WO2011013360A1 - Treatment liquid for forming protective film for steel member having nitrogen compound layer, and compound layer protective film - Google Patents

Treatment liquid for forming protective film for steel member having nitrogen compound layer, and compound layer protective film Download PDF

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WO2011013360A1
WO2011013360A1 PCT/JP2010/004780 JP2010004780W WO2011013360A1 WO 2011013360 A1 WO2011013360 A1 WO 2011013360A1 JP 2010004780 W JP2010004780 W JP 2010004780W WO 2011013360 A1 WO2011013360 A1 WO 2011013360A1
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compound layer
protective film
treatment
treatment liquid
steel material
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PCT/JP2010/004780
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French (fr)
Japanese (ja)
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小西知義
池田芳宏
別府正昭
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日本パーカライジング株式会社
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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
    • 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
    • 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
    • C21D1/06—Surface hardening
    • 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
    • C21D1/06—Surface hardening
    • C21D1/09—Surface hardening by direct application of electrical or wave energy; by particle radiation
    • C21D1/10—Surface hardening by direct application of electrical or wave energy; by particle radiation by electric induction
    • 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
    • C21D1/68—Temporary coatings or embedding materials applied before or during heat treatment
    • 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
    • C23C8/24—Nitriding
    • C23C8/26—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
    • C23C8/42—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
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/004—Dispersions; Precipitations
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/008—Martensite
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • the present invention relates to a hardened steel material used as a mechanical structural component having excellent mechanical strength such as surface pressure strength, wear resistance, bending fatigue strength, a manufacturing method thereof, and a treatment liquid used therefor.
  • nitriding treatment including soft nitriding treatment
  • carburizing and quenching and induction hardening
  • induction hardening are performed on cast iron and steel mechanical structural parts.
  • a compound layer made of nitride formed on the outermost surface by nitriding treatment is known to have excellent sliding properties, wear resistance, and high seizure resistance (hereinafter referred to as nitrogen compound).
  • nitrogen compound a compound layer made of nitride formed on the outermost surface by nitriding treatment
  • nitrogen compound high seizure resistance
  • Called layer effect I
  • nitriding treatment is inferior in surface pressure strength, fatigue strength, etc. compared to carburizing quenching and induction quenching.
  • the nitrogen compound layer peels from the steel substrate. There is a case.
  • the nitrogen compound layer had rather an adverse effect in fatigue tests at high surface pressures exceeding 2 GPa.
  • the present inventors have found that this factor is not in the compound layer itself but because the hardened layer depth of the substrate supporting the compound layer is shallow. In other words, the nitriding unit alone has insufficient the depth of the hardened layer immediately below it in order to make full use of the good slidability of the outermost compound layer.
  • a steel material containing nitrogen has a finer martensite structure obtained after quenching than a steel material not containing nitrogen, so that the hardness is increased, and the hardening depth is increased by improving the hardenability.
  • the nitriding treatment can also be used as a nitrogen diffusion pretreatment for forming a nitrogen diffusion layer for improving hardenability (hereinafter referred to as effect II by forming a nitrogen compound layer). That is, the characteristics that can be obtained by using this effect II are not due to the action of the nitrogen compound layer itself, but due to the action of diffused nitrogen in the steel immediately below the nitrogen compound layer generated when the nitrogen compound layer is formed.
  • the nitrogen-containing martensite structure obtained by quenching has high surface pressure strength and high fatigue strength due to resistance to temper softening, resistance to crack initiation and growth, in addition to the above-mentioned high hardness and hardenability improvement. It has been known.
  • the quenching temperature needs to be at least the temperature Ac3 transformation point at which an austenite structure is formed, and is usually selected from a temperature range of 750 to 1050 ° C.
  • the nitrogen compound layer formed at a nitriding temperature of 570 ° C. is a combination of iron and nitrogen.
  • the nitrogen compound layer undergoes oxidation and decomposes. It is released as a gas and the nitrogen compound layer disappears. This has been reported for a long time (Non-Patent Document 1).
  • the combined heat treatment technique by nitriding and quenching usually uses only the effect II of the nitrogen diffusion layer obtained by nitriding, and does not use the effect I of the nitrogen compound layer formed by nitriding. That is, the nitrogen compound layer does not stop disappearing during quenching, which is a subsequent process of nitriding.
  • this technology for example, the composite heat treatment disclosed in Patent Documents 1 to 5.
  • Patent Document 6 discloses a composite heat treatment method in which a nitriding treatment is performed at a temperature of 600 ° C. or higher to form a nitrogen compound layer having a thickness of 5 ⁇ m or less, followed by induction hardening to obtain a quenched member having a nitrogen compound layer having a thickness of 2 ⁇ m or less. ing.
  • the reason why the nitriding condition is set to a high temperature of 600 ° C. or higher in the present technology is that a higher concentration of nitrogen diffusion can be expected at the deeper side of the steel material, but the nitrogen compound layer obtained at a nitriding temperature exceeding 600 ° C. has a hardness.
  • Patent Document 7 discloses this.
  • Patent Document 8 to be used for both effects I and II, a hard nitride layer is formed on the surface of the steel material, and further, Ti, Zr, Hf, V, Nb, Ta, Cr, W are formed thereon.
  • hardened steel member characterized by the inorganic compound layer containing at least one metal oxide selected from the group consisting of Mo and Al is formed is disclosed.
  • Patent No. 3193320 Japanese Patent No. 3327386 Japanese Patent No. 3145517 JP-A-7-90364 JP 2007-154254 A JP 2007-77411 A JP 58-96815 Heat treatment Vol.16 No.4 P206 1976 JP 2008-038220
  • the object of the present invention is to provide a method for producing a hardened steel material, a steel material, and a treatment liquid used therefor that prevent oxidation by induction hardening of a compound layer formed on the surface of the steel material by nitriding.
  • the present invention (1) is a treatment liquid for forming a protective film for protecting a nitride on a nitride layer formed after nitriding treatment on a steel material, and includes Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg, and at least one selected from the group consisting of Mo, phosphate ion, condensed phosphate ion, Contains 0.1 to 60 g / L of at least one anion selected from the group consisting of phosphite ions, fluoride ions, carbonate ions and silicate ions, and the treatment solution has a pH of 4 to 14 It is a compound layer protective film formation processing liquid characterized by being.
  • the treatment solution is a compound layer protective film formation treatment liquid in the invention (1), characterized in that it comprises at least one amine of 0.1 ⁇ 400g / L.
  • the treatment liquid is selected from the group consisting of Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg, and Mo.
  • At least one dissolved ion selected from the group consisting of Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg and Mo Dispersed particles having an average particle size of 4 to 40 nm including at least one selected from the group consisting of Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al,
  • the compound layer protective film of the invention (4) is formed on the nitride layer and is heated to a predetermined heating temperature. subjected to heat 0.3-5 seconds until it reaches its ultimate temperature is hardened steel material, characterized in that the induction hardening process is applied is 750 ⁇ 860 ° C..
  • Application process invention (6) preparing a steel nitride layer is formed on the surface by nitriding treatment, to be applied to the invention (1) to (3) one of the process liquid nitride layer A protective film forming step of drying the treatment liquid after the application step and forming a compound layer protective film on the nitride layer; and after the protective film forming step, 0.3 to 5 seconds until a predetermined heating temperature is reached.
  • a method for producing a hardened steel material comprising: heating and induction hardening with an ultimate temperature of 750 to 860 ° C.
  • the protective layer forming film of the present invention is formed on the compound layer obtained by nitriding treatment.
  • the compound layer protective film it is possible to effectively suppress oxidative decomposition of the compound layer due to subsequent induction hardening.
  • the steel member obtained by the present invention maintains the mechanical strength, sliding resistance, wear resistance and the like based on the characteristics of the compound layer as a result of the remaining compound layer having good sliding characteristics.
  • steel members whose hardenability is improved by the diffused nitrogen can obtain a deep hardening depth and high hardness by induction hardening, so that the surface pressure strength, wear resistance, and bending fatigue strength are high. It can be suitably used for machine structural parts that require strength.
  • the steel material to which the present invention is applied is not particularly limited, and examples thereof include carbon steel, low alloy steel, medium alloy steel, high alloy steel, cast iron and the like.
  • a preferable material in terms of cost is carbon steel, low alloy steel, or the like.
  • carbon steel for machine structural use (S20C to S58C) is suitable as carbon steel, and nickel chrome steel (SNC 236 to 836), nickel chrome molybdenum steel (SNCM 220 to 815), chrome, etc. as low alloy steel.
  • Molybdenum steel (SCM 415 to 445, 822), chromium steel (SCr 415 to 445), manganese steel for mechanical structure (SMn 420 to 443), manganese chrome steel (SMnC 420, 443) and the like are suitable.
  • a tempered steel material (H material) whose hardenability is ensured by tempering
  • a tempered steel material with a non-tempered ferrite-pearlite structure may be used.
  • Preferred materials from the viewpoint of cost are carbon steel, low alloy steel, and the like.
  • alloy steel tends to have higher surface hardness, a sufficiently deep hardening depth can be obtained even with carbon steel because of the effect of improving the hardenability of effect II by nitrogen.
  • the effect II by nitrogen in yet present invention, it is not always necessary to use the heat-treated steel, a non-heat treated steels ferritic - obtain a sufficient mechanical strength even in pearlite structure of the steel.
  • the nitrogen compound layer on the surface of the steel material is obtained by a surface hardening treatment that diffuses active nitrogen on the surface of the steel material to generate a hard and stable nitride.
  • a nitrogen compound layer it is usually composed mainly of Fe as a base material component, and a nitride containing Ti, Zr, Mo, W, Cr, Mn, Al, Ni, C, B, Si, etc. It is preferable that it is a layer.
  • a nitrogen compound layer having an effect I such as salt bath nitriding treatment such as tuftride treatment, isonite treatment, and pulsonite treatment, gas soft nitriding treatment, ion nitriding treatment, plasma nitriding treatment, and nitrogen immediately below the nitrogen compound layer
  • the nitriding heat treatment temperature for forming the nitrogen compound layer for achieving the effect I is preferably 600 ° C. or lower, more preferably 580 ° C. or lower, and further preferably 570 ° C. or lower.
  • the thickness of the nitrogen compound layer obtained at a processing temperature exceeding 600 ° C. is increased, the effect I can no longer be expected because the hardness decreases.
  • a minimum is not specifically limited, For example, it is 350 degreeC.
  • the thickness of the nitrogen compound layer obtained by nitriding before induction hardening is not particularly limited, but it is usually sufficient if it is formed with a thickness of 1 to 30 ⁇ m, more preferably 2 to 20 ⁇ m, and even more preferably 3 ⁇ 15 ⁇ m.
  • a protective film is formed using a treatment liquid for protecting the nitrogen compound layer.
  • the treatment liquid is at least one selected from the group consisting of Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg, and Mo.
  • the aqueous treatment liquid is contained and the pH of the treatment liquid is 4 to 14.
  • the aqueous treatment liquid in the present invention is a single phase, the content of water in the solvent is 30 mass% or more, more preferably 80% by mass or more, the even more preferably not less than 95 wt% Say.
  • the content of water in the solvent since the scatter is small environmental impact of carbon compounds to the protective film forming time in the atmosphere is reduced, the content of water from the environmental aspect is the more preferred.
  • concentration containing species the coating method, and may be a concentration which can be a predetermined deposition amount of the compound layer protective film by the coating repeat count, for example, if the content of 0.5 ⁇ 100 g / L Good.
  • the treatment liquid of the present invention is at least selected from the group consisting of Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg, and Mo. From 4 to 40 nm in average particle size including one dissolved ion and / or at least one selected from the group consisting of Si, Ti, Zr, Hf, Nb, Cr, W, Al, Sr and Mo And at least one selected from the group consisting of Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg, and Mo And a dispersed particle having an average particle size of 40 to 400 nm, the ratio of the mass occupied by the former as a dry solid state and the mass occupied by the latter as a dry solid state is 1:10 to 10: 1 Preferably there is.
  • the average particle diameter in the present specification can be measured using a particle size distribution measuring apparatus by a dynamic light scattering method.
  • Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg and Mo decompose and oxidize the nitrogen compound layer during high-frequency heating performed thereafter.
  • Si, Ti, Zr, Ce, Cr, W, Al, and Mo are more preferable because the diffusion rate of ions in these metal compounds is small.
  • the main components of the protective film Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg, and Mo are film forming components and stress relaxation components. It is preferable to be composed of two. As a film-forming component, the above components are dissolved as ions, oxoacid ions, peroxoacid ions, or complex ions, or in the liquid as very fine particles of 4 to 40 nm with many active sites on the surface. It is distributed.
  • the stress relaxation component of the protective film is selected from the group consisting of Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg, and Mo.
  • the average particle diameter comprising at least one member contains dispersed particles, consisting of 40 ⁇ 400 nm.
  • dispersed particles consisting of 40 ⁇ 400 nm.
  • oxides, hydroxides, nitrides, fluorides, carbonates, and phosphate compounds can be used as the dispersed particles of the film forming component and the stress relaxation component.
  • the amorphous particles are more preferable than the crystalline particles because they have many active points on the surface and good film-forming properties.
  • the dispersed particles of the stress relaxation component the crystalline particles are preferable to the amorphous particles because the volume shrinkage during heating is small, and the effect as a protective film is high because the particles are chemically and physically stable.
  • the film formation is poor because the reactivity is low and the average particle size is large, and as a result, the continuity and adhesion as a film are weak, so that it does not work as a protective film. May be sufficient.
  • the film forming component When only the film forming component is applied, a continuous film can be formed on the nitrogen compound layer, but the stress in the protective film caused by large volume shrinkage during drying cannot be relieved, and the protective film may crack or peel. is there.
  • the film-forming component has high bonding reactivity, but it cannot be said to have sufficient chemical and physical stability and may not always exhibit the protective film effect.
  • the film forming component and the stress relaxation component are both incorporated into the film and formed, and the mass ratio of the two in the dry solid state (the dry solid state in the protective film before quenching) is 1:10 to 10
  • the effect as a protective film becomes the highest. More preferably, it is 1: 5 to 5: 1, and still more preferably 1: 3 to 3: 1.
  • the “dried solid state” in the claims and the present specification refers to an oxide equivalent value assuming that all of the metal-containing components as raw materials are oxides. In practice, there may be components that volatilize or exist in other forms or remain in the form of raw material components. However, the ⁇ dry solid state '' in the claims and the specification is only It is an assumed value (theoretical value) on a raw material basis.
  • Phosphate ions, condensed phosphate ions, phosphite ions, fluoride ions, carbonate ions, and silicate ions effectively prevent decomposition and oxidation of the nitrogen compound layer, especially when applying and drying treatment liquids. .
  • the technique described in Japanese Patent Application Laid-Open No. 2008-038220 is not necessarily sufficient for preventing the oxidation of the nitrogen compound layer.
  • a part of the surface layer of the nitrogen compound layer is oxidatively decomposed after high-frequency heating. There was a case.
  • the role required of the protective film is not only to prevent decomposition and oxidation of the nitrogen compound layer that occurs during high-frequency heating performed after the formation of the protective film, but first of all. Furthermore, it has been found that it is essential to prevent decomposition and oxidation of the nitrogen compound layer when forming the protective film itself. Although the nitrogen compound layer has higher corrosion resistance than the iron substrate itself, it decomposes and oxidizes when it is heated to 50 ° C or higher, especially during wet semi-drying, until the treatment liquid is applied and fixed and dried as a protective film. Cheap.
  • Conceivable It contains 0.1 to 60 g / L of at least one anion selected from the group consisting of phosphate ion, condensed phosphate ion, phosphite ion, fluoride ion, carbonate ion and silicate ion. Preferably, it is 0.5 to 30 g / L, and more preferably 1 to 10 g / L. If the content is less than 0.1 g / L, the effect due to the addition does not sufficiently appear, and if it exceeds 60 g / L, the effect is already saturated and disadvantageous in cost.
  • the treatment liquid of the present invention is aqueous
  • the pH is preferably 4 to 14 in the passive region of iron in order to prevent corrosion of the steel substrate. More preferably, it is 7 to 13, and still more preferably 8 to 12.
  • this processing liquid contains a solvent other than water as a liquid medium
  • the above-mentioned pH value is a pH when the liquid medium is only water.
  • the treatment liquid of the present invention preferably further contains 0.1 to 400 g / L of amines. More preferably, it is 0.5 to 200 g / L, and still more preferably 1 to 100 g / L.
  • the amines keeping the processing solution at a predetermined pH, also high adsorptivity to the surface of the nitrogen compound layer is added nitrogen compound layer to the same stable state as passivation region of iron. These amines also have an effect of suppressing oxidation / decomposition of the nitrogen compound layer during high-frequency heating. As a mechanism for this, the present inventors have released nitrogen during high-frequency heating, and the nitrogen is on the nitrogen compound layer side. I guess to spread.
  • amines to be added include ammonia, urea, methylamine, ethylamine, trimethylamine, triethylamine, triethanolamine, N, N-diisopropylethylamine, piperidine, piperazine, morpholine, pyridine, 4-dimethylaminopyridine, ethylenediamine, Tetramethylethylenediamine, hexamethylenediamine, aniline, catecholamine, phenethylamine, and the like can be used. Any of these can be decomposed or volatilized when heated.
  • a non-volatile material such as an alkali metal is used to maintain the pH here, it will remain in the protective film that has been dried and fixed, and in particular, Li ions, Na ions, and K ions will easily enter the protective film when subjected to high temperature load. Since it may be a factor that can move and reduce the effect as an antioxidant, it is preferable not to use it as much as possible.
  • an antifoaming agent or a surfactant called a wettability improver for obtaining a uniform film on the surface to be coated, a thickener, and other organic / inorganic additions are suitably supplemented. It can also be added.
  • the components in the treatment solution according to the present invention may be derived from the same raw material Good.
  • first component such as Si
  • the second component is an anion such as phosphate ion
  • a third component such as an amine
  • ammonium zirconium carbonate is one raw material in Example 1, zirconium as a first component, a carbonate ion as a second component, and supplies the ammonium as a third component in the liquid.
  • one component in the treatment liquid according to the present invention may have a function as a plurality of components.
  • silicate ions are both Si as the first component and anions as the second component.
  • the existence form of these components in the treatment liquid may be in a state separated from each other, or may exist as a complex such as a complex.
  • the numerical value of each component in this invention shall be calculated on a raw material basis (it estimates from the numerical value of a raw material about the numerical value of a reaction product).
  • the numerical value of each component is calculated independently of each other. Specifically, in the case of functions both as a first component as being components (content or amount A) is, for example, the first component, calculates a first component amount based on the content A, the content A Based on this, the second component amount is calculated. The same applies when a plurality of components are present in the liquid as a complex.
  • the coating method of the treatment liquid is not particularly limited, but a dip coating method, a spin coating method, a spray method, a brush coating, or the like can be used.
  • the coating drying / firing temperature at the time of application is preferably 60 to 550 ° C., more preferably 100 to 400 ° C., and further preferably 120 to 300 ° C.
  • the heating time may be 30 seconds to 60 minutes, for example, and it may be sufficiently solidified, dried and fixed by exposure to the atmosphere.
  • the atmosphere during drying is preferably an inert atmosphere, but may be an air atmosphere.
  • the compound layer protective film is formed by coating Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, and the like on a nitride layer formed after nitriding treatment on a steel material as a dry solid state. Containing at least one metal selected from the group consisting of Cr, W, Al, Sr, Zn, Mg, and Mo, and 0.05 to 3 g / m 2 in total in terms of the metal Formed in range. More preferably, it is 0.1 to 1 g / m 2 .
  • the protective effect of the nitride layer is insufficient, and if it exceeds 3000 mg / m 2 , the effect is already saturated, which is not preferable in terms of cost.
  • the film thickness is about 2 to 4 ⁇ m, which is overwhelmingly thinner than Patent Document 7 covering a millimeter-order film and does not impair hardenability. It is thick.
  • induction hardening performed after forming the compound layer protective film it is subjected to induction heating by heating for 0.3 to 5 seconds so as to reach a predetermined heating temperature set at 750 to 860 ° C. After reaching a predetermined temperature, it is immediately cooled by a coolant, whereby a fine martensitic structure containing nitrogen can be obtained.
  • a more preferable heating temperature is 770 to 840 ° C.
  • a further preferable heating temperature is 780 to 830 ° C.
  • the heating time is more preferably 0.8 to 3 seconds, and further preferably 1 to 2 seconds.
  • the heating exceeds 860 ° C., the effect of the compound layer protective film is no longer effective, and the decomposition of the compound layer can no longer be suppressed, and excessive residual austenite tends to be generated in the martensite structure immediately below the compound layer. It is not preferable. Even if the heating time is 0.3 seconds or less, nitrogen is diffused, but it is not sufficiently austenitized, resulting in insufficient quenching. A heating time exceeding 5 seconds is not preferable because the effect of the heating time is almost saturated and the function of the compound layer protective film is lowered.
  • the nitrogen compound layer is sufficiently suppressed from oxidation and decomposition even when the atmosphere during high-frequency heating is in the air.
  • the atmosphere during high-frequency heating may be a vacuum atmosphere, an inert atmosphere with argon gas or nitrogen gas, a low oxygen atmosphere, a hydrocarbon-based reducing atmosphere, an ammonia gas atmosphere, or the like. it can.
  • a multistage temperature raising method including preheating can be appropriately performed. After quenching by high-frequency heating, tempering treatment may be performed under appropriate conditions in the same manner as a normal quenching technique.
  • compound layer protective film may not be removed be removed can be selected as needed.
  • the removal of the protective film of the compound layer can be easily performed because the hardness is lower than that of the compound layer, and can be appropriately performed by, for example, lapping, emery paper polishing, buffing, shot blasting, shot pinning, or the like.
  • the nitrogen compound layer remains with the compound layer protective film of the present invention, but the nitrogen compound layer does not necessarily remain 100% of the state of the compound layer before the high frequency heating, and the minimum film thickness is 1 ⁇ m or more.
  • the layer thickness should just be ensured. More preferably, it is 2 ⁇ m or more, and more preferably 3 ⁇ m or more.
  • the hardness of the nitrogen compound layer is HV630 or more in terms of Vickers hardness
  • the hardness region exceeding HV550 of the hard layer containing a fine martensite structure is 200 ⁇ m or more, preferably 400 ⁇ m or more, more preferably 600 ⁇ m or more in terms of the distance from the surface.
  • a steel material having an existing hardness distribution can be obtained.
  • an upper limit is not specifically limited, For example, it is 1.5 mm.
  • the machine part subjected to the treatment of the present invention has high slidability and seizure resistance due to the nitrogen compound layer formed on the outermost surface, and high temper softening resistance due to the nitrogen-containing fine martensite structure. It has crack initiation / crack growth resistance, surface pressure resistance, high fatigue strength, and deep cure depth.
  • the quenching by induction heating by the composite heat treatment according to the present invention is 750 to 860 ° C., and the quenching temperature is sufficiently lower than the induction quenching and carburizing quenching usually performed at temperatures exceeding 900 ° C. This is extremely advantageous in terms of thermal deformation and cracking, and enables a significant reduction in the post-cutting process for adjusting the dimensional accuracy performed after general induction hardening or carburizing and quenching.
  • the steel material to which the present invention is applied is not necessarily required to use a tempered steel because of the effect of improving the hardenability of the effect II caused by nitrogen. Sufficient mechanical strength can be obtained even with steel.
  • alloy steel tends to have a slightly higher surface hardness
  • a sufficiently deep hardening depth can be obtained even with inexpensive carbon steel due to the effect II of nitrogen.
  • a carbon steel for mechanical structure such as S45C is a heat treatment material having a hardness profile with sufficient hardness and sufficient depth.
  • S45C is not necessarily a tempered material, and even if the heat treatment of the present invention is applied to a steel member having a non-tempered ferrite-pearlite structure, sufficient martensitic transformation occurs, and sufficient mechanical properties are obtained. It can be a heat-treated machine part with high strength.
  • the application of the present invention improves the mechanical strength of the parts, reduces the cutting process and switches to inexpensive materials, thereby reducing the size and weight of the entire mechanical parts by downsizing the parts, and nitriding and induction hardening. It is possible to reduce the actual cost by surplus to compensate for the cost increase due to the combined processing.
  • the compound layer protective film of the present invention is formed after nitriding treatment by, for example, laser quenching by short-time heating for several seconds at the longest or impact quenching for short heating of several milliseconds. If you make quenching the component, a nitride layer is sufficiently protected, base steel lower part of the layer can be obtained quenched structure according to the quenching method using.
  • the hardened steel member according to the present invention is suitable for those used in a high load / high surface pressure region.
  • the shape and part type of the steel member are not particularly limited, and examples thereof include shafts, gears, pistons, shafts, cams, and the like, which are suitable for transmission-related parts and powertrain parts for automobiles and construction machinery.
  • Example 1 SCM435 tempered material having a diameter of 8 mm and a length of 50 mm was used as a base material. After degreasing and cleaning this surface, salt bath soft nitriding treatment at 560 ° C. for 2 hours in a molten salt bath (Isonite treatment: Nippon Parkerizing Co., Ltd.) Ltd.) to oil cooling, to form a nitrogen compound layer consisting mainly of iron nitride having a thickness of about 10 ⁇ m on the surface of the steel material.
  • salt bath soft nitriding treatment at 560 ° C. for 2 hours in a molten salt bath (Isonite treatment: Nippon Parkerizing Co., Ltd.) Ltd.) to oil cooling, to form a nitrogen compound layer consisting mainly of iron nitride having a thickness of about 10 ⁇ m on the surface of the steel material.
  • Zirconium-dissolved zirconium carbonate solution was 22.2 g / L in terms of zirconium (11 g / L as carbonate ions), and zirconium oxide particles having an average particle size of 50 nm (tetragonal crystal structure) was 7.4 g / L in terms of zirconium.
  • a pH 9.5 treatment solution containing 1 g / L of ammonium orthophosphate as phosphate ions and 11 g / L of methylamine was prepared.
  • the treatment liquid was applied to the substrate using a dip coating method, and after removing excess liquid, the process of drying at 40 ° C. ⁇ 10 minutes was repeated three times, and finally, baking was performed at 200 ° C. for 10 minutes.
  • the adhesion amount as Zr was 520 mg / m 2 .
  • the ratio of the film-forming component / stress-relaxing component was 3 with respect to the calculated film-forming component zirconium oxide and the stress-relaxing component zirconium oxide.
  • the heating is stopped immediately after reaching 820 ° C. in 1 second after the start of heating using the induction hardening apparatus. Then, it was cooled and quenched. Later, the steel surface was shot blasted to remove only the compound layer protective film.
  • Example 2 S45C tempered material having a diameter of 8 mm and a length of 50 mm was used as a base material. After degreasing and cleaning this surface, salt bath soft nitriding treatment (Isonite treatment: Nippon Parkerizing Co., Ltd.) at 560 ° C. in a molten salt bath for 2 hours Ltd.) to oil cooling, to form a nitrogen compound layer mainly having a thickness of about 13 ⁇ m iron nitride surface of the steel material.
  • salt bath soft nitriding treatment Isonite treatment: Nippon Parkerizing Co., Ltd.
  • Polymer titanium hydroxide sol particles (crystal structure is amorphous) with an average particle size of 7 nm is 9.0 g / L in terms of titanium, and titanium oxide particles with an average particle size of 45 nm (crystal structure is anatase) is converted to titanium.
  • the treatment liquid was applied to the substrate using the dip coating method, and after removing the excess liquid, the process of drying at 150 ° C. for 20 minutes was repeated twice.
  • the adhesion amount of the Ti was 250 mg / m 2.
  • the ratio of the film-forming component / stress-relaxing component was 0.6 for the calculated film-forming component of titanium oxide and the stress-relaxing component of titanium oxide.
  • the heating is stopped immediately after reaching 820 ° C. in 1 second after the start of heating using the induction hardening apparatus. Then, it was cooled and quenched. Later, the steel surface was shot blasted to remove the compound layer protective film.
  • Example 3 An S45C non-heat treated material (ferrite / pearlite structure) having a diameter of 8 mm and a length of 50 mm was used as a base material. After degreasing and cleaning this surface, salt bath soft nitriding treatment (Isonite) at 560 ° C. for 1 hour in a molten salt bath Treatment: manufactured by Nihon Parkerizing Co., Ltd.) and water-cooled to form a nitrogen compound layer mainly composed of iron nitride having a thickness of about 12 ⁇ m on the steel surface.
  • salt bath soft nitriding treatment Isonite
  • a treatment solution was prepared. This treatment liquid was applied to the substrate using a spray method, and after removing excess liquid, baking was performed at 320 ° C. for 10 minutes. Measurement of the Si deposition amount on the substrate with a fluorescent X-ray analyzer, the adhesion amount of the Si was 70 mg / m 2.
  • the heating is stopped immediately after reaching 820 ° C. in 1 second after the start of heating using the induction hardening apparatus. Then, it was cooled and quenched. Later, the steel surface was shot blasted to remove the compound layer protective film.
  • Example 4 A SCM440 tempered material with a diameter of 8 mm and a length of 50 mm was used as a base material. After this surface was degreased and cleaned, gas nitriding was performed in an ammonia atmosphere at 570 ° C. for 24 hours, and the steel material surface was nitrided with a thickness of about 8 ⁇ m A nitrogen compound layer mainly composed of iron was formed.
  • the temperature reached 830 ° C. in 0.8 seconds after the start of heating using an induction hardening apparatus, and immediately thereafter. Heating was stopped, cooling was performed, and quenching was performed. Later, the steel surface was shot blasted to remove the compound layer protective film.
  • Example 5 A non-refined SCM440 material (ferrite / pearlite structure) with a diameter of 8 mm and a length of 50 mm was used as the base material, and after degreasing and cleaning this surface, a gas at 570 ° C. in a mixed atmosphere of RX gas and ammonia for 3 hours. treated soft nitrided to form a nitrogen compound layer consisting mainly of iron nitride having a thickness of about 12 ⁇ m on the surface of the steel material.
  • Chromium fluoride is 14.3 g / L in terms of Cr (18 g / L as fluoride ion), orthophosphoric acid is 10 g / L as phosphate ion, and ammonia is 5.4 g / L.
  • a treatment solution was prepared. This treatment liquid was applied to the substrate using a dip coating method, and after removing the excess liquid, baking was performed at 120 ° C. for 30 minutes. Measurement of the Cr deposition amount on the substrate with a fluorescent X-ray analyzer, the adhesion amount of the Cr was 180 mg / m 2.
  • the steel material in which the compound layer protective film containing chromium oxide was formed on the nitrogen compound layer in this way was further heated using an induction hardening device after reaching 820 ° C. in 1 second after the start of heating. Then, it was cooled and quenched. Later, the steel surface was shot blasted to remove the compound layer protective film.
  • Example 6 S45C tempered material with a diameter of 8 mm and a length of 50 mm was used as the base material, and after this surface was degreased and cleaned, it was subjected to plasma nitriding treatment at 570 ° C. for 40 hours in a mixed atmosphere of nitrogen gas and hydrogen gas. A nitrogen compound layer mainly composed of iron nitride having a thickness of about 15 ⁇ m was formed.
  • Zircon hydrofluoric acid in terms of zirconium oxide was 20 g / L (14.8 g / L as Zr, 18.5 g / L as fluoride ion), 3 g / L as ethylamine, and 5 g / L as orthophosphoric acid as phosphate ion.
  • a treatment solution having a pH of 4.5 was prepared.
  • 50% of zirconium in zircon hydrofluoric acid was converted to zirconium hydroxide particles having an average particle diameter of 50 nm, and was dispersed and clouded. The process of applying this treatment liquid to the substrate using the dip coating method, removing excess liquid, and baking at 180 ° C. for 20 minutes was repeated 10 times.
  • the adhesion amount as Zr was 1200 mg / m 2 .
  • the ratio of the film-forming component / stress-relaxing component was 1 with respect to the calculated film-forming component zirconium oxide and the stress-relaxing component zirconium oxide.
  • the steel material on which the compound layer protective film containing zirconium oxide is formed on the nitrogen compound layer is further heated immediately after reaching 800 ° C. in 1.5 seconds after the start of heating using an induction hardening apparatus. After stopping, it was cooled and quenched. Later, the steel surface was shot blasted to remove the compound layer protective film.
  • Example 7 SCM440 tempered material having a diameter of 8 mm and a length of 50 mm was used as the base material, and after degreasing and cleaning the surface, salt bath soft nitriding treatment at 560 ° C. in a molten salt bath (Isonite treatment: Nippon Parkerizing Co., Ltd. And a nitrogen compound layer mainly composed of iron nitride having a thickness of about 7 ⁇ m was formed on the surface of the steel material.
  • the steel material on which the compound layer protective film containing tungsten oxide is formed on the nitrogen compound layer is further heated immediately after reaching 860 ° C. in 0.8 seconds after the start of heating using an induction hardening apparatus. After stopping, it was cooled and quenched. Later, the steel surface was shot blasted to remove the compound layer protective film.
  • Example 8 SCM440 tempered material having a diameter of 8 mm and a length of 50 mm was used as a base material. After degreasing and cleaning the surface, salt bath soft nitriding treatment at 560 ° C. for 2 hours in a molten salt bath (Isonite treatment: Nippon Parkerizing Co., Ltd.) And a nitrogen compound layer mainly composed of iron nitride having a thickness of about 9 ⁇ m was formed on the surface of the steel material.
  • Zirconium oxide sol particles having an average particle size of 5 nm are 7.4 g / L in terms of zirconium, and zirconium oxide particles having an average particle size of 70 nm (crystal structure is tetragonal) are 22 in terms of zirconium.
  • a treatment solution of pH 9.5 containing 2 g / L, 4 g / L of pyrophosphate as pyrophosphate ions, and 9 g / L of ammonia was prepared. This treatment liquid was applied to the base material using a dip coating method, and after removing the excess liquid, it was calcined at 50 ° C. for 20 minutes, and then calcined at 200 ° C. for 30 minutes.
  • the adhesion amount as Zr was 280 mg / m 2 .
  • the ratio of the film-forming component / stress-relaxing component was 0.3 for the calculated film-forming component zirconium oxide and the stress-relaxing component zirconium oxide.
  • the heating is stopped immediately after reaching 790 ° C. in one second after the start of heating using an induction hardening apparatus. Then, it was cooled and quenched. Later, the steel surface was shot blasted to remove the compound layer protective film.
  • Example 9 SCM440 tempered material having a diameter of 8 mm and a length of 50 mm was used as a base material. After degreasing and cleaning this surface, salt bath soft nitriding treatment at 560 ° C. in a molten salt bath (Isonite treatment: Nippon Parkerizing Co., Ltd.) And a nitrogen compound layer mainly composed of iron nitride having a thickness of about 9 ⁇ m was formed on the surface of the steel material.
  • a pH 8.5 treatment solution containing 10.3 g / L of potassium aluminate in terms of aluminum, 12 g / L of pyrophosphate as pyrophosphate ions, and 42 g / L of morpholine was prepared.
  • the treatment liquid a polymer body of aluminum hydroxide having an average particle diameter of 25 nm was formed and became cloudy.
  • This treatment liquid was applied to the substrate using a dip coating method, and after removing the excess liquid, baking was performed at 150 ° C. for 30 minutes.
  • the adhesion amount of Al on the substrate was measured with a fluorescent X-ray analyzer, the adhesion amount as Al was 150 mg / m 2 .
  • the steel material in which the compound layer protective film containing aluminum oxide was thus formed on the nitrogen compound layer was further heated using an induction hardening device after reaching 780 ° C. in 3 seconds after heating was started. Then, it was cooled and quenched. Later, the steel surface was shot blasted to remove the compound layer protective film.
  • Chromium fluoride is 14.3 g / L in terms of Cr (18 g / L as fluoride ion), orthophosphoric acid is 50 g / L as phosphate ion, and ammonia is 5.4 g / L.
  • a treatment solution was prepared. This treatment liquid was applied to the substrate using a dip coating method, and after removing the excess liquid, baking was performed at 120 ° C. for 30 minutes. When the amount of Cr deposited on the substrate was measured with a fluorescent X-ray analyzer, the amount deposited as Cr was 210 mg / m 2 .
  • the steel material in which the compound layer protective film containing chromium oxide is formed on the nitrogen compound layer is further heated immediately after reaching 860 ° C. in 0.8 seconds after the start of heating using an induction hardening apparatus. After stopping, it was cooled and quenched. Later, the steel surface was shot blasted to remove the compound layer protective film.
  • a treatment liquid having a pH of 8.8 was prepared by adding 60 g / L of ammonium tungstate in terms of tungsten oxide (47.6 g / L as W) and 20 g / L of ammonia together with components from ammonium tungstate.
  • This treatment liquid was applied to the substrate using a dip coating method, and after removing the excess liquid, it was baked at 180 ° C. for 30 minutes.
  • the adhesion amount of W on the substrate was measured with a fluorescent X-ray analyzer, the adhesion amount as W was 160 mg / m 2 .
  • the steel material on which the compound layer protective film containing tungsten oxide is formed on the nitrogen compound layer is further heated immediately after reaching 860 ° C. in 0.8 seconds after the start of heating using an induction hardening apparatus. After stopping, it was cooled and quenched. Later, the steel surface was shot blasted to remove the compound layer protective film.
  • Table 1 shows a list of evaluation results.
  • the effective hardening depth in the table the depth from the surface portion having a hardness of more than Hv 550 (mm).
  • Figure 1 respectively in Example 1 in FIGS. 2 and 3, a cross-sectional photograph of Example 7 and Comparative Example 1, respectively as an example.
  • the cross-sectional hardness distribution of Example 3 and 9 is shown in FIG.
  • Example 1 the nitrogen compound layer on the surface remains without significant damage even after induction hardening as shown in FIG.
  • Example 1 the nitrogen compound layer was more effectively protected.
  • Comparative Example 1 without the compound layer protective film, it was observed that the entire surface was oxidized as shown in FIG. Further, in Comparative Examples 2 and 3, which are outside the scope of the present invention, the nitrogen compound layer was significantly oxidized as in Comparative Example 1, and the action as a protective film was insufficient.

Abstract

Disclosed is a means for preventing oxidation of a compound layer by high-frequency hardening, said compound layer having been formed on the surface of a steel material by nitriding. Specifically disclosed is a treatment liquid for forming a compound layer protective film, which is a treatment liquid for forming a protective layer on a nitride layer for the purpose of protecting the nitride, said nitride layer having been formed on a steel material after nitriding. The treatment liquid for forming a compound layer protective film is characterized by containing at least one element selected from the group consisting of Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg and Mo, and containing 0.1-60 g/L of at least one kind of anions selected from the group consisting of phosphate ions, condensed phosphate ions, phosphite ions, fluoride ions, carbonate ions and silicate ions. The treatment liquid for forming a compound layer protective film is also characterized by having a pH of 4-14.

Description

窒素化合物層を有する鉄鋼部材の保護膜形成処理液、および化合物層保護膜Protective film forming treatment liquid for steel member having nitrogen compound layer, and compound layer protective film
　本発明は、面圧強度、耐摩耗性、曲げ疲労強度等の機械的強度に優れた機械構造部品として使用される焼入れ鉄鋼材料、その製造方法及びそれに用いる処理液に関するものである。 The present invention relates to a hardened steel material used as a mechanical structural component having excellent mechanical strength such as surface pressure strength, wear resistance, bending fatigue strength, a manufacturing method thereof, and a treatment liquid used therefor.
　従来、機械的強度の向上のために、鋳鉄や鋼の機械構造部品に窒化処理（軟窒化処理も含む），浸炭焼入れ，高周波焼入れ等の表面硬化処理が施されている。
　このうち、窒化処理により最表面に形成される窒化物からなる化合物層は、摺動性に優れており、摩耗に強く、焼き付き抵抗性が高いことが知られている（以下、これを窒素化合物層による効果Ｉと呼ぶ）。しかし、一般的に窒化処理は、浸炭焼入れ、高周波焼入れに比較して、面圧強度、疲労強度等において劣っており、例えばローラーピッチング試験を行った場合、窒素化合物層が鋼素地より剥離を生じる場合がある。その為、窒素化合物層は２ＧＰａを越えるような高面圧における疲労試験においては、むしろ悪影響を与える存在であると広く信じられていた。本発明者等は、この要因は化合物層そのものにあるのではなく、化合物層を支える素地の硬化層深さが浅いためであることを見出した。すなわち、窒化処理単体では、最表面の化合物層の良好な摺動性を十分に生かす為には、その直下の硬化層深さが不足していたのである。 Conventionally, in order to improve mechanical strength, surface hardening treatments such as nitriding treatment (including soft nitriding treatment), carburizing and quenching, and induction hardening are performed on cast iron and steel mechanical structural parts.
Among these, a compound layer made of nitride formed on the outermost surface by nitriding treatment is known to have excellent sliding properties, wear resistance, and high seizure resistance (hereinafter referred to as nitrogen compound). Called layer effect I ). However, in general, nitriding treatment is inferior in surface pressure strength, fatigue strength, etc. compared to carburizing quenching and induction quenching. For example, when a roller pitching test is performed, the nitrogen compound layer peels from the steel substrate. There is a case. For this reason, it was widely believed that the nitrogen compound layer had rather an adverse effect in fatigue tests at high surface pressures exceeding 2 GPa. The present inventors have found that this factor is not in the compound layer itself but because the hardened layer depth of the substrate supporting the compound layer is shallow. In other words, the nitriding unit alone has insufficient the depth of the hardened layer immediately below it in order to make full use of the good slidability of the outermost compound layer.
　ところで、窒素を含有する鋼材は、窒素を含有しない鋼材よりも、焼入れ後に得られるマルテンサイト組織が微細になり、そのため硬度は高くなり、また、焼入れ性が向上することによって硬化深さが増大することが知られている。つまり、窒化処理は、焼入れ性向上のための窒素拡散層を形成するための窒素拡散前処理としても利用可能（以下、窒素化合物層を形成することによる効果ＩＩと呼ぶ）である。すなわち、この効果ＩＩを利用し得られる特性とは、窒素化合物層そのものの作用によるものではなく、窒素化合物層を形成する際に生じた窒素化合物層の直下にある鋼材中の拡散窒素の作用によるものである。
　焼入れによって得られた窒素含有のマルテンサイト組織は、上述の高硬度や焼入れ性向上の他に、焼き戻し軟化抵抗性、亀裂発生・成長に対する抵抗故の高面圧強度、高疲労強度を有することが知られている。 By the way, a steel material containing nitrogen has a finer martensite structure obtained after quenching than a steel material not containing nitrogen, so that the hardness is increased, and the hardening depth is increased by improving the hardenability. It is known. That is, the nitriding treatment can also be used as a nitrogen diffusion pretreatment for forming a nitrogen diffusion layer for improving hardenability (hereinafter referred to as effect II by forming a nitrogen compound layer). That is, the characteristics that can be obtained by using this effect II are not due to the action of the nitrogen compound layer itself, but due to the action of diffused nitrogen in the steel immediately below the nitrogen compound layer generated when the nitrogen compound layer is formed. Is.
The nitrogen-containing martensite structure obtained by quenching has high surface pressure strength and high fatigue strength due to resistance to temper softening, resistance to crack initiation and growth, in addition to the above-mentioned high hardness and hardenability improvement. It has been known.
　窒化処理後にそのまま高周波焼入れを行う場合、焼入れ温度は少なくともオーステナイト組織となる温度Ａｃ３変態点以上が必要であり、通常７５０～１０５０℃の温度範囲から選択される。窒化温度５７０℃で形成される窒素化合物層は、鉄と窒素の結合であり、大気雰囲気で６５０℃以上に再加熱されると酸化を受け分解し、窒素化合物層の窒素は、最表面では窒素ガスとして放出され窒素化合物層が消失してしまう。このことは古くから報告されている（非特許文献１）。 When induction hardening is performed as it is after the nitriding treatment, the quenching temperature needs to be at least the temperature Ac3 transformation point at which an austenite structure is formed, and is usually selected from a temperature range of 750 to 1050 ° C. The nitrogen compound layer formed at a nitriding temperature of 570 ° C. is a combination of iron and nitrogen. When reheated to 650 ° C. or higher in an air atmosphere, the nitrogen compound layer undergoes oxidation and decomposes. It is released as a gas and the nitrogen compound layer disappears. This has been reported for a long time (Non-Patent Document 1).
　窒化処理と焼入れとによる複合熱処理技術は、通常、窒化処理で得られた窒素拡散層による効果ＩＩを利用するのみであり、窒化処理で形成される窒素化合物層の効果Ｉを利用していない。すなわち窒素化合物層が、窒化処理の後工程である焼入れの際に消失してしまう事を止むなしとしている。この技術に対する開示例は多く、例えば、特許文献１～５の複合熱処理を挙げることができる。 The combined heat treatment technique by nitriding and quenching usually uses only the effect II of the nitrogen diffusion layer obtained by nitriding, and does not use the effect I of the nitrogen compound layer formed by nitriding. That is, the nitrogen compound layer does not stop disappearing during quenching, which is a subsequent process of nitriding. There are many disclosure examples for this technology, for example, the composite heat treatment disclosed in Patent Documents 1 to 5.
　特許文献６には、６００℃以上の温度で窒化処理を施し５μｍ以下の窒素化合物層を形成させた後に高周波焼入れを行い、２μｍ以下の窒素化合物層を有する焼入れ部材を得る複合熱処理方法が開示されている。本技術で窒化条件を６００℃以上の高温とする理由は、高温ほど鋼材奥側へ高濃度の窒素拡散が期待できるためであるが、６００℃を越える窒化処理温度で得られる窒素化合物層は硬度が低く、効果Ｉを有さない窒素化合物層である。すなわち、本技術も窒素化合物層による効果ＩＩのみを期待するものであり、２μｍ以下の残留する窒素化合物層はなくてもよい程度のものである。 Patent Document 6 discloses a composite heat treatment method in which a nitriding treatment is performed at a temperature of 600 ° C. or higher to form a nitrogen compound layer having a thickness of 5 μm or less, followed by induction hardening to obtain a quenched member having a nitrogen compound layer having a thickness of 2 μm or less. ing. The reason why the nitriding condition is set to a high temperature of 600 ° C. or higher in the present technology is that a higher concentration of nitrogen diffusion can be expected at the deeper side of the steel material, but the nitrogen compound layer obtained at a nitriding temperature exceeding 600 ° C. has a hardness. Is a nitrogen compound layer having a low effect I. That is, the present technology also expects only the effect II by the nitrogen compound layer, and the remaining nitrogen compound layer of 2 μm or less may be omitted.
　前述のように高面圧における疲労強度においては、窒素化合物層はむしろ悪影響を与える存在であると広く誤信されてきた為に、窒素化合物による効果Ｉ、効果ＩＩを兼ね備えようとした技術はほぼ皆無である。このような窒化処理により表面に形成された窒化物層をそのまま高周波焼入れすることによる高温加熱での窒化物層の損傷や消失という問題を解決し、効果Ｉ、効果ＩＩを兼ね備えようとした前例のない技術として、窒化処理後の表面上に、酸化ケイ素を成分とするガス窒化・イオン窒化防止剤、浸炭防止剤、酸化防止剤を１～３ｍｍの厚みで被覆し、その後に焼入れを行う方法が、特許文献７に開示されている。 As described above, in fatigue strength at high surface pressure, there has been a widespread misconception that the nitrogen compound layer is rather detrimental, so there is almost no technology that tries to combine the effects I and II with the nitrogen compound. It is. The problem of the damage and disappearance of the nitride layer caused by high-temperature heating by induction-hardening the nitride layer formed on the surface by such nitriding treatment as it is is solved, and both the effects I and II are attempted. As a non-technical technique, there is a method in which a gas nitriding / ion nitriding inhibitor containing silicon oxide as a component, a carburizing inhibitor, and an antioxidant are coated on the surface after nitriding treatment to a thickness of 1 to 3 mm, followed by quenching. Patent Document 7 discloses this.
　しかし、この方法では、仮に加熱時での酸化現象は防止できても、１ｍｍ以上の厚膜のために熱伝導性も低いことから、マルテンサイト変態に必要な焼入れ時の冷却速度が不十分となり、目的とする微細マルテンサイトを得る事は実際には困難であった。 However, in this method, even if the oxidation phenomenon during heating can be prevented, since the thermal conductivity is low due to the thick film of 1 mm or more, the cooling rate during quenching necessary for martensitic transformation becomes insufficient. It was actually difficult to obtain the desired fine martensite.
　また、効果Ｉ、ＩＩとも利用しようとした特許文献８には、鉄鋼材料の表面に硬質窒化物層が形成され、さらにその上層として、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｎｂ、Ｔａ、Ｃｒ、Ｗ、Ｍｏ及びＡｌから成る群の中から選択される少なくとも一種の金属酸化物を含む無機化合物層が形成されたことを特徴とする焼入れ鉄鋼部材が開示されている。 Further, in Patent Document 8 to be used for both effects I and II, a hard nitride layer is formed on the surface of the steel material, and further, Ti, Zr, Hf, V, Nb, Ta, Cr, W are formed thereon. hardened steel member characterized by the inorganic compound layer containing at least one metal oxide selected from the group consisting of Mo and Al is formed is disclosed.
　この当該特許は中性～アルカリ性の水を溶媒とする「焼入れ表面保護剤」についてのものであるが、必ずしも窒素化合物層の酸化防止に対して十分とは言えず、状況によっては窒素化合物層の表層が酸化分解する場合があった。
特許第３１９３３２０号 特許第３３２７３８６号 特許第３１４５５１７号 特開平７－９０３６４号 特開２００７－１５４２５４号 特開２００７－７７４１１号 特開昭５８－９６８１５号 熱処理１６巻４号 Ｐ２０６ 昭和５１年 特開２００８－０３８２２０号 This patent relates to a “quenched surface protective agent” using neutral to alkaline water as a solvent, but is not necessarily sufficient for preventing oxidation of the nitrogen compound layer. In some cases, the surface layer was oxidatively decomposed.
Patent No. 3193320 Japanese Patent No. 3327386 Japanese Patent No. 3145517 JP-A-7-90364 JP 2007-154254 A JP 2007-77411 A JP 58-96815 Heat treatment Vol.16 No.4 P206 1976 JP 2008-038220
　本発明は上記課題に鑑み、窒化処理によって得られた窒素化合物層が、その後の高周波熱処理の際、酸化を生じるメカニズムを調査・解明し、それを防止する効果的な酸化防止剤を開発するに至り、鉄鋼材料の表面に窒化処理によって形成された化合物層の高周波焼入れによる酸化を防止する焼入れ鉄鋼材料の製造方法、鉄鋼材料及びそれに用いる処理液を提供することを目的としている。 In view of the above problems, the present invention investigates and elucidates the mechanism by which the nitrogen compound layer obtained by nitriding treatment causes oxidation during the subsequent high-frequency heat treatment, and develops an effective antioxidant that prevents it. The object of the present invention is to provide a method for producing a hardened steel material, a steel material, and a treatment liquid used therefor that prevent oxidation by induction hardening of a compound layer formed on the surface of the steel material by nitriding.
　本発明（１）は、鋼材に対し窒化処理後に形成される窒化物層上に当該窒化物を保護するための保護膜を形成するための処理液であって、Ｓｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｔａ、Ｃａ、Ｃｅ、Ｓｃ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ、Ｚｎ、Ｍｇ及びＭｏからなる群の中から選択される少なくとも１種を含有し、りん酸イオン、縮合りん酸イオン、亜りん酸イオン、フッ化物イオン、炭酸イオン及びケイ酸イオンからなる群の中から選択される少なくとも１種のアニオンを０．１～６０ｇ／Ｌ含有し、その処理液のｐＨが４～１４であることを特徴とする化合物層保護皮膜形成処理液である。 The present invention (1) is a treatment liquid for forming a protective film for protecting a nitride on a nitride layer formed after nitriding treatment on a steel material, and includes Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg, and at least one selected from the group consisting of Mo, phosphate ion, condensed phosphate ion, Contains 0.1 to 60 g / L of at least one anion selected from the group consisting of phosphite ions, fluoride ions, carbonate ions and silicate ions, and the treatment solution has a pH of 4 to 14 It is a compound layer protective film formation processing liquid characterized by being.
　本発明（２）は、前記処理液が、少なくとも１種のアミン類を０．１～４００ｇ／Ｌ含むことを特徴とする前記発明（１）の化合物層保護皮膜形成処理液である。 The present invention (2), the treatment solution is a compound layer protective film formation treatment liquid in the invention (1), characterized in that it comprises at least one amine of 0.1 ~ 400g / L.
　本発明（３）は、前記処理液が、Ｓｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｔａ、Ｃａ、Ｃｅ、Ｓｃ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ、Ｚｎ、Ｍｇ及びＭｏからなる群の中から選択される少なくとも１種の溶解したイオン並びに／又はＳｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｔａ、Ｃａ、Ｃｅ、Ｓｃ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ、Ｚｎ、Ｍｇ及びＭｏからなる群の中から選択される少なくとも１種を含む平均粒径が４～４０ｎｍからなる分散粒子と、Ｓｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｔａ、Ｃａ、Ｃｅ、Ｓｃ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ、Ｚｎ、Ｍｇ及びＭｏからなる群の中から選択される少なくとも１種を含む平均粒径が４０～４００ｎｍからなる分散粒子と、をともに含有し、前者が乾燥固形状態として占める質量と、後者が乾燥固形状態として占める質量との比が１：１０～１０：１であることを特徴とする前記発明（１）又は（２）の化合物層保護皮膜形成処理液である。 In the present invention (3), the treatment liquid is selected from the group consisting of Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg, and Mo. At least one dissolved ion selected from the group consisting of Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg and Mo Dispersed particles having an average particle size of 4 to 40 nm including at least one selected from the group consisting of Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, A dispersion particle having an average particle diameter of 40 to 400 nm including at least one selected from the group consisting of Sr, Zn, Mg, and Mo, the former occupying as a dry solid state, and the latter Occupies the dry solid state Ratio of 1: 10 ~ 10: The invention (1) or a compound layer protective coating-treatment liquid (2), which is a 1.
　本発明（４）は、鋼材に対し窒化処理後に形成される窒化物層上に乾燥固形状態として被覆されるＳｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｔａ、Ｃａ、Ｃｅ、Ｓｃ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ、Ｚｎ、Ｍｇ及びＭｏからなる群の中から選択される少なくとも１種の金属を含有する化合物層保護膜であって、その化合物層保護膜が前記発明（１）～（３）のいずれか一つの処理液から該金属換算の合計で０．０５～３ｇ／ｍ２の範囲で形成され、所定の加熱温度に到達するまで０．３～５秒間の加熱を行い、その到達温度が７５０～８６０℃である高周波焼入れ時に前記化合物層の分解を抑制することを特徴とする化合物層保護膜である。 In the present invention (4), Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, coated as a dry solid state on a nitride layer formed after nitriding treatment on a steel material A compound layer protective film containing at least one metal selected from the group consisting of W, Al, Sr, Zn, Mg and Mo, wherein the compound layer protective film comprises the inventions (1) to (3). ) In the range of 0.05 to 3 g / m 2 in total in terms of the metal, and heated for 0.3 to 5 seconds until reaching a predetermined heating temperature. A compound layer protective film characterized by suppressing decomposition of the compound layer during induction hardening at a temperature of 750 to 860 ° C.
　本発明（５）は、窒化処理により表面に窒化物層が形成された鋼材において、前記発明（４）の化合物層保護膜が当該窒化物層上に形成された状態で、所定の加熱温度に到達するまで０．３～５秒間の加熱を行い、その到達温度が７５０～８６０℃である高周波焼入れ処理が施されたものであることを特徴とする焼き入れ鋼材である。 According to the present invention (5), in a steel material having a nitride layer formed on the surface by nitriding treatment, the compound layer protective film of the invention (4) is formed on the nitride layer and is heated to a predetermined heating temperature. subjected to heat 0.3-5 seconds until it reaches its ultimate temperature is hardened steel material, characterized in that the induction hardening process is applied is 750 ~ 860 ° C..
　本発明（６）は、窒化処理により表面に窒化物層が形成された鋼材を準備し、前記発明（１）～（３）のいずれか一つの処理液を窒化物層上に適用する適用工程と、適用工程後に処理液を乾燥させ、窒化物層上に化合物層保護膜を形成する保護膜形成工程と、保護膜形成工程後に、所定の加熱温度に到達するまで０．３～５秒間の加熱を行い、その到達温度が７５０～８６０℃である高周波焼入れ処理と、を有することを特徴とする焼き入れ鋼材の製造方法である。 Application process invention (6), preparing a steel nitride layer is formed on the surface by nitriding treatment, to be applied to the invention (1) to (3) one of the process liquid nitride layer A protective film forming step of drying the treatment liquid after the application step and forming a compound layer protective film on the nitride layer; and after the protective film forming step, 0.3 to 5 seconds until a predetermined heating temperature is reached. A method for producing a hardened steel material, comprising: heating and induction hardening with an ultimate temperature of 750 to 860 ° C.
　本発明の金属の窒素化合物層を有する鉄鋼部材の化合物層を高温酸化分解から保護する保護膜形成処理液、および化合物層保護膜によれば、窒化処理によって得られた化合物層上に本発明の化合物層保護膜を形成することにより、その後の高周波焼入れによる化合物層の酸化分解を効果的に抑制可能である。本発明によって得られた鉄鋼部材は、良好な摺動特性を有する化合物層が残存する結果、化合物層の特性に基づく機械的強度や耐摺動性，耐摩耗性等が維持される。さらに、拡散した窒素により焼入れ性が向上している鉄鋼部材は、高周波焼入れにより深い硬化深さ、及び高い硬度を得ることができるため、面圧強度、耐摩耗性、曲げ疲労強度について高い機械的強度を要求する機械構造部品用途に対し好適に利用可能である。 According to the protective film forming treatment liquid for protecting a compound layer of a steel member having a metal nitrogen compound layer of the present invention from high-temperature oxidative decomposition, and the compound layer protective film, the protective layer forming film of the present invention is formed on the compound layer obtained by nitriding treatment. By forming the compound layer protective film, it is possible to effectively suppress oxidative decomposition of the compound layer due to subsequent induction hardening. The steel member obtained by the present invention maintains the mechanical strength, sliding resistance, wear resistance and the like based on the characteristics of the compound layer as a result of the remaining compound layer having good sliding characteristics. Furthermore, steel members whose hardenability is improved by the diffused nitrogen can obtain a deep hardening depth and high hardness by induction hardening, so that the surface pressure strength, wear resistance, and bending fatigue strength are high. It can be suitably used for machine structural parts that require strength.
　本発明の適用対象となる鉄鋼材料は、特に限定されず、例えば、炭素鋼、低合金鋼、中合金鋼、高合金鋼、鋳鉄等を挙げることができる。コストの点から好ましい材料は、炭素鋼や低合金鋼等である。例えば、炭素鋼としては機械構造用炭素鋼鋼材（Ｓ２０Ｃ～Ｓ５８Ｃ）が好適であり、低合金鋼としては、ニッケルクロム鋼鋼材（ＳＮＣ２３６～８３６）、ニッケルクロムモリブデン鋼鋼材（ＳＮＣＭ２２０～８１５）、クロムモリブデン鋼鋼材（ＳＣＭ４１５～４４５、８２２）、クロム鋼鋼材（ＳＣｒ４１５～４４５）、機械構造用マンガン鋼鋼材（ＳＭｎ４２０～４４３）、マンガンクロム鋼鋼材（ＳＭｎＣ４２０、４４３）等が好適である。これらの鋼材は、必ずしも調質を行うことによって焼入れ性を保証した調質鋼材（Ｈ材）を用いる必要はなく、調質されていないフェライト－パーライト組織ままのならし鋼材を用いてもよい。コストの点から好ましい材料は、炭素鋼、低合金鋼等である。また、本発明では合金鋼の方が高い表面硬度が得られる傾向はあるものの、窒素による効果ＩＩの焼入れ性向上作用の為、炭素鋼であっても十分に深い硬化深さが得られる。さらに本発明では窒素による効果ＩＩにより、必ずしも調質鋼を用いる必要はなく、非調質鋼であるフェライト－パーライト組織の鋼でも十分な機械強度を得られる。 The steel material to which the present invention is applied is not particularly limited, and examples thereof include carbon steel, low alloy steel, medium alloy steel, high alloy steel, cast iron and the like. A preferable material in terms of cost is carbon steel, low alloy steel, or the like. For example, carbon steel for machine structural use (S20C to S58C) is suitable as carbon steel, and nickel chrome steel (SNC 236 to 836), nickel chrome molybdenum steel (SNCM 220 to 815), chrome, etc. as low alloy steel. Molybdenum steel (SCM 415 to 445, 822), chromium steel (SCr 415 to 445), manganese steel for mechanical structure (SMn 420 to 443), manganese chrome steel (SMnC 420, 443) and the like are suitable. For these steel materials, it is not always necessary to use a tempered steel material (H material) whose hardenability is ensured by tempering, and a tempered steel material with a non-tempered ferrite-pearlite structure may be used. Preferred materials from the viewpoint of cost are carbon steel, low alloy steel, and the like. Further, in the present invention, although alloy steel tends to have higher surface hardness, a sufficiently deep hardening depth can be obtained even with carbon steel because of the effect of improving the hardenability of effect II by nitrogen. The effect II by nitrogen in yet present invention, it is not always necessary to use the heat-treated steel, a non-heat treated steels ferritic - obtain a sufficient mechanical strength even in pearlite structure of the steel.
　本発明における鉄鋼材料表面の窒素化合物層は、鉄鋼材料の表面に活性窒素を拡散させ、硬質で安定な窒化物を生成する表面硬化処理によって得られる。窒素化合物層である限り特に限定されないが、通常は母材成分であるＦｅを主体とし、Ｔｉ、Ｚｒ、Ｍｏ、Ｗ、Ｃｒ、Ｍｎ、Ａｌ、Ｎｉ、Ｃ、Ｂ、Ｓｉ等を含む窒化物からなる層であることが好ましい。窒素化合物層の形成方法としては、タフトライド処理、イソナイト処理、パルソナイト処理等の塩浴窒化処理、ガス軟窒化処理、イオン窒化処理、プラズマ窒化処理等、効果Ｉを有する窒素化合物層およびその直下に窒素が拡散した領域が形成される手法であれば何れの窒化方法でも用いることができる。効果Ｉを有するための窒素化合物層が形成されるための窒化熱処理温度として、６００℃以下であることが好ましく、さらに好ましくは５８０℃以下、さらに好ましくは５７０℃以下であることが好ましい。６００℃を上回る処理温度で得られる窒素化合物層の厚さは増すが、硬度が低下するため効果Ｉがもはや期待できなくなる。尚、下限は特に限定されないが、例えば３５０℃である。
　高周波焼入れ前の窒化処理により得られる窒素化合物層の厚さは特に限定されないが、通常は１～３０μｍの厚さで形成されていればよく、さらに好ましくは２～２０μｍであり、さらに好ましくは３～１５μｍである。 In the present invention, the nitrogen compound layer on the surface of the steel material is obtained by a surface hardening treatment that diffuses active nitrogen on the surface of the steel material to generate a hard and stable nitride. Although it is not particularly limited as long as it is a nitrogen compound layer, it is usually composed mainly of Fe as a base material component, and a nitride containing Ti, Zr, Mo, W, Cr, Mn, Al, Ni, C, B, Si, etc. It is preferable that it is a layer. As a method for forming the nitrogen compound layer, a nitrogen compound layer having an effect I, such as salt bath nitriding treatment such as tuftride treatment, isonite treatment, and pulsonite treatment, gas soft nitriding treatment, ion nitriding treatment, plasma nitriding treatment, and nitrogen immediately below the nitrogen compound layer There can be used in any of the nitriding process as long as it is a method for diffused region is formed. The nitriding heat treatment temperature for forming the nitrogen compound layer for achieving the effect I is preferably 600 ° C. or lower, more preferably 580 ° C. or lower, and further preferably 570 ° C. or lower. Although the thickness of the nitrogen compound layer obtained at a processing temperature exceeding 600 ° C. is increased, the effect I can no longer be expected because the hardness decreases. In addition, although a minimum is not specifically limited, For example, it is 350 degreeC.
The thickness of the nitrogen compound layer obtained by nitriding before induction hardening is not particularly limited, but it is usually sufficient if it is formed with a thickness of 1 to 30 μm, more preferably 2 to 20 μm, and even more preferably 3 ~ 15 μm.
　本発明では、鋼材に窒素化合物層を形成後に、この窒素化合物層を保護するための処理液を用いて保護皮膜を形成する。この処理液は、Ｓｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｔａ、Ｃａ、Ｃｅ、Ｓｃ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ、Ｚｎ、Ｍｇ及びＭｏからなる群の中から選択される少なくとも１種を含有し、りん酸イオン、縮合りん酸イオン、亜りん酸イオン、フッ化物イオン、炭酸イオン及びケイ酸イオンからなる群の中から選択される少なくとも１種のアニオンを０．１～６０ｇ／Ｌ含有し、その処理液のｐＨが４～１４である水系処理液であることが好ましい。本発明における水系処理液とは、溶媒が単一相からなり、その溶媒中の水の含有量が３０質量％以上、より好ましくは８０質量％以上、更に好ましくは９５質量％以上であるものをいう。溶媒中の水の含有量が多い程、保護膜形成時の大気中への炭素化合物の飛散が少なく環境負荷が小さくなるため、環境側面から水の含有量は多いほどが好ましい。 In the present invention, after forming the nitrogen compound layer on the steel material, a protective film is formed using a treatment liquid for protecting the nitrogen compound layer. The treatment liquid is at least one selected from the group consisting of Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg, and Mo. 0.1 to 60 g / L of at least one anion selected from the group consisting of phosphate ion, condensed phosphate ion, phosphite ion, fluoride ion, carbonate ion and silicate ion It is preferable that the aqueous treatment liquid is contained and the pH of the treatment liquid is 4 to 14. The aqueous treatment liquid in the present invention, the solvent is a single phase, the content of water in the solvent is 30 mass% or more, more preferably 80% by mass or more, the even more preferably not less than 95 wt% Say. The more the content of water in the solvent, since the scatter is small environmental impact of carbon compounds to the protective film forming time in the atmosphere is reduced, the content of water from the environmental aspect is the more preferred.
　この処理液中に、Ｓｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｔａ、Ｃａ、Ｃｅ、Ｓｃ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ、Ｚｎ、Ｍｇ及びＭｏからなる群の中から選択される少なくとも１種を含有する濃度は、その塗布法、及びその塗布繰り返し回数によって化合物層保護膜を所定付着量とすることができる濃度であればよく、例えば０．５～１００ｇ／Ｌの含有量とすればよい。 In the treatment liquid, at least one selected from the group consisting of Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg, and Mo. concentration containing species, the coating method, and may be a concentration which can be a predetermined deposition amount of the compound layer protective film by the coating repeat count, for example, if the content of 0.5 ~ 100 g / L Good.
　本発明の処理液は、Ｓｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｔａ、Ｃａ、Ｃｅ、Ｓｃ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ、Ｚｎ、Ｍｇ及びＭｏからなる群の中から選択される少なくとも１種の溶解したイオン並びに／又はＳｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ及びＭｏからなる群の中から選択される少なくとも１種を含む平均粒径が４～４０ｎｍからなる分散粒子と、Ｓｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｔａ、Ｃａ、Ｃｅ、Ｓｃ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ、Ｚｎ、Ｍｇ及びＭｏからなる群の中から選択される少なくとも１種を含む平均粒径が４０～４００ｎｍからなる分散粒子と、をともに含有し、前者が乾燥固形状態として占める質量と、後者が乾燥固形状態として占める質量との比が１：１０～１０：１であることが好ましい。尚、本明細書における平均粒径は、例えば動的光散乱法による粒径分布測定装置を用いて測定可能である。
　Ｓｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｔａ、Ｃａ、Ｃｅ、Ｓｃ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ、Ｚｎ、Ｍｇ及びＭｏは、その後に行われる高周波加熱時に窒素化合物層の分解や酸化を防ぐための保護膜の主たる成分であり、その酸化物が熱的、化学的に安定なものである。特に、Ｓｉ、Ｔｉ、Ｚｒ、Ｃｅ、Ｃｒ、Ｗ、Ａｌ、Ｍｏは、これら金属化合物中でのイオンの拡散速度が小さいためより好ましい。 The treatment liquid of the present invention is at least selected from the group consisting of Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg, and Mo. From 4 to 40 nm in average particle size including one dissolved ion and / or at least one selected from the group consisting of Si, Ti, Zr, Hf, Nb, Cr, W, Al, Sr and Mo And at least one selected from the group consisting of Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg, and Mo And a dispersed particle having an average particle size of 40 to 400 nm, the ratio of the mass occupied by the former as a dry solid state and the mass occupied by the latter as a dry solid state is 1:10 to 10: 1 Preferably there is. The average particle diameter in the present specification, for example, can be measured using a particle size distribution measuring apparatus by a dynamic light scattering method.
Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg and Mo decompose and oxidize the nitrogen compound layer during high-frequency heating performed thereafter. is the main component of the protective film for preventing, its oxide is thermal, those chemically stable. In particular, Si, Ti, Zr, Ce, Cr, W, Al, and Mo are more preferable because the diffusion rate of ions in these metal compounds is small.
　保護膜の主成分であるＳｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｔａ、Ｃａ、Ｃｅ、Ｓｃ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ、Ｚｎ、Ｍｇ及びＭｏは、造膜成分と応力緩和成分の２つから構成されることが好ましい。造膜成分としては、上記の成分がイオン、オキソ酸イオン、ペルオキソ酸イオン、あるいは錯イオンとして溶解していることであり、もしくは表面に活性点の多い４～４０ｎｍと非常に細かい粒子として液中分散していることである。
　保護膜の応力緩和成分としては、Ｓｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｔａ、Ｃａ、Ｃｅ、Ｓｃ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ、Ｚｎ、Ｍｇ、及びＭｏからなる群の中から選択される少なくとも１種を含む平均粒径が４０～４００ｎｍからなる分散粒子、を含有することが好ましい。
　造膜成分と応力緩和成分の分散粒子は、例えば、酸化物、水酸化物、窒化物、フッ化物、炭酸塩、りん酸塩化合物を用いることができる。造膜成分の分散粒子は、結晶性のものよりもアモルファスのものの方が表面の活性点が多く造膜性が良好であるため好ましい。応力緩和成分の分散粒子は、アモルファスのものよりも結晶性のものの方が、加熱時の体積収縮が小さく、また化学的・物理的に安定で保護皮膜としての効果が高くなるため好ましい。 The main components of the protective film, Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg, and Mo are film forming components and stress relaxation components. It is preferable to be composed of two. As a film-forming component, the above components are dissolved as ions, oxoacid ions, peroxoacid ions, or complex ions, or in the liquid as very fine particles of 4 to 40 nm with many active sites on the surface. It is distributed.
The stress relaxation component of the protective film is selected from the group consisting of Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg, and Mo. it is preferred that the average particle diameter comprising at least one member contains dispersed particles, consisting of 40 ~ 400 nm.
For example, oxides, hydroxides, nitrides, fluorides, carbonates, and phosphate compounds can be used as the dispersed particles of the film forming component and the stress relaxation component. As the dispersed particles of the film-forming component, the amorphous particles are more preferable than the crystalline particles because they have many active points on the surface and good film-forming properties. As the dispersed particles of the stress relaxation component, the crystalline particles are preferable to the amorphous particles because the volume shrinkage during heating is small, and the effect as a protective film is high because the particles are chemically and physically stable.
　応力緩和成分単体のみを塗布しても、反応性が低く平均粒子径が大きいために造膜性に乏しく、その結果、皮膜としての連続性・密着性が弱いため、保護皮膜としての作用が不十分となる場合がある。
　造膜成分単体のみを塗布した場合、窒素化合物層上に連続皮膜を形成できるが、乾燥時の大きな体積収縮で生じる保護皮膜内の応力を緩和できず、保護膜に亀裂や剥離が生じる場合がある。また、造膜成分は結合の反応性が高い反面、化学的・物理的な安定性が十分とは言えず、保護皮膜としての作用が必ずしも発揮されない場合がある。
　上記の理由により、造膜成分と応力緩和成分を、共に皮膜内に取り込み形成させ、乾燥固形状態（焼入れ前の保護皮膜内での乾燥固体状態）として占める両者の質量比が１：１０～１０：１とすることが、最も保護皮膜としての作用が高くなる。より好ましくは１：５～５：１であり、さらに好ましくは１：３～３：１である。ここで、本特許請求の範囲及び本明細書における「乾燥固体状態」とは、原料である金属含有成分がすべて酸化物になったことを想定した酸化物換算値を指す。尚、実際には、揮発したり他の形態で存在する形態や原料成分の形態で留まる成分も存在することがあるが、本特許請求の範囲及び本明細書における「乾燥固体状態」は、あくまで原料ベースでの想定値（理論値）である。 Even if only the stress relaxation component is applied alone, the film formation is poor because the reactivity is low and the average particle size is large, and as a result, the continuity and adhesion as a film are weak, so that it does not work as a protective film. May be sufficient.
When only the film forming component is applied, a continuous film can be formed on the nitrogen compound layer, but the stress in the protective film caused by large volume shrinkage during drying cannot be relieved, and the protective film may crack or peel. is there. In addition, the film-forming component has high bonding reactivity, but it cannot be said to have sufficient chemical and physical stability and may not always exhibit the protective film effect.
For the above reasons, the film forming component and the stress relaxation component are both incorporated into the film and formed, and the mass ratio of the two in the dry solid state (the dry solid state in the protective film before quenching) is 1:10 to 10 When it is set to 1, the effect as a protective film becomes the highest. More preferably, it is 1: 5 to 5: 1, and still more preferably 1: 3 to 3: 1. Here, the “dried solid state” in the claims and the present specification refers to an oxide equivalent value assuming that all of the metal-containing components as raw materials are oxides. In practice, there may be components that volatilize or exist in other forms or remain in the form of raw material components. However, the `` dry solid state '' in the claims and the specification is only It is an assumed value (theoretical value) on a raw material basis.
　りん酸イオン、縮合りん酸イオン、亜りん酸イオン、フッ化物イオン、炭酸イオン、ケイ酸イオンは、特に処理液を塗布乾燥させる際、効果的に窒素化合物層の分解や酸化を防ぐ働きをする。
　前述のように、特開２００８－０３８２２０号記載の手法では、必ずしも窒素化合物層の酸化防止に対して十分とは言えず、状況によっては高周波加熱後に窒素化合物層の表層の一部が酸化分解する場合があった。本発明者等はその要因を鋭意調査した結果、保護膜に求められる役割は、保護膜形成後に行われる高周波加熱時に生じる窒素化合物層の分解や酸化を防ぐことにあるのみでなく、まず第一に、保護膜そのものの形成時に窒素化合物層の分解や酸化を防ぐことが必須であることを見出した。窒素化合物層は鉄素地そのものよりも耐食性は高いものの、処理液が塗布され保護膜として固着乾燥するまでの、特にウェットの半乾燥で５０℃以上に加温されている時、分解や酸化を生じやすい。ウェットで５０～２００℃程度の温度負荷時は、ウェットである故、場合によっては７５０～８６０℃で行われるドライな保護皮膜での高周波加熱負荷の場合より、窒素化合物層の分解や酸化を生じやすくなる。
　処理液中にりん酸イオン、縮合りん酸イオン、亜りん酸イオン、フッ化物イオン、炭酸イオン、ケイ酸イオンを添加することによって、処理液を塗布乾燥させる際、窒素化合物層の分解や酸化を防ぐメカニズムは必ずしも明らかでないが、これら化合物はいずれも鉄の不動態化を促進する働きがあることが知られており、窒素化合物層の溶解に対しても同様な働きをし、溶解を抑制すると考えられる。りん酸イオン、縮合りん酸イオン、亜りん酸イオン、フッ化物イオン、炭酸イオン及びケイ酸イオンからなる群の中から選択される少なくとも１種のアニオンを０．１～６０ｇ／Ｌ含有するのが好ましく、より好ましくは、０．５～３０ｇ／Ｌであり、さらに好ましくは１～１０ｇ／Ｌである。０．１ｇ／Ｌ以下の含有ではその添加による効果が十分には現れず、また６０ｇ／Ｌを越える量は既にその効果が飽和しコスト的に不利となる。
　本発明の処理液は水系であるため、鋼素地の腐食を防ぐためにｐＨが鉄の不動態領域である４～１４であることが好ましい。より好ましくは、７～１３であり、さらに好ましくは８～１２である。尚、本処理液が液体媒体として水の他に溶剤を含有する場合には、前述のｐＨ値は液体媒体を水のみとした場合のｐＨとする。 Phosphate ions, condensed phosphate ions, phosphite ions, fluoride ions, carbonate ions, and silicate ions effectively prevent decomposition and oxidation of the nitrogen compound layer, especially when applying and drying treatment liquids. .
As described above, the technique described in Japanese Patent Application Laid-Open No. 2008-038220 is not necessarily sufficient for preventing the oxidation of the nitrogen compound layer. Depending on the situation, a part of the surface layer of the nitrogen compound layer is oxidatively decomposed after high-frequency heating. There was a case. As a result of earnest investigations by the inventors, the role required of the protective film is not only to prevent decomposition and oxidation of the nitrogen compound layer that occurs during high-frequency heating performed after the formation of the protective film, but first of all. Furthermore, it has been found that it is essential to prevent decomposition and oxidation of the nitrogen compound layer when forming the protective film itself. Although the nitrogen compound layer has higher corrosion resistance than the iron substrate itself, it decomposes and oxidizes when it is heated to 50 ° C or higher, especially during wet semi-drying, until the treatment liquid is applied and fixed and dried as a protective film. Cheap. When wet with a temperature load of about 50 to 200 ° C, it is wet, so in some cases, decomposition and oxidation of the nitrogen compound layer occurs more than with a high-frequency heating load with a dry protective film performed at 750 to 860 ° C. It becomes easy.
By adding phosphate ions, condensed phosphate ions, phosphite ions, fluoride ions, carbonate ions, and silicate ions to the treatment solution, the nitrogen compound layer is decomposed and oxidized when the treatment solution is applied and dried. The mechanism to prevent is not always clear, but it is known that all of these compounds have a function of promoting the passivation of iron, and the same action is taken for the dissolution of the nitrogen compound layer. Conceivable. It contains 0.1 to 60 g / L of at least one anion selected from the group consisting of phosphate ion, condensed phosphate ion, phosphite ion, fluoride ion, carbonate ion and silicate ion. Preferably, it is 0.5 to 30 g / L, and more preferably 1 to 10 g / L. If the content is less than 0.1 g / L, the effect due to the addition does not sufficiently appear, and if it exceeds 60 g / L, the effect is already saturated and disadvantageous in cost.
Since the treatment liquid of the present invention is aqueous, the pH is preferably 4 to 14 in the passive region of iron in order to prevent corrosion of the steel substrate. More preferably, it is 7 to 13, and still more preferably 8 to 12. In addition, when this processing liquid contains a solvent other than water as a liquid medium, the above-mentioned pH value is a pH when the liquid medium is only water.
　本発明の処理液は、さらにアミン類を０．１～４００ｇ／Ｌ含むことが好ましい。より好ましくは、０．５～２００ｇ／Ｌであり、さらに好ましくは１～１００ｇ／Ｌである。このアミン類は所定のｐＨに処理液を保ち、また窒素化合物層の表面への吸着性が高く、窒素化合物層を鉄の不動態領域と同じ安定な状態とするために添加される。またこれらアミン類は、高周波加熱時の窒素化合物層の酸化・分解を抑制する効果も有するが、この機構として本発明者等は高周波加熱時にアミン類が窒素を放出しその窒素が窒素化合物層側へ拡散するためと推測している。添加されるアミン類としては、例えば、アンモニア、尿素、メチルアミン、エチルアミン、トリメチルアミン、トリエチルアミン、トリエタノールアミン、Ｎ，Ｎ－ジイソプロピルエチルアミン、ピペリジン、ピペラジン、モルホリン、ピリジン、４－ジメチルアミノピリジン、エチレンジアミン、テトラメチルエチレンジアミン、ヘキサメチレンジアミン、アニリン、カテコールアミン、フェネチルアミン等、を使用することができる。これらのいずれもが加熱時に分解や揮発可能なものである。ここでｐＨ保持のために、例えばアルカリ金属等の不揮発なものを用いると、乾燥固着された保護皮膜内に残留し、特にＬｉイオン、Ｎａイオン、Ｋイオンは高温負荷時に保護皮膜内を容易に移動でき酸化防止剤としての効果が低下する要因となる場合があるため、できるだけ使わない方が好ましい。 The treatment liquid of the present invention preferably further contains 0.1 to 400 g / L of amines. More preferably, it is 0.5 to 200 g / L, and still more preferably 1 to 100 g / L. The amines keeping the processing solution at a predetermined pH, also high adsorptivity to the surface of the nitrogen compound layer is added nitrogen compound layer to the same stable state as passivation region of iron. These amines also have an effect of suppressing oxidation / decomposition of the nitrogen compound layer during high-frequency heating. As a mechanism for this, the present inventors have released nitrogen during high-frequency heating, and the nitrogen is on the nitrogen compound layer side. I guess to spread. Examples of amines to be added include ammonia, urea, methylamine, ethylamine, trimethylamine, triethylamine, triethanolamine, N, N-diisopropylethylamine, piperidine, piperazine, morpholine, pyridine, 4-dimethylaminopyridine, ethylenediamine, Tetramethylethylenediamine, hexamethylenediamine, aniline, catecholamine, phenethylamine, and the like can be used. Any of these can be decomposed or volatilized when heated. If a non-volatile material such as an alkali metal is used to maintain the pH here, it will remain in the protective film that has been dried and fixed, and in particular, Li ions, Na ions, and K ions will easily enter the protective film when subjected to high temperature load. Since it may be a factor that can move and reduce the effect as an antioxidant, it is preferable not to use it as much as possible.
　尚、本発明の処理液には、消泡剤や被塗面に均一な皮膜を得るための濡性向上剤と呼ばれる界面活性剤、増粘剤、その他の有機／無機添加を補助的に適宜添加することもできる。 In the treatment liquid of the present invention, an antifoaming agent or a surfactant called a wettability improver for obtaining a uniform film on the surface to be coated, a thickener, and other organic / inorganic additions are suitably supplemented. It can also be added.
　また、本発明に係る処理液中の各成分（Ｓｉ等の第一成分、りん酸イオン等のアニオンである第二成分、アミン類である第三成分等）は、同一原料に由来してもよい。例えば、実施例１における一原料である炭酸ジルコニウムアンモニウムは、第一成分としてジルコニウム、第二成分として炭酸イオン、第三成分としてアンモニウムを液中に供給する。更には、本発明に係る処理液中の一成分が複数の成分としての機能を有していてもよい。例えば、ケイ酸イオンは、第一成分としてのＳｉでもあるし、第二成分としてのアニオンでもある。更には、処理液中のこれら成分の存在形態は、相互に分離した状態であってもよいし、例えば錯体等の複合体として存在してもよい。尚、本発明における各成分の数値は、原料ベースで算出するものとする（反応生成物の数値については原料の数値から推定）。ここで、ある成分が複数の成分として機能する場合には、相互に独立して各成分の数値を算出する。具体的には、ある成分（含有量又は添加量Ａ）が例えば第一成分としても第二成分としても機能する場合には、含有量Ａに基づき第一成分量を算出し、含有量Ａに基づき第二成分量を算出する。また、液中で複数の成分が複合体として存在している場合も同様である。 Further, the components in the treatment solution according to the present invention (first component such as Si, the second component is an anion such as phosphate ion, a third component such as an amine) may be derived from the same raw material Good. For example, ammonium zirconium carbonate is one raw material in Example 1, zirconium as a first component, a carbonate ion as a second component, and supplies the ammonium as a third component in the liquid. Furthermore, one component in the treatment liquid according to the present invention may have a function as a plurality of components. For example, silicate ions are both Si as the first component and anions as the second component. Further, the existence form of these components in the treatment liquid may be in a state separated from each other, or may exist as a complex such as a complex. In addition, the numerical value of each component in this invention shall be calculated on a raw material basis (it estimates from the numerical value of a raw material about the numerical value of a reaction product). Here, when a certain component functions as a plurality of components, the numerical value of each component is calculated independently of each other. Specifically, in the case of functions both as a first component as being components (content or amount A) is, for example, the first component, calculates a first component amount based on the content A, the content A Based on this, the second component amount is calculated. The same applies when a plurality of components are present in the liquid as a complex.
　処理液の塗布方法は特に限定されないが、ディップコート法、スピンコート法、スプレー法、刷毛塗りなどを用いることができる。塗布時の皮膜乾燥・焼成温度は、好ましくは６０～５５０℃で行えばよく、より好ましくは１００～４００℃であり、さらに好ましくは１２０～３００℃である。加温時間は、例えば３０秒～６０分間とし雰囲気にさらし、十分に固化乾燥・固着させればよい。乾燥時の雰囲気は不活性な雰囲気が好ましいが、大気雰囲気でもよい。鋼部品形状によっては液溜まり部での高温かつ長時間ウェットが保たれる厳しい状態を避けるため、室温や５０℃以下において送風乾燥させた後、所定温度で焼成する多段階の加熱方法を採ってもよい。また、所定の膜厚とするために塗布乾燥を複数回繰り返し行い、膜厚調整をしてもよい。 The coating method of the treatment liquid is not particularly limited, but a dip coating method, a spin coating method, a spray method, a brush coating, or the like can be used. The coating drying / firing temperature at the time of application is preferably 60 to 550 ° C., more preferably 100 to 400 ° C., and further preferably 120 to 300 ° C. The heating time may be 30 seconds to 60 minutes, for example, and it may be sufficiently solidified, dried and fixed by exposure to the atmosphere. The atmosphere during drying is preferably an inert atmosphere, but may be an air atmosphere. Depending on the shape of the steel part, in order to avoid the severe condition where the wet state is maintained at the liquid reservoir for a long time, air-drying is performed at room temperature or below 50 ° C, and then firing at a predetermined temperature is adopted. Also good. In order to obtain a predetermined film thickness, coating and drying may be repeated a plurality of times to adjust the film thickness.
　本発明における化合物層保護膜は、鋼材に対し窒化処理後に形成される窒化物層上に乾燥固形状態として被覆されるＳｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｔａ、Ｃａ、Ｃｅ、Ｓｃ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ、Ｚｎ、Ｍｇ及びＭｏからなる群の中から選択される少なくとも１種の金属を含有するものであって、該金属換算の合計で０．０５～３ｇ／ｍ２の範囲で形成される。より好ましくは０．１～１ｇ／ｍ２である。
　該金属換算の合計が０．０５ｇ／ｍ２未満では窒化物層の保護効果が不十分となり、また、３０００ｍｇ／ｍ２を超えると既に効果が飽和するためコスト的に好ましくない。この該金属換算の合計付着量が３０００ｍｇ／ｍ２の時、その皮膜厚さは２～４μｍ程度であり、ミリオーダーの皮膜を被覆する特許文献７に比べ圧倒的に薄く、焼入れ性を阻害しない厚さとなっている。 In the present invention, the compound layer protective film is formed by coating Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, and the like on a nitride layer formed after nitriding treatment on a steel material as a dry solid state. Containing at least one metal selected from the group consisting of Cr, W, Al, Sr, Zn, Mg, and Mo, and 0.05 to 3 g / m 2 in total in terms of the metal Formed in range. More preferably, it is 0.1 to 1 g / m 2 .
If the total metal conversion is less than 0.05 g / m 2 , the protective effect of the nitride layer is insufficient, and if it exceeds 3000 mg / m 2 , the effect is already saturated, which is not preferable in terms of cost. When the total metal deposition amount is 3000 mg / m 2 , the film thickness is about 2 to 4 μm, which is overwhelmingly thinner than Patent Document 7 covering a millimeter-order film and does not impair hardenability. It is thick.
　化合物層保護膜を形成した後に行う高周波焼入れとして、７５０～８６０℃に設定された所定の加熱温度に到達するように、０．３～５秒間加熱することによる高周波加熱に供される。所定の温度に到達後は、冷却剤によって直ちに冷却されることによって、窒素を含有する微細なマルテンサイト組織を得ることができる。加熱温度について、より好ましい加熱温度は７７０～８４０℃であり、さらに好ましい加熱温度は７８０～８３０℃である。また加熱時間について、より好ましい加熱時間は０．８～３秒間で、さらに好ましくは１～２秒間である。
　７５０℃以下の加熱では窒素が入っているとは言え、この温度では十分にオーステナイト化されないため焼入れ不十分となる。加熱が８６０℃を上回る温度では、もはや化合物層保護膜の作用が効かなくなり、化合物層の分解を抑制しきれず、また、化合物層直下のマルテンサイト組織中に過剰な残留オーステナイトが発生しやすくなるため好ましくない。加熱時間が０．３秒以下の加熱では窒素が拡散しているとは言え、十分にオーステナイト化されないため焼入れ不十分となる。５秒を上回る加熱時間では、もはや加熱時間の効果がほぼ飽和する上、化合物層保護膜の作用が低下するため好ましくない。
　本発明の化合物層保護膜を用いることにより、高周波加熱時の雰囲気が大気中であっても、窒素化合物層は酸化や分解から十分に抑制される。また、設備導入が可能であれば、高周波加熱時の雰囲気は、真空雰囲気、アルゴンガスや窒素ガスによる不活性雰囲気、低酸素雰囲気、炭化水素系の還元性雰囲気、アンモニアガス雰囲気等で行うこともできる。
　高周波加熱時、処理物が大きい場合などは、予備加熱を含めた多段の昇温法を適宜行うことができる。高周波加熱による焼入れ後は、通常の焼入れ手法と同様に適当な条件にて焼き戻し処理を行ってもよい。 As induction hardening performed after forming the compound layer protective film, it is subjected to induction heating by heating for 0.3 to 5 seconds so as to reach a predetermined heating temperature set at 750 to 860 ° C. After reaching a predetermined temperature, it is immediately cooled by a coolant, whereby a fine martensitic structure containing nitrogen can be obtained. Regarding the heating temperature, a more preferable heating temperature is 770 to 840 ° C., and a further preferable heating temperature is 780 to 830 ° C. The heating time is more preferably 0.8 to 3 seconds, and further preferably 1 to 2 seconds.
Although heating is performed at 750 ° C. or lower, nitrogen is contained, at this temperature, the material is not sufficiently austenitic, and thus quenching is insufficient. When the heating exceeds 860 ° C., the effect of the compound layer protective film is no longer effective, and the decomposition of the compound layer can no longer be suppressed, and excessive residual austenite tends to be generated in the martensite structure immediately below the compound layer. It is not preferable. Even if the heating time is 0.3 seconds or less, nitrogen is diffused, but it is not sufficiently austenitized, resulting in insufficient quenching. A heating time exceeding 5 seconds is not preferable because the effect of the heating time is almost saturated and the function of the compound layer protective film is lowered.
By using the compound layer protective film of the present invention, the nitrogen compound layer is sufficiently suppressed from oxidation and decomposition even when the atmosphere during high-frequency heating is in the air. If equipment can be introduced, the atmosphere during high-frequency heating may be a vacuum atmosphere, an inert atmosphere with argon gas or nitrogen gas, a low oxygen atmosphere, a hydrocarbon-based reducing atmosphere, an ammonia gas atmosphere, or the like. it can.
When the treatment is large at the time of high-frequency heating, a multistage temperature raising method including preheating can be appropriately performed. After quenching by high-frequency heating, tempering treatment may be performed under appropriate conditions in the same manner as a normal quenching technique.
　一連の熱処理終了後、本発明による処理品を機械部品として組み込む際、化合物層保護膜は除去しても除去しなくてもよく、必要に応じて選定することができる。化合物層保護膜の除去は、化合物層に比べ硬度が低いため容易にでき、例えばラッピング処理、エメリー紙研磨、バフ研磨、ショットブラスト、ショットピニング等によって適宜行うことができる。 After a series of completion of the heat treatment, when incorporating the treated product according to the invention as a machine part, compound layer protective film may not be removed be removed can be selected as needed. The removal of the protective film of the compound layer can be easily performed because the hardness is lower than that of the compound layer, and can be appropriately performed by, for example, lapping, emery paper polishing, buffing, shot blasting, shot pinning, or the like.
　高周波加熱後、本発明の化合物層保護膜によって窒素化合物層は残存するが、窒素化合物層は高周波加熱前の化合物層状態に対し必ずしも１００％残存する必要はなく、最低膜厚として１μｍ以上の化合物層厚さが確保されていればよい。より好ましくは２μｍ以上の残存であり、さらに好ましくは３μｍ以上である。窒素化合物層の酸化を受けた部位が表層に存在する場合、そこは脆く硬度が低いため、前述の化合物層保護膜の除去作業工程を行った場合は、保護膜とともにほとんどが除去されることになる。 After the high frequency heating, the nitrogen compound layer remains with the compound layer protective film of the present invention, but the nitrogen compound layer does not necessarily remain 100% of the state of the compound layer before the high frequency heating, and the minimum film thickness is 1 μm or more. The layer thickness should just be ensured. More preferably, it is 2 μm or more, and more preferably 3 μm or more. When the oxidized layer of the nitrogen compound layer is present on the surface layer, it is brittle and low in hardness. Therefore, when the above-described compound layer protective film removal operation step is performed, most of the protective layer is removed together with the protective film. Become.
　以上のような複合熱処理によって、表面に１～３０μｍの厚みを有する窒素化合物層を有し、その直下から内部に向かって漸減する硬度分布を有する窒素を含有する微細マルテンサイト組織を含む硬質層を兼ね備え、窒素化合物層の硬度がビッカーズ硬度換算でＨＶ６３０以上であり、微細マルテンサイト組織を含む硬質層のＨＶ５５０を越える硬度領域が表面からの距離で２００μｍ以上、好ましくは４００μｍ以上、さらに好ましくは６００μｍ以上存在する硬度分布を持つ鉄鋼材料を得ることができる。尚、上限は特に限定されないが、例えば１．５ｍｍである。 A hard layer containing a fine martensite structure containing nitrogen having a nitrogen compound layer having a thickness of 1 to 30 μm on the surface and having a hardness distribution gradually decreasing from directly below to the inside by the composite heat treatment as described above. In addition, the hardness of the nitrogen compound layer is HV630 or more in terms of Vickers hardness, and the hardness region exceeding HV550 of the hard layer containing a fine martensite structure is 200 μm or more, preferably 400 μm or more, more preferably 600 μm or more in terms of the distance from the surface. A steel material having an existing hardness distribution can be obtained. In addition, although an upper limit is not specifically limited, For example, it is 1.5 mm.
　以上の本発明の処理によって、窒素化合物層の効果Ｉ、ＩＩを兼ね備える機械部品が得られる。すなわち、本発明の処理が施された機械部品は、最表面に形成された窒素化合物層による高い摺動性、耐焼付き性を有し、かつ、窒素含有微細マルテンサイト組織による高い焼き戻し軟化抵抗、亀裂発生・亀裂成長抵抗性、耐面圧強度、高疲労強度、深い硬化深さを有している。 By the above-described treatment according to the present invention, a mechanical component having effects I and II of the nitrogen compound layer can be obtained. That is, the machine part subjected to the treatment of the present invention has high slidability and seizure resistance due to the nitrogen compound layer formed on the outermost surface, and high temper softening resistance due to the nitrogen-containing fine martensite structure. It has crack initiation / crack growth resistance, surface pressure resistance, high fatigue strength, and deep cure depth.
　本発明による複合熱処理による高周波加熱による焼入れは７５０～８６０℃であり、通常９００℃を越える温度で行う高周波焼入れや浸炭焼入れに対して、焼入れ温度は十分に低い。これは熱変形や焼き割れにおいて極めて有利であり、一般的な高周波焼入れや浸炭焼入れ後に行う寸法精度調整の為の後切削工程の大幅な低減を可能とするものである。
　先に述べたように本発明の適用対象となる鉄鋼材料は、窒素による効果ＩＩの焼入れ性向上作用の為、必ずしも調質鋼を用いる必要はなく、非調質鋼であるフェライト－パーライト組織の鋼でも十分な機械強度を得られる。また合金鋼の方がやや高い表面硬度が得られる傾向はあるものの、窒素による効果ＩＩにより、安価な炭素鋼であっても十分に深い硬化深さが得られる。例えば、Ｓ４５Ｃなどの機械構造用炭素鋼においても、十分な硬度、かつ十分な深さの硬度プロファイルを持つ熱処理材となる。また、そのＳ４５Ｃでさえ、必ずしも調質材である必要はなく、非調質のフェライト－パーライト組織の鋼部材に本発明の熱処理を適用しても、十分なマルテンサイト変態を生じ、十分な機械的強度を有する熱処理機械部品となりえる。
　以上のように本発明の適用により、部品の機械強度の向上、切削工程の低減や安価な材料への切り替えによって、部品の小型化による機械部品全体の小型・軽量化、および窒化処理と高周波焼入れとの複合処理によるコスト増を補って余るだけの実質コストの低減が可能となる。 The quenching by induction heating by the composite heat treatment according to the present invention is 750 to 860 ° C., and the quenching temperature is sufficiently lower than the induction quenching and carburizing quenching usually performed at temperatures exceeding 900 ° C. This is extremely advantageous in terms of thermal deformation and cracking, and enables a significant reduction in the post-cutting process for adjusting the dimensional accuracy performed after general induction hardening or carburizing and quenching.
As described above, the steel material to which the present invention is applied is not necessarily required to use a tempered steel because of the effect of improving the hardenability of the effect II caused by nitrogen. Sufficient mechanical strength can be obtained even with steel. Further, although alloy steel tends to have a slightly higher surface hardness, a sufficiently deep hardening depth can be obtained even with inexpensive carbon steel due to the effect II of nitrogen. For example, a carbon steel for mechanical structure such as S45C is a heat treatment material having a hardness profile with sufficient hardness and sufficient depth. Further, even S45C is not necessarily a tempered material, and even if the heat treatment of the present invention is applied to a steel member having a non-tempered ferrite-pearlite structure, sufficient martensitic transformation occurs, and sufficient mechanical properties are obtained. It can be a heat-treated machine part with high strength.
As described above, the application of the present invention improves the mechanical strength of the parts, reduces the cutting process and switches to inexpensive materials, thereby reducing the size and weight of the entire mechanical parts by downsizing the parts, and nitriding and induction hardening. It is possible to reduce the actual cost by surplus to compensate for the cost increase due to the combined processing.
　本発明の高周波焼入れによる焼入れ手法の置き換えとして、例えば長くとも数秒の短時間加熱によるレーザー焼入れ、あるいは数ミリ秒の短時間加熱となる衝撃焼入れによって、窒化処理後に本発明の化合物層保護皮膜を形成した部品に焼入れを行った場合は、窒化物層は十分に保護され、その層の下の鋼素地部分は用いた焼入れ手法に応じた焼入れ組織を得ることができる。 As a replacement of the quenching method by induction quenching of the present invention, the compound layer protective film of the present invention is formed after nitriding treatment by, for example, laser quenching by short-time heating for several seconds at the longest or impact quenching for short heating of several milliseconds. If you make quenching the component, a nitride layer is sufficiently protected, base steel lower part of the layer can be obtained quenched structure according to the quenching method using.
　次に、本発明に係る焼入れ鉄鋼材料の用途について説明する。本発明に係る焼入れ鉄鋼部材は、高負荷・高面圧領域で使用されるものに好適である。鉄鋼部材の形状、部品種は特に限定されず、例えば、軸、歯車、ピストン、シャフト、カム等を挙げることができ、自動車や建機のミッション関連部品、パワートレイン用部品に好適である。 Next, the use of the hardened steel material according to the present invention will be described. The hardened steel member according to the present invention is suitable for those used in a high load / high surface pressure region. The shape and part type of the steel member are not particularly limited, and examples thereof include shafts, gears, pistons, shafts, cams, and the like, which are suitable for transmission-related parts and powertrain parts for automobiles and construction machinery.
　以下に本発明の実施形態について実施例を挙げて説明するが、本発明の範囲は、以下の実施例に限定されるものではない。 Hereinafter, embodiments of the present invention will be described with reference to examples, but the scope of the present invention is not limited to the following examples.
＜実施例１＞
　基材として直径８ｍｍ、長さ５０ｍｍのＳＣＭ４３５調質材を使用し、この表面を脱脂洗浄したのち、溶融塩浴中において５６０℃で２時間塩浴軟窒化処理（イソナイト処理：日本パーカライジング（株）製）して油冷し、鋼材表面に厚さ約１０μｍの窒化鉄を主体とする窒素化合物層を形成した。 <Example 1>
SCM435 tempered material having a diameter of 8 mm and a length of 50 mm was used as a base material. After degreasing and cleaning this surface, salt bath soft nitriding treatment at 560 ° C. for 2 hours in a molten salt bath (Isonite treatment: Nippon Parkerizing Co., Ltd.) Ltd.) to oil cooling, to form a nitrogen compound layer consisting mainly of iron nitride having a thickness of about 10μm on the surface of the steel material.
　炭酸ジルコニウムアンモニウムによるジルコニウム溶解液をジルコニウム換算で２２．２ｇ／Ｌ（炭酸イオンとしては１１ｇ／Ｌ）、平均粒径５０ｎｍの酸化ジルコニウム粒子（結晶構造は正方晶）をジルコニウム換算で７．４ｇ／Ｌ、オルトリン酸アンモニウムをりん酸イオンとして１ｇ／Ｌ、及びメチルアミン１１ｇ／Ｌを各々含有するｐＨ９．５の処理液を準備した。基材にディップコーティング法を用いてこの処理液を塗布し、余分な液を除去した後に４０℃×１０分で乾燥させる工程を３回繰り返し、最後に２００℃で１０分間焼成した。基材上のＺｒ付着量を蛍光Ｘ線分析装置で測定したところ、Ｚｒとしての付着量は５２０ｍｇ／ｍ２であった。この保護皮膜において、計算される造膜成分の酸化ジルコニウムと応力緩和成分の酸化ジルコニウムについて、造膜成分／応力緩和成分の比率は３であった。 Zirconium-dissolved zirconium carbonate solution was 22.2 g / L in terms of zirconium (11 g / L as carbonate ions), and zirconium oxide particles having an average particle size of 50 nm (tetragonal crystal structure) was 7.4 g / L in terms of zirconium. Then, a pH 9.5 treatment solution containing 1 g / L of ammonium orthophosphate as phosphate ions and 11 g / L of methylamine was prepared. The treatment liquid was applied to the substrate using a dip coating method, and after removing excess liquid, the process of drying at 40 ° C. × 10 minutes was repeated three times, and finally, baking was performed at 200 ° C. for 10 minutes. When the Zr adhesion amount on the substrate was measured with a fluorescent X-ray analyzer, the adhesion amount as Zr was 520 mg / m 2 . In this protective coating, the ratio of the film-forming component / stress-relaxing component was 3 with respect to the calculated film-forming component zirconium oxide and the stress-relaxing component zirconium oxide.
　このようにして酸化ジルコニウムを含む化合物層保護膜を窒素化合物層上に形成した鋼材に対し、さらに高周波焼入れ装置を使用して加熱開始後１秒で８２０℃に達した後、直ちに加熱を停止して、冷却を行い焼入れを行った。後に鋼材表面をショットブラストし化合物層保護膜のみを除去した。 In this way, with respect to the steel material in which the compound layer protective film containing zirconium oxide is formed on the nitrogen compound layer, the heating is stopped immediately after reaching 820 ° C. in 1 second after the start of heating using the induction hardening apparatus. Then, it was cooled and quenched. Later, the steel surface was shot blasted to remove only the compound layer protective film.
＜実施例２＞
　基材として直径８ｍｍ、長さ５０ｍｍのＳ４５Ｃ調質材を使用し、この表面を脱脂洗浄したのち、溶融塩浴中において５６０℃で２時間塩浴軟窒化処理（イソナイト処理：日本パーカライジング（株）製）して油冷し、鋼材表面に厚さ約１３μｍの窒化鉄を主体とする窒素化合物層を形成した。 <Example 2>
S45C tempered material having a diameter of 8 mm and a length of 50 mm was used as a base material. After degreasing and cleaning this surface, salt bath soft nitriding treatment (Isonite treatment: Nippon Parkerizing Co., Ltd.) at 560 ° C. in a molten salt bath for 2 hours Ltd.) to oil cooling, to form a nitrogen compound layer mainly having a thickness of about 13μm iron nitride surface of the steel material.
　平均粒径が７ｎｍの高分子チタン水酸化物のゾル粒子（結晶構造は非晶質）をチタン換算で９．０ｇ／Ｌ、平均粒径４５ｎｍの酸化チタン粒子（結晶構造はアナターゼ）をチタン換算で１５．０ｇ／Ｌ、ピロリン酸をピロリン酸イオンとして４ｇ／Ｌ、及びモルホリン５０ｇ／Ｌを各々含有するｐＨ９．０の処理液を準備した。基材にディップコーティング法を用いてこの処理液を塗布し、余分な液を除去した後に１５０℃×２０分で乾燥させる工程を２回繰り返し焼成した。基材上のチタン付着量を蛍光Ｘ線分析装置で測定したところ、Ｔｉとしての付着量は２５０ｍｇ／ｍ２であった。この保護皮膜において、計算される造膜成分の酸化チタンと応力緩和成分の酸化チタンについて、造膜成分／応力緩和成分の比率は０．６であった。 Polymer titanium hydroxide sol particles (crystal structure is amorphous) with an average particle size of 7 nm is 9.0 g / L in terms of titanium, and titanium oxide particles with an average particle size of 45 nm (crystal structure is anatase) is converted to titanium. Prepared a pH 9.0 treatment solution containing 15.0 g / L, 4 g / L of pyrophosphate as pyrophosphate ion, and 50 g / L of morpholine. The treatment liquid was applied to the substrate using the dip coating method, and after removing the excess liquid, the process of drying at 150 ° C. for 20 minutes was repeated twice. Was then measured for Ti deposition amount on the substrate with a fluorescent X-ray analyzer, the adhesion amount of the Ti was 250 mg / m 2. In this protective film, the ratio of the film-forming component / stress-relaxing component was 0.6 for the calculated film-forming component of titanium oxide and the stress-relaxing component of titanium oxide.
　このようにして酸化チタンを含む化合物層保護膜を窒素化合物層上に形成した鋼材に対し、さらに高周波焼入れ装置を使用して加熱開始後１秒で８２０℃に達した後、直ちに加熱を停止して、冷却を行い焼入れを行った。後に鋼材表面をショットブラストし化合物層保護膜を除去した。 In this way, with respect to the steel material in which the compound layer protective film containing titanium oxide is formed on the nitrogen compound layer, the heating is stopped immediately after reaching 820 ° C. in 1 second after the start of heating using the induction hardening apparatus. Then, it was cooled and quenched. Later, the steel surface was shot blasted to remove the compound layer protective film.
＜実施例３＞
　基材として直径８ｍｍ、長さ５０ｍｍのＳ４５Ｃ非調質材（フェライト・パーライト組織）を使用し、この表面を脱脂洗浄したのち、溶融塩浴中において５６０℃で１時間塩浴軟窒化処理（イソナイト処理：日本パーカライジング（株）製）して水冷し、鋼材表面に厚さ約１２μｍの窒化鉄を主体とする窒素化合物層を形成した。 <Example 3>
An S45C non-heat treated material (ferrite / pearlite structure) having a diameter of 8 mm and a length of 50 mm was used as a base material. After degreasing and cleaning this surface, salt bath soft nitriding treatment (Isonite) at 560 ° C. for 1 hour in a molten salt bath Treatment: manufactured by Nihon Parkerizing Co., Ltd.) and water-cooled to form a nitrogen compound layer mainly composed of iron nitride having a thickness of about 12 μm on the steel surface.
　ケイ酸ナトリウムをＳｉ換算で１８．７ｇ／Ｌ（ケイ酸イオンとしては５０．６ｇ／Ｌ）、平均粒径３０ｎｍの酸化ケイ素粒子をケイ素換算で４．７ｇ／Ｌを各々含有するｐＨ１３．１の処理液を準備した。基材にスプレー法を用いてこの処理液を塗布し、余分な液を除去した後に３２０℃×１０分で焼成した。基材上のＳｉ付着量を蛍光Ｘ線分析装置で測定したところ、Ｓｉとしての付着量は７０ｍｇ／ｍ２であった。 Sodium silicate having a pH of 13.1 containing 18.7 g / L in terms of Si (50.6 g / L as silicate ions) and silicon oxide particles having an average particle size of 30 nm in terms of silicon of 4.7 g / L. A treatment solution was prepared. This treatment liquid was applied to the substrate using a spray method, and after removing excess liquid, baking was performed at 320 ° C. for 10 minutes. Measurement of the Si deposition amount on the substrate with a fluorescent X-ray analyzer, the adhesion amount of the Si was 70 mg / m 2.
　このようにしてシリカを含む化合物層保護膜を窒素化合物層上に形成した鋼材に対し、さらに高周波焼入れ装置を使用して加熱開始後１秒で８２０℃に達した後、直ちに加熱を停止して、冷却を行い焼入れを行った。後に鋼材表面をショットブラストし化合物層保護膜を除去した。 In this way, for the steel material in which the compound layer protective film containing silica is formed on the nitrogen compound layer, the heating is stopped immediately after reaching 820 ° C. in 1 second after the start of heating using the induction hardening apparatus. Then, it was cooled and quenched. Later, the steel surface was shot blasted to remove the compound layer protective film.
＜実施例４＞
　基材として直径８ｍｍ、長さ５０ｍｍのＳＣＭ４４０調質材を使用し、この表面を脱脂洗浄したのち、５７０℃で２４時間のアンモニア雰囲気でのガス窒化処理し、鋼材表面に厚さ約８μｍの窒化鉄を主体とする窒素化合物層を形成した。 <Example 4>
A SCM440 tempered material with a diameter of 8 mm and a length of 50 mm was used as a base material. After this surface was degreased and cleaned, gas nitriding was performed in an ammonia atmosphere at 570 ° C. for 24 hours, and the steel material surface was nitrided with a thickness of about 8 μm A nitrogen compound layer mainly composed of iron was formed.
　ケイ酸ナトリウムをＳｉ換算で２０ｇ／Ｌ（ケイ酸イオンとしては９．４ｇ／Ｌ）、平均粒径４５ｎｍの酸化チタン粒子（結晶構造はアナターゼ）をＴｉ換算で６．０ｇ／Ｌを各々含有するｐＨ１２．５の処理液を準備した。基材に刷毛塗りによってこの処理液を塗布し、余分な液を除去した後に５０℃×１０分で２回繰り返し仮焼きし、後に１５０℃で３０分の焼成をした。基材上のＳｉとＴｉの合計付着量を蛍光Ｘ線分析装置で測定したところ、合計付着量は２３０ｍｇ／ｍ２であった。この保護皮膜において、計算される造膜成分のシリカ（酸化ケイ素）と応力緩和成分の酸化チタンについて、造膜成分／応力緩和成分の比率は２であった。 20 g / L of sodium silicate in terms of Si (9.4 g / L as silicate ions), titanium oxide particles having an average particle size of 45 nm (crystal structure is anatase) each containing 6.0 g / L in terms of Ti A treatment liquid having a pH of 12.5 was prepared. This treatment liquid was applied to the substrate by brushing, and after removing the excess liquid, it was calcined twice at 50 ° C. for 10 minutes, and then baked at 150 ° C. for 30 minutes. When the total adhesion amount of Si and Ti on the substrate was measured with a fluorescent X-ray analyzer, the total adhesion amount was 230 mg / m 2 . In this protective film, the ratio of the film-forming component / stress-relaxing component was 2 for the calculated film-forming component silica (silicon oxide) and the stress-relaxing component titanium oxide.
　このようにしてシリカと酸化チタンを含む化合物層保護膜を窒素化合物層上に形成した鋼材に対し、さらに高周波焼入れ装置を使用して加熱開始後０．８秒で８３０℃に達した後、直ちに加熱を停止して、冷却を行い焼入れを行った。後に鋼材表面をショットブラストし化合物層保護膜を除去した。 For the steel material in which the compound layer protective film containing silica and titanium oxide was formed on the nitrogen compound layer in this way, the temperature reached 830 ° C. in 0.8 seconds after the start of heating using an induction hardening apparatus, and immediately thereafter. Heating was stopped, cooling was performed, and quenching was performed. Later, the steel surface was shot blasted to remove the compound layer protective film.
＜実施例５＞
　基材として直径８ｍｍ、長さ５０ｍｍのＳＣＭ４４０非調質材（フェライト・パーライト組織）を使用し、この表面を脱脂洗浄したのち、ＲＸガスとアンモニアとの混合雰囲気での５７０℃で３時間のガス軟窒化処理し、鋼材表面に厚さ約１２μｍの窒化鉄を主体とする窒素化合物層を形成した。 <Example 5>
A non-refined SCM440 material (ferrite / pearlite structure) with a diameter of 8 mm and a length of 50 mm was used as the base material, and after degreasing and cleaning this surface, a gas at 570 ° C. in a mixed atmosphere of RX gas and ammonia for 3 hours. treated soft nitrided to form a nitrogen compound layer consisting mainly of iron nitride having a thickness of about 12μm on the surface of the steel material.
　フッ化クロムをＣｒ換算で１４．３ｇ／Ｌ（フッ化物イオンとしては１８ｇ／Ｌ）、オルトリン酸をリン酸イオンとして１０ｇ／Ｌ、およびアンモニアを５．４ｇ／Ｌを各々含有するｐＨ５．０の処理液を準備した。基材にディップコーティング法を用いてこの処理液を塗布し、余分な液を除去した後に１２０℃×３０分で焼成した。基材上のＣｒ付着量を蛍光Ｘ線分析装置で測定したところ、Ｃｒとしての付着量は１８０ｍｇ／ｍ２であった。 Chromium fluoride is 14.3 g / L in terms of Cr (18 g / L as fluoride ion), orthophosphoric acid is 10 g / L as phosphate ion, and ammonia is 5.4 g / L. A treatment solution was prepared. This treatment liquid was applied to the substrate using a dip coating method, and after removing the excess liquid, baking was performed at 120 ° C. for 30 minutes. Measurement of the Cr deposition amount on the substrate with a fluorescent X-ray analyzer, the adhesion amount of the Cr was 180 mg / m 2.
　このようにして酸化クロムを含む化合物層保護膜を窒素化合物層上に形成した鋼材に対し、さらに高周波焼入れ装置を使用して加熱開始後１秒で８２０℃に達した後、直ちに加熱を停止して、冷却を行い焼入れを行った。後に鋼材表面をショットブラストし化合物層保護膜を除去した。 The steel material in which the compound layer protective film containing chromium oxide was formed on the nitrogen compound layer in this way was further heated using an induction hardening device after reaching 820 ° C. in 1 second after the start of heating. Then, it was cooled and quenched. Later, the steel surface was shot blasted to remove the compound layer protective film.
＜実施例６＞
　基材として直径８ｍｍ、長さ５０ｍｍのＳ４５Ｃ調質材を使用し、この表面を脱脂洗浄したのち、窒素ガスと水素ガスとの混合雰囲気での５７０℃で４０時間のプラズマ窒化処理し、鋼材表面に厚さ約１５μｍの窒化鉄を主体とする窒素化合物層を形成した。 <Example 6>
S45C tempered material with a diameter of 8 mm and a length of 50 mm was used as the base material, and after this surface was degreased and cleaned, it was subjected to plasma nitriding treatment at 570 ° C. for 40 hours in a mixed atmosphere of nitrogen gas and hydrogen gas. A nitrogen compound layer mainly composed of iron nitride having a thickness of about 15 μm was formed.
　ジルコンフッ化水素酸を酸化ジルコニウム換算で２０ｇ／Ｌ（Ｚｒとして１４．８ｇ／Ｌ、フッ化物イオンとして１８．５ｇ／Ｌ）、エチルアミンを３ｇ／Ｌ、及びオルトリン酸をリン酸イオンとして５ｇ／Ｌを各々含有するｐＨ４．５の処理液を準備した。処理液はジルコンフッ化水素酸のジルコニウムのうち５０％が平均粒径５０ｎｍの水酸化ジルコニウム粒子となり、分散し白濁していた。基材にディップコーティング法を用いてこの処理液を塗布し、余分な液を除去した後に１８０℃×２０分で焼成する工程を１０回繰り返した。基材上のＺｒ付着量を蛍光Ｘ線分析装置で測定したところ、Ｚｒとしての付着量は１２００ｍｇ／ｍ２であった。この保護皮膜において、計算される造膜成分の酸化ジルコニウムと応力緩和成分の酸化ジルコニウムについて、造膜成分／応力緩和成分の比率は１であった。 Zircon hydrofluoric acid in terms of zirconium oxide was 20 g / L (14.8 g / L as Zr, 18.5 g / L as fluoride ion), 3 g / L as ethylamine, and 5 g / L as orthophosphoric acid as phosphate ion. A treatment solution having a pH of 4.5 was prepared. In the treatment liquid, 50% of zirconium in zircon hydrofluoric acid was converted to zirconium hydroxide particles having an average particle diameter of 50 nm, and was dispersed and clouded. The process of applying this treatment liquid to the substrate using the dip coating method, removing excess liquid, and baking at 180 ° C. for 20 minutes was repeated 10 times. When the Zr adhesion amount on the substrate was measured with a fluorescent X-ray analyzer, the adhesion amount as Zr was 1200 mg / m 2 . In this protective coating, the ratio of the film-forming component / stress-relaxing component was 1 with respect to the calculated film-forming component zirconium oxide and the stress-relaxing component zirconium oxide.
　このようにして酸化ジルコニウムを含む化合物層保護膜を窒素化合物層上に形成した鋼材に対し、さらに高周波焼入れ装置を使用して加熱開始後１．５秒で８００℃に達した後、直ちに加熱を停止して、冷却を行い焼入れを行った。後に鋼材表面をショットブラストし化合物層保護膜を除去した。 In this way, the steel material on which the compound layer protective film containing zirconium oxide is formed on the nitrogen compound layer is further heated immediately after reaching 800 ° C. in 1.5 seconds after the start of heating using an induction hardening apparatus. After stopping, it was cooled and quenched. Later, the steel surface was shot blasted to remove the compound layer protective film.
　＜実施例７＞
　基材として直径８ｍｍ、長さ５０ｍｍのＳＣＭ４４０調質材を使用し、この表面を脱脂洗浄したのち、溶融塩浴中において５６０℃で１時間塩浴軟窒化処理（イソナイト処理：日本パーカライジング（株）製）して油冷し、鋼材表面に厚さ約７μｍの窒化鉄を主体とする窒素化合物層を形成した。 <Example 7>
SCM440 tempered material having a diameter of 8 mm and a length of 50 mm was used as the base material, and after degreasing and cleaning the surface, salt bath soft nitriding treatment at 560 ° C. in a molten salt bath (Isonite treatment: Nippon Parkerizing Co., Ltd. And a nitrogen compound layer mainly composed of iron nitride having a thickness of about 7 μm was formed on the surface of the steel material.
　タングステン酸アンモニウムを酸化タングステン換算で６０ｇ／Ｌ（Ｗとして４７．６ｇ／Ｌ）、トリポリリン酸をトリポリリン酸イオンとして０．５ｇ／Ｌ、アンモニアをタングステン酸アンモニウムからの成分と合わせ２０ｇ／Ｌを各々含有するｐＨ７．８の処理液を準備した。基材にディップコーティング法を用いてこの処理液を塗布し、余分な液を除去した後に１８０℃×３０分で焼成した。基材上のＷ付着量を蛍光Ｘ線分析装置で測定したところ、Ｗとしての付着量は１５０ｍｇ／ｍ２であった。 Contains 60 g / L of ammonium tungstate in terms of tungsten oxide (47.6 g / L as W), 0.5 g / L of tripolyphosphate as tripolyphosphate ion, 20 g / L of ammonia combined with components from ammonium tungstate A treatment solution having a pH of 7.8 was prepared. This treatment liquid was applied to the substrate using a dip coating method, and after removing the excess liquid, it was baked at 180 ° C. for 30 minutes. Measurement of the W deposition amount on the substrate with a fluorescent X-ray analyzer, the adhesion amount of the W was 150 mg / m 2.
　このようにして酸化タングステンを含む化合物層保護膜を窒素化合物層上に形成した鋼材に対し、さらに高周波焼入れ装置を使用して加熱開始後０．８秒で８６０℃に達した後、直ちに加熱を停止して、冷却を行い焼入れを行った。後に鋼材表面をショットブラストし化合物層保護膜を除去した。 In this way, the steel material on which the compound layer protective film containing tungsten oxide is formed on the nitrogen compound layer is further heated immediately after reaching 860 ° C. in 0.8 seconds after the start of heating using an induction hardening apparatus. After stopping, it was cooled and quenched. Later, the steel surface was shot blasted to remove the compound layer protective film.
＜実施例８＞
　基材として直径８ｍｍ、長さ５０ｍｍのＳＣＭ４４０調質材を使用し、この表面を脱脂洗浄したのち、溶融塩浴中において５６０℃で２時間塩浴軟窒化処理（イソナイト処理：日本パーカライジング（株）製）して油冷し、鋼材表面に厚さ約９μｍの窒化鉄を主体とする窒素化合物層を形成した。 <Example 8>
SCM440 tempered material having a diameter of 8 mm and a length of 50 mm was used as a base material. After degreasing and cleaning the surface, salt bath soft nitriding treatment at 560 ° C. for 2 hours in a molten salt bath (Isonite treatment: Nippon Parkerizing Co., Ltd.) And a nitrogen compound layer mainly composed of iron nitride having a thickness of about 9 μm was formed on the surface of the steel material.
　平均粒径が５ｎｍのジルコニウム酸化物のゾル粒子（結晶構造は非晶質）をジルコニウム換算で７．４ｇ／Ｌ、平均粒径７０ｎｍの酸化ジルコニウム粒子（結晶構造は正方晶）をジルコニウム換算で２２．２ｇ／Ｌ、ピロリン酸をピロリン酸イオンとして４ｇ／Ｌ、及びアンモニア９ｇ／Ｌを各々含有するｐＨ９．５の処理液を準備した。基材にディップコーティング法を用いてこの処理液を塗布し、余分な液を除去した後に５０℃×２０分で仮焼きし、のち２００℃で３０分焼成した。基材上のＺｒ付着量を蛍光Ｘ線分析装置で測定したところ、Ｚｒとしての付着量は２８０ｍｇ／ｍ２であった。この保護皮膜において、計算される造膜成分の酸化ジルコニウムと応力緩和成分の酸化ジルコニウムについて、造膜成分／応力緩和成分の比率は０．３であった。 Zirconium oxide sol particles (crystal structure is amorphous) having an average particle size of 5 nm are 7.4 g / L in terms of zirconium, and zirconium oxide particles having an average particle size of 70 nm (crystal structure is tetragonal) are 22 in terms of zirconium. A treatment solution of pH 9.5 containing 2 g / L, 4 g / L of pyrophosphate as pyrophosphate ions, and 9 g / L of ammonia was prepared. This treatment liquid was applied to the base material using a dip coating method, and after removing the excess liquid, it was calcined at 50 ° C. for 20 minutes, and then calcined at 200 ° C. for 30 minutes. When the Zr adhesion amount on the substrate was measured with a fluorescent X-ray analyzer, the adhesion amount as Zr was 280 mg / m 2 . In this protective coating, the ratio of the film-forming component / stress-relaxing component was 0.3 for the calculated film-forming component zirconium oxide and the stress-relaxing component zirconium oxide.
　このようにして酸化ジルコニウムを含む化合物層保護膜を窒素化合物層上に形成した鋼材に対し、さらに高周波焼入れ装置を使用して加熱開始後１秒で７９０℃に達した後、直ちに加熱を停止して、冷却を行い焼入れを行った。後に鋼材表面をショットブラストし化合物層保護膜を除去した。 In this way, with respect to the steel material in which the compound layer protective film containing zirconium oxide is formed on the nitrogen compound layer, the heating is stopped immediately after reaching 790 ° C. in one second after the start of heating using an induction hardening apparatus. Then, it was cooled and quenched. Later, the steel surface was shot blasted to remove the compound layer protective film.
＜実施例９＞
　基材として直径８ｍｍ、長さ５０ｍｍのＳＣＭ４４０調質材を使用し、この表面を脱脂洗浄したのち、溶融塩浴中において５６０℃で２時間塩浴軟窒化処理（イソナイト処理：日本パーカライジング（株）製）して油冷し、鋼材表面に厚さ約９μｍの窒化鉄を主体とする窒素化合物層を形成した。 <Example 9>
SCM440 tempered material having a diameter of 8 mm and a length of 50 mm was used as a base material. After degreasing and cleaning this surface, salt bath soft nitriding treatment at 560 ° C. in a molten salt bath (Isonite treatment: Nippon Parkerizing Co., Ltd.) And a nitrogen compound layer mainly composed of iron nitride having a thickness of about 9 μm was formed on the surface of the steel material.
　アルミン酸カリウムをアルミニウム換算で１０．３ｇ／Ｌ、ピロリン酸をピロリン酸イオンとして１２ｇ／Ｌ、及びモルホリン４２ｇ／Ｌを各々含有するｐＨ８．５の処理液を準備した。処理液中には、平均粒径２５ｎｍの水酸化アルミニウムの高分子体が生成し白濁していた。基材にディップコーティング法を用いてこの処理液を塗布し、余分な液を除去した後に１５０℃×３０分焼成した。基材上のＡｌ付着量を蛍光Ｘ線分析装置で測定したところ、Ａｌとしての付着量は１５０ｍｇ／ｍ２であった。 A pH 8.5 treatment solution containing 10.3 g / L of potassium aluminate in terms of aluminum, 12 g / L of pyrophosphate as pyrophosphate ions, and 42 g / L of morpholine was prepared. In the treatment liquid, a polymer body of aluminum hydroxide having an average particle diameter of 25 nm was formed and became cloudy. This treatment liquid was applied to the substrate using a dip coating method, and after removing the excess liquid, baking was performed at 150 ° C. for 30 minutes. When the adhesion amount of Al on the substrate was measured with a fluorescent X-ray analyzer, the adhesion amount as Al was 150 mg / m 2 .
　このようにして酸化アルミニウムを含む化合物層保護膜を窒素化合物層上に形成した鋼材に対し、さらに高周波焼入れ装置を使用して加熱開始後３秒で７８０℃に達した後、直ちに加熱を停止して、冷却を行い焼入れを行った。後に鋼材表面をショットブラストし化合物層保護膜を除去した。 The steel material in which the compound layer protective film containing aluminum oxide was thus formed on the nitrogen compound layer was further heated using an induction hardening device after reaching 780 ° C. in 3 seconds after heating was started. Then, it was cooled and quenched. Later, the steel surface was shot blasted to remove the compound layer protective film.
＜比較例１＞
　基材として直径８ｍｍ、長さ５０ｍｍのＳＣＭ４４０調質材を使用し、この表面を脱脂洗浄したのち、溶融塩浴中において５６０℃で１時間塩浴軟窒化処理（イソナイト処理：日本パーカライジング（株）製）して油冷し、鋼材表面に厚さ約７μｍの窒化鉄を主体とする窒素化合物層を形成した。これに化合物層保護膜を塗布せずに、さらに高周波焼入れ装置を使用して加熱開始後１秒で８６０℃に達した後、直ちに加熱を停止して、冷却を行い焼入れを行った。 <Comparative Example 1>
SCM440 tempered material having a diameter of 8 mm and a length of 50 mm was used as a base material, and after degreasing and cleaning the surface, salt bath soft nitriding treatment at 560 ° C. for 1 hour in a molten salt bath (Isonite treatment: Nippon Parkerizing Co., Ltd.) Ltd.) to oil cooling, to form a nitrogen compound layer consisting mainly of iron nitride having a thickness of about 7μm on the steel material surface. Without applying the compound layer protective film to this, after reaching 860 ° C. in 1 second after the start of heating using an induction hardening apparatus, heating was immediately stopped, cooling was performed, and quenching was performed.
＜比較例２＞
　基材として直径８ｍｍ、長さ５０ｍｍのＳＣＭ４４０調質材を使用し、この表面を脱脂洗浄したのち、溶融塩浴中において５６０℃で１時間塩浴軟窒化処理（イソナイト処理：日本パーカライジング（株）製）して油冷し、鋼材表面に厚さ約７μｍの窒化鉄を主体とする窒素化合物層を形成した。 <Comparative Example 2>
SCM440 tempered material having a diameter of 8 mm and a length of 50 mm was used as a base material, and after degreasing and cleaning the surface, salt bath soft nitriding treatment at 560 ° C. for 1 hour in a molten salt bath (Isonite treatment: Nippon Parkerizing Co., Ltd.) Ltd.) to oil cooling, to form a nitrogen compound layer consisting mainly of iron nitride having a thickness of about 7μm on the steel material surface.
　フッ化クロムをＣｒ換算で１４．３ｇ／Ｌ（フッ化物イオンとしては１８ｇ／Ｌ）、オルトリン酸をリン酸イオンとして５０ｇ／Ｌ、およびアンモニアを５．４ｇ／Ｌを各々含有するｐＨ２．５の処理液を準備した。基材にディップコーティング法を用いてこの処理液を塗布し、余分な液を除去した後に１２０℃×３０分で焼成した。基材上のＣｒ付着量を蛍光Ｘ線分析装置で測定したところ、Ｃｒとしての付着量は２１０ｍｇ／ｍ２であった。 Chromium fluoride is 14.3 g / L in terms of Cr (18 g / L as fluoride ion), orthophosphoric acid is 50 g / L as phosphate ion, and ammonia is 5.4 g / L. A treatment solution was prepared. This treatment liquid was applied to the substrate using a dip coating method, and after removing the excess liquid, baking was performed at 120 ° C. for 30 minutes. When the amount of Cr deposited on the substrate was measured with a fluorescent X-ray analyzer, the amount deposited as Cr was 210 mg / m 2 .
　このようにして酸化クロムを含む化合物層保護膜を窒素化合物層上に形成した鋼材に対し、さらに高周波焼入れ装置を使用して加熱開始後０．８秒で８６０℃に達した後、直ちに加熱を停止して、冷却を行い焼入れを行った。後に鋼材表面をショットブラストし化合物層保護膜を除去した。 In this way, the steel material in which the compound layer protective film containing chromium oxide is formed on the nitrogen compound layer is further heated immediately after reaching 860 ° C. in 0.8 seconds after the start of heating using an induction hardening apparatus. After stopping, it was cooled and quenched. Later, the steel surface was shot blasted to remove the compound layer protective film.
＜比較例３＞
　基材として直径８ｍｍ、長さ５０ｍｍのＳＣＭ４４０調質材を使用し、この表面を脱脂洗浄したのち、溶融塩浴中において５６０℃で１時間塩浴軟窒化処理（イソナイト処理：日本パーカライジング（株）製）して油冷し、鋼材表面に厚さ約７μｍの窒化鉄を主体とする窒素化合物層を形成した。 <Comparative Example 3>
SCM440 tempered material having a diameter of 8 mm and a length of 50 mm was used as a base material, and after degreasing and cleaning the surface, salt bath soft nitriding treatment at 560 ° C. for 1 hour in a molten salt bath (Isonite treatment: Nippon Parkerizing Co., Ltd.) And a nitrogen compound layer mainly composed of iron nitride having a thickness of about 7 μm was formed on the surface of the steel material.
　タングステン酸アンモニウムを酸化タングステン換算で６０ｇ／Ｌ（Ｗとして４７．６ｇ／Ｌ）、アンモニアをタングステン酸アンモニウムからの成分と合わせ２０ｇ／Ｌを各々含有するｐＨ８．８の処理液を準備した。基材にディップコーティング法を用いてこの処理液を塗布し、余分な液を除去した後に１８０℃×３０分で焼成した。基材上のＷ付着量を蛍光Ｘ線分析装置で測定したところ、Ｗとしての付着量は１６０ｍｇ／ｍ２であった。 A treatment liquid having a pH of 8.8 was prepared by adding 60 g / L of ammonium tungstate in terms of tungsten oxide (47.6 g / L as W) and 20 g / L of ammonia together with components from ammonium tungstate. This treatment liquid was applied to the substrate using a dip coating method, and after removing the excess liquid, it was baked at 180 ° C. for 30 minutes. When the adhesion amount of W on the substrate was measured with a fluorescent X-ray analyzer, the adhesion amount as W was 160 mg / m 2 .
　このようにして酸化タングステンを含む化合物層保護膜を窒素化合物層上に形成した鋼材に対し、さらに高周波焼入れ装置を使用して加熱開始後０．８秒で８６０℃に達した後、直ちに加熱を停止して、冷却を行い焼入れを行った。後に鋼材表面をショットブラストし化合物層保護膜を除去した。 In this way, the steel material on which the compound layer protective film containing tungsten oxide is formed on the nitrogen compound layer is further heated immediately after reaching 860 ° C. in 0.8 seconds after the start of heating using an induction hardening apparatus. After stopping, it was cooled and quenched. Later, the steel surface was shot blasted to remove the compound layer protective film.
（評価試験）
　これらの処理を行った鋼材をマイクロカッターで切断し、樹脂中に埋め込み、金属顕微鏡により断面観察を行った。また、この埋め込みサンプルを用いて、マイクロビッカース硬度計を用いて断面硬度測定を行った。 (Evaluation test)
The steel material subjected to these treatments was cut with a microcutter, embedded in a resin, and cross-sectional observation was performed with a metal microscope. Moreover, cross-sectional hardness measurement was performed using this embedded sample using a micro Vickers hardness tester.
　表１に評価の結果一覧を示す。表中の有効硬化深さとは、Ｈｖ５５０以上の硬度を有する部分の表面からの深さ（ｍｍ）である。例として図１、図２及び図３にそれぞれ実施例１、実施例７及び比較例１の断面写真をそれぞれ示す。また、図４に実施例３及び９の断面硬度分布を示す。
Figure JPOXMLDOC01-appb-T000001
 Table 1 shows a list of evaluation results. The effective hardening depth in the table, the depth from the surface portion having a hardness of more than Hv 550 (mm). Figure 1, respectively in Example 1 in FIGS. 2 and 3, a cross-sectional photograph of Example 7 and Comparative Example 1, respectively as an example. Moreover, the cross-sectional hardness distribution of Example 3 and 9 is shown in FIG.
Figure JPOXMLDOC01-appb-T000001
　表１より、本発明の実施例１～９においては、図１のように高周波焼入れ後においても表面の窒素化合物層が大きくダメージを受けることなく残存しており、さらに保護膜構成要素が造膜成分と応力緩和成分から構成される場合（実施例１、２、４及び８）において、より効果的に窒素化合物層が保護されていた。化合物層保護膜のない比較例１においては、図２のように全面が酸化している様子が観察された。また本発明の範囲外である比較例２及び３も比較例１と同様に窒素化合物層が著しく酸化しており、保護膜としての作用が不十分であった。 As shown in Table 1, in Examples 1 to 9 of the present invention, the nitrogen compound layer on the surface remains without significant damage even after induction hardening as shown in FIG. In the case of being composed of components and stress relaxation components (Examples 1, 2, 4 and 8), the nitrogen compound layer was more effectively protected. In Comparative Example 1 without the compound layer protective film, it was observed that the entire surface was oxidized as shown in FIG. Further, in Comparative Examples 2 and 3, which are outside the scope of the present invention, the nitrogen compound layer was significantly oxidized as in Comparative Example 1, and the action as a protective film was insufficient.
実施例１の鋼材の焼入れ後の窒素化合物層の断面写真Cross-sectional photograph of nitrogen compound layer after quenching of steel material of Example 1 比較例７の鋼材の焼入れ後の窒素化合物層の断面写真Cross-sectional photograph of nitrogen compound layer after quenching of steel of Comparative Example 7 比較例１の鋼材の焼入れ後の窒素化合物層の断面写真Cross-sectional photograph of nitrogen compound layer after quenching of steel of Comparative Example 1 実施例３、９の鋼材の断面硬度分布Cross-sectional hardness distribution of steel materials of Examples 3 and 9

Claims (6)

  1. 　鋼材に対し窒化処理後に形成される窒化物層上に当該窒化物を保護するための保護膜を形成するための処理液であって、Ｓｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｔａ、Ｃａ、Ｃｅ、Ｓｃ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ、Ｚｎ、Ｍｇ及びＭｏからなる群の中から選択される少なくとも１種を含有し、りん酸イオン、縮合りん酸イオン、亜りん酸イオン、フッ化物イオン、炭酸イオン及びケイ酸イオンからなる群の中から選択される少なくとも１種のアニオンを０．１～６０ｇ／Ｌ含有し、その処理液のｐＨが４～１４であることを特徴とする化合物層保護皮膜形成処理液。 A treatment liquid for forming a protective film for protecting a nitride on a nitride layer formed after nitriding treatment on a steel material, comprising Si, Ti, Zr, Hf, V, Ta, Ca, Ce , Sc, Nb, Cr, W, Al, Sr, Zn, Mg and Mo, containing at least one selected from the group consisting of phosphate ion, condensed phosphate ion, phosphite ion, fluoride ions, at least one anion selected from the group consisting of carbonate ion and silicate ions contained 0.1 ~ 60 g / L, compound wherein the pH of the processing solution is 4 to 14 Layer protective film forming treatment liquid.
  2. 　前記処理液が、少なくとも１種のアミン類を０．１～４００ｇ／Ｌ含むことを特徴とする請求項１に記載の化合物層保護皮膜形成処理液。 The compound layer protective film-forming treatment solution according to claim 1, wherein the treatment solution contains 0.1 to 400 g / L of at least one amine.
  3. 　前記処理液が、Ｓｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｔａ、Ｃａ、Ｃｅ、Ｓｃ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ、Ｚｎ、Ｍｇ及びＭｏからなる群の中から選択される少なくとも１種の溶解したイオン並びに／又はＳｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｔａ、Ｃａ、Ｃｅ、Ｓｃ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ、Ｚｎ、Ｍｇ及びＭｏからなる群の中から選択される少なくとも１種を含む平均粒径が４～４０ｎｍからなる分散粒子と、Ｓｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｔａ、Ｃａ、Ｃｅ、Ｓｃ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ、Ｚｎ、Ｍｇ及びＭｏからなる群の中から選択される少なくとも１種を含む平均粒径が４０～４００ｎｍからなる分散粒子と、をともに含有し、前者が乾燥固形状態として占める質量と、後者が乾燥固形状態として占める質量との比が１：１０～１０：１であることを特徴とする請求項１又は２に記載の化合物層保護皮膜形成処理液。 The treatment liquid is at least one selected from the group consisting of Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg, and Mo. At least selected from the group consisting of dissolved ions and / or Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg and Mo Dispersed particles having an average particle size of 4 to 40 nm including one kind, Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn, Mg, and Mo And a dispersed particle having an average particle diameter of 40 to 400 nm including at least one selected from the group consisting of: a mass occupied by the former as a dry solid state and a mass occupied by the latter as a dry solid state The ratio is 1: 1 ~ 10: Compound layer protective film formation treatment solution according to claim 1 or 2, characterized in that it is 1.
  4. 　鋼材に対し窒化処理後に形成される窒化物層上に乾燥固形状態として被覆されるＳｉ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｔａ、Ｃａ、Ｃｅ、Ｓｃ、Ｎｂ、Ｃｒ、Ｗ、Ａｌ、Ｓｒ、Ｚｎ、Ｍｇ及びＭｏからなる群の中から選択される少なくとも１種の金属を含有する化合物層保護膜であって、その化合物層保護膜が請求項１～３のいずれか一項に記載の処理液から該金属換算の合計で０．０５～３ｇ／ｍ２の範囲で形成され、所定の加熱温度に到達するまで０．３～５秒間の加熱を行い、その到達温度が７５０～８６０℃である高周波焼入れ時に前記化合物層の分解を抑制することを特徴とする化合物層保護膜。 Si, Ti, Zr, Hf, V, Ta, Ca, Ce, Sc, Nb, Cr, W, Al, Sr, Zn coated as a dry solid state on a nitride layer formed after nitriding treatment on a steel material A compound layer protective film containing at least one metal selected from the group consisting of Mg, Mo, and the compound layer protective film according to any one of claims 1 to 3. To a total of 0.05 to 3 g / m 2 in terms of metal, and heating is performed for 0.3 to 5 seconds until reaching a predetermined heating temperature, and the reaching temperature is 750 to 860 ° C. compound layer protective film, characterized in that to suppress the decomposition of the compound layer at the time of induction hardening.
  5. 　窒化処理により表面に窒化物層が形成された鋼材において、請求項４に記載された化合物層保護膜が当該窒化物層上に形成された状態で、所定の加熱温度に到達するまで０．３～５秒間の加熱を行い、その到達温度が７５０～８６０℃である高周波焼入れ処理が施されたものであることを特徴とする焼き入れ鋼材。 In a steel material having a nitride layer formed on the surface by nitriding treatment, the compound layer protective film according to claim 4 is 0.3 on the nitride layer until reaching a predetermined heating temperature. A hardened steel material, which has been subjected to induction hardening at a temperature of 750 to 860 ° C. after heating for ˜5 seconds.
  6. 　窒化処理により表面に窒化物層が形成された鋼材を準備し、請求項１～３のいずれか一項記載の処理液を窒化物層上に適用する適用工程と、適用工程後に処理液を乾燥させ、窒化物層上に化合物層保護膜を形成する保護膜形成工程と、保護膜形成工程後に、所定の加熱温度に到達するまで０．３～５秒間の加熱を行い、その到達温度が７５０～８６０℃である高周波焼入れ処理と、を有することを特徴とする焼き入れ鋼材の製造方法。 A steel material having a nitride layer formed on the surface by nitriding treatment is prepared, and an application step of applying the treatment liquid according to any one of claims 1 to 3 on the nitride layer, and drying the treatment liquid after the application step A protective film forming step for forming a compound layer protective film on the nitride layer, and after the protective film forming step, heating is performed for 0.3 to 5 seconds until a predetermined heating temperature is reached. A method for producing a quenched steel material, comprising: induction hardening at 860 ° C.
PCT/JP2010/004780 2009-07-31 2010-07-28 Treatment liquid for forming protective film for steel member having nitrogen compound layer, and compound layer protective film WO2011013360A1 (en)

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CN111621777A (en) * 2020-04-30 2020-09-04 华帝股份有限公司 Metal material, surface treating agent and surface treating method
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US10400337B2 (en) 2012-08-29 2019-09-03 Ppg Industries Ohio, Inc. Zirconium pretreatment compositions containing lithium, associated methods for treating metal substrates, and related coated metal substrates
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