EP1865088B1 - Procédé destiné au durcissement de l'acier inoxydable et de sels fondus pour l'exécution du procédé - Google Patents

Procédé destiné au durcissement de l'acier inoxydable et de sels fondus pour l'exécution du procédé Download PDF

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EP1865088B1
EP1865088B1 EP07010534A EP07010534A EP1865088B1 EP 1865088 B1 EP1865088 B1 EP 1865088B1 EP 07010534 A EP07010534 A EP 07010534A EP 07010534 A EP07010534 A EP 07010534A EP 1865088 B1 EP1865088 B1 EP 1865088B1
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weight
molten salt
carbon
chloride
stainless steel
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German (de)
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EP1865088A1 (fr
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Ulrich Dr. Baudis
Michael Niedermeyer
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Durferrit GmbH Thermotechnik
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Durferrit GmbH Thermotechnik
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/34—Methods of heating
    • C21D1/44—Methods of heating in heat-treatment baths
    • C21D1/46—Salt baths
    • 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
    • C23C8/40—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 liquids, e.g. salt baths, liquid suspensions
    • C23C8/42—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 liquids, e.g. salt baths, liquid suspensions only one element being applied
    • C23C8/44—Carburising
    • C23C8/46—Carburising of ferrous surfaces
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • 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
    • C23C8/40—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 liquids, e.g. salt baths, liquid suspensions
    • C23C8/42—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 liquids, e.g. salt baths, liquid suspensions only one element being applied
    • C23C8/48—Nitriding
    • C23C8/50—Nitriding of ferrous surfaces
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • 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
    • C23C8/40—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 liquids, e.g. salt baths, liquid suspensions
    • C23C8/52—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 liquids, e.g. salt baths, liquid suspensions more than one element being applied in one step
    • C23C8/54—Carbo-nitriding
    • C23C8/56—Carbo-nitriding of ferrous surfaces

Definitions

  • the invention relates to a method for hardening stainless steel and a molten salt for carrying out the method.
  • stainless steel Due to its excellent corrosion resistance, stainless steel is used in chemical apparatus engineering, in food technology, in the petrochemical industry, in the offshore sector, in shipbuilding and aircraft construction, in architecture, in building construction and equipment construction and in many other industrial sectors.
  • the steel is generally not sufficiently resistant to corrosion to be considered stainless steel.
  • the content of metallic chromium in the steel is thus an important criterion for the Corrosion resistance, as in P. Gümpel et al. Stainless Steels, Expert Verlag, Volume 349, Renningen Malmsheim 1998 is executed.
  • a major disadvantage of most common stainless steels such as 1.4301, 1.4441, 1.4541 or 1.4575 is that these steels are quite soft and thus susceptible to scratching the surface by hard particles such as dust or sand.
  • Most stainless steels - except for the very special martensitic stainless steels - are not hardenable by physical methods such as annealing and quenching. The low surface hardness often hinders the use of stainless steel.
  • Another disadvantage of most stainless steels is their strong tendency to seize, i. for welding the surface of two mutually sliding surfaces due to adhesion.
  • thermochemical treatment e.g. By nitriding or nitrocarburizing in gas (under ammonia atmosphere), in plasma (under nitrogen / argon) or in molten salt (in molten cyanates), the surface of stainless steel can be enriched with nitrogen to form iron and chromium nitrides.
  • the resulting layers form out of the material, so they are - unlike galvanic or physical layers - not applied from the outside and therefore extremely adherent.
  • hard layers of 5 to 50 ⁇ m thickness are formed. The hardness of such nitrided or nitrocarburized layers on stainless steel reaches over 1000 units on the Vickers hardness scale due to the high hardness of the resulting iron and chromium nitrides.
  • nitrided or nitrocarburized layers on stainless steel The problem with the practical use of such nitrided or nitrocarburized layers on stainless steel is that although these layers are hard, they lose their corrosion resistance.
  • the reason for this is the relatively high treatment temperature, which is around 580 ° C during nitriding or nitrocarburizing.
  • the diffusing elements form nitrogen and carbon with the chromium-stable chromium nitride (CrN) or chromium carbides (Cr 7 C 3 ) in the area of the component surface.
  • the corrosion resistance-free free chromium is removed from the stainless steel matrix to a depth of about 50 ⁇ m below the surface and converted into chromium nitride or chromium carbide.
  • the surface of the component becomes hard due to the formation of iron and chromium nitride, but it is susceptible to corrosion. In use, such layers are rapidly worn away due to corrosion.
  • a hard and at the same time corrosion-resistant layer can be thermochemically produced by the so-called Kolsterizing® on stainless steel.
  • This process is for example in Kolster by® - corrosion-resistant surface hardening of austenitic stainless steel - Information Sheet of Bodycote Hardiffbv, Parimariboweg 45, NL-7333 Apeldoorn, info@hardiff.de and M. Wägner Increasing the wear resistance of stainless steels. Steel STEEL No. 2 (2004) 40-43 mentioned.
  • the conditions of the process are described neither in the patent literature nor in the generally accessible scientific literature.
  • treated components have a hard, wear-resistant layer between 10 and 20 microns thick, the corrosion resistance of the base material remains.
  • Kolsterised® components must not be heated above 400 ° C, otherwise they will lose their corrosion resistance.
  • the workpiece to be cured is first surface activated by treatment with an acid and then treated in a heated fluidized bed containing active nitrogen and preferably also active carbon capable of diffusing into the workpiece.
  • a method for carburizing austenitic metal is described. According to this method, the metal is kept in a fluorine-containing or fluoride-containing guest atmosphere under heating prior to carburizing. The carburizing of the metal is then carried out at a temperature of at most 680 ° C.
  • US-A-19996269 discloses a melt for curing iron parts comprising the following components: 50 parts of barium chloride, 25 parts of sodium chloride, 25 parts of potassium chloride, 5-10 parts of sodium cyanide and 3-5% of a mixture of 1 part of strontium chloride and 7 parts of barium chloride.
  • JP-A-52123345 discloses a melt for nitriding iron at 690 ° C comprising the following components: 15% potassium chloride, 15% sodium chloride, 80% barium chloride, sodium titanate and potassium hexacyanoferrate.
  • the invention has for its object to provide a cost-effective rational method by means of which a hardening of stainless steel is made possible, in which the corrosion resistance of the stainless steel is maintained as much as possible.
  • the molten salt according to the invention comprises the following components: 30-60% by weight Potassium chloride (KCL) 20-40% by weight Lithium chloride (LiCl) 15-30% by weight an activator substance consisting of barium chloride (BaCl 2 ) and / or strontium chloride (SrCl 2 ) and / or magnesium chloride (MgCl 2 ) and / or calcium chloride (CaCl 2 ) 0.2-25% by weight a carbon donating substance consisting of a free cyanide and / or a complex cyanide.
  • KCL Potassium chloride
  • LiCl Lithium chloride
  • BaCl 2 barium chloride
  • SrCl 2 strontium chloride
  • MgCl 2 magnesium chloride
  • CaCl 2 calcium chloride
  • the present invention avoids high equipment and energy costs and makes use of a light, easy for less qualified personnel easily executable procedure.
  • the invention further enhances the tendency of the stainless steel to eat, i. For cold welding and thus the adhesive wear significantly reduced.
  • the hardness of the surface of the stainless steel is increased from 200 - 300 Vickers to values up to 1000 Vickers, which results in a high scratch resistance.
  • the use of the molten salt according to the invention makes it possible to harden stainless steel while maintaining its corrosion resistance.
  • the method according to the invention is based on the following principle
  • these processes using the molten salt of the invention are used as a reactive medium and as a heat transfer agent.
  • the molten salt according to the invention contains constituents from which diffusible carbon and / or nitrogen can be liberated and suitable activator substances which cause the release of diffusible nitrogen and / or carbon at low temperatures. It is essential that the treatment temperatures in the molten salt below 450 ° C and are particularly advantageous to lower than the formation temperature of chromium carbide (420 - 440 ° C) or chromium nitride (350 - 370 ° C) to the formation of nitrides and To avoid carbides in the steel matrix completely or as far as possible.
  • the concentration of the active carbon or nitrogen donating substances in the form of complex or free cyanides in the molten salt of the invention is very high compared with the concentration of corresponding substances (ammonia, methane, carbon monoxide) in gas atmospheres or in a plasma.
  • the relatively long treatment times required for the method according to the invention are based on the fact that the diffusion rate of C and N is a function of the temperature and decreases significantly at temperatures below 450 ° C. At the low temperatures necessary to avoid chromium carbide and chromium nitride formation, long diffusion times of 12 to 60 hours must be used.
  • Austenitic stainless steels or so-called duplex steels (ferritic-austenitic steels) are against such long heat treatment times very insensitive and change their other mechanical properties or the structure as good as not.
  • the molten salt consists of a salt mixture of potassium chloride, barium chloride and lithium chloride.
  • a melt of strontium chloride, potassium chloride and lithium chloride can be used.
  • magnesium chloride and / or calcium chloride instead of barium chloride or strontium chloride.
  • the melting points of the eutectic mixtures of these salts are from 320 ° C to 350 ° C.
  • the salt should be dried for at least 12 to 24 hours at 120-140 ° C before the addition and freed from the water of crystallization, since it contains 3 mol equivalents of water of crystallization in the form supplied.
  • the red potassium hexacyanoferrate (III) that is, K 3 Fe (CN) 6 , which contains no water of crystallization, can be added to the melt.
  • the amount of complex cyanide added is in the range of 2 to 10% by weight.
  • complex metal cyanides can also be used as carbon donors.
  • these are tetracyanoxide or tetracyanozinc compounds, for example Na 2 Ni (CN) 4 or Na 2 Zn (CN) 4 .
  • complex nontoxic iron cyanides or metal cyanides and sodium and / or potassium cyanide can be added in free form, in an amount of 0.1 to 25 wt.%, Preferably between 3 and 10 wt.%.
  • the results are similar to the use of complex cyanides, and mixtures of complex and free cyanides can also be used.
  • molten salts with complex cyanides is that it does not handle toxic substances because hexacyanoferrate is non-toxic per se.
  • the decay is very slow.
  • the carbon formed during the decomposition diffuses into the austenitic stainless steel to be hardened and remains there at temperatures below 420 ° C. in solid, saturated or supersaturated solution.
  • Austenite has a high solubility for carbon, a lower one for nitrogen.
  • Part of the resulting nitrogen also diffuses into the stainless steel surface. If the treatment temperature is below 350 - 370 ° C, so does the nitrogen - like the carbon - in solid solution, the temperature is between 370 ° C and 420 ° C, so the nitrogen forms with the alloying element chromium chromium nitride and thus potentially reduce the corrosion resistance of stainless steel on the surface. However, even in this temperature range, a formation of chromium carbide is still avoided, so that the alloy matrix of the stainless steel, despite the Chromnitridön given in this temperature range still little chromium is removed, so that reducing the corrosion resistance of the stainless steel may still be acceptable.
  • Cyanide ions which resulted from the decomposition of the complex metal salt, are oxidized to cyanate ions by atmospheric oxygen, which is omnipresent in the melt. These can decompose to form carbon monoxide and nitrogen. Cyanations are usually the source of diffusible nitrogen. However, cyanide ions can also be further oxidized to carbonate ions, resulting in carbon monoxide. Carbon monoxide can continue to react with carbon dioxide by releasing diffusible carbon.
  • cyanide can react with barium ions of the activator substance contained as barium chloride in the molten salt to barium cyanide Ba (CN) 2 , which turns into barium cyanamide BaNCN. This releases carbon, which can diffuse into the components.
  • the barium cyanamide further reacts with atmospheric oxygen to form barium carbonate and nitrogen which is released. Similar reactions are to be expected with strontium, calcium and magnesium, if strontium chloride, calcium chloride or magnesium chloride is used as the activator substance.
  • strontium, calcium and magnesium if strontium chloride, calcium chloride or magnesium chloride is used as the activator substance.
  • the alkaline earth metals in the form of their halides thus form in the process according to the invention activator substances which bring about the release of diffusible nitrogen and carbon in the temperature range of the process according to the invention. Without the participation of at least one alkaline earth element of the series magnesium, calcium, strontium and barium, the diffusion of the necessary carbon into the stainless steel surface is not possible.
  • the other alkali metals Na, K, Rb and Cs do not show this effect.
  • An analytical control of the molten salts according to the invention can be carried out as follows:
  • the change in the concentration of the active Ingredients can be monitored by potentiometric titration.
  • K 4 Fe (CN) 6 can be titrated with cerium (IV) sulfate solution.
  • Free cyanide can be determined very well with nickel (II) sulfate. Consumed cyanide or complex cyanide is added accordingly.
  • an inert gas such as argon, nitrogen or carbon dioxide may be introduced therein.
  • the molten salt can be operated in a closed retort using nitrogen, argon or carbon dioxide as a protective gas.
  • a crucible made of heat-resistant steel e.g. from the material 1.4828, 42 kg dry potassium chloride, 34 kg dry lithium chloride and 20 kg barium chloride siccum weighed and mixed loosely. All salts must have a residual moisture content of less than 0.3% by weight.
  • the mixture is heated to 400 ° C and gives a water-clear melt.
  • 4 kg of potassium hexacyanoferrate (II) are slowly added, which had previously been dried for 12 h at 140 ° C in a muffle furnace.
  • the potassium hexacyanoferrate (II) is introduced, a very small amount of carbon deposits on the crucible wall and on the surface of the melt. This carbon is skimmed off with a sifting spoon.
  • a water-clear melt is present, which is brought to an operating temperature of 400 ° C.
  • V2A stain is a mixture of 100 ml of water and conc. 100 ml of hydrochloric acid. (HCI, 30%) and 0.3% "bird's reagent".
  • Vogel's reagent is a mixture of 60% 2-methoxy-2-propanol (H3C-O-CH2Oh-CH3) 5% thiourea (H2N-CS-NH2) 5% nonylphenol ethoxylate residue ethanol.
  • the cross section is photographically in FIG. 1 shown in a 500-fold magnification.
  • the surface hardness of this layer is determined to be 642 - 715 HV (0.5) or 1100 - 1210 HV (0.025).
  • the element distribution within the layer can be determined by glow discharge spectroscopy (GDOES) and is exemplified in FIG. 2 shown.
  • GDOES glow discharge spectroscopy
  • FIG. 2 is the penetration depth of the elements N, C, Fe, Cr 2 , Ni, Mo shown in the surface of the cured with the molten salt workpiece, that is, the mass concentrations of these elements in percent, depending on the depth in the workpiece in microns.
  • FIG. 3 shows the hardness curve as a function of the depth (in ⁇ m) for this workpiece.
  • the hardness profile was measured by the Vickers method under a test load of 0.010 kp (10 grams).
  • the hardness of the workpiece is significantly increased.
  • the result of this treatment is a 10-25 ⁇ m thick diffusion layer on the surface of the treated components and samples. which can be made visible metallographically by a cross-section and etching with the etchant V2A-stain.
  • the result of this treatment is an approx. 10 ⁇ m thick diffusion layer on the surface of the treated components and samples, which can be made visible metallographically by cross-sectioning and etching with the etchant V2A-stain.
  • the hardness of this layer is determined to be 620 HV (0.5).

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  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
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  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Thermal Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Heat Treatment Of Articles (AREA)
  • Coating With Molten Metal (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
  • Chemical Treatment Of Metals (AREA)

Claims (17)

  1. Sel fondu permettant de durcir des surfaces en acier spécial, comportant les composants suivants : 30 à 60 % en poids de chlorure de potassium (KCl) 20 à 40 % en poids de chlorure de lithium (LiCl) 15 à 30 % en poids d'une substance d'activation composée de chlorure de baryum (BaCl2) et/ou de chlorure de strontium (SrCl2) et/ou de chlorure de magnésium (MgCl2) et/ou de chlorure de calcium (CaCl2) 0,2 à 25 % en poids d'une substance donatrice de carbone composée d'un cyanure libre et/ou d'un cyanure complexe.
  2. Sel fondu selon la revendication 1, caractérisé en ce que celui-ci contient en tant que substance d'activation en plus du chlorure de baryum et/ou du chlorure de strontium aussi du chlorure de magnésium et/ou du chlorure de calcium dans une quantité comprise entre 0,1 et 10 % en poids.
  3. Sel fondu selon l'une des revendications 1 ou 2, caractérisé en ce que celui-ci contient en tant que substance donatrice de carbone de l'hexacyanoferrate (II) de potassium et/ou de l'hexacyanoferrate (III) de potassium.
  4. Sel fondu selon la revendication 3, caractérisé en ce que celui-ci contient les composants suivants : 42 % en poids de KCl 34 % en poids de LiCl 20 % en poids de BaCl2 en tant que substance d'activation 4 % en poids d'hexacyanoferrate (II) de potassium en tant que substance donatrice de carbone.
  5. Sel fondu selon la revendication 3, caractérisé en ce que celui-ci contient les composants suivants : 40 % en poids de KCl 33 % en poids de LiCl 2 % en poids de BaCl2 et 20 % en poids de SrCl2 en tant que substances d'activation 5 % en poids d'hexacyanoferrate (II) de potassium en tant que substance donatrice de carbone.
  6. Sel fondu selon l'une des revendications 1 ou 2, caractérisé en ce que celui-ci contient en tant que substance donatrice de carbone un composé tétracyanonickel ou un composé tétracyanozinc.
  7. Sel fondu selon la revendication 6, caractérisé en ce que celui-ci contient en tant que substance donatrice de carbone Na2Ni(CN)4 ou Na2Zn(CN)4.
  8. Sel fondu selon l'une des revendications 1 à 7, caractérisé en ce qu'il contient en tant que substance donatrice de carbone du cyanure libre des métaux alcalins Li, Na et/ou K dans une quantité comprise entre 0,1 et 25 % en poids.
  9. Sel fondu selon la revendication 8, caractérisé en ce que celui-ci contient les composants suivants : 44 % en poids de KCl 30 % en poids de LiCl 5 % en poids de BaCl2 et 15 % de SrCl2 en tant que substances d'activation 3 % en poids d'hexacyanoferrate (II) de potassium, 2 % en poids de NaCN et 1 % en poids de KCN en tant que substances donatrices de carbone.
  10. Sel fondu selon la revendication 8, caractérisé en ce que celui-ci contient les composants suivants : 37 % en poids de KCl 26 % en poids de LiCl 17 % en poids de SrCl2 en tant que substance d'activation 10 % en poids de NaCN et 10 % en poids de KCN en tant que substances donatrices de carbone.
  11. Sel fondu selon l'une des revendications 1 à 10, caractérisé en ce que celui-ci contient en tant que composants supplémentaires des ions cyanate (NCO-) dans une quantité comprise entre 0,1 % en poids et 10 % en poids et des ions carbonate (CO3)2- dans une concentration comprise entre 0,1 et 10 % en poids.
  12. Procédé de durcissement de pièces composées d'acier spécial en incorporant par diffusion les éléments carbone et/ou azote dans les surfaces des pièces, en ce que les pièces sont plongées dans un sel fondu selon l'une des revendications 1 à 11 et sont soumises à celui-ci à des températures inférieures à 450 °C pendant une durée allant de 15 minutes à 240 heures.
  13. Procédé selon la revendication 12, caractérisé en ce que les pièces sont soumises à un sel fondu à une température comprise dans la plage allant de 350 °C à 410 °C.
  14. Procédé selon l'une des revendications 12 ou 13, caractérisé en ce que les pièces sont soumises, pendant une durée de 48 heures, à un sel fondu présentant la composition suivante : 42 % en poids de KCl 34 % en poids de LiCl 20 % en poids de BaCl2 4 % en poids d'hexacyanoferrate (II) de potassium.
  15. Procédé selon l'une des revendications 12 à 14, caractérisé en ce que pour chasser l'air et pour éviter l'oxydation du cyanure libre et complexe, on dirige un gaz inerte à travers le sel fondu.
  16. Procédé selon la revendication 15, caractérisé en ce que l'on utilise en tant que gaz inerte de l'argon, de l'azote ou du dioxyde de carbone.
  17. Procédé selon l'une des revendications 12 à 16, caractérisé en ce que pour chasser l'air et pour éviter l'oxydation du cyanure libre et complexe, on exploite le sel fondu dans une cornue fermée en utilisant de l'azote, de l'argon ou du dioxyde de carbone en tant que gaz protecteur.
EP07010534A 2006-06-09 2007-05-26 Procédé destiné au durcissement de l'acier inoxydable et de sels fondus pour l'exécution du procédé Active EP1865088B1 (fr)

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US (1) US7909943B2 (fr)
EP (1) EP1865088B1 (fr)
JP (1) JP5101173B2 (fr)
KR (1) KR20070118008A (fr)
CN (1) CN101235477B (fr)
AT (1) ATE443163T1 (fr)
BR (1) BRPI0702568B1 (fr)
CA (1) CA2591244A1 (fr)
DE (2) DE102006026883B8 (fr)
ES (1) ES2331383T3 (fr)
MX (1) MX2007006969A (fr)
PL (1) PL1865088T3 (fr)
ZA (1) ZA200704591B (fr)

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DE502007001522D1 (de) 2009-10-29
DE102006026883B3 (de) 2007-08-16
DE102006026883B8 (de) 2007-10-04
CN101235477B (zh) 2011-05-18
JP5101173B2 (ja) 2012-12-19
ATE443163T1 (de) 2009-10-15
BRPI0702568A (pt) 2008-02-19
PL1865088T3 (pl) 2010-01-29
MX2007006969A (es) 2008-10-30
KR20070118008A (ko) 2007-12-13
ES2331383T3 (es) 2009-12-30
EP1865088A1 (fr) 2007-12-12
BRPI0702568B1 (pt) 2015-10-13
US20080099108A1 (en) 2008-05-01
CA2591244A1 (fr) 2007-12-09
US7909943B2 (en) 2011-03-22
ZA200704591B (en) 2008-08-27
CN101235477A (zh) 2008-08-06

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