C. As will be seen below, the setting of the oven temperature is a function of the speed of the line and the color that is to be obtained. The line speed which depends on the length of the furnace, the operating temperature and the desired color is preferably greater than 1 m / min and more preferably greater than or equal to 10 m / min.

Le procédé selon l'invention permet d'obtenir différentes couleurs en jouant d'une part sur la température du four et d'autre part sur la vitesse de défilement du fil. On a ainsi réalisé une série d'essais sur un four cyclique de laboratoire (cf. figure 1), comprenant une zone de chauffe de 610mm en traitant des fils d'acier inoxydable de type 304L.The method according to the invention makes it possible to obtain different colors by playing on the one hand on the temperature of the furnace and on the other hand on the running speed of the wire. Thus, a series of tests were carried out on a laboratory cyclic oven (see FIG. 1), comprising a 610 mm heating zone by treating 304L type stainless steel wires.

En faisant varier la température du four à vitesse de défilement constante, on observe que le substrat prend tout d'abord une teinte dorée, puis cuivrée, et enfin une couleur bleu-violette. Tableau 1 - paramètres de coloration et couleurs correspondantes Température de consigne du four (°C) Vitesse de défilement réelle (cm.s-1) purée dans le four (s) Couleur obtenue 500 0 420 doré-cuivré 650 0 105 doré-cuivré 910-920 1,91 31,9 doré-cuivré 920-930 1,91 31,9 doré-cuivré 1000 2,1 29 bleu-violet 1000 3,26 18,7 doré-cuivré 1100 3,1 19,7 violet 1100 3,78 16,1 cuivré 1200 4,59 13,3 cuivré 1240 6,24 9,8 doré 1400 9 6,8 doré By varying the temperature of the oven at constant speed of movement, it is observed that the substrate first takes a golden hue, then copper, and finally a blue-violet color. <u> Table 1 - matching color and color settings </ u> Oven set temperature (° C) Actual scrolling speed (cm.s -1 ) mashed in the oven (s) Obtained color 500 0 420 gold-copper 650 0 105 gold-copper 910-920 1.91 31,9 gold-copper 920-930 1.91 31,9 gold-copper 1000 2.1 29 blue-violet 1000 3.26 18.7 gold-copper 1100 3.1 19.7 purple 1100 3.78 16.1 copper 1200 4.59 13.3 copper 1240 6.24 9.8 golden 1400 9 6.8 golden

On a représenté en figure 2, un certain nombre d'essais complémentaires dans lesquels on a fait varier les durées de séjour dans le four à température fixée. On voit qu'en jouant sur cette durée, on peut obtenir toute la gamme des colorations.FIG. 2 shows a number of additional tests in which the residence times in the oven at fixed temperature have been varied. We see that by playing on this time, we can get the full range of colorations.

Par ailleurs, l'atmosphère utilisée dans le four peut être oxydante ou inerte. Lorsque l'on souhaite avoir une atmosphère oxydante, on pourra en particulier utiliser de l'air afin de maintenir une vitesse de ligne la plus grande possible et avoir une bonne productivité. Il est bien sur possible de travailler avec des gaz inertes comme l'azote, l'hydrogène ou un mélange azote/hydrogène. Pour ces mélanges gazeux, le point de rosée sera, de préférence, contrôlé dans une plage de -20°C à +30°C en fonction de la couleur visée et de la vitesse de la ligne. Lorsque l'atmosphère doit être inerte, il est alors nécessaire que le traitement d'oxydation se fasse au sein d'une enceinte pour pouvoir y contrôler la composition de l'atmosphère.Moreover, the atmosphere used in the oven may be oxidizing or inert. When it is desired to have an oxidizing atmosphere, it will be possible in particular to use air in order to maintain the highest possible line speed and to have good productivity. It is of course possible to work with inert gases such as nitrogen, hydrogen or a nitrogen / hydrogen mixture. For these gaseous mixtures, the dew point will preferably be controlled in a range of -20 ° C to + 30 ° C depending on the target color and the speed of the line. When the atmosphere must be inert, it is then necessary that the oxidation treatment is done within a chamber to be able to control the composition of the atmosphere.

On a ainsi réalisé un certain nombre d'essais sur des fils d'acier inoxydable de type 304L sous une atmosphère entièrement composée d'argon, en faisant varier les durées de séjour dans un four à passage à température fixée. Les résultats de ces essais sont représentés en figure 3 et on peut voir qu'on attend des couleurs inaccessibles sous une atmosphère à base d'air, tel que du bleu, du vert doré, et du doré foncé.A number of tests were thus carried out on type 304L stainless steel wires under an atmosphere entirely composed of argon, by varying the residence times in an oven passing through temperature set. The results of these tests are shown in Figure 3 and it can be seen that inaccessible colors are expected under an air-based atmosphere, such as blue, golden green, and dark walleye.

A l'issue du traitement thermique, un système de refroidissement est prévu pour amener la température du substrat à une valeur inférieure ou égale à 70°C. On pourra en particulier utiliser des buses de soufflage d'air.At the end of the heat treatment, a cooling system is provided to bring the temperature of the substrate to a value less than or equal to 70 ° C. In particular, it is possible to use air blast nozzles.

Dans une variante du procédé selon l'invention, on procède à un traitement anti-corrosion du substrat selon l'invention, à l'issue de sa coloration et de son refroidissement. Ce traitement consiste en une mise en contact entre le substrat et une solution aqueuse d'acide minéral jusqu'à dissolution partielle de la couche oxydée formée lors de la coloration, suivie d'un rinçage à l'eau.In a variant of the process according to the invention, an anti-corrosion treatment of the substrate according to the invention is carried out after coloring and cooling. This treatment consists in placing the substrate in contact with an aqueous solution of mineral acid until the oxidized layer formed during the coloration is partially dissolved, followed by rinsing with water.

Le traitement anti-corrosion permet d'améliorer fortement la résistance à la corrosion par piqûre en milieu chloruré. On obtient ainsi une résistance à la corrosion par piqûre voisine de celle du métal de base.The anti-corrosion treatment greatly improves the resistance to pitting corrosion in a chloride medium. This gives a pitting corrosion resistance close to that of the base metal.

On utilise de préférence un bain acide contenant un ou plusieurs acides minéraux, tels que l'acide nitrique ou préférentiellement l'acide phosphorique. De préférence également, un bain de rinçage à l'eau est prévu à l'issue de ce traitement. Le substrat peut alors défiler en continu dans ces bacs successifs.An acid bath containing one or more mineral acids, such as nitric acid or preferably phosphoric acid, is preferably used. Also preferably, a water rinsing bath is provided at the end of this treatment. The substrate can then scroll continuously in these successive bins.

Il est cependant parfaitement possible de mettre en contact le substrat coloré et les solutions de traitement par un autre procédé que le passage dans des bacs. On pourra notamment envisager un traitement par aspersion des substrats au moyen de buses raccordées à des récipients contenant les solutions adaptées.However, it is perfectly possible to contact the colored substrate and the treatment solutions by a method other than the passage in tanks. In particular, spray treatment of the substrates may be envisaged by means of nozzles connected to containers containing the appropriate solutions.

Le traitement anti-corrosion est effectué de préférence à température ambiante, mais il est notamment possible de travailler entre 20 et 70°C, en particulier si on veut augmenter la vitesse de la ligne et donc la productivité du procédé de coloration. La température maximale d'utilisation des solutions dépendra en outre de la nature des acides utilisés ainsi que de leurs concentrations. Les paramètres optimaux de ce traitement ont été définis à l'aide de différents essais.The anti-corrosion treatment is preferably carried out at ambient temperature, but it is especially possible to work between 20 and 70 ° C., in particular if it is desired to increase the speed of the line and therefore the productivity of the coloring process. The maximum temperature of use of the solutions will also depend on the nature of the acids used as well as their concentrations. The optimal parameters of this treatment have been defined using different tests.

Durée du traitementDuration of treatment

Des essais ont été effectués sur des fils d'acier inoxydable austénitique de type 316, qui avaient été précédemment colorés à une température du four comprise entre 920°C et 930°C, avec un temps de séjour dans le four de 32 s.Tests were carried out on 316 type austenitic stainless steel wires, which had previously been colored at an oven temperature of 920 ° C to 930 ° C, with an oven residence time of 32 seconds.

Le bain utilisé pour le traitement anti-corrosion contenait une solution aqueuse d'acide nitrique à 20% en volume et à une température de 60°C.The bath used for the anti-corrosion treatment contained an aqueous nitric acid solution at 20% by volume and at a temperature of 60 ° C.

On a testé plusieurs durées de traitement : 10min, 2min, 30s et 5s, puis on a soumis les échantillons au test de résistance à la corrosion OCP (Open Circuit Potentiel- suivi du potentiel d'abandon de l'échantillon dans un milieu NaCl 0,02M) Tableau 2 - Influence du temps d'immersion Echantillon Résultat test OCP Fil non coloré A Fil coloré non traité B+ Fil coloré + traitement 5 s A- Fil coloré + traitement 30 s A Fil coloré + traitement 2 min A+ Fil coloré + traitement 10 min A+ Fil coloré + traitement 30 min A+ A+ = Aucune piqûre
A = de très rares piqûres
A- = quelques piqûres métastables
B+ = piqûres métastables nombreuses mais de faibles amplitudes
B = des piqûres métastables importantes en fréquence et amplitude
C = piqûres stables et produits de corrosion visibles Several treatment times were tested: 10min, 2min, 30s and 5s, and then the samples were subjected to the OCP (Open Circuit Potential) corrosion resistance test, monitoring the potential for dropout of the sample in NaCl 0 medium. , 02M) <u> Table 2 - Influence of immersion time </ u> Sample OCP test result Non colored thread AT Untreated colored yarn B + Colored thread + treatment 5 s AT- Colored thread + 30 s treatment AT Colored thread + treatment 2 min A + Colored thread + treatment 10 min A + Colored thread + treatment 30 min A + A + = No sting
A = very rare bites
A- = some metastable punctures
B + = many metastable punctures but small amplitudes
B = metastable pits important in frequency and amplitude
C = Stable pitting and visible corrosion products

Ces résultats montrent l'efficacité d'un tel traitement post-coloration, puisqu'on retrouve une résistance à la corrosion comparable à celle du métal de base, et ce même dans le cas de temps très courts (jusqu'à 5s). Pour la suite des essais, une durée de 30s, plus en accord avec les vitesses de défilement utilisées, est sélectionnée.These results show the effectiveness of such a post-color treatment, since we find a resistance to corrosion comparable to that of metal basic, even in the case of very short times (up to 5s). For the continuation of the tests, a duration of 30s, more in agreement with the speeds of scrolling used, is selected.

Type d'acide utiliséType of acid used

Les essais ont été réalisés sur des fils d'acier inoxydable austénitique de type 316, qui avaient été précédemment colorés à une température du four comprise entre 920°C et 930°C, avec un temps de séjour dans le four de 32s. Les échantillons ont été plongés dans un bain d'acide pendant 30 secondes. L'acide nitrique pouvant poser des problèmes au niveau de la santé et de l'environnement, on a également testé l'efficacité de l'acide phosphorique. Tableau 3 - Influence du type d'acide Echantillon Résultat test OCP Fil non coloré A Fil coloré non traité B+ Fil coloré + traitement HNO3 (20% en volume) A Fil coloré + traitement H3PO4 (20% en volume) A A+ = Aucune piqûre
A = de très rares piqûres
A- = quelques piqûres métastables
B+ = piqûres métastables nombreuses mais de faibles amplitudes
B = des piqûres métastables importantes en fréquence et amplitude
C = piqûres stables et produits de corrosion visibles The tests were carried out on 316 type austenitic stainless steel wire, which had previously been colored at an oven temperature between 920 ° C and 930 ° C, with a residence time in the oven of 32s. The samples were immersed in an acid bath for 30 seconds. Since nitric acid can pose health and environmental problems, the effectiveness of phosphoric acid has also been tested. <u> Table 3 - Influence of Acid Type </ u> Sample OCP test result Non colored thread AT Untreated colored yarn B + Colored wire + HNO 3 treatment (20% by volume) AT Colored wire + H 3 PO 4 treatment (20% by volume) AT A + = No sting
A = very rare bites
A- = some metastable punctures
B + = many metastable punctures but small amplitudes
B = metastable pits important in frequency and amplitude
C = Stable pitting and visible corrosion products

On peut observer que pour une même température, une même concentration et une même durée de traitement, les deux acides sont efficaces de manière équivalente, puisqu'ils permettent de retrouver la résistance à la corrosion du métal de base. Pour la suite, on utilisera l'acide phosphorique (H3PO4), moins nocif que l'acide nitrique (HNO3).It can be observed that for the same temperature, the same concentration and the same duration of treatment, the two acids are equally efficient, since they make it possible to recover the corrosion resistance of the base metal. For the following, use phosphoric acid (H 3 PO 4 ), less harmful than nitric acid (HNO 3 ).

Température du traitementTreatment temperature

Pour voir l'influence de cette température sur l'efficacité du traitement, des essais ont été réalisés en faisant varier la température d'un bain d'acide phosphorique à 20% en volume dans lequel on fait défiler du fil en acier inoxydable de type 304L. Tableau 4 - influence de la température Echantillon Résultat test OCP Fil non coloré A Fil coloré non traité B+ Fil coloré + traitement à 20°C A+ Fil coloré + traitement à 60°C A A+ = Aucune piqûre
A = de très rares piqûres
A- = quelques piqûres métastables
B+ = piqûres métastables nombreuses mais de faibles amplitudes
B = des piqûres métastables importantes en fréquence et amplitude
C = piqûres stables et produits de corrosion visibles To see the influence of this temperature on the effectiveness of the treatment, tests were carried out by varying the temperature of a phosphoric acid bath at 20% by volume in which stainless steel wire of type 304L. <u> Table 4 - influence of temperature </ u> Sample OCP test result Non colored thread AT Untreated colored yarn B + Colored wire + treatment at 20 ° C A + Colored wire + treatment at 60 ° C AT A + = No sting
A = very rare bites
A- = some metastable punctures
B + = many metastable punctures but small amplitudes
B = metastable pits important in frequency and amplitude
C = Stable pitting and visible corrosion products

Etant donnés les résultats obtenus, on peut dire qu'il n'est pas indispensable de porter la solution de traitement à 60°C pour que celui-ci soit efficace. Pour la suite, on travaillera donc à température ambiante (20°C), ce qui permettra de ne pas chauffer la solution de traitement.Given the results obtained, it can be said that it is not essential to bring the treatment solution to 60 ° C so that it is effective. For the rest, we will work at room temperature (20 ° C), which will not heat the treatment solution.

Cette étude des différents paramètres du procédé a également été réalisée à 0,5M, et a permis de tirer les mêmes conclusions qu'à 0,02M.This study of the different parameters of the process was also carried out at 0.5M, and made it possible to draw the same conclusions as at 0.02M.

On a finalement un traitement anti-corrosion permettant, après coloration d'échantillons par oxydation thermique, de retrouver une résistance à la corrosion équivalente à celle du métal de base. Les paramètres expérimentaux optimaux de ce traitement sont au total les suivants :

  • H3PO4 (20% en volume) ; H2O (80% en volume)
  • température ambiante
  • t = 30s
Finally, an anti-corrosion treatment is used which, after staining samples by thermal oxidation, to find a corrosion resistance equivalent to that of the base metal. The optimal experimental parameters of this treatment are as follows:
  • H 3 PO 4 (20% by volume); H 2 O (80% by volume)
  • ambient temperature
  • t = 30s

Dans un autre mode de réalisation du procédé selon l'invention, on réalise un traitement de déformation plastique à froid du substrat venant d'être refroidi, de sorte à obtenir un taux de déformation compris entre 5 et 15%. En fonction du type de substrat traité, cette opération pourra être constituée d'un skin-pass (fils et bandes laminées à froid), d'un étirage (barres) ou bien encore d'un profilage.In another embodiment of the process according to the invention, a cold plastic deformation treatment of the substrate which has just been cooled is carried out so as to obtain a degree of deformation of between 5 and 15%. Depending on the type of substrate treated, this operation may consist of a skin-pass (cold-rolled wire and strip), stretching (bars) or even profiling.

Les présents inventeurs ont en effet constaté que cette opération permettait d'améliorer sensiblement, et de façon surprenante, différentes propriétés de la surface du substrat traité, telles que la sensibilité aux traces de doigt, la sensibilité aux rayures, et la résistance à la corrosion. En outre, l'homogénéité de la coloration et la résistance à la corrosion s'en trouve également améliorée.The present inventors have indeed found that this operation made it possible to improve, and surprisingly, various properties of the surface of the treated substrate, such as sensitivity to fingerprints, sensitivity to scratching, and corrosion resistance. . In addition, the homogeneity of the coloration and the corrosion resistance is also improved.

Il est bien sur possible de procéder à ce traitement de déformation sans avoir mis le substrat en contact avec au moins un acide minéral. Il est également possible de procéder au traitement en combinaison avec une mise en contact avec au moins un acide minéral, l'ordre dans lequel on procèdera aux deux traitements étant indifférent.It is of course possible to carry out this deformation treatment without having put the substrate in contact with at least one mineral acid. It is also possible to proceed with the treatment in combination with a contact with at least one mineral acid, the order in which the two treatments are carried out being indifferent.

Ces propriétés améliorées ont été mises en évidence au moyen de quatre essais spécifiques.These improved properties were highlighted by means of four specific tests.

Les essais de sensibilité aux traces de doigts ont été réalisés sur des fils de diamètre initial 2,2 mm en acier inoxydable de type 316L. La vitesse de défilement dans le four à passage a été réglée à 2,6 cm/s. Les résultats obtenus sont rassemblés dans le tableau 5 et cotés de la façon suivante :

  • A= insensible (pas de changement de ton)
  • B= peu sensible
  • C= sensible (changement de teinte)
Tableau 5 - Sensibilité aux traces de doigts Essai Paramètres oxydation Skin pass Cotation Température Couleur obtenue % Diamètre final 1 800 Doré très clair 0 2,2 B 2 833 Doré clair 0 2,2 B 3 873 Doré clair 0 2,2 B 4 900 Doré 0 2,2 C 5 933 Doré cuivré 0 2,2 C 6 970 Violine 0 2,2 C 7 1005 Violet bleuté 0 2,2 C 8 900 Doré 5 2,14 A 9 933 Bronze 5 2,14 A 10 970 Cuivré 5 2,14 A 11 1005 Bronze violine 5 2,14 A Fingerprint sensitivity tests were carried out on 2.2 mm diameter stainless steel type 316L initial diameter wires. The scroll speed in the through oven was set at 2.6 cm / sec. The results obtained are summarized in Table 5 and scored as follows:
  • A = insensitive (no change of tone)
  • B = not very sensitive
  • C = sensitive (change of color)
<u> Table 5 - Fingerprint Sensitivity </ u> Trial Oxidation parameters Skin pass Quote Temperature Obtained color % Final diameter 1 800 Very light golden 0 2.2 B 2 833 Light walleye 0 2.2 B 3 873 Light walleye 0 2.2 B 4 900 Golden 0 2.2 VS 5 933 Golden coppery 0 2.2 VS 6 970 Violine 0 2.2 VS 7 1005 Bluish Violet 0 2.2 VS 8 900 Golden 5 2.14 AT 9 933 Bronze 5 2.14 AT 10 970 Copper 5 2.14 AT 11 1005 Bronze purple 5 2.14 AT

On constate bien que l'opération de déformation plastique à froid permet d'améliorer manifestement la sensibilité aux traces de doigts.It is clear that the cold plastic deformation operation obviously improves the sensitivity to fingerprints.

Les essais de sensibilité aux rayures ont été réalisés sur des fils identiques à ceux utilisés pour le test de sensibilité aux traces de doigts. Le test consiste ici à frotter un nombre donné de fois les fils avec différents matériaux de dureté variable. Les résultats obtenus sont rassemblés dans le tableau 6 et cotés de la façon suivante :

  • A= pas de rayures visibles
  • B = rayures non sévères
  • C= rayures sévères
Tableau 6 - Sensibilité aux rayures Essai Cotation acier tranchant/fil Cotation fil/fil 1 C C 2 C C 3 C C 4 C C 5 C C 6 C C 7 C C 8 B A 9 C A 10 C A 11 C A The scratch sensitivity tests were carried out on yarns identical to those used for the fingerprint sensitivity test. The test here consists in rubbing a given number of times the wires with different materials of variable hardness. The results obtained are summarized in Table 6 and scored as follows:
  • A = no visible scratches
  • B = non-severe scratches
  • C = severe scratches
<u> Table 6 - Sensitivity to scratches </ u> Trial Steel cutting / wire quotation Wire / wire rating 1 VS VS 2 VS VS 3 VS VS 4 VS VS 5 VS VS 6 VS VS 7 VS VS 8 B AT 9 VS AT 10 VS AT 11 VS AT

On constate effectivement que cette variante du procédé selon l'invention améliore sensiblement la résistance aux rayures.It is found that this variant of the method according to the invention substantially improves the scratch resistance.

Les essais d'évaluation de l'homogénéité de la coloration ont été réalisés sur des fils identiques à ceux utilisés pour le test de sensibilité aux traces de doigts. L'évaluation est effectuée visuellement par un opérateur.The tests for evaluating the homogeneity of the coloration were carried out on threads identical to those used for the fingerprint sensitivity test. The evaluation is performed visually by an operator.

Les résultats obtenus sont rassemblés dans le tableau 7 et cotés de la façon suivante :

  • A= couleur homogène
  • B = couleur assez homogène
  • C= couleur non homogène
Tableau 7 - homogénéité de la coloration Essai Cotation 1 A 2 A 3 A 4 B 5 C 6 C 7 C 8 A 9 A 10 A 11 A The results obtained are summarized in Table 7 and scored as follows:
  • A = homogeneous color
  • B = fairly homogeneous color
  • C = non-homogeneous color
<u> Table 7 - homogeneity of color </ u> Trial Quote 1 AT 2 AT 3 AT 4 B 5 VS 6 VS 7 VS 8 AT 9 AT 10 AT 11 AT

On constate effectivement que cette variante du procédé selon l'invention améliore l'homogénéité de la coloration, en particulier lorsque la température d'oxydation dépasse 900°C.It is indeed noted that this variant of the process according to the invention improves the homogeneity of the coloration, in particular when the oxidation temperature exceeds 900 ° C.

La résistance à la corrosion a été mesurée par le potentiel de piqûre mesuré par rapport à une électrode saturée au calomel sur une nuance AISI 316L dans une solution NaCl 0.02M à 23°C. Les résultats sont rassemblés dans le Tableau 8. Tableau 8 Mesures de potentiel de piqûre Potentiel de piqûre NaCl 0.02M 23°C 316L nu 658 mV 316L coloré 900°C 253 mV 316L coloré 900°C + Skin Pass 5% 602 mV Corrosion resistance was measured by the pitting potential measured against a saturated calomel electrode on AISI 316L grade in 0.02M NaCl solution at 23 ° C. The results are collated in Table 8. <u> Table 8 Pitting potential measurements </ u> Potential for puncture NaCl 0.02M 23 ° C 316L naked 658 mV Colored 316L 900 ° C 253 mV Colored 316L 900 ° C + Skin Pass 5% 602 mV

Ces résultats montrent clairement l'intérêt d'un skin pass sur le film coloré pour améliorer la résistance à la corrosion.These results clearly show the interest of a skin pass on the colored film to improve the resistance to corrosion.

Afin d'évaluer la nettoyabilité de deux fils d'acier de type 316 L dont l'un a été soumis au procédé selon l'invention et l'autre non, on mesure l'angle de contact d'une goutte d'eau sur leurs surfaces.In order to evaluate the cleanability of two steel wires of type 316 L, one of which was subjected to the process according to the invention and the other not, the contact angle of a drop of water is measured on their surfaces.

Après dégraissage aux ultrasons dans un bain acétone/éthanol, on obtient les valeurs ci-dessous : Tableau 9 - Nettoyabilité Fil Angle de contact Non coloré 63° ± 2° coloré 81° ± 2° After ultrasonic degreasing in an acetone / ethanol bath, the following values are obtained: <u> Table 9 - Cleanability </ u> wire Contact angle Not colored 63 ° ± 2 ° colored 81 ° ± 2 °

On constate que l'angle de contact du fil selon l'invention est nettement augmenté par rapport à celui n'ayant pas été soumis au procédé selon l'invention, ce qui signifie que la surface de ce fil présente une hydrophobicité améliorée, ce qui le rend plus facile à nettoyer et moins réactif à la contamination.It is found that the contact angle of the yarn according to the invention is significantly increased compared to that which has not been subjected to the process according to the invention, which means that the surface of this yarn has an improved hydrophobicity, which makes it easier to clean and less reactive to contamination.

Le procédé selon l'invention présente un intérêt pour de nombreux utilisateurs, parmi lesquels on citera :

  • l'industrie du bâtiment, l'architecture, la décoration, qui recherche des surfaces attrayantes, une harmonie des couleurs, une rupture avec l'aspect métallique de l'acier inoxydable ;
  • l'industrie automobile pour des éléments tels que les enjoliveurs ;
  • les arts ménagers et l'hygiène, pour lesquels on apprécie les aspects décoratifs (boîtes à papier des aéroports japonais) et la facilité d'entretien
  • l'industrie pharmaceutique et la chirurgie, domaines dans lesquels l'invention trouve une application pour tout ce qui concerne la sécurité (une couleur par outil) et/ou l'ordonnancement ;
  • l'équipement, les routes, pour des éléments tels que les panneaux de signalisation ;
  • la Défense nationale qui recherche des matériaux permettant de fabriquer des pièces d'aspect mat, de couleur verte ou jaune
The method according to the invention is of interest to many users, among whom are:
  • the building industry, architecture, decoration, looking for attractive surfaces, a harmony of colors, a break with the metallic appearance of stainless steel;
  • the automotive industry for items such as hubcaps;
  • the domestic arts and hygiene, for which one appreciates the decorative aspects (paper boxes of the Japanese airports) and the ease of maintenance
  • the pharmaceutical industry and surgery, fields in which the invention finds application in all matters of safety (one color per tool) and / or scheduling;
  • equipment, roads, for items such as signs;
  • National Defense looking for materials to make matt, green or yellow pieces

Claims (18)

Procédé de coloration en continu d'un substrat en acier inoxydable ou en alliage base nickel contenant du chrome, selon lequel on fait défiler ledit substrat dans une zone de chauffage réglée à une température de consigne comprise entre 800 et 1500°C, afin d'obtenir une couche oxydée en surface présentant une épaisseur inférieure à 200 nm et un rapport entre les teneurs en chrome et en fer supérieur à 0,02 dans ladite couche oxydée, puis on refroidit ledit substrat à une température inférieure ou égale à 70°C.A method of continuously coloring a substrate made of stainless steel or chromium-containing nickel base alloy, wherein said substrate is passed through a controlled heating zone at a set temperature between 800 and 1500 ° C, in order to obtaining a surface oxidized layer having a thickness of less than 200 nm and a chromium to iron ratio greater than 0.02 in said oxidized layer, and then cooling said substrate to a temperature of less than or equal to 70 ° C. Procédé selon la revendication 1, selon lequel, avant d'introduire le substrat dans ladite zone de chauffage, on effectue une préparation de surface du substrat pour homogénéiser ladite surface.The method of claim 1 wherein prior to introducing the substrate into said heating zone, a surface preparation of the substrate is performed to homogenize said surface. Procédé selon la revendication 1 ou 2, selon lequel, après avoir été refroidi, ledit substrat est mis en contact avec une solution aqueuse d'acide minéral, puis rincé à l'eau.A process according to claim 1 or 2, wherein after cooling, said substrate is contacted with an aqueous solution of mineral acid and then rinsed with water. Procédé selon la revendication 3, selon lequel l'acide minéral est l'acide phosphorique.The process of claim 3 wherein the mineral acid is phosphoric acid. Procédé selon l'une quelconque des revendications 1 à 4, selon lequel, après avoir été coloré, ledit substrat est soumis à une déformation plastique à froid (dite skin pass) permettant d'obtenir un taux de déformation compris entre 5 et 15%.A method according to any one of claims 1 to 4, wherein, after being colored, said substrate is subjected to a cold plastic deformation (skin pass) to obtain a deformation rate of between 5 and 15%. Procédé selon l'une quelconque des revendications 1 à 5, selon lequel ledit substrat est un fil d'acier inoxydable choisi parmi un acier inoxydable austénitique, un acier inoxydable ferritique, un acier inoxydable martensitique et un acier inoxydable duplex et présentant un diamètre inférieur à 32 mm, que l'on bobine à l'issue du procédé.A process according to any one of claims 1 to 5, wherein said substrate is a stainless steel wire selected from austenitic stainless steel, a ferritic stainless steel, a steel martensitic stainless steel and a duplex stainless steel and having a diameter less than 32 mm, which is reeled at the end of the process. Procédé selon la revendication 6, selon lequel l'opération de déformation plastique à froid dudit fil est une opération de tréfilage.The method of claim 6, wherein the cold plastic deformation operation of said wire is a wire drawing operation. Procédé selon l'une quelconque des revendications 1 à 5, selon lequel ledit substrat est une barre d'acier inoxydable choisi parmi un acier inoxydable austénitique, un acier inoxydable ferritique, un acier inoxydable martensitique et un acier inoxydable duplex et présentant un diamètre supérieur à 2 mm et une longueur inférieure ou égale à 12 m.A process according to any one of claims 1 to 5, wherein said substrate is a stainless steel bar selected from austenitic stainless steel, ferritic stainless steel, martensitic stainless steel and duplex stainless steel and having a diameter greater than 2 mm and a length less than or equal to 12 m. Procédé selon la revendication 8, selon lequel l'opération de déformation plastique à froid de ladite barre est une opération d'étirage.The method of claim 8, wherein the cold plastic deformation operation of said bar is a drawing operation. Procédé selon l'une quelconque des revendications 1 à 9, selon lequel le substrat défile dans ladite zone de chauffage par passage dans une enceinte dans laquelle règne une atmosphère inerteProcess according to any one of Claims 1 to 9, in which the substrate passes through said heating zone by passing through a chamber in which there is an inert atmosphere. installation pour la fabrication d'un substrat en acier inoxydable ou en alliage base nickel contenant du chrome, par le procédé selon l'une quelconque des revendications 1 à 10, comprenant : - des moyens de défilement dudit substrat, - des moyens de chauffage dudit substrat, comprenant des moyens de réglage de la température de consigne et - des moyens de refroidissement dudit substrat jusqu'à une température inférieure à 70°C. plant for the production of a chromium-containing nickel-base or stainless steel substrate, according to the method according to any one of claims 1 to 10, comprising: means for scrolling said substrate, means for heating said substrate, comprising means for adjusting the set temperature and means for cooling said substrate to a temperature below 70 ° C. Installation selon la revendication 11, comprenant en outre des moyens permettant d'homogénéiser la surface dudit substrat, lesdits moyens étant placés en amont desdits moyens de chauffage.Installation according to claim 11, further comprising means for homogenizing the surface of said substrate, said means being placed upstream of said heating means. Installation selon l'une ou l'autre des revendications 11 ou 12, comprenant en outre des moyens de mise en contact dudit substrat avec une solution aqueuse d'acide minéral, ainsi que des moyens de rinçage du dit substrat.Installation according to either of claims 11 or 12, further comprising means for bringing said substrate into contact with an aqueous solution of mineral acid, as well as means for rinsing said substrate. Installation selon l'une quelconque des revendications 11 à 13, comprenant en outre des moyens de déformation plastique à froid dudit substrat, placés en aval desdits moyens de chauffage.Installation according to any one of claims 11 to 13, further comprising cold plastic deformation means of said substrate, placed downstream of said heating means. Substrat en acier inoxydable ou en alliage base nickel contenant du chrome, comprenant une couche oxydée en surface présentant une épaisseur inférieure à 200 nm et un rapport entre les teneurs en chrome et en fer supérieur à 0,02 dans ladite couche oxydée.A stainless steel or chromium-containing nickel base alloy substrate comprising a surface-oxidized layer having a thickness of less than 200 nm and a ratio of chromium to iron content of greater than 0.02 in said oxidized layer. Substrat selon la revendication 15, ayant en outre subi une déformation plastique à froid avec un taux de déformation compris entre 5 et 15%, ladite déformation ayant eu lieu après oxydation de la surface.Substrate according to claim 15, furthermore having undergone cold plastic deformation with a degree of deformation of between 5 and 15%, said deformation having occurred after oxidation of the surface. Substrat selon l'une ou l'autre des revendications 15 ou 16, caractérisé en ce qu'il est sous forme d'une bobine d'un fil d'acier inoxydable présentant un diamètre inférieur à 32 mm, ledit acier étant choisi parmi un acier inoxydable austénitique, un acier inoxydable ferritique, un acier inoxydable martensitique et un acier inoxydable duplex.Substrate according to either of Claims 15 and 16, characterized in that it is in the form of a coil of a stainless steel wire having a diameter of less than 32 mm, said steel being chosen from a austenitic stainless steel, ferritic stainless steel, martensitic stainless steel and duplex stainless steel. Substrat selon l'une ou l'autre des revendications 15 ou 16, caractérisé en ce qu'il est sous forme d'une barre d'acier inoxydable présentant un diamètre supérieur à 2 mm et une longueur inférieure ou égale à 12 m, ledit acier étant choisi parmi un acier inoxydable austénitique, un acier inoxydable ferritique, un acier inoxydable martensitique et un acier inoxydable duplex.Substrate according to either of Claims 15 or 16, characterized in that it is in the form of a stainless steel bar having a diameter greater than 2 mm and a length less than or equal to 12 m, said steel being selected from austenitic stainless steel, a steel ferritic stainless steel, martensitic stainless steel and duplex stainless steel.
EP06291130A 2006-06-06 2006-06-06 Process of continuous colouring of a stainless steel or nickel-based containing chromium substrate and installation of implementation of the process Withdrawn EP1865081A1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014009727A1 (en) * 2012-07-10 2014-01-16 Kts Wire Ltd Method for treating elongated metal product by heating and oxidizing the surface in a controlled environment

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Publication number Priority date Publication date Assignee Title
JPS59232233A (en) * 1983-06-16 1984-12-27 Kawasaki Steel Corp Method for annealing cold rolled stainless steel strip
JPH0211784A (en) * 1988-06-29 1990-01-16 Nippon Steel Corp Surface cleaning treatment of drawn steel wire rod
EP0453321A1 (en) * 1990-04-20 1991-10-23 Kawasaki Steel Corporation Method for descaling hot-rolled stainless steel strip
JPH06271938A (en) * 1993-03-23 1994-09-27 Koyo Tetsusen Kk Production of annealed iron wire excellent in corrosion resistance
JP2001234371A (en) * 2000-02-21 2001-08-31 Bridgestone Corp Steel wire with copper alloy plating excellent in adhesive property with rubber, cord and rubber article
CN1519065A (en) * 2003-09-02 2004-08-11 黄 澄 Method for manufacturing wire of bearing steel

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Publication number Priority date Publication date Assignee Title
JPS59232233A (en) * 1983-06-16 1984-12-27 Kawasaki Steel Corp Method for annealing cold rolled stainless steel strip
JPH0211784A (en) * 1988-06-29 1990-01-16 Nippon Steel Corp Surface cleaning treatment of drawn steel wire rod
EP0453321A1 (en) * 1990-04-20 1991-10-23 Kawasaki Steel Corporation Method for descaling hot-rolled stainless steel strip
JPH06271938A (en) * 1993-03-23 1994-09-27 Koyo Tetsusen Kk Production of annealed iron wire excellent in corrosion resistance
JP2001234371A (en) * 2000-02-21 2001-08-31 Bridgestone Corp Steel wire with copper alloy plating excellent in adhesive property with rubber, cord and rubber article
CN1519065A (en) * 2003-09-02 2004-08-11 黄 澄 Method for manufacturing wire of bearing steel

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014009727A1 (en) * 2012-07-10 2014-01-16 Kts Wire Ltd Method for treating elongated metal product by heating and oxidizing the surface in a controlled environment

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