WO2010070942A1 - Galvanized steel sheet and method for manufacturing the same - Google Patents
Galvanized steel sheet and method for manufacturing the same Download PDFInfo
- Publication number
- WO2010070942A1 WO2010070942A1 PCT/JP2009/058426 JP2009058426W WO2010070942A1 WO 2010070942 A1 WO2010070942 A1 WO 2010070942A1 JP 2009058426 W JP2009058426 W JP 2009058426W WO 2010070942 A1 WO2010070942 A1 WO 2010070942A1
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- WIPO (PCT)
- Prior art keywords
- steel sheet
- zinc
- aqueous solution
- oxide layer
- galvanized steel
- Prior art date
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- 229910001335 Galvanized steel Inorganic materials 0.000 title claims abstract description 34
- 239000008397 galvanized steel Substances 0.000 title claims abstract description 34
- 238000000034 method Methods 0.000 title claims abstract description 27
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 20
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 63
- 239000010959 steel Substances 0.000 claims abstract description 63
- 239000011701 zinc Substances 0.000 claims abstract description 46
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims abstract description 45
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 45
- 239000007864 aqueous solution Substances 0.000 claims abstract description 41
- PTFCDOFLOPIGGS-UHFFFAOYSA-N Zinc dication Chemical compound [Zn+2] PTFCDOFLOPIGGS-UHFFFAOYSA-N 0.000 claims abstract description 26
- NWONKYPBYAMBJT-UHFFFAOYSA-L zinc sulfate Chemical compound [Zn+2].[O-]S([O-])(=O)=O NWONKYPBYAMBJT-UHFFFAOYSA-L 0.000 claims abstract description 3
- 229960001763 zinc sulfate Drugs 0.000 claims abstract description 3
- 229910000368 zinc sulfate Inorganic materials 0.000 claims abstract description 3
- 239000007788 liquid Substances 0.000 claims description 26
- 238000007747 plating Methods 0.000 claims description 15
- 238000005406 washing Methods 0.000 claims description 9
- 238000001035 drying Methods 0.000 claims description 4
- 229910052751 metal Inorganic materials 0.000 claims description 4
- 239000002184 metal Substances 0.000 claims description 4
- 239000000243 solution Substances 0.000 abstract description 12
- 239000010410 layer Substances 0.000 description 34
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 12
- 239000011324 bead Substances 0.000 description 11
- 230000000694 effects Effects 0.000 description 11
- 238000005755 formation reaction Methods 0.000 description 11
- 238000000465 moulding Methods 0.000 description 11
- 239000000523 sample Substances 0.000 description 11
- 238000012360 testing method Methods 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- 230000015572 biosynthetic process Effects 0.000 description 10
- 238000004140 cleaning Methods 0.000 description 8
- 239000011248 coating agent Substances 0.000 description 8
- 238000000576 coating method Methods 0.000 description 8
- 230000003139 buffering effect Effects 0.000 description 7
- 230000007423 decrease Effects 0.000 description 7
- 238000005259 measurement Methods 0.000 description 7
- 239000003929 acidic solution Substances 0.000 description 6
- 238000005275 alloying Methods 0.000 description 6
- 238000010828 elution Methods 0.000 description 6
- 238000012545 processing Methods 0.000 description 6
- 239000011787 zinc oxide Substances 0.000 description 6
- 239000010960 cold rolled steel Substances 0.000 description 5
- 238000005246 galvanizing Methods 0.000 description 5
- 238000007654 immersion Methods 0.000 description 5
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000003825 pressing Methods 0.000 description 4
- 238000005096 rolling process Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 3
- 230000001771 impaired effect Effects 0.000 description 3
- 239000010687 lubricating oil Substances 0.000 description 3
- 101000993059 Homo sapiens Hereditary hemochromatosis protein Proteins 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- 229910001297 Zn alloy Inorganic materials 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000003111 delayed effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- -1 hydrogen ions Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 150000002484 inorganic compounds Chemical class 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052745 lead Inorganic materials 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000012925 reference material Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 235000017281 sodium acetate Nutrition 0.000 description 1
- 239000001632 sodium acetate Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 230000037303 wrinkles Effects 0.000 description 1
- 150000003752 zinc compounds Chemical class 0.000 description 1
- RZLVQBNCHSJZPX-UHFFFAOYSA-L zinc sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Zn+2].[O-]S([O-])(=O)=O RZLVQBNCHSJZPX-UHFFFAOYSA-L 0.000 description 1
Images
Classifications
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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
- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/48—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 not containing phosphates, hexavalent chromium compounds, fluorides or complex fluorides, molybdates, tungstates, vanadates or oxalates
- C23C22/53—Treatment of zinc or alloys based thereon
-
- 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
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
- C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
- C23C18/1204—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material inorganic material, e.g. non-oxide and non-metallic such as sulfides, nitrides based compounds
- C23C18/1208—Oxides, e.g. ceramics
- C23C18/1216—Metal oxides
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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
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
- C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
- C23C18/1229—Composition of the substrate
- C23C18/1241—Metallic substrates
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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
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
- C23C2/06—Zinc or cadmium or alloys based thereon
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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
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/26—After-treatment
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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
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
- C23C2/36—Elongated material
- C23C2/40—Plates; Strips
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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
- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
- C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
- C23C28/32—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer
- C23C28/322—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer only coatings of metal elements only
- C23C28/3225—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer only coatings of metal elements only with at least one zinc-based layer
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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
- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
- C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
- C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
- C23C28/345—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer
Definitions
- the present invention relates to a method for stably producing a galvanized steel sheet having a small sliding resistance during press forming and having an excellent press formability, and to a galvanized steel sheet having an excellent press formability.
- Zinc-based galvanized steel sheets are widely used in a wide range of fields centering on automobile body applications. Zinc-based plated steel sheets for such applications are subjected to press forming and used. However, the zinc-based plated steel sheet has a drawback that the press formability is inferior to that of the cold-rolled steel sheet. This is because the sliding resistance of the galvanized steel sheet in the press die is larger than that of the cold-rolled steel sheet. That is, the galvanized steel sheet is less likely to flow into the press mold at a portion where the sliding resistance between the mold and the bead is large, and the steel sheet tends to break.
- alloyed hot dip galvanized steel sheets that are subjected to alloying after hot dip galvanizing are superior in weldability and paintability compared to hot dip galvanized steel sheets that are not subjected to alloying. Therefore, it is more suitably used for automobile body applications.
- An alloyed hot-dip galvanized steel sheet is formed by galvanizing the steel sheet and then heat-treating to form an Fe-Zn alloy phase by causing Fe in the steel sheet and Zn in the plating layer to diffuse and cause an alloying reaction. It has been made.
- This Fe—Zn alloy phase is usually a film composed of a ⁇ phase, a ⁇ 1 phase, and a ⁇ phase, and as the Fe concentration decreases, that is, in the order of ⁇ phase ⁇ ⁇ 1 phase ⁇ ⁇ phase, hardness and melting point Tends to decrease. For this reason, from the viewpoint of slidability, a coating with a high hardness, a high melting point and a high Fe concentration that is difficult to cause adhesion is effective, and an alloyed hot-dip galvanized steel sheet that places importance on press formability Manufactured with high average Fe concentration.
- Patent Document 1 and Patent Document 2 disclose that the surface of a zinc-based plated steel sheet is subjected to electrolytic treatment, immersion treatment, coating oxidation treatment, or heat treatment to oxidize mainly ZnO. A technique for improving weldability and workability by forming a film is disclosed.
- Patent Documents 1 and 2 when the techniques of Patent Documents 1 and 2 are applied to an alloyed hot dip galvanized steel sheet, the surface of the alloyed hot dip galvanized steel sheet is inferior due to the presence of Al oxide, and the surface irregularities are large. In addition, the effect of improving the press formability cannot be obtained stably. That is, since the surface reactivity is low, it is difficult to form a predetermined film on the surface even when electrolytic treatment, immersion treatment, coating oxidation treatment, heat treatment, and the like are performed. The film thickness becomes thin at the portion where the amount of Al oxide is large.
- Patent Document 3 after hot-dip galvanizing and alloying by heat treatment and further temper rolling, the steel sheet is contacted with an acidic solution having a pH buffering action, held for 1 to 30 seconds, and washed with water.
- an acidic solution having a pH buffering action held for 1 to 30 seconds, and washed with water.
- Patent Document 4 As a method for uniformly forming an oxide layer on a surface flat portion of a hot dip galvanized steel sheet that is not subjected to alloying treatment, in Patent Document 4, the hot dip galvanized steel sheet after temper rolling is treated with an acidic solution having a pH buffering action. The method of making it contact, and then washing
- the present invention provides a production method capable of stably producing a galvanized steel sheet having excellent press formability even in a short time and a galvanized steel sheet having excellent press formability. For the purpose.
- the inventors of the present invention have made extensive studies to solve the above problems. As a result, the following knowledge was obtained.
- the acidic solution used in the techniques of Patent Documents 3 and 4 has a pH buffering action for the purpose of promoting the dissolution of zinc. Therefore, it is considered that the increase in pH is delayed and the formation of the oxide layer is delayed.
- the elution time of zinc is included in the generation time of the oxide film. As a result, it is considered difficult to form a thick oxide film in a short time.
- the present inventors have devised a technique for generating an oxide film in a shorter time by omitting the zinc elution time by previously containing zinc ions in an aqueous solution for generating an oxide film.
- the formation of the oxide film was not promoted simply by previously containing zinc ions in the aqueous solution.
- formation of an oxide film was not promoted even when zinc was contained in the treatment liquid. The reason for this is that, in the techniques of Patent Documents 3 and 4, the reduction of hydrogen ions that occurs simultaneously when zinc elutes increases the pH in the vicinity of the surface and makes it easy to generate zinc oxide.
- the present inventors have devised a technique for adjusting the pH of the aqueous solution to pH 4 to 6 at which zinc oxide is easily generated. It was also found that when the pH of the treatment solution is 4 to 6, zinc is generated as a hydroxide due to a slight increase in the surface pH caused by slight elution of zinc in the plating film.
- the present invention has been made based on the above findings, and the gist thereof is as follows.
- the steel sheet is contacted with an aqueous solution, and after the contact treatment is completed, the oxide layer is formed on the surface of the steel sheet by holding for 1 to 60 seconds and then washing and drying.
- the aqueous solution for contact-treating the steel sheet contains zinc ions in a zinc ion concentration range of 5 to 100 g / l, has a pH of 4 to 6, and a liquid temperature of 20 to 70.
- the galvanized steel sheet is a galvanized steel sheet on which a coating containing zinc as a main component is formed, a hot dip galvanized steel sheet (referred to as GI steel sheet for short), an galvannealed steel sheet.
- GI steel sheet hot dip galvanized steel sheet
- EG steel plate electrogalvanized steel plate
- vapor-deposited galvanized steel plate alloy galvanized steel plate containing alloy elements such as Fe, Al, Ni, MgCo and the like.
- FIG. 1 is a diagram showing a main part of the oxide layer forming treatment equipment used in the examples.
- FIG. 2 is a schematic front view showing the friction coefficient measuring apparatus.
- FIG. 3 is a schematic perspective view showing the bead shape and dimensions in FIG.
- FIG. 4 is a schematic perspective view showing the bead shape and dimensions in FIG.
- FIG. 5 is a diagram showing the influence of the zinc ion concentration on the oxide film thickness.
- the steel sheet is contact-treated with an aqueous solution, held for 1 to 60 seconds after completion of the contact processing, and then washed with water and dried, whereby an oxide is formed on the surface of the zinc-based plated steel sheet.
- the aqueous solution contains zinc ions in a zinc ion concentration range of 5 to 100 g / l, has a pH of 4 to 6, and a liquid temperature of 20 to 70 ° C.
- an aqueous solution containing a predetermined concentration of zinc ions and having a defined pH and liquid temperature is used as an aqueous solution for contact-treating a steel sheet.
- the term “after contact treatment” means that after the immersion process is completed in the case of immersion treatment, after the spray process is completed in the case of spray treatment, and after the application step is completed in the case of roll coating. is there.
- an aqueous solution containing zinc ions as the aqueous solution for contact-treating the steel sheet, it is possible to omit the elution time of zinc.
- the zinc ion has a zinc ion concentration in the range of 5 to 100 g / l. When the zinc ion concentration is less than 5 g / l, sufficient zinc is not supplied and the oxide layer is not formed.
- the concentration of sulfuric acid contained in the oxide layer to be formed becomes high, and there is a concern that the treatment liquid is contaminated when the oxide is dissolved in the chemical conversion treatment step performed thereafter.
- zinc ions as sulfates.
- sulfate ions are taken into the oxide layer to be formed, which seems to have an effect of stabilizing the oxide layer.
- the formation of the oxide film is not promoted simply by previously containing zinc ions in the treatment liquid. Therefore, in the present invention, it is necessary to adjust the pH to pH 4 to 6 where zinc oxide is easily generated.
- the pH of the treatment solution is 4 to 6
- zinc is generated as a hydroxide by a slight increase in surface pH caused by slight elution of zinc in the plating film.
- zinc elution time can be omitted and zinc oxide can be produced.
- zinc ions precipitate in the aqueous solution (formation of hydroxide), and are no longer formed as oxides on the steel sheet surface.
- the pH is less than 4, as described above, the formation of the oxide layer is hindered due to the delay of the pH increase.
- the temperature of the aqueous solution is 20 to 70 ° C.
- the formation reaction of the oxide layer occurs when it is held for a predetermined time after contact with the aqueous solution, it is effective to control the plate temperature at the time of holding in the range of 20 to 70 ° C. If it is lower than 20 ° C., the reaction for forming the oxide layer takes a long time, resulting in a decrease in productivity. On the other hand, when the temperature exceeds 70 ° C., the reaction proceeds relatively quickly, but on the contrary, processing unevenness tends to occur on the surface of the steel sheet.
- the aqueous solutions used in Patent Documents 3 and 4 are characterized by being acidic and having a pH buffering action.
- the present invention uses an aqueous solution containing zinc ions, a sufficient oxide layer can be formed even if the pH of the aqueous solution is high and zinc does not sufficiently dissolve. Moreover, it seems that it is advantageous for the formation of the oxide that the pH rises rapidly. Therefore, the pH buffering action is not always essential.
- zinc is contained in the aqueous solution in contact with the steel sheet surface, an oxide layer excellent in slidability can be stably formed. Therefore, other metal ions, inorganic compounds, and the like are added to the aqueous solution. Even if it contains as an impurity or deliberately, the effect of this invention is not impaired.
- the amount of the aqueous film formed on the surface of the steel sheet is 30 g / m 2 or less.
- a liquid film amount of 5 g / m 2 or more is suitable for the purpose of preventing the liquid film from drying.
- the liquid film formed on the surface of the steel sheet after contacting with the aqueous solution is 5 to 30 g / m 2 .
- the amount of the aqueous film can be adjusted by a squeeze roll, air wiping or the like.
- the time from immersing in an aqueous solution to washing with water is 1 to 60 seconds.
- the holding time is set to 60 seconds or less from the viewpoint of sufficiently exerting the effects of the present invention. From the above, an oxide layer containing zinc as a main component and having an average thickness of 10 nm or more is obtained on the surface of the plated steel sheet of the present invention.
- the phrase “mainly composed of zinc” means that the metal component contains 50% by mass or more of zinc.
- the oxide layer in the present invention is a layer made of an oxide and / or hydroxide mainly containing zinc as a metal component.
- the average thickness of the oxide layer needs to be 10 nm or more. When the average thickness of the oxide layer is reduced to less than 10 nm, the effect of reducing the sliding resistance becomes insufficient. On the other hand, if the average thickness of the oxide layer containing zinc as an essential component exceeds 100 nm, the coating is destroyed during press working, the sliding resistance increases, and the weldability tends to decrease, which is not preferable.
- a GI steel sheet was prepared by applying hot-dip galvanizing with an adhesion amount per side of 45 g / m 2 and an Al concentration of 0.20 mass%, followed by temper rolling. did. Further, on a cold-rolled steel sheet having a thickness of 0.8 mm, the amount of plating adhesion per side is 45 g / m 2 , the Fe concentration is 10% by mass, and the Al concentration is 0.20 by a conventional alloying hot dip galvanizing method. A GA steel sheet having a mass% plating film formed thereon and further subjected to temper rolling was prepared.
- the EG steel plate which has a plating film
- surface is 30 g / m ⁇ 2 > on the cold rolled steel plate with a plate
- an oxide layer was formed using a processing facility having the configuration shown in FIG.
- steel plates S such as GI steel plates, GA steel plates and EG steel plates obtained as described above were immersed in aqueous solutions having different treatment liquid compositions, temperatures and pHs shown in Table 1-1 and Table 1-2 in the solution tank 2. .
- the amount of liquid film on the steel sheet surface was adjusted with the drawing roll 3. The liquid film amount was adjusted by changing the pressure of the squeeze roll.
- a cleaning tank 1 can be provided in front of the solution layer 2.
- the aqueous solution in which the immersion treatment was performed in the solution tank 2 was an aqueous solution to which a predetermined amount of zinc sulfate heptahydrate was added for the purpose of adding zinc ions.
- a solution containing 20 g / L of sodium acetate with a pH adjusted with sulfuric acid was also used for comparison.
- the holding time until water washing is the time until the liquid film amount is adjusted with the squeezing roll 3 and the cleaning is started in the cleaning tank 7, and is adjusted by changing the line speed. What washed the steel plate immediately after squeezing using the shower water washing apparatus 4 of the side was also produced.
- the steel sheet produced as described above it is determined whether it has a sufficient appearance as an automobile outer plate, and as a method for simply evaluating the press formability, the measurement of the friction coefficient and the actual formability are further improved.
- a ball head overhang test was conducted for the purpose of simulating in detail.
- the measuring method is as follows. (1) Press formability evaluation test (Friction coefficient measurement test) In order to evaluate the press formability, the friction coefficient of each test material was measured as follows. FIG.
- FIG. 2 is a schematic front view showing the friction coefficient measuring apparatus.
- a friction coefficient measurement sample 11 collected from a test material is fixed to a sample table 12, and the sample table 12 is fixed to the upper surface of a slide table 13 that can move horizontally.
- a slide table support base 15 On the lower surface of the slide table 13, there is provided a slide table support base 15 having a roller 14 in contact with the slide table 13 and capable of moving up and down.
- a first load cell 17 is attached to the slide table support 15.
- a second load cell 18 is attached to one end of the slide table 13 in order to measure the sliding resistance force F for horizontally moving the slide table 13 along the rail 19 with the pressing force applied. ing.
- 3 and 4 are schematic perspective views showing the shape and dimensions of the beads used.
- the bead 16 slides with its lower surface pressed against the surface of the sample 11.
- the bead 16 shown in FIG. 3 has a width of 10 mm, a length of 12 mm in the sliding direction of the sample, and a lower portion at both ends in the sliding direction is formed by a curved surface having a curvature of 4.5 mmR. It has a plane with a direction length of 3 mm.
- Ball head overhang test Using a 150 mm ⁇ punch for a 200 x 200 mm sample material, the maximum forming height when a bulge was formed by a hydraulic bulge tester. Was measured. At this time, a wrinkle holding force of 100 Ton was applied for the purpose of preventing the inflow of the material, and the lubricating oil was applied only to the surface in contact with the punch. The used lubricating oil is the same as that in the friction coefficient measurement test described above.
- oxide layer thickness (oxide film thickness) Using a Si wafer on which a thermally oxidized SiO2 film with a film thickness of 96 nm is formed as a reference material, measure O / K ⁇ X-rays with a fluorescent X-ray analyzer. Thus, the average thickness of the oxide layer in terms of SiO 2 was obtained. The analysis area is 30 mm ⁇ .
- the test results obtained above are shown in Table 1-1 and Table 1-2. The following items became clear from the test results shown in Table 1-1 and Table 1-2. (1) No. Since 1, 47 and 60 are not treated with a solution, an oxide film sufficient to improve the slidability is not formed on the flat portion, and the coefficient of friction is high. (2) No. 2-4, no. 48-50 and no.
- 61 to 63 are comparative examples using an acidic solution having a pH buffering action. Although the friction coefficient is low and the maximum formation height is high at 30 seconds or more, the treatment for 10 seconds does not satisfy a sufficient decrease in the friction coefficient and an improvement in the maximum molding height.
- (3) No. 5 to 7 are comparative examples using an acidic solution having a pH buffering action. It shows a high coefficient of friction.
- (4) No. 8-10, no. 51-53 and no. 64 to 66 are comparative examples which contain zinc ions but whose amount is less than the range of the present invention. Although the friction coefficient is low and the maximum formation height is high at 30 seconds or more, the treatment for 10 seconds does not satisfy a sufficient decrease in the friction coefficient and an improvement in the maximum molding height. (5) No.
- No. Nos. 17 to 22 are examples in which the time until the solution film is formed on the steel plate surface and washed with water is changed. No. which was washed with water without holding. No. 17 has a slight decrease in the friction coefficient, whereas No. 17 has a holding time of 1 second or more. In 18 to 22, the friction coefficient is lowered and the overhanging property is stably improved.
- No. Nos. 23 to 40 are examples in which the treatment liquid temperature was changed. 23 to 25 are not sufficient in improving the friction coefficient and the maximum molding height as compared with the other examples. On the other hand, no. Nos.
- FIG. 5 shows the numbers in Table 1-1 and Table 1-2. 8-22 and no. 4 is a graph showing the influence of zinc ion concentration on the oxide film thickness using 44 to 46.
- FIG. 5 when the zinc concentration is 5 g / l or more, the oxide film thickness is sufficiently thick even when the holding time is short (for example, 10 seconds), and the oxide film thickness is thin when the holding time is short. It can be seen that the problem of the present invention is solved.
- a galvanized steel sheet having excellent press formability with a small sliding resistance during press forming can be stably produced even under short production conditions.
- the sliding resistance during press forming is small, and excellent press formability can be achieved. Since it is excellent in press formability, it can be applied in a wide range of fields, mainly for automobile body applications.
Abstract
Provided is a method for manufacturing a galvanized steel sheet, wherein: a steel sheet is galvanized, the surface is exposed for 1 to 60 seconds to an aqueous solution with a pH of 4-6 and a temperature of 20-70°C containing zinc ion with a concentration in the range of 5-100g/l, and then the steel sheet is washed and dried. An example of an ideal zinc-containing solution would be, for instance, a solution that contains zinc sulfate. The aforementioned method enables an oxide layer, mainly composed of zinc with an average thickness of no less than 10nm, to be formed on the surface of the steel sheet, thereby enabling a galvanized steel sheet with excellent press-formability to be manufactured in a stable manner and over a short period of time.
Description
本発明は、プレス成形時の摺動抵抗が小さく優れたプレス成形性を有する亜鉛系めっき鋼板を安定して製造する方法および優れたプレス成形性を有する亜鉛系めっき鋼板に関するものである。
The present invention relates to a method for stably producing a galvanized steel sheet having a small sliding resistance during press forming and having an excellent press formability, and to a galvanized steel sheet having an excellent press formability.
亜鉛系めっき鋼板は、自動車車体用途を中心に広範な分野で広く利用されている。そのような用途での亜鉛系めっき鋼板は、プレス成形を施されて使用に供される。しかし、亜鉛系めっき鋼板は、冷延鋼板に比べてプレス成形性が劣るという欠点を有する。これはプレス金型での亜鉛系めっき鋼板の摺動抵抗が冷延鋼板に比べて大きいことが原因である。すなわち、金型とビードでの摺動抵抗が大きい部分で亜鉛系めっき鋼板がプレス金型に流入しにくくなり、鋼板の破断が起こりやすい。
ここで、亜鉛系めっき鋼板の中でも特に、溶融亜鉛めっき処理後に合金化処理を施す合金化溶融亜鉛めっき鋼板は、合金化処理を施さない溶融亜鉛めっき鋼板と比較して溶接性および塗装性に優れることから、自動車車体用途としてはより好適に用いられている。
合金化溶融亜鉛めっき鋼板は、鋼板に亜鉛めっきを施した後、加熱処理を行い、鋼板中のＦｅとめっき層中のＺｎが拡散し合金化反応が生じることにより、Ｆｅ−Ｚｎ合金相を形成させたものである。このＦｅ−Ｚｎ合金相は、通常、Γ相、δ１相、ζ相からなる皮膜であり、Ｆｅ濃度が低くなるに従い、すなわち、Γ相→δ１相→ζ相の順で、硬度ならびに融点が低下する傾向がある。このため、摺動性の観点からは、高硬度で、融点が高く凝着の起こりにくい高Ｆｅ濃度の皮膜が有効であり、プレス成形性を重視する合金化溶融亜鉛めっき鋼板は、皮膜中の平均Ｆｅ濃度を高めに製造されている。
しかしながら、高Ｆｅ濃度の皮膜では、めっき−鋼板界面に硬くて脆いΓ相が形成されやすく、加工時に界面から剥離する現象、いわゆるパウダリングが生じやすい問題を有している。
上記の問題を解決する方法として、特許文献１および特許文献２には、亜鉛系めっき鋼板の表面に電解処理、浸漬処理、塗布酸化処理、または加熱処理を施すことにより、ＺｎＯを主体とする酸化膜を形成させて溶接性、加工性を向上させる技術が開示されている。
しかしながら、特許文献１および２の技術を合金化溶融亜鉛めっき鋼板に適用した場合、合金化溶融めっき鋼板はＡｌ酸化物が存在することにより、表面の反応性が劣る、そして表面の凹凸が大きいためにプレス成形性の改善効果を安定して得ることはできない。即ち、表面の反応性が低いため、電解処理、浸漬処理、塗布酸化処理及び加熱処理等を行っても、所定の皮膜を表面に形成することは困難であり、反応性の低い部分、すなわち、Ａｌ酸化物量が多い部分では膜厚が薄くなってしまう。また、表面の凹凸が大きいため、プレス成型時にプレス金型と直接接触するのは表面の凸部となるが、凸部のうち膜厚の薄い部分と金型との接触部での摺動抵抗が大きくなり、プレス成形性の改善効果が十分には得られない。
そこで、特許文献３では、鋼板を溶融亜鉛めっき後、加熱処理により合金化し、さらに調質圧延を施した後に、ｐＨ緩衝作用を有する酸性溶液と接触させ、１~３０秒保持し、水洗することで、めっき表層に酸化物層を形成させる技術を開示している。
同じく合金化処理を施さない溶融亜鉛めっき鋼板の表面平坦部に均一に酸化物層を形成させる手法として、特許文献４では、調質圧延後の溶融亜鉛めっき鋼板をｐＨ緩衝作用を有する酸性溶液と接触させ、その後、鋼板表面に酸性溶液の液膜が形成された状態で所定時間保持した後水洗、乾燥する方法が開示している。
特開昭５３−６０３３２号公報
特開平２−１９０４８３号公報
特開２００３−３０６７８１号公報
特開２００４−３００４号公報
Zinc-based galvanized steel sheets are widely used in a wide range of fields centering on automobile body applications. Zinc-based plated steel sheets for such applications are subjected to press forming and used. However, the zinc-based plated steel sheet has a drawback that the press formability is inferior to that of the cold-rolled steel sheet. This is because the sliding resistance of the galvanized steel sheet in the press die is larger than that of the cold-rolled steel sheet. That is, the galvanized steel sheet is less likely to flow into the press mold at a portion where the sliding resistance between the mold and the bead is large, and the steel sheet tends to break.
Here, especially among galvanized steel sheets, alloyed hot dip galvanized steel sheets that are subjected to alloying after hot dip galvanizing are superior in weldability and paintability compared to hot dip galvanized steel sheets that are not subjected to alloying. Therefore, it is more suitably used for automobile body applications.
An alloyed hot-dip galvanized steel sheet is formed by galvanizing the steel sheet and then heat-treating to form an Fe-Zn alloy phase by causing Fe in the steel sheet and Zn in the plating layer to diffuse and cause an alloying reaction. It has been made. This Fe—Zn alloy phase is usually a film composed of a Γ phase, a δ 1 phase, and a ζ phase, and as the Fe concentration decreases, that is, in the order of Γ phase → δ 1 phase → ζ phase, hardness and melting point Tends to decrease. For this reason, from the viewpoint of slidability, a coating with a high hardness, a high melting point and a high Fe concentration that is difficult to cause adhesion is effective, and an alloyed hot-dip galvanized steel sheet that places importance on press formability Manufactured with high average Fe concentration.
However, a coating with a high Fe concentration has a problem that a hard and brittle Γ phase is easily formed at the plating-steel plate interface, and a phenomenon of peeling from the interface during processing, that is, so-called powdering is likely to occur.
As a method for solving the above problem,Patent Document 1 and Patent Document 2 disclose that the surface of a zinc-based plated steel sheet is subjected to electrolytic treatment, immersion treatment, coating oxidation treatment, or heat treatment to oxidize mainly ZnO. A technique for improving weldability and workability by forming a film is disclosed.
However, when the techniques of Patent Documents 1 and 2 are applied to an alloyed hot dip galvanized steel sheet, the surface of the alloyed hot dip galvanized steel sheet is inferior due to the presence of Al oxide, and the surface irregularities are large. In addition, the effect of improving the press formability cannot be obtained stably. That is, since the surface reactivity is low, it is difficult to form a predetermined film on the surface even when electrolytic treatment, immersion treatment, coating oxidation treatment, heat treatment, and the like are performed. The film thickness becomes thin at the portion where the amount of Al oxide is large. In addition, since the surface irregularities are large, it is the surface protrusions that come into direct contact with the press die during press molding, but the sliding resistance at the contact portion between the thin part of the protrusions and the mold As a result, the effect of improving press formability cannot be sufficiently obtained.
Therefore, inPatent Document 3, after hot-dip galvanizing and alloying by heat treatment and further temper rolling, the steel sheet is contacted with an acidic solution having a pH buffering action, held for 1 to 30 seconds, and washed with water. Thus, a technique for forming an oxide layer on the plating surface layer is disclosed.
Similarly, as a method for uniformly forming an oxide layer on a surface flat portion of a hot dip galvanized steel sheet that is not subjected to alloying treatment, inPatent Document 4, the hot dip galvanized steel sheet after temper rolling is treated with an acidic solution having a pH buffering action. The method of making it contact, and then washing | cleaning and drying after hold | maintaining for a predetermined time in the state in which the liquid film of the acidic solution was formed in the steel plate surface is disclosed.
JP-A-53-60332 Japanese Patent Laid-Open No. 2-190483 JP 2003-306781 A JP 2004-3004 A
ここで、亜鉛系めっき鋼板の中でも特に、溶融亜鉛めっき処理後に合金化処理を施す合金化溶融亜鉛めっき鋼板は、合金化処理を施さない溶融亜鉛めっき鋼板と比較して溶接性および塗装性に優れることから、自動車車体用途としてはより好適に用いられている。
合金化溶融亜鉛めっき鋼板は、鋼板に亜鉛めっきを施した後、加熱処理を行い、鋼板中のＦｅとめっき層中のＺｎが拡散し合金化反応が生じることにより、Ｆｅ−Ｚｎ合金相を形成させたものである。このＦｅ−Ｚｎ合金相は、通常、Γ相、δ１相、ζ相からなる皮膜であり、Ｆｅ濃度が低くなるに従い、すなわち、Γ相→δ１相→ζ相の順で、硬度ならびに融点が低下する傾向がある。このため、摺動性の観点からは、高硬度で、融点が高く凝着の起こりにくい高Ｆｅ濃度の皮膜が有効であり、プレス成形性を重視する合金化溶融亜鉛めっき鋼板は、皮膜中の平均Ｆｅ濃度を高めに製造されている。
しかしながら、高Ｆｅ濃度の皮膜では、めっき−鋼板界面に硬くて脆いΓ相が形成されやすく、加工時に界面から剥離する現象、いわゆるパウダリングが生じやすい問題を有している。
上記の問題を解決する方法として、特許文献１および特許文献２には、亜鉛系めっき鋼板の表面に電解処理、浸漬処理、塗布酸化処理、または加熱処理を施すことにより、ＺｎＯを主体とする酸化膜を形成させて溶接性、加工性を向上させる技術が開示されている。
しかしながら、特許文献１および２の技術を合金化溶融亜鉛めっき鋼板に適用した場合、合金化溶融めっき鋼板はＡｌ酸化物が存在することにより、表面の反応性が劣る、そして表面の凹凸が大きいためにプレス成形性の改善効果を安定して得ることはできない。即ち、表面の反応性が低いため、電解処理、浸漬処理、塗布酸化処理及び加熱処理等を行っても、所定の皮膜を表面に形成することは困難であり、反応性の低い部分、すなわち、Ａｌ酸化物量が多い部分では膜厚が薄くなってしまう。また、表面の凹凸が大きいため、プレス成型時にプレス金型と直接接触するのは表面の凸部となるが、凸部のうち膜厚の薄い部分と金型との接触部での摺動抵抗が大きくなり、プレス成形性の改善効果が十分には得られない。
そこで、特許文献３では、鋼板を溶融亜鉛めっき後、加熱処理により合金化し、さらに調質圧延を施した後に、ｐＨ緩衝作用を有する酸性溶液と接触させ、１~３０秒保持し、水洗することで、めっき表層に酸化物層を形成させる技術を開示している。
同じく合金化処理を施さない溶融亜鉛めっき鋼板の表面平坦部に均一に酸化物層を形成させる手法として、特許文献４では、調質圧延後の溶融亜鉛めっき鋼板をｐＨ緩衝作用を有する酸性溶液と接触させ、その後、鋼板表面に酸性溶液の液膜が形成された状態で所定時間保持した後水洗、乾燥する方法が開示している。
Here, especially among galvanized steel sheets, alloyed hot dip galvanized steel sheets that are subjected to alloying after hot dip galvanizing are superior in weldability and paintability compared to hot dip galvanized steel sheets that are not subjected to alloying. Therefore, it is more suitably used for automobile body applications.
An alloyed hot-dip galvanized steel sheet is formed by galvanizing the steel sheet and then heat-treating to form an Fe-Zn alloy phase by causing Fe in the steel sheet and Zn in the plating layer to diffuse and cause an alloying reaction. It has been made. This Fe—Zn alloy phase is usually a film composed of a Γ phase, a δ 1 phase, and a ζ phase, and as the Fe concentration decreases, that is, in the order of Γ phase → δ 1 phase → ζ phase, hardness and melting point Tends to decrease. For this reason, from the viewpoint of slidability, a coating with a high hardness, a high melting point and a high Fe concentration that is difficult to cause adhesion is effective, and an alloyed hot-dip galvanized steel sheet that places importance on press formability Manufactured with high average Fe concentration.
However, a coating with a high Fe concentration has a problem that a hard and brittle Γ phase is easily formed at the plating-steel plate interface, and a phenomenon of peeling from the interface during processing, that is, so-called powdering is likely to occur.
As a method for solving the above problem,
However, when the techniques of
Therefore, in
Similarly, as a method for uniformly forming an oxide layer on a surface flat portion of a hot dip galvanized steel sheet that is not subjected to alloying treatment, in
上記特許文献３および４に開示されている技術を適用した場合、従来の製造条件においては良好なプレス成形性を得ることができる。しかし、近年では、生産性向上のためにより短時間でより厚い酸化膜を生成させる製造方法の開発が望まれており、このような条件で行った場合、特許文献３、４に開示される技術では十分な酸化膜が形成されず、良好なプレス成形性が得られないことがある。
本発明は、かかる事情に鑑み、優れたプレス成形性を有する亜鉛系めっき鋼板を短時間でも安定的に製造することが可能な製造方法および優れたプレス成形性を有する亜鉛系めっき鋼板を提供することを目的とする。 When the techniques disclosed in Patent Documents 3 and 4 are applied, good press formability can be obtained under conventional manufacturing conditions. However, in recent years, it has been desired to develop a manufacturing method for generating a thicker oxide film in a shorter time in order to improve productivity, and the techniques disclosed in Patent Documents 3 and 4 are performed under such conditions. In such a case, a sufficient oxide film is not formed, and good press formability may not be obtained.
In view of such circumstances, the present invention provides a production method capable of stably producing a galvanized steel sheet having excellent press formability even in a short time and a galvanized steel sheet having excellent press formability. For the purpose.
本発明は、かかる事情に鑑み、優れたプレス成形性を有する亜鉛系めっき鋼板を短時間でも安定的に製造することが可能な製造方法および優れたプレス成形性を有する亜鉛系めっき鋼板を提供することを目的とする。 When the techniques disclosed in
In view of such circumstances, the present invention provides a production method capable of stably producing a galvanized steel sheet having excellent press formability even in a short time and a galvanized steel sheet having excellent press formability. For the purpose.
本発明者らは、上記の課題を解決すべく、鋭意研究を重ねた。その結果、以下の知見を得た。
特許文献３および４の技術に使われる酸性溶液は、亜鉛の溶解を促進する目的でｐＨ緩衝作用を有している。そのため、ｐＨの上昇が遅らされ、酸化物層の形成が遅れていることが考えられる。そして、酸化物層を形成する亜鉛をめっき皮膜から溶出した亜鉛で補うために、酸化膜の生成時間に亜鉛の溶出時間が含まれる。その結果、短時間で厚い酸化膜を生成させることが困難になっていると考えられる。
そこで、本発明者らは酸化膜を生成させる水溶液中に亜鉛イオンを予め含有させることによって亜鉛の溶出時間を省略してより短時間で酸化膜を生成させる技術を考案した。しかしながら、単に水溶液中に亜鉛イオンを予め含有させるだけでは酸化膜の形成は促進されなかった。特に、特許文献３および４の実施例に示されるｐＨ２では処理液中に亜鉛を含有させても酸化膜の形成は促進されなかった。
この理由は、特許文献３および４の技術では、亜鉛が溶出する際に同時に起こる水素イオンの還元で表面近傍のｐＨが上昇して亜鉛酸化物が生成しやすい環境になっているのに対して、単に水溶液中に亜鉛イオンを含有させただけでは表面近傍のｐＨの上昇が起こらず亜鉛酸化物が生成しやすい環境が形成されないためであると考えられる。
そこで、本発明者等は、水溶液のｐＨを亜鉛酸化物が生成しやすいｐＨ４~６とする技術を考案した。そして、処理液のｐＨを４~６とすることで、めっき皮膜の亜鉛がわずかに溶出して起こる表面ｐＨの微小な上昇により亜鉛が水酸化物として生成することを見出した。
本発明は、以上の知見に基づきなされたものであり、その要旨は以下の通りである。
［１］鋼板に亜鉛系めっきを施した後、鋼板を水溶液に接触処理し、接触処理終了後１~６０秒間保持した後、水洗・乾燥を行うことにより、鋼板表面に酸化物層を形成する亜鉛系めっき鋼板の製造方法において、鋼板を接触処理する前記水溶液は、亜鉛イオン濃度として５~１００ｇ／ｌの範囲で亜鉛イオンを含有し、ｐＨが４~６であり、液温が２０~７０℃であることを特徴とする亜鉛系めっき鋼板の製造方法。
［２］前記［１］において、前記水溶液中には、亜鉛の硫酸塩を含むことを特徴とする亜鉛系めっき鋼板の製造方法。
［３］前記［１］または［２］において、前記水溶液に接触後に鋼板表面に形成する液膜が５~３０ｇ／ｍ２であることを特徴とする亜鉛系めっき鋼板の製造方法。
［４］前記［１］~［３］のいずれかに記載の亜鉛系めっき鋼板の製造方法により製造され、金属成分としては亜鉛を主体として含む酸化物層を鋼板表面に平均厚さ１０ｎｍ以上形成したことを特徴とする亜鉛系めっき鋼板。
なお、本発明において、亜鉛系めっき鋼板とは、亜鉛を主成分とする皮膜を表面に形成させためっき鋼板であり、溶融亜鉛めっき鋼板（略してＧＩ鋼板と称す）、合金化溶融亜鉛めっき鋼板（略してＧＡ鋼板と称す）、電気亜鉛めっき鋼板（略してＥＧ鋼板と称す）、蒸着亜鉛めっき鋼板やＦｅ、Ａｌ、Ｎｉ、ＭｇＣｏ等の合金元素を含有する合金亜鉛めっき鋼板等が含まれる。 The inventors of the present invention have made extensive studies to solve the above problems. As a result, the following knowledge was obtained.
The acidic solution used in the techniques of Patent Documents 3 and 4 has a pH buffering action for the purpose of promoting the dissolution of zinc. Therefore, it is considered that the increase in pH is delayed and the formation of the oxide layer is delayed. And in order to make up for the zinc which forms an oxide layer with the zinc eluted from the plating film, the elution time of zinc is included in the generation time of the oxide film. As a result, it is considered difficult to form a thick oxide film in a short time.
Accordingly, the present inventors have devised a technique for generating an oxide film in a shorter time by omitting the zinc elution time by previously containing zinc ions in an aqueous solution for generating an oxide film. However, the formation of the oxide film was not promoted simply by previously containing zinc ions in the aqueous solution. In particular, atpH 2 shown in Examples of Patent Documents 3 and 4, formation of an oxide film was not promoted even when zinc was contained in the treatment liquid.
The reason for this is that, in the techniques of Patent Documents 3 and 4, the reduction of hydrogen ions that occurs simultaneously when zinc elutes increases the pH in the vicinity of the surface and makes it easy to generate zinc oxide. It is considered that simply adding zinc ions in the aqueous solution does not increase the pH in the vicinity of the surface and does not form an environment in which zinc oxide is easily generated.
Accordingly, the present inventors have devised a technique for adjusting the pH of the aqueous solution topH 4 to 6 at which zinc oxide is easily generated. It was also found that when the pH of the treatment solution is 4 to 6, zinc is generated as a hydroxide due to a slight increase in the surface pH caused by slight elution of zinc in the plating film.
The present invention has been made based on the above findings, and the gist thereof is as follows.
[1] After the steel sheet is subjected to zinc-based plating, the steel sheet is contacted with an aqueous solution, and after the contact treatment is completed, the oxide layer is formed on the surface of the steel sheet by holding for 1 to 60 seconds and then washing and drying. In the method for producing a zinc-based plated steel sheet, the aqueous solution for contact-treating the steel sheet contains zinc ions in a zinc ion concentration range of 5 to 100 g / l, has a pH of 4 to 6, and a liquid temperature of 20 to 70. A method for producing a zinc-based galvanized steel sheet, characterized by being at ° C.
[2] The method for producing a galvanized steel sheet according to [1], wherein the aqueous solution contains zinc sulfate.
[3] The method for producing a galvanized steel sheet according to [1] or [2], wherein a liquid film formed on the steel sheet surface after contact with the aqueous solution is 5 to 30 g / m 2 .
[4] Manufactured by the method for producing a zinc-based plated steel sheet according to any one of [1] to [3], and an oxide layer mainly containing zinc as a metal component is formed on the steel sheet surface with an average thickness of 10 nm or more. A galvanized steel sheet characterized by that.
In the present invention, the galvanized steel sheet is a galvanized steel sheet on which a coating containing zinc as a main component is formed, a hot dip galvanized steel sheet (referred to as GI steel sheet for short), an galvannealed steel sheet. (Abbreviated as GA steel plate), electrogalvanized steel plate (abbreviated as EG steel plate), vapor-deposited galvanized steel plate, alloy galvanized steel plate containing alloy elements such as Fe, Al, Ni, MgCo and the like.
特許文献３および４の技術に使われる酸性溶液は、亜鉛の溶解を促進する目的でｐＨ緩衝作用を有している。そのため、ｐＨの上昇が遅らされ、酸化物層の形成が遅れていることが考えられる。そして、酸化物層を形成する亜鉛をめっき皮膜から溶出した亜鉛で補うために、酸化膜の生成時間に亜鉛の溶出時間が含まれる。その結果、短時間で厚い酸化膜を生成させることが困難になっていると考えられる。
そこで、本発明者らは酸化膜を生成させる水溶液中に亜鉛イオンを予め含有させることによって亜鉛の溶出時間を省略してより短時間で酸化膜を生成させる技術を考案した。しかしながら、単に水溶液中に亜鉛イオンを予め含有させるだけでは酸化膜の形成は促進されなかった。特に、特許文献３および４の実施例に示されるｐＨ２では処理液中に亜鉛を含有させても酸化膜の形成は促進されなかった。
この理由は、特許文献３および４の技術では、亜鉛が溶出する際に同時に起こる水素イオンの還元で表面近傍のｐＨが上昇して亜鉛酸化物が生成しやすい環境になっているのに対して、単に水溶液中に亜鉛イオンを含有させただけでは表面近傍のｐＨの上昇が起こらず亜鉛酸化物が生成しやすい環境が形成されないためであると考えられる。
そこで、本発明者等は、水溶液のｐＨを亜鉛酸化物が生成しやすいｐＨ４~６とする技術を考案した。そして、処理液のｐＨを４~６とすることで、めっき皮膜の亜鉛がわずかに溶出して起こる表面ｐＨの微小な上昇により亜鉛が水酸化物として生成することを見出した。
本発明は、以上の知見に基づきなされたものであり、その要旨は以下の通りである。
［１］鋼板に亜鉛系めっきを施した後、鋼板を水溶液に接触処理し、接触処理終了後１~６０秒間保持した後、水洗・乾燥を行うことにより、鋼板表面に酸化物層を形成する亜鉛系めっき鋼板の製造方法において、鋼板を接触処理する前記水溶液は、亜鉛イオン濃度として５~１００ｇ／ｌの範囲で亜鉛イオンを含有し、ｐＨが４~６であり、液温が２０~７０℃であることを特徴とする亜鉛系めっき鋼板の製造方法。
［２］前記［１］において、前記水溶液中には、亜鉛の硫酸塩を含むことを特徴とする亜鉛系めっき鋼板の製造方法。
［３］前記［１］または［２］において、前記水溶液に接触後に鋼板表面に形成する液膜が５~３０ｇ／ｍ２であることを特徴とする亜鉛系めっき鋼板の製造方法。
［４］前記［１］~［３］のいずれかに記載の亜鉛系めっき鋼板の製造方法により製造され、金属成分としては亜鉛を主体として含む酸化物層を鋼板表面に平均厚さ１０ｎｍ以上形成したことを特徴とする亜鉛系めっき鋼板。
なお、本発明において、亜鉛系めっき鋼板とは、亜鉛を主成分とする皮膜を表面に形成させためっき鋼板であり、溶融亜鉛めっき鋼板（略してＧＩ鋼板と称す）、合金化溶融亜鉛めっき鋼板（略してＧＡ鋼板と称す）、電気亜鉛めっき鋼板（略してＥＧ鋼板と称す）、蒸着亜鉛めっき鋼板やＦｅ、Ａｌ、Ｎｉ、ＭｇＣｏ等の合金元素を含有する合金亜鉛めっき鋼板等が含まれる。 The inventors of the present invention have made extensive studies to solve the above problems. As a result, the following knowledge was obtained.
The acidic solution used in the techniques of
Accordingly, the present inventors have devised a technique for generating an oxide film in a shorter time by omitting the zinc elution time by previously containing zinc ions in an aqueous solution for generating an oxide film. However, the formation of the oxide film was not promoted simply by previously containing zinc ions in the aqueous solution. In particular, at
The reason for this is that, in the techniques of
Accordingly, the present inventors have devised a technique for adjusting the pH of the aqueous solution to
The present invention has been made based on the above findings, and the gist thereof is as follows.
[1] After the steel sheet is subjected to zinc-based plating, the steel sheet is contacted with an aqueous solution, and after the contact treatment is completed, the oxide layer is formed on the surface of the steel sheet by holding for 1 to 60 seconds and then washing and drying. In the method for producing a zinc-based plated steel sheet, the aqueous solution for contact-treating the steel sheet contains zinc ions in a zinc ion concentration range of 5 to 100 g / l, has a pH of 4 to 6, and a liquid temperature of 20 to 70. A method for producing a zinc-based galvanized steel sheet, characterized by being at ° C.
[2] The method for producing a galvanized steel sheet according to [1], wherein the aqueous solution contains zinc sulfate.
[3] The method for producing a galvanized steel sheet according to [1] or [2], wherein a liquid film formed on the steel sheet surface after contact with the aqueous solution is 5 to 30 g / m 2 .
[4] Manufactured by the method for producing a zinc-based plated steel sheet according to any one of [1] to [3], and an oxide layer mainly containing zinc as a metal component is formed on the steel sheet surface with an average thickness of 10 nm or more. A galvanized steel sheet characterized by that.
In the present invention, the galvanized steel sheet is a galvanized steel sheet on which a coating containing zinc as a main component is formed, a hot dip galvanized steel sheet (referred to as GI steel sheet for short), an galvannealed steel sheet. (Abbreviated as GA steel plate), electrogalvanized steel plate (abbreviated as EG steel plate), vapor-deposited galvanized steel plate, alloy galvanized steel plate containing alloy elements such as Fe, Al, Ni, MgCo and the like.
図１は、実施例で使用した酸化物層形成処理設備の要部を示す図である。
図２は、摩擦係数測定装置を示す概略正面図である。
図３は、図２中のビード形状・寸法を示す概略斜視図である。
図４は、図２中のビード形状・寸法を示す概略斜視図である。
図５は、酸化膜厚への亜鉛イオン濃度の影響を示す図である。 FIG. 1 is a diagram showing a main part of the oxide layer forming treatment equipment used in the examples.
FIG. 2 is a schematic front view showing the friction coefficient measuring apparatus.
FIG. 3 is a schematic perspective view showing the bead shape and dimensions in FIG.
FIG. 4 is a schematic perspective view showing the bead shape and dimensions in FIG.
FIG. 5 is a diagram showing the influence of the zinc ion concentration on the oxide film thickness.
図２は、摩擦係数測定装置を示す概略正面図である。
図３は、図２中のビード形状・寸法を示す概略斜視図である。
図４は、図２中のビード形状・寸法を示す概略斜視図である。
図５は、酸化膜厚への亜鉛イオン濃度の影響を示す図である。 FIG. 1 is a diagram showing a main part of the oxide layer forming treatment equipment used in the examples.
FIG. 2 is a schematic front view showing the friction coefficient measuring apparatus.
FIG. 3 is a schematic perspective view showing the bead shape and dimensions in FIG.
FIG. 4 is a schematic perspective view showing the bead shape and dimensions in FIG.
FIG. 5 is a diagram showing the influence of the zinc ion concentration on the oxide film thickness.
本発明は、鋼板に亜鉛系めっきを施した後、鋼板を水溶液に接触処理し、接触処理終了後１~６０秒間保持した後、水洗・乾燥を行うことにより、亜鉛系めっき鋼板表面に酸化物層を形成するに際し、前記水溶液として、亜鉛イオン濃度として５~１００ｇ／ｌの範囲で亜鉛イオンを含有し、ｐＨが４~６であり、液温が２０~７０℃とする。このように、鋼板を接触処理する水溶液として、所定の濃度の亜鉛イオンを含み、ｐＨと液温を規定した水溶液とすることは、本発明において、重要な要件であり、特徴である。これにより、良好なプレス成形性を確保するために十分な酸化物層を短時間で形成させることができる。
なお、接触処理終了後とは、浸漬処理の場合は浸漬工程を終了した後を、スプレー処理の場合はスプレー工程が終了した後を、ロール塗布の場合は塗布工程が終了した後を示すものである。
鋼板を接触処理する水溶液として、亜鉛イオンを含有する水溶液を使用することにより、亜鉛の溶出時間を省略することが可能となる。この時、亜鉛イオンは亜鉛イオン濃度として、５~１００ｇ／ｌの範囲とする。亜鉛イオン濃度が５ｇ／ｌ未満であると、十分な亜鉛が供給されずに酸化物層の形成がおこらなくなる。一方、１００ｇ／ｌを超えると形成される酸化物層に含まれる硫酸濃度が高くなり、その後に行われる化成処理工程で酸化物が溶解したときに処理液を汚染することが懸念される。
安定な亜鉛化合物を酸化物層として形成させるためには、亜鉛イオンを硫酸塩として添加するのが好ましい。硫酸塩として添加した場合、形成される酸化物層に硫酸イオンが取り込まれ、酸化物層を安定させる効果があると思われる。
また、前述した通り、単に処理液中に亜鉛イオンを予め含有させるだけでは酸化膜の形成は促進されない。そこで、本発明では、ｐＨを亜鉛酸化物が生成しやすいｐＨ４~６とする必要がある。処理液のｐＨを４~６とすれば、めっき皮膜の亜鉛がわずかに溶出して起こる表面ｐＨの微小な上昇により亜鉛が水酸化物として生成する。これらの結果として、亜鉛溶出時間を省略し、かつ、亜鉛酸化物の生成が可能となる。ｐＨが６を超える場合には水溶液中で亜鉛イオンは沈殿（水酸化物の形成）し、鋼板表面に酸化物として形成されなくなる。また、ｐＨが４未満の場合は、上に記したように、ｐＨ上昇の遅延による酸化物層の形成の阻害となる。
水溶液の温度については、２０~７０℃とする。酸化物層の形成反応は、水溶液への接触後、所定時間保持する際に生じるため、保持時の板温を２０~７０℃の範囲に制御することは有効である。２０℃未満であると、酸化物層の生成反応に長時間を有し、生産性の低下を招く。一方、７０℃を超える場合には、反応は比較的すばやく進行するが、逆に鋼板表面に処理ムラを発生しやすくなる。
特許文献３および４で用いられる水溶液は酸性であることと、ｐＨ緩衝作用を有することを特徴としている。しかし、本発明は亜鉛イオンを含む水溶液を使用するため、水溶液のｐＨが高くして亜鉛の溶解を十分に起こさなくても、十分な酸化物層を形成させることができる。また、ｐＨの上昇が速やかに起こった方が酸化物の形成には有利であると思われる。ゆえに、ｐＨ緩衝作用は必ずしも必須ではない。
本発明では、鋼板表面に接触する水溶液中には亜鉛を含有していれば、摺動性に優れた酸化物層を安定して形成できるため、水溶液中にその他の金属イオンや無機化合物などを不純物として、あるいは故意に含有していても本発明の効果が損なわれるものではない。そして、Ｎ、Ｐ、Ｂ、Ｃｌ、Ｎａ、Ｍｎ、Ｃａ、Ｍｇ、Ｂａ、Ｓｒ、Ｓｉなどが酸化物層中に取り込まれても、本発明の効果が損なわれない限り適用可能である。
亜鉛系めっき鋼板を以上からなる水溶液に接触させた後に、その水溶液が薄い液膜状で鋼板表面に存在することが望ましい。これは、鋼板表面に存在する水溶液の量が多いと、亜鉛の溶解が生じても水溶液のｐＨが上昇しにくく、酸化物層を形成するまでに長時間を有するためである。この観点から、鋼板表面に形成する水溶液膜の量は、３０ｇ／ｍ２以下に調整することが好ましく有効である。また、液膜の乾燥を防ぐ目的で５ｇ／ｍ２以上の液膜量が適している。以上より、好ましくは、前記水溶液に接触後に鋼板表面に形成する液膜は５~３０ｇ／ｍ２とする。なお、水溶液膜量の調整は、絞りロール、エアワイピング等で行うことができる。
また、水溶液に浸漬後、水洗までの時間（水洗までの保持時間）は、１~６０秒間とする。水洗までの時間が１秒未満であると、十分な酸化物層が形成される前に、水溶液が洗い流されるため、摺動性の向上効果が得られない。一方、６０秒を超えた場合の保持時間では生産性を落としてしまう。短時間でも安定的に製造することを本発明の目的とするため、本発明の効果を十分に発揮する点から保持時間は６０秒以下とする。
以上より、本発明のめっき鋼板の表面には、金属成分として亜鉛を主体として含み、平均厚さが１０ｎｍ以上の酸化物層が得られることになる。
なお、亜鉛を主体とするとは、金属成分としては亜鉛を５０質量％以上含むことである。
なお、本発明における酸化物層とは、金属成分として亜鉛を主体として含んだ酸化物及び／又は水酸化物などからなる層のことである。この酸化物層の平均厚さが１０ｎｍ以上であることが必要である。酸化物層の平均厚さが１０ｎｍ未満に薄くなると摺動抵抗を低下させる効果が不十分となる。一方、亜鉛を必須成分として含む酸化物層の平均厚さが１００ｎｍを越えると、プレス加工中に皮膜が破壊し摺動抵抗が上昇し、また溶接性が低下する傾向にあるため好ましくない。
なお、亜鉛系めっき鋼板を、亜鉛を含む水溶液に接触処理させる方法には特に制限はなく、めっき鋼板を水溶液に浸漬する方法、めっき鋼板に水溶液をスプレーする方法、塗布ロールを介して水溶液をめっき鋼板に塗布する方法等があり、最終的に薄い液膜状で鋼板表面に存在することが望ましい。
また本発明に係る合金化溶融亜鉛めっき鋼板を製造するに関しては、めっき浴中にＡｌが添加されていることが必要であるが、Ａｌ以外の添加元素成分は特に限定されない。すなわち、Ａｌの他にＰｂ、Ｓｂ、Ｓｉ、Ｓｎ、Ｍｇ、Ｍｎ、Ｎｉ、Ｔｉ、Ｌｉ、Ｃｕなどが含有または添加されていても、本発明の効果が損なわれない限り適用可能である。 In the present invention, after zinc plating is applied to a steel sheet, the steel sheet is contact-treated with an aqueous solution, held for 1 to 60 seconds after completion of the contact processing, and then washed with water and dried, whereby an oxide is formed on the surface of the zinc-based plated steel sheet. In forming the layer, the aqueous solution contains zinc ions in a zinc ion concentration range of 5 to 100 g / l, has a pH of 4 to 6, and a liquid temperature of 20 to 70 ° C. Thus, it is an important requirement and feature in the present invention that an aqueous solution containing a predetermined concentration of zinc ions and having a defined pH and liquid temperature is used as an aqueous solution for contact-treating a steel sheet. Thereby, a sufficient oxide layer can be formed in a short time to ensure good press moldability.
The term “after contact treatment” means that after the immersion process is completed in the case of immersion treatment, after the spray process is completed in the case of spray treatment, and after the application step is completed in the case of roll coating. is there.
By using an aqueous solution containing zinc ions as the aqueous solution for contact-treating the steel sheet, it is possible to omit the elution time of zinc. At this time, the zinc ion has a zinc ion concentration in the range of 5 to 100 g / l. When the zinc ion concentration is less than 5 g / l, sufficient zinc is not supplied and the oxide layer is not formed. On the other hand, when the concentration exceeds 100 g / l, the concentration of sulfuric acid contained in the oxide layer to be formed becomes high, and there is a concern that the treatment liquid is contaminated when the oxide is dissolved in the chemical conversion treatment step performed thereafter.
In order to form a stable zinc compound as an oxide layer, it is preferable to add zinc ions as sulfates. When added as a sulfate, sulfate ions are taken into the oxide layer to be formed, which seems to have an effect of stabilizing the oxide layer.
Further, as described above, the formation of the oxide film is not promoted simply by previously containing zinc ions in the treatment liquid. Therefore, in the present invention, it is necessary to adjust the pH topH 4 to 6 where zinc oxide is easily generated. If the pH of the treatment solution is 4 to 6, zinc is generated as a hydroxide by a slight increase in surface pH caused by slight elution of zinc in the plating film. As a result of these, zinc elution time can be omitted and zinc oxide can be produced. When the pH exceeds 6, zinc ions precipitate in the aqueous solution (formation of hydroxide), and are no longer formed as oxides on the steel sheet surface. On the other hand, when the pH is less than 4, as described above, the formation of the oxide layer is hindered due to the delay of the pH increase.
The temperature of the aqueous solution is 20 to 70 ° C. Since the formation reaction of the oxide layer occurs when it is held for a predetermined time after contact with the aqueous solution, it is effective to control the plate temperature at the time of holding in the range of 20 to 70 ° C. If it is lower than 20 ° C., the reaction for forming the oxide layer takes a long time, resulting in a decrease in productivity. On the other hand, when the temperature exceeds 70 ° C., the reaction proceeds relatively quickly, but on the contrary, processing unevenness tends to occur on the surface of the steel sheet.
The aqueous solutions used in Patent Documents 3 and 4 are characterized by being acidic and having a pH buffering action. However, since the present invention uses an aqueous solution containing zinc ions, a sufficient oxide layer can be formed even if the pH of the aqueous solution is high and zinc does not sufficiently dissolve. Moreover, it seems that it is advantageous for the formation of the oxide that the pH rises rapidly. Therefore, the pH buffering action is not always essential.
In the present invention, if zinc is contained in the aqueous solution in contact with the steel sheet surface, an oxide layer excellent in slidability can be stably formed. Therefore, other metal ions, inorganic compounds, and the like are added to the aqueous solution. Even if it contains as an impurity or deliberately, the effect of this invention is not impaired. And even if N, P, B, Cl, Na, Mn, Ca, Mg, Ba, Sr, Si, etc. are taken into the oxide layer, they are applicable as long as the effect of the present invention is not impaired.
After the galvanized steel sheet is brought into contact with the aqueous solution comprising the above, it is desirable that the aqueous solution exists in the form of a thin liquid film on the steel sheet surface. This is because if the amount of the aqueous solution existing on the surface of the steel sheet is large, the pH of the aqueous solution is unlikely to rise even if zinc is dissolved, and it takes a long time to form the oxide layer. From this viewpoint, it is preferable and effective to adjust the amount of the aqueous film formed on the surface of the steel sheet to 30 g / m 2 or less. Further, a liquid film amount of 5 g / m 2 or more is suitable for the purpose of preventing the liquid film from drying. From the above, preferably, the liquid film formed on the surface of the steel sheet after contacting with the aqueous solution is 5 to 30 g / m 2 . The amount of the aqueous film can be adjusted by a squeeze roll, air wiping or the like.
In addition, the time from immersing in an aqueous solution to washing with water (holding time until washing with water) is 1 to 60 seconds. If the time until washing with water is less than 1 second, the aqueous solution is washed out before the sufficient oxide layer is formed, so that the effect of improving the slidability cannot be obtained. On the other hand, productivity is reduced in the holding time when it exceeds 60 seconds. Since it is an object of the present invention to manufacture stably even in a short time, the holding time is set to 60 seconds or less from the viewpoint of sufficiently exerting the effects of the present invention.
From the above, an oxide layer containing zinc as a main component and having an average thickness of 10 nm or more is obtained on the surface of the plated steel sheet of the present invention.
The phrase “mainly composed of zinc” means that the metal component contains 50% by mass or more of zinc.
The oxide layer in the present invention is a layer made of an oxide and / or hydroxide mainly containing zinc as a metal component. The average thickness of the oxide layer needs to be 10 nm or more. When the average thickness of the oxide layer is reduced to less than 10 nm, the effect of reducing the sliding resistance becomes insufficient. On the other hand, if the average thickness of the oxide layer containing zinc as an essential component exceeds 100 nm, the coating is destroyed during press working, the sliding resistance increases, and the weldability tends to decrease, which is not preferable.
In addition, there is no restriction | limiting in particular in the method of making a zinc-based plated steel plate contact-process with the aqueous solution containing zinc, the method of immersing a plated steel plate in aqueous solution, the method of spraying aqueous solution on a plated steel plate, and plating aqueous solution through a coating roll There is a method of applying to a steel plate, and it is desirable that it is finally in the form of a thin liquid film on the steel plate surface.
Moreover, regarding the production of the alloyed hot-dip galvanized steel sheet according to the present invention, it is necessary that Al be added to the plating bath, but the additive element components other than Al are not particularly limited. That is, even if Pb, Sb, Si, Sn, Mg, Mn, Ni, Ti, Li, Cu, or the like other than Al is contained or added, it is applicable as long as the effect of the present invention is not impaired.
なお、接触処理終了後とは、浸漬処理の場合は浸漬工程を終了した後を、スプレー処理の場合はスプレー工程が終了した後を、ロール塗布の場合は塗布工程が終了した後を示すものである。
鋼板を接触処理する水溶液として、亜鉛イオンを含有する水溶液を使用することにより、亜鉛の溶出時間を省略することが可能となる。この時、亜鉛イオンは亜鉛イオン濃度として、５~１００ｇ／ｌの範囲とする。亜鉛イオン濃度が５ｇ／ｌ未満であると、十分な亜鉛が供給されずに酸化物層の形成がおこらなくなる。一方、１００ｇ／ｌを超えると形成される酸化物層に含まれる硫酸濃度が高くなり、その後に行われる化成処理工程で酸化物が溶解したときに処理液を汚染することが懸念される。
安定な亜鉛化合物を酸化物層として形成させるためには、亜鉛イオンを硫酸塩として添加するのが好ましい。硫酸塩として添加した場合、形成される酸化物層に硫酸イオンが取り込まれ、酸化物層を安定させる効果があると思われる。
また、前述した通り、単に処理液中に亜鉛イオンを予め含有させるだけでは酸化膜の形成は促進されない。そこで、本発明では、ｐＨを亜鉛酸化物が生成しやすいｐＨ４~６とする必要がある。処理液のｐＨを４~６とすれば、めっき皮膜の亜鉛がわずかに溶出して起こる表面ｐＨの微小な上昇により亜鉛が水酸化物として生成する。これらの結果として、亜鉛溶出時間を省略し、かつ、亜鉛酸化物の生成が可能となる。ｐＨが６を超える場合には水溶液中で亜鉛イオンは沈殿（水酸化物の形成）し、鋼板表面に酸化物として形成されなくなる。また、ｐＨが４未満の場合は、上に記したように、ｐＨ上昇の遅延による酸化物層の形成の阻害となる。
水溶液の温度については、２０~７０℃とする。酸化物層の形成反応は、水溶液への接触後、所定時間保持する際に生じるため、保持時の板温を２０~７０℃の範囲に制御することは有効である。２０℃未満であると、酸化物層の生成反応に長時間を有し、生産性の低下を招く。一方、７０℃を超える場合には、反応は比較的すばやく進行するが、逆に鋼板表面に処理ムラを発生しやすくなる。
特許文献３および４で用いられる水溶液は酸性であることと、ｐＨ緩衝作用を有することを特徴としている。しかし、本発明は亜鉛イオンを含む水溶液を使用するため、水溶液のｐＨが高くして亜鉛の溶解を十分に起こさなくても、十分な酸化物層を形成させることができる。また、ｐＨの上昇が速やかに起こった方が酸化物の形成には有利であると思われる。ゆえに、ｐＨ緩衝作用は必ずしも必須ではない。
本発明では、鋼板表面に接触する水溶液中には亜鉛を含有していれば、摺動性に優れた酸化物層を安定して形成できるため、水溶液中にその他の金属イオンや無機化合物などを不純物として、あるいは故意に含有していても本発明の効果が損なわれるものではない。そして、Ｎ、Ｐ、Ｂ、Ｃｌ、Ｎａ、Ｍｎ、Ｃａ、Ｍｇ、Ｂａ、Ｓｒ、Ｓｉなどが酸化物層中に取り込まれても、本発明の効果が損なわれない限り適用可能である。
亜鉛系めっき鋼板を以上からなる水溶液に接触させた後に、その水溶液が薄い液膜状で鋼板表面に存在することが望ましい。これは、鋼板表面に存在する水溶液の量が多いと、亜鉛の溶解が生じても水溶液のｐＨが上昇しにくく、酸化物層を形成するまでに長時間を有するためである。この観点から、鋼板表面に形成する水溶液膜の量は、３０ｇ／ｍ２以下に調整することが好ましく有効である。また、液膜の乾燥を防ぐ目的で５ｇ／ｍ２以上の液膜量が適している。以上より、好ましくは、前記水溶液に接触後に鋼板表面に形成する液膜は５~３０ｇ／ｍ２とする。なお、水溶液膜量の調整は、絞りロール、エアワイピング等で行うことができる。
また、水溶液に浸漬後、水洗までの時間（水洗までの保持時間）は、１~６０秒間とする。水洗までの時間が１秒未満であると、十分な酸化物層が形成される前に、水溶液が洗い流されるため、摺動性の向上効果が得られない。一方、６０秒を超えた場合の保持時間では生産性を落としてしまう。短時間でも安定的に製造することを本発明の目的とするため、本発明の効果を十分に発揮する点から保持時間は６０秒以下とする。
以上より、本発明のめっき鋼板の表面には、金属成分として亜鉛を主体として含み、平均厚さが１０ｎｍ以上の酸化物層が得られることになる。
なお、亜鉛を主体とするとは、金属成分としては亜鉛を５０質量％以上含むことである。
なお、本発明における酸化物層とは、金属成分として亜鉛を主体として含んだ酸化物及び／又は水酸化物などからなる層のことである。この酸化物層の平均厚さが１０ｎｍ以上であることが必要である。酸化物層の平均厚さが１０ｎｍ未満に薄くなると摺動抵抗を低下させる効果が不十分となる。一方、亜鉛を必須成分として含む酸化物層の平均厚さが１００ｎｍを越えると、プレス加工中に皮膜が破壊し摺動抵抗が上昇し、また溶接性が低下する傾向にあるため好ましくない。
なお、亜鉛系めっき鋼板を、亜鉛を含む水溶液に接触処理させる方法には特に制限はなく、めっき鋼板を水溶液に浸漬する方法、めっき鋼板に水溶液をスプレーする方法、塗布ロールを介して水溶液をめっき鋼板に塗布する方法等があり、最終的に薄い液膜状で鋼板表面に存在することが望ましい。
また本発明に係る合金化溶融亜鉛めっき鋼板を製造するに関しては、めっき浴中にＡｌが添加されていることが必要であるが、Ａｌ以外の添加元素成分は特に限定されない。すなわち、Ａｌの他にＰｂ、Ｓｂ、Ｓｉ、Ｓｎ、Ｍｇ、Ｍｎ、Ｎｉ、Ｔｉ、Ｌｉ、Ｃｕなどが含有または添加されていても、本発明の効果が損なわれない限り適用可能である。 In the present invention, after zinc plating is applied to a steel sheet, the steel sheet is contact-treated with an aqueous solution, held for 1 to 60 seconds after completion of the contact processing, and then washed with water and dried, whereby an oxide is formed on the surface of the zinc-based plated steel sheet. In forming the layer, the aqueous solution contains zinc ions in a zinc ion concentration range of 5 to 100 g / l, has a pH of 4 to 6, and a liquid temperature of 20 to 70 ° C. Thus, it is an important requirement and feature in the present invention that an aqueous solution containing a predetermined concentration of zinc ions and having a defined pH and liquid temperature is used as an aqueous solution for contact-treating a steel sheet. Thereby, a sufficient oxide layer can be formed in a short time to ensure good press moldability.
The term “after contact treatment” means that after the immersion process is completed in the case of immersion treatment, after the spray process is completed in the case of spray treatment, and after the application step is completed in the case of roll coating. is there.
By using an aqueous solution containing zinc ions as the aqueous solution for contact-treating the steel sheet, it is possible to omit the elution time of zinc. At this time, the zinc ion has a zinc ion concentration in the range of 5 to 100 g / l. When the zinc ion concentration is less than 5 g / l, sufficient zinc is not supplied and the oxide layer is not formed. On the other hand, when the concentration exceeds 100 g / l, the concentration of sulfuric acid contained in the oxide layer to be formed becomes high, and there is a concern that the treatment liquid is contaminated when the oxide is dissolved in the chemical conversion treatment step performed thereafter.
In order to form a stable zinc compound as an oxide layer, it is preferable to add zinc ions as sulfates. When added as a sulfate, sulfate ions are taken into the oxide layer to be formed, which seems to have an effect of stabilizing the oxide layer.
Further, as described above, the formation of the oxide film is not promoted simply by previously containing zinc ions in the treatment liquid. Therefore, in the present invention, it is necessary to adjust the pH to
The temperature of the aqueous solution is 20 to 70 ° C. Since the formation reaction of the oxide layer occurs when it is held for a predetermined time after contact with the aqueous solution, it is effective to control the plate temperature at the time of holding in the range of 20 to 70 ° C. If it is lower than 20 ° C., the reaction for forming the oxide layer takes a long time, resulting in a decrease in productivity. On the other hand, when the temperature exceeds 70 ° C., the reaction proceeds relatively quickly, but on the contrary, processing unevenness tends to occur on the surface of the steel sheet.
The aqueous solutions used in
In the present invention, if zinc is contained in the aqueous solution in contact with the steel sheet surface, an oxide layer excellent in slidability can be stably formed. Therefore, other metal ions, inorganic compounds, and the like are added to the aqueous solution. Even if it contains as an impurity or deliberately, the effect of this invention is not impaired. And even if N, P, B, Cl, Na, Mn, Ca, Mg, Ba, Sr, Si, etc. are taken into the oxide layer, they are applicable as long as the effect of the present invention is not impaired.
After the galvanized steel sheet is brought into contact with the aqueous solution comprising the above, it is desirable that the aqueous solution exists in the form of a thin liquid film on the steel sheet surface. This is because if the amount of the aqueous solution existing on the surface of the steel sheet is large, the pH of the aqueous solution is unlikely to rise even if zinc is dissolved, and it takes a long time to form the oxide layer. From this viewpoint, it is preferable and effective to adjust the amount of the aqueous film formed on the surface of the steel sheet to 30 g / m 2 or less. Further, a liquid film amount of 5 g / m 2 or more is suitable for the purpose of preventing the liquid film from drying. From the above, preferably, the liquid film formed on the surface of the steel sheet after contacting with the aqueous solution is 5 to 30 g / m 2 . The amount of the aqueous film can be adjusted by a squeeze roll, air wiping or the like.
In addition, the time from immersing in an aqueous solution to washing with water (holding time until washing with water) is 1 to 60 seconds. If the time until washing with water is less than 1 second, the aqueous solution is washed out before the sufficient oxide layer is formed, so that the effect of improving the slidability cannot be obtained. On the other hand, productivity is reduced in the holding time when it exceeds 60 seconds. Since it is an object of the present invention to manufacture stably even in a short time, the holding time is set to 60 seconds or less from the viewpoint of sufficiently exerting the effects of the present invention.
From the above, an oxide layer containing zinc as a main component and having an average thickness of 10 nm or more is obtained on the surface of the plated steel sheet of the present invention.
The phrase “mainly composed of zinc” means that the metal component contains 50% by mass or more of zinc.
The oxide layer in the present invention is a layer made of an oxide and / or hydroxide mainly containing zinc as a metal component. The average thickness of the oxide layer needs to be 10 nm or more. When the average thickness of the oxide layer is reduced to less than 10 nm, the effect of reducing the sliding resistance becomes insufficient. On the other hand, if the average thickness of the oxide layer containing zinc as an essential component exceeds 100 nm, the coating is destroyed during press working, the sliding resistance increases, and the weldability tends to decrease, which is not preferable.
In addition, there is no restriction | limiting in particular in the method of making a zinc-based plated steel plate contact-process with the aqueous solution containing zinc, the method of immersing a plated steel plate in aqueous solution, the method of spraying aqueous solution on a plated steel plate, and plating aqueous solution through a coating roll There is a method of applying to a steel plate, and it is desirable that it is finally in the form of a thin liquid film on the steel plate surface.
Moreover, regarding the production of the alloyed hot-dip galvanized steel sheet according to the present invention, it is necessary that Al be added to the plating bath, but the additive element components other than Al are not particularly limited. That is, even if Pb, Sb, Si, Sn, Mg, Mn, Ni, Ti, Li, Cu, or the like other than Al is contained or added, it is applicable as long as the effect of the present invention is not impaired.
次に、本発明を実施例により更に詳細に説明する。
板厚０．８ｍｍの冷延鋼板上に、片面当たりの付着量が４５ｇ／ｍ２、Ａｌ濃度が０．２０質量％の溶融亜鉛めっきを施した後に、調質圧延を行ったＧＩ鋼板を作製した。また、板厚０．８ｍｍの冷延鋼板上に、常法の合金化溶融亜鉛めっき法により、片面当たりのめっき付着量が４５ｇ／ｍ２、Ｆｅ濃度が１０質量％、Ａｌ濃度が０．２０質量％のめっき皮膜を形成し、更に調質圧延を行ったＧＡ鋼板を作製した。また、板厚０．８ｍｍの冷延鋼板上に、常法の電気亜鉛めっき法により、片面当たりのめっき付着量が３０ｇ／ｍ２のめっき皮膜を有するＥＧ鋼板を作成した。
引き続き、図１に示す構成の処理設備を用いて酸化物層を形成した。まず、上記により得られたＧＩ鋼板、ＧＡ鋼板およびＥＧ鋼板などの鋼板Ｓを、溶液槽２で、表１−１および表１−２に示す処理液組成、温度およびｐＨが異なる水溶液に浸漬した。次いで、絞りロール３で鋼板表面の液膜量を調整した。液膜量の調整は、絞りロールの圧力を変化させることで行った。次いで、洗浄槽５、洗浄槽６を空通しし、洗浄槽７で５０℃の温水を鋼板にスプレーして洗浄し、ドライヤ８で乾燥し、めっき表面に酸化物層を形成した。なお、溶液層２の前に洗浄槽１を設けることができる。
溶液槽２で浸漬処理を行う水溶液は、亜鉛イオンを添加する目的で硫酸亜鉛七水和物を所定量添加した水溶液を使用した。なお、一部、比較のために酢酸ナトリウム２０ｇ／Ｌを含んだ溶液を硫酸でｐＨを調整した溶液も用いた。
水洗までの保持時間は、絞りロール３で液膜量の調整を行い、洗浄槽７で洗浄開始するまでの時間であり、ラインスピードを変化させることで調整するとともに、一部、絞りロール３出側のシャワー水洗装置４を用いて絞り直後に鋼板を洗浄するものも作製した。
次に、以上のように作製した鋼板について、自動車用外板として十分な外観を有するか判定するとともに、プレス成形性を簡易的に評価する手法として摩擦係数の測定、および実際の成形性をより詳細にシミュレートする目的で球頭張出試験を実施した。なお、測定方法は以下の通りである。
（１）プレス成形性評価試験（摩擦係数測定試験）
プレス成形性を評価するために、各供試材の摩擦係数を以下のようにして測定した。
図２は摩擦係数測定装置を示す概略正面図である。同図に示すように、供試材から採取した摩擦係数測定用試料１１が試料台１２に固定され、試料台１２は、水平移動可能なスライドテーブル１３の上面に固定されている。スライドテーブル１３の下面には、これに接したローラ１４を有する上下動可能なスライドテーブル支持台１５が設けられ、これを押し上げることによりビード１６による摩擦係数測定用試料１１への押し付け荷重Ｎを測定するための第１ロードセル１７がスライドテーブル支持台１５に取り付けられている。上記押し付け力を作用させた状態でスライドテーブル１３をレール１９に沿って水平移動させるための摺動抵抗力Ｆを測定するために第２ロードセル１８が、スライドテーブル１３の一方の端部に取り付けられている。なお、潤滑油としてスギムラ化学社製のプレス用洗浄油プレトンＲ３５２Ｌを摩擦係数測定用試料１１の表面に塗布して試験を行った。
図３と図４は使用したビードの形状・寸法を示す概略斜視図である。ビード１６の下面が試料１１の表面に押し付けられた状態で摺動する。図３に示すビード１６の形状は幅１０ｍｍ、試料の摺動方向長さ１２ｍｍ、摺動方向両端の下部は曲率４．５ｍｍＲの曲面で構成され、試料が押し付けられるビード下面は幅１０ｍｍ、摺動方向長さ３ｍｍの平面を有する。図４に示すビード１６の形状は幅１０ｍｍ、試料の摺動方向長さ６９ｍｍ、摺動方向両端の下部は曲率４．５ｍｍＲの曲面で構成され、試料が押し付けられるビード下面は幅１０ｍｍ、摺動方向長さ６０ｍｍの平面を有する。
摩擦係数測定試験は下に示す２条件で行った。
［条件１］
図３に示すビードを用い、押し付け荷重Ｎ：４００ｋｇｆ、試料の引き抜き速度（スライドテーブル１３の水平移動速度）：１００ｃｍ／ｍｉｎとした。
［条件２］
図４に示すビードを用い、押し付け荷重Ｎ：４００ｋｇｆ、試料の引き抜き速度（スライドテーブル１３の水平移動速度）：２０ｃｍ／ｍｉｎとした。
供試材とビードとの間の摩擦係数μは、式：μ＝Ｆ／Ｎで算出した。
（２）球頭張出試験
２００×２００ｍｍサイズの供試材に対して、１５０ｍｍφのポンチを使用して、液圧バルジ試験機により張出成形を行い、破断が生じた際の最大成形高さを測定した。この際、材料の流入を阻止する目的で１００Ｔｏｎのしわ押さえ力をかけ、ポンチが接触する面にのみ潤滑油を塗布した。使用した潤滑油は、前述した摩擦係数測定試験と同様のものである。
（３）酸化物層の厚さ（酸化膜厚）の測定
膜厚が９６ｎｍの熱酸化ＳｉＯ２膜が形成されたＳｉウエハを参照物質として用い、蛍光Ｘ線分析装置でＯ・Ｋα Ｘ線を測定することで、ＳｉＯ２換算の酸化層の平均厚さを求めた。分析面積は３０ｍｍφである。
以上より得られた試験結果を表１−１および表１−２に示す。
表１−１および表１−２に示す試験結果から下記事項が明らかとなった。
（１）Ｎｏ．１、４７および６０は溶液による処理を行っていないため、平坦部に摺動性を向上させるのに十分な酸化膜が形成されず、摩擦係数が高い。
（２）Ｎｏ．２~４、Ｎｏ．４８~５０およびＮｏ．６１~６３はｐＨ緩衝作用を有する酸性溶液を用いた比較例である。３０秒以上では摩擦係数が低く、最大形成高さも高くなっているものの、１０秒の処理では十分な摩擦係数の低下および最大成形高さの向上を満たしていない。
（３）Ｎｏ．５~７は、ｐＨ緩衝作用を有する酸性溶液を用いた比較例である。高い摩擦係数を示している。
（４）Ｎｏ．８~１０、Ｎｏ．５１~５３およびＮｏ．６４~６６は、亜鉛イオンを含有しているが、その量が本発明の範囲よりも少ない比較例である。３０秒以上では摩擦係数が低く、最大形成高さも高くなっているものの、１０秒の処理では十分な摩擦係数の低下および最大成形高さの向上を満たしていない。
（５）Ｎｏ．１１~１３、Ｎｏ．５４~５６およびＮｏ．６７~６９は、は、亜鉛イオンを含有した溶液での処理を行った本発明例であり、摩擦係数が低下し、最大成形高さも増加している。また、Ｎｏ．１４~１６およびＮｏ．４４~４６はＮｏ．１１~１３と同一の処理条件で液中の亜鉛イオン濃度を増加させた本発明例である。摩擦係数が低位安定化し、最大成形高さもさらに増加している。同様に、Ｎｏ．５７~５９およびＮｏ．７０~７２はＮｏ．５４~５６と同一の処理条件で液中の亜鉛イオン濃度を増加させた本発明例である。摩擦係数が低位安定化し、最大成形高さもさらに増加している。
（６）Ｎｏ．１７~２２は、鋼板表面に溶液膜を形成し、水洗を施すまでの時間を変化させた例である。保持なく水洗を行ったＮｏ．１７ではわずかに摩擦係数が低下するのみであるのに対して、１秒以上の保持時間となるＮｏ．１８~２２は、摩擦係数は低下し、張出性も安定向上している。
（７）Ｎｏ．２３~４０は、処理液温度を変化させた例であるが、処理液温度の低いＮｏ．２３~２５は、それ以外の例と比較して、摩擦係数および最大成形高さの向上効果が十分でない。一方、Ｎｏ．３２~３４は、処理液温度の高い例であり、摩擦係数や最大成形高さの向上効果は十分であるが、処理ムラが多く見られ、自動車用外板として良好な外観を示していなかった。
（８）Ｎｏ．３５~４０は、Ｎｏ．２０~２２に対して、液膜形成量を変化させた本発明例である。水洗までの保持時間が同一のもので比較すると、液膜量が多い場合には、十分な摩擦係数の低下および最大成形高さの向上が得られているものの、液膜量が少ない場合に比べるとやや摩擦係数が高く最大成形高さも低くなっている。
（９）Ｎｏ．４１~４３はｐＨが本発明の範囲よりも低い処理液を用いた比較例であるが、Ｎｏ．２０~２２と比較して摩擦係数の低下の効果は認められず、最大成形高さの向上も見られない。
図５は、表１−１および表１−２のＮｏ．８~２２及びＮｏ．４４~４６を用いて、酸化膜厚への亜鉛イオン濃度の影響を示した図である。図５によれば、亜鉛の濃度が５ｇ／ｌ以上であれば保持時間が短い場合（例えば、１０秒）でも酸化膜厚が十分に厚く形成され、保持時間が短い場合に酸化膜厚が薄くなるという本発明の課題が解決されていることがわかる。 Next, the present invention will be described in more detail with reference to examples.
On a cold-rolled steel sheet with a thickness of 0.8 mm, a GI steel sheet was prepared by applying hot-dip galvanizing with an adhesion amount per side of 45 g / m 2 and an Al concentration of 0.20 mass%, followed by temper rolling. did. Further, on a cold-rolled steel sheet having a thickness of 0.8 mm, the amount of plating adhesion per side is 45 g / m 2 , the Fe concentration is 10% by mass, and the Al concentration is 0.20 by a conventional alloying hot dip galvanizing method. A GA steel sheet having a mass% plating film formed thereon and further subjected to temper rolling was prepared. Moreover, the EG steel plate which has a plating film | membrane whose plating adhesion amount per single side | surface is 30 g / m < 2 > on the cold rolled steel plate with a plate | board thickness of 0.8 mm with the usual electrogalvanization method was created.
Subsequently, an oxide layer was formed using a processing facility having the configuration shown in FIG. First, steel plates S such as GI steel plates, GA steel plates and EG steel plates obtained as described above were immersed in aqueous solutions having different treatment liquid compositions, temperatures and pHs shown in Table 1-1 and Table 1-2 in thesolution tank 2. . Next, the amount of liquid film on the steel sheet surface was adjusted with the drawing roll 3. The liquid film amount was adjusted by changing the pressure of the squeeze roll. Next, the cleaning tank 5 and the cleaning tank 6 were evacuated, and the cleaning tank 7 was sprayed and washed with hot water of 50 ° C. on the steel plate, and dried with a dryer 8 to form an oxide layer on the plating surface. A cleaning tank 1 can be provided in front of the solution layer 2.
The aqueous solution in which the immersion treatment was performed in thesolution tank 2 was an aqueous solution to which a predetermined amount of zinc sulfate heptahydrate was added for the purpose of adding zinc ions. For comparison, a solution containing 20 g / L of sodium acetate with a pH adjusted with sulfuric acid was also used for comparison.
The holding time until water washing is the time until the liquid film amount is adjusted with the squeezingroll 3 and the cleaning is started in the cleaning tank 7, and is adjusted by changing the line speed. What washed the steel plate immediately after squeezing using the shower water washing apparatus 4 of the side was also produced.
Next, regarding the steel sheet produced as described above, it is determined whether it has a sufficient appearance as an automobile outer plate, and as a method for simply evaluating the press formability, the measurement of the friction coefficient and the actual formability are further improved. A ball head overhang test was conducted for the purpose of simulating in detail. The measuring method is as follows.
(1) Press formability evaluation test (Friction coefficient measurement test)
In order to evaluate the press formability, the friction coefficient of each test material was measured as follows.
FIG. 2 is a schematic front view showing the friction coefficient measuring apparatus. As shown in the figure, a frictioncoefficient measurement sample 11 collected from a test material is fixed to a sample table 12, and the sample table 12 is fixed to the upper surface of a slide table 13 that can move horizontally. On the lower surface of the slide table 13, there is provided a slide table support base 15 having a roller 14 in contact with the slide table 13 and capable of moving up and down. By pushing up the slide table support base 15, the pressing load N applied to the friction coefficient measuring sample 11 by the beads 16 is measured. A first load cell 17 is attached to the slide table support 15. A second load cell 18 is attached to one end of the slide table 13 in order to measure the sliding resistance force F for horizontally moving the slide table 13 along the rail 19 with the pressing force applied. ing. In addition, the cleaning oil Preton R352L for press made by Sugimura Chemical Co., Ltd. as a lubricating oil was applied to the surface of the friction coefficient measurement sample 11 and tested.
3 and 4 are schematic perspective views showing the shape and dimensions of the beads used. Thebead 16 slides with its lower surface pressed against the surface of the sample 11. The bead 16 shown in FIG. 3 has a width of 10 mm, a length of 12 mm in the sliding direction of the sample, and a lower portion at both ends in the sliding direction is formed by a curved surface having a curvature of 4.5 mmR. It has a plane with a direction length of 3 mm. The bead 16 shown in FIG. 4 has a width of 10 mm, a length of 69 mm in the sliding direction of the sample, and a lower portion at both ends in the sliding direction is formed by a curved surface having a curvature of 4.5 mmR. It has a plane with a direction length of 60 mm.
The friction coefficient measurement test was performed under the following two conditions.
[Condition 1]
The bead shown in FIG. 3 was used, the pressing load N was 400 kgf, and the sample drawing speed (horizontal moving speed of the slide table 13) was 100 cm / min.
[Condition 2]
The bead shown in FIG. 4 was used, the pressing load N was 400 kgf, and the sample drawing speed (horizontal moving speed of the slide table 13) was 20 cm / min.
The friction coefficient μ between the test material and the bead was calculated by the formula: μ = F / N.
(2) Ball head overhang test Using a 150 mmφ punch for a 200 x 200 mm sample material, the maximum forming height when a bulge was formed by a hydraulic bulge tester. Was measured. At this time, a wrinkle holding force of 100 Ton was applied for the purpose of preventing the inflow of the material, and the lubricating oil was applied only to the surface in contact with the punch. The used lubricating oil is the same as that in the friction coefficient measurement test described above.
(3) Measurement of oxide layer thickness (oxide film thickness) Using a Si wafer on which a thermally oxidized SiO2 film with a film thickness of 96 nm is formed as a reference material, measure O / Kα X-rays with a fluorescent X-ray analyzer. Thus, the average thickness of the oxide layer in terms of SiO 2 was obtained. The analysis area is 30 mmφ.
The test results obtained above are shown in Table 1-1 and Table 1-2.
The following items became clear from the test results shown in Table 1-1 and Table 1-2.
(1) No. Since 1, 47 and 60 are not treated with a solution, an oxide film sufficient to improve the slidability is not formed on the flat portion, and the coefficient of friction is high.
(2) No. 2-4, no. 48-50 and no. 61 to 63 are comparative examples using an acidic solution having a pH buffering action. Although the friction coefficient is low and the maximum formation height is high at 30 seconds or more, the treatment for 10 seconds does not satisfy a sufficient decrease in the friction coefficient and an improvement in the maximum molding height.
(3) No. 5 to 7 are comparative examples using an acidic solution having a pH buffering action. It shows a high coefficient of friction.
(4) No. 8-10, no. 51-53 and no. 64 to 66 are comparative examples which contain zinc ions but whose amount is less than the range of the present invention. Although the friction coefficient is low and the maximum formation height is high at 30 seconds or more, the treatment for 10 seconds does not satisfy a sufficient decrease in the friction coefficient and an improvement in the maximum molding height.
(5) No. 11-13, no. 54-56 and no. Nos. 67 to 69 are examples of the present invention in which a treatment with a solution containing zinc ions was performed. The friction coefficient decreased and the maximum molding height increased. No. 14-16 and no. Nos. 44 to 46 are No. This is an example of the present invention in which the zinc ion concentration in the liquid was increased under the same processing conditions as in 11-13. The friction coefficient is stabilized at a low level, and the maximum molding height is further increased. Similarly, no. 57-59 and no. Nos. 70 to 72 are No. This is an example of the present invention in which the zinc ion concentration in the liquid is increased under the same processing conditions as 54 to 56. The friction coefficient is stabilized at a low level, and the maximum molding height is further increased.
(6) No. Nos. 17 to 22 are examples in which the time until the solution film is formed on the steel plate surface and washed with water is changed. No. which was washed with water without holding. No. 17 has a slight decrease in the friction coefficient, whereas No. 17 has a holding time of 1 second or more. In 18 to 22, the friction coefficient is lowered and the overhanging property is stably improved.
(7) No. Nos. 23 to 40 are examples in which the treatment liquid temperature was changed. 23 to 25 are not sufficient in improving the friction coefficient and the maximum molding height as compared with the other examples. On the other hand, no. Nos. 32 to 34 are examples of high treatment liquid temperatures, and the effect of improving the friction coefficient and the maximum molding height is sufficient, but many treatment irregularities were seen and did not show a good appearance as an automobile outer plate. .
(8) No. 35 to 40 are No. This is an example of the present invention in which the liquid film formation amount is changed with respect to 20-22. Compared with the case where the liquid film amount is small, the retention time until washing with water is the same, but when the liquid film amount is large, the friction coefficient is sufficiently reduced and the maximum molding height is improved. Slightly higher coefficient of friction and lower maximum molding height.
(9) No. Nos. 41 to 43 are comparative examples using treatment solutions having a pH lower than the range of the present invention. Compared with 20-22, the effect of lowering the friction coefficient is not recognized, and the maximum molding height is not improved.
FIG. 5 shows the numbers in Table 1-1 and Table 1-2. 8-22 and no. 4 is a graph showing the influence of zinc ion concentration on the oxide film thickness using 44 to 46. FIG. According to FIG. 5, when the zinc concentration is 5 g / l or more, the oxide film thickness is sufficiently thick even when the holding time is short (for example, 10 seconds), and the oxide film thickness is thin when the holding time is short. It can be seen that the problem of the present invention is solved.
板厚０．８ｍｍの冷延鋼板上に、片面当たりの付着量が４５ｇ／ｍ２、Ａｌ濃度が０．２０質量％の溶融亜鉛めっきを施した後に、調質圧延を行ったＧＩ鋼板を作製した。また、板厚０．８ｍｍの冷延鋼板上に、常法の合金化溶融亜鉛めっき法により、片面当たりのめっき付着量が４５ｇ／ｍ２、Ｆｅ濃度が１０質量％、Ａｌ濃度が０．２０質量％のめっき皮膜を形成し、更に調質圧延を行ったＧＡ鋼板を作製した。また、板厚０．８ｍｍの冷延鋼板上に、常法の電気亜鉛めっき法により、片面当たりのめっき付着量が３０ｇ／ｍ２のめっき皮膜を有するＥＧ鋼板を作成した。
引き続き、図１に示す構成の処理設備を用いて酸化物層を形成した。まず、上記により得られたＧＩ鋼板、ＧＡ鋼板およびＥＧ鋼板などの鋼板Ｓを、溶液槽２で、表１−１および表１−２に示す処理液組成、温度およびｐＨが異なる水溶液に浸漬した。次いで、絞りロール３で鋼板表面の液膜量を調整した。液膜量の調整は、絞りロールの圧力を変化させることで行った。次いで、洗浄槽５、洗浄槽６を空通しし、洗浄槽７で５０℃の温水を鋼板にスプレーして洗浄し、ドライヤ８で乾燥し、めっき表面に酸化物層を形成した。なお、溶液層２の前に洗浄槽１を設けることができる。
溶液槽２で浸漬処理を行う水溶液は、亜鉛イオンを添加する目的で硫酸亜鉛七水和物を所定量添加した水溶液を使用した。なお、一部、比較のために酢酸ナトリウム２０ｇ／Ｌを含んだ溶液を硫酸でｐＨを調整した溶液も用いた。
水洗までの保持時間は、絞りロール３で液膜量の調整を行い、洗浄槽７で洗浄開始するまでの時間であり、ラインスピードを変化させることで調整するとともに、一部、絞りロール３出側のシャワー水洗装置４を用いて絞り直後に鋼板を洗浄するものも作製した。
次に、以上のように作製した鋼板について、自動車用外板として十分な外観を有するか判定するとともに、プレス成形性を簡易的に評価する手法として摩擦係数の測定、および実際の成形性をより詳細にシミュレートする目的で球頭張出試験を実施した。なお、測定方法は以下の通りである。
（１）プレス成形性評価試験（摩擦係数測定試験）
プレス成形性を評価するために、各供試材の摩擦係数を以下のようにして測定した。
図２は摩擦係数測定装置を示す概略正面図である。同図に示すように、供試材から採取した摩擦係数測定用試料１１が試料台１２に固定され、試料台１２は、水平移動可能なスライドテーブル１３の上面に固定されている。スライドテーブル１３の下面には、これに接したローラ１４を有する上下動可能なスライドテーブル支持台１５が設けられ、これを押し上げることによりビード１６による摩擦係数測定用試料１１への押し付け荷重Ｎを測定するための第１ロードセル１７がスライドテーブル支持台１５に取り付けられている。上記押し付け力を作用させた状態でスライドテーブル１３をレール１９に沿って水平移動させるための摺動抵抗力Ｆを測定するために第２ロードセル１８が、スライドテーブル１３の一方の端部に取り付けられている。なお、潤滑油としてスギムラ化学社製のプレス用洗浄油プレトンＲ３５２Ｌを摩擦係数測定用試料１１の表面に塗布して試験を行った。
図３と図４は使用したビードの形状・寸法を示す概略斜視図である。ビード１６の下面が試料１１の表面に押し付けられた状態で摺動する。図３に示すビード１６の形状は幅１０ｍｍ、試料の摺動方向長さ１２ｍｍ、摺動方向両端の下部は曲率４．５ｍｍＲの曲面で構成され、試料が押し付けられるビード下面は幅１０ｍｍ、摺動方向長さ３ｍｍの平面を有する。図４に示すビード１６の形状は幅１０ｍｍ、試料の摺動方向長さ６９ｍｍ、摺動方向両端の下部は曲率４．５ｍｍＲの曲面で構成され、試料が押し付けられるビード下面は幅１０ｍｍ、摺動方向長さ６０ｍｍの平面を有する。
摩擦係数測定試験は下に示す２条件で行った。
［条件１］
図３に示すビードを用い、押し付け荷重Ｎ：４００ｋｇｆ、試料の引き抜き速度（スライドテーブル１３の水平移動速度）：１００ｃｍ／ｍｉｎとした。
［条件２］
図４に示すビードを用い、押し付け荷重Ｎ：４００ｋｇｆ、試料の引き抜き速度（スライドテーブル１３の水平移動速度）：２０ｃｍ／ｍｉｎとした。
供試材とビードとの間の摩擦係数μは、式：μ＝Ｆ／Ｎで算出した。
（２）球頭張出試験
２００×２００ｍｍサイズの供試材に対して、１５０ｍｍφのポンチを使用して、液圧バルジ試験機により張出成形を行い、破断が生じた際の最大成形高さを測定した。この際、材料の流入を阻止する目的で１００Ｔｏｎのしわ押さえ力をかけ、ポンチが接触する面にのみ潤滑油を塗布した。使用した潤滑油は、前述した摩擦係数測定試験と同様のものである。
（３）酸化物層の厚さ（酸化膜厚）の測定
膜厚が９６ｎｍの熱酸化ＳｉＯ２膜が形成されたＳｉウエハを参照物質として用い、蛍光Ｘ線分析装置でＯ・Ｋα Ｘ線を測定することで、ＳｉＯ２換算の酸化層の平均厚さを求めた。分析面積は３０ｍｍφである。
以上より得られた試験結果を表１−１および表１−２に示す。
（１）Ｎｏ．１、４７および６０は溶液による処理を行っていないため、平坦部に摺動性を向上させるのに十分な酸化膜が形成されず、摩擦係数が高い。
（２）Ｎｏ．２~４、Ｎｏ．４８~５０およびＮｏ．６１~６３はｐＨ緩衝作用を有する酸性溶液を用いた比較例である。３０秒以上では摩擦係数が低く、最大形成高さも高くなっているものの、１０秒の処理では十分な摩擦係数の低下および最大成形高さの向上を満たしていない。
（３）Ｎｏ．５~７は、ｐＨ緩衝作用を有する酸性溶液を用いた比較例である。高い摩擦係数を示している。
（４）Ｎｏ．８~１０、Ｎｏ．５１~５３およびＮｏ．６４~６６は、亜鉛イオンを含有しているが、その量が本発明の範囲よりも少ない比較例である。３０秒以上では摩擦係数が低く、最大形成高さも高くなっているものの、１０秒の処理では十分な摩擦係数の低下および最大成形高さの向上を満たしていない。
（５）Ｎｏ．１１~１３、Ｎｏ．５４~５６およびＮｏ．６７~６９は、は、亜鉛イオンを含有した溶液での処理を行った本発明例であり、摩擦係数が低下し、最大成形高さも増加している。また、Ｎｏ．１４~１６およびＮｏ．４４~４６はＮｏ．１１~１３と同一の処理条件で液中の亜鉛イオン濃度を増加させた本発明例である。摩擦係数が低位安定化し、最大成形高さもさらに増加している。同様に、Ｎｏ．５７~５９およびＮｏ．７０~７２はＮｏ．５４~５６と同一の処理条件で液中の亜鉛イオン濃度を増加させた本発明例である。摩擦係数が低位安定化し、最大成形高さもさらに増加している。
（６）Ｎｏ．１７~２２は、鋼板表面に溶液膜を形成し、水洗を施すまでの時間を変化させた例である。保持なく水洗を行ったＮｏ．１７ではわずかに摩擦係数が低下するのみであるのに対して、１秒以上の保持時間となるＮｏ．１８~２２は、摩擦係数は低下し、張出性も安定向上している。
（７）Ｎｏ．２３~４０は、処理液温度を変化させた例であるが、処理液温度の低いＮｏ．２３~２５は、それ以外の例と比較して、摩擦係数および最大成形高さの向上効果が十分でない。一方、Ｎｏ．３２~３４は、処理液温度の高い例であり、摩擦係数や最大成形高さの向上効果は十分であるが、処理ムラが多く見られ、自動車用外板として良好な外観を示していなかった。
（８）Ｎｏ．３５~４０は、Ｎｏ．２０~２２に対して、液膜形成量を変化させた本発明例である。水洗までの保持時間が同一のもので比較すると、液膜量が多い場合には、十分な摩擦係数の低下および最大成形高さの向上が得られているものの、液膜量が少ない場合に比べるとやや摩擦係数が高く最大成形高さも低くなっている。
（９）Ｎｏ．４１~４３はｐＨが本発明の範囲よりも低い処理液を用いた比較例であるが、Ｎｏ．２０~２２と比較して摩擦係数の低下の効果は認められず、最大成形高さの向上も見られない。
図５は、表１−１および表１−２のＮｏ．８~２２及びＮｏ．４４~４６を用いて、酸化膜厚への亜鉛イオン濃度の影響を示した図である。図５によれば、亜鉛の濃度が５ｇ／ｌ以上であれば保持時間が短い場合（例えば、１０秒）でも酸化膜厚が十分に厚く形成され、保持時間が短い場合に酸化膜厚が薄くなるという本発明の課題が解決されていることがわかる。 Next, the present invention will be described in more detail with reference to examples.
On a cold-rolled steel sheet with a thickness of 0.8 mm, a GI steel sheet was prepared by applying hot-dip galvanizing with an adhesion amount per side of 45 g / m 2 and an Al concentration of 0.20 mass%, followed by temper rolling. did. Further, on a cold-rolled steel sheet having a thickness of 0.8 mm, the amount of plating adhesion per side is 45 g / m 2 , the Fe concentration is 10% by mass, and the Al concentration is 0.20 by a conventional alloying hot dip galvanizing method. A GA steel sheet having a mass% plating film formed thereon and further subjected to temper rolling was prepared. Moreover, the EG steel plate which has a plating film | membrane whose plating adhesion amount per single side | surface is 30 g / m < 2 > on the cold rolled steel plate with a plate | board thickness of 0.8 mm with the usual electrogalvanization method was created.
Subsequently, an oxide layer was formed using a processing facility having the configuration shown in FIG. First, steel plates S such as GI steel plates, GA steel plates and EG steel plates obtained as described above were immersed in aqueous solutions having different treatment liquid compositions, temperatures and pHs shown in Table 1-1 and Table 1-2 in the
The aqueous solution in which the immersion treatment was performed in the
The holding time until water washing is the time until the liquid film amount is adjusted with the squeezing
Next, regarding the steel sheet produced as described above, it is determined whether it has a sufficient appearance as an automobile outer plate, and as a method for simply evaluating the press formability, the measurement of the friction coefficient and the actual formability are further improved. A ball head overhang test was conducted for the purpose of simulating in detail. The measuring method is as follows.
(1) Press formability evaluation test (Friction coefficient measurement test)
In order to evaluate the press formability, the friction coefficient of each test material was measured as follows.
FIG. 2 is a schematic front view showing the friction coefficient measuring apparatus. As shown in the figure, a friction
3 and 4 are schematic perspective views showing the shape and dimensions of the beads used. The
The friction coefficient measurement test was performed under the following two conditions.
[Condition 1]
The bead shown in FIG. 3 was used, the pressing load N was 400 kgf, and the sample drawing speed (horizontal moving speed of the slide table 13) was 100 cm / min.
[Condition 2]
The bead shown in FIG. 4 was used, the pressing load N was 400 kgf, and the sample drawing speed (horizontal moving speed of the slide table 13) was 20 cm / min.
The friction coefficient μ between the test material and the bead was calculated by the formula: μ = F / N.
(2) Ball head overhang test Using a 150 mmφ punch for a 200 x 200 mm sample material, the maximum forming height when a bulge was formed by a hydraulic bulge tester. Was measured. At this time, a wrinkle holding force of 100 Ton was applied for the purpose of preventing the inflow of the material, and the lubricating oil was applied only to the surface in contact with the punch. The used lubricating oil is the same as that in the friction coefficient measurement test described above.
(3) Measurement of oxide layer thickness (oxide film thickness) Using a Si wafer on which a thermally oxidized SiO2 film with a film thickness of 96 nm is formed as a reference material, measure O / Kα X-rays with a fluorescent X-ray analyzer. Thus, the average thickness of the oxide layer in terms of SiO 2 was obtained. The analysis area is 30 mmφ.
The test results obtained above are shown in Table 1-1 and Table 1-2.
(1) No. Since 1, 47 and 60 are not treated with a solution, an oxide film sufficient to improve the slidability is not formed on the flat portion, and the coefficient of friction is high.
(2) No. 2-4, no. 48-50 and no. 61 to 63 are comparative examples using an acidic solution having a pH buffering action. Although the friction coefficient is low and the maximum formation height is high at 30 seconds or more, the treatment for 10 seconds does not satisfy a sufficient decrease in the friction coefficient and an improvement in the maximum molding height.
(3) No. 5 to 7 are comparative examples using an acidic solution having a pH buffering action. It shows a high coefficient of friction.
(4) No. 8-10, no. 51-53 and no. 64 to 66 are comparative examples which contain zinc ions but whose amount is less than the range of the present invention. Although the friction coefficient is low and the maximum formation height is high at 30 seconds or more, the treatment for 10 seconds does not satisfy a sufficient decrease in the friction coefficient and an improvement in the maximum molding height.
(5) No. 11-13, no. 54-56 and no. Nos. 67 to 69 are examples of the present invention in which a treatment with a solution containing zinc ions was performed. The friction coefficient decreased and the maximum molding height increased. No. 14-16 and no. Nos. 44 to 46 are No. This is an example of the present invention in which the zinc ion concentration in the liquid was increased under the same processing conditions as in 11-13. The friction coefficient is stabilized at a low level, and the maximum molding height is further increased. Similarly, no. 57-59 and no. Nos. 70 to 72 are No. This is an example of the present invention in which the zinc ion concentration in the liquid is increased under the same processing conditions as 54 to 56. The friction coefficient is stabilized at a low level, and the maximum molding height is further increased.
(6) No. Nos. 17 to 22 are examples in which the time until the solution film is formed on the steel plate surface and washed with water is changed. No. which was washed with water without holding. No. 17 has a slight decrease in the friction coefficient, whereas No. 17 has a holding time of 1 second or more. In 18 to 22, the friction coefficient is lowered and the overhanging property is stably improved.
(7) No. Nos. 23 to 40 are examples in which the treatment liquid temperature was changed. 23 to 25 are not sufficient in improving the friction coefficient and the maximum molding height as compared with the other examples. On the other hand, no. Nos. 32 to 34 are examples of high treatment liquid temperatures, and the effect of improving the friction coefficient and the maximum molding height is sufficient, but many treatment irregularities were seen and did not show a good appearance as an automobile outer plate. .
(8) No. 35 to 40 are No. This is an example of the present invention in which the liquid film formation amount is changed with respect to 20-22. Compared with the case where the liquid film amount is small, the retention time until washing with water is the same, but when the liquid film amount is large, the friction coefficient is sufficiently reduced and the maximum molding height is improved. Slightly higher coefficient of friction and lower maximum molding height.
(9) No. Nos. 41 to 43 are comparative examples using treatment solutions having a pH lower than the range of the present invention. Compared with 20-22, the effect of lowering the friction coefficient is not recognized, and the maximum molding height is not improved.
FIG. 5 shows the numbers in Table 1-1 and Table 1-2. 8-22 and no. 4 is a graph showing the influence of zinc ion concentration on the oxide film thickness using 44 to 46. FIG. According to FIG. 5, when the zinc concentration is 5 g / l or more, the oxide film thickness is sufficiently thick even when the holding time is short (for example, 10 seconds), and the oxide film thickness is thin when the holding time is short. It can be seen that the problem of the present invention is solved.
本発明によれば、短時間の製造条件においても、省スペースで、プレス成形時の摺動抵抗が小さく優れたプレス成形性を有する亜鉛系めっき鋼板を安定して製造できる。そして、例えば、成形荷重が高く型かじりを生じやすい高強度亜鉛系めっき鋼板を製造するに際しても、プレス成形時の摺動抵抗が小さく、優れたプレス成形性を有することができる。プレス成形性に優れることから、自動車車体用途を中心に広範な分野で適用できる。
According to the present invention, a galvanized steel sheet having excellent press formability with a small sliding resistance during press forming can be stably produced even under short production conditions. For example, when producing a high-strength galvanized steel sheet that has a high forming load and is likely to cause mold galling, the sliding resistance during press forming is small, and excellent press formability can be achieved. Since it is excellent in press formability, it can be applied in a wide range of fields, mainly for automobile body applications.
Claims (4)
- 鋼板に亜鉛系めっきを施した後、水溶液に接触処理し、接触処理終了後１~６０秒間保持した後、水洗・乾燥を行うことにより、鋼板表面に酸化物層を形成する亜鉛系めっき鋼板の製造方法において、亜鉛系めっき鋼板を接触処理する前記水溶液は、亜鉛イオン濃度として５~１００ｇ／ｌの範囲で亜鉛イオンを含有し、ｐＨが４~６であり、液温が２０~７０℃であることを特徴とする亜鉛系めっき鋼板の製造方法。 After applying zinc-based plating to the steel plate, contact treatment with the aqueous solution, holding for 1 to 60 seconds after completion of the contact treatment, and then washing and drying to form an oxide layer on the steel plate surface. In the production method, the aqueous solution for contact-treating a zinc-based plated steel sheet contains zinc ions in a zinc ion concentration range of 5 to 100 g / l, has a pH of 4 to 6, and a liquid temperature of 20 to 70 ° C. A method for producing a zinc-based plated steel sheet, comprising:
- 前記水溶液中には、亜鉛の硫酸塩を含むことを特徴とする請求項１に記載の亜鉛系めっき鋼板の製造方法。 The method for producing a galvanized steel sheet according to claim 1, wherein the aqueous solution contains a zinc sulfate.
- 前記水溶液に接触後に鋼板表面に形成する液膜が５~３０ｇ／ｍ２であることを特徴とする請求項１または２に記載の亜鉛系めっき鋼板の製造方法． Method for manufacturing a galvanized steel sheet according to claim 1 or 2, characterized in that the liquid film formed on the surface of the steel sheet after contacting the aqueous solution is 5 ~ 30g / m 2.
- 請求項１~３のいずれか一項に記載の亜鉛系めっき鋼板の製造方法により製造され、金属成分としては亜鉛を主体として含む酸化物層を鋼板表面に平均厚さ１０ｎｍ以上形成したことを特徴とする亜鉛系めっき鋼板。 It is manufactured by the method for manufacturing a zinc-based plated steel sheet according to any one of claims 1 to 3, wherein an oxide layer mainly containing zinc as a metal component is formed on the steel sheet surface with an average thickness of 10 nm or more. Zinc-based plated steel sheet.
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| CN2009801454920A CN102216493A (en) | 2008-12-16 | 2009-04-22 | Galvanized steel sheet and method for manufacturing the same |
| EP09833249.7A EP2366812B1 (en) | 2008-12-16 | 2009-04-22 | Method for manufacturing a galvanized steel sheet |
| US13/129,504 US20110226387A1 (en) | 2008-01-30 | 2009-04-22 | Galvanized steel sheet and method for manufacturing the same |
| CA2742354A CA2742354C (en) | 2008-12-16 | 2009-04-22 | Galvanized steel sheet and method for manufacturing the same |
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| JP2008319131A JP5354165B2 (en) | 2008-01-30 | 2008-12-16 | Method for producing galvanized steel sheet |
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| KR (1) | KR20110073573A (en) |
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| WO2012119973A1 (en) * | 2011-03-08 | 2012-09-13 | Thyssenkrupp Steel Europe Ag | Flat steel product, method for producing a flat steel product, and method for producing a component |
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| KR20150014517A (en) * | 2012-07-18 | 2015-02-06 | 제이에프이 스틸 가부시키가이샤 | Method for producing steel sheet having excellent chemical conversion properties and galling resistance |
| WO2019073273A1 (en) * | 2017-10-12 | 2019-04-18 | Arcelormittal | Metal sheet treatment method and metal sheet treated with this method |
| WO2019073274A1 (en) * | 2017-10-12 | 2019-04-18 | Arcelormittal | Metal sheet treatment method and metal sheet treated with this method |
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| JPH02190483A (en) | 1989-01-19 | 1990-07-26 | Nippon Steel Corp | Galvanized steel sheet having superior press formability |
| JP2000328220A (en) * | 1999-05-18 | 2000-11-28 | Sumitomo Metal Ind Ltd | Galvanized steel sheet and its production |
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| US6528182B1 (en) * | 1998-09-15 | 2003-03-04 | Sollac | Zinc coated steel plates coated with a pre-lubricating hydroxysulphate layer and methods for obtaining same |
| WO2001081646A1 (en) * | 2000-04-24 | 2001-11-01 | Nkk Corporation | Galvannealed sheet steel and method for production thereof |
| EP2071048B1 (en) * | 2003-04-18 | 2020-01-22 | JFE Steel Corporation | A method for producing a hot-dip galvanized steel sheet having excellent press formability. |
| WO2005021823A1 (en) * | 2003-08-29 | 2005-03-10 | Jfe Steel Corporation | Hot dip zinc plated steel sheet and method for production thereof |
| FR2864552B1 (en) * | 2003-12-24 | 2006-07-21 | Usinor | SURFACE TREATMENT WITH HYDROXYSULFATE |
| MX2008013860A (en) * | 2006-05-02 | 2008-11-14 | Jfe Steel Corp | Process for producing alloyed hot-dip zinc-plated steel sheet and alloyed hot-dip zinc-plated steel sheet. |
| JP5239570B2 (en) * | 2007-09-04 | 2013-07-17 | Ｊｆｅスチール株式会社 | Galvanized steel sheet |
-
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| JPS5360332A (en) | 1976-11-10 | 1978-05-30 | Nippon Steel Corp | Alloyed zincciron plate having excellent weldability |
| JPH02190483A (en) | 1989-01-19 | 1990-07-26 | Nippon Steel Corp | Galvanized steel sheet having superior press formability |
| JP2000328220A (en) * | 1999-05-18 | 2000-11-28 | Sumitomo Metal Ind Ltd | Galvanized steel sheet and its production |
| JP2003306781A (en) | 2002-04-18 | 2003-10-31 | Jfe Steel Kk | Method of producing hot dip galvannealed steel sheet |
| JP2004003004A (en) | 2002-04-18 | 2004-01-08 | Jfe Steel Kk | Hot-dip galvanized steel sheet showing excellent press formability and its manufacturing process |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2012119973A1 (en) * | 2011-03-08 | 2012-09-13 | Thyssenkrupp Steel Europe Ag | Flat steel product, method for producing a flat steel product, and method for producing a component |
| EP2683848B1 (en) * | 2011-03-08 | 2020-11-04 | ThyssenKrupp Steel Europe AG | Use of a flat steel prouduct for hot pres forming into a component and method of hot press forming a component |
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| CN102216493A (en) | 2011-10-12 |
| EP2366812A1 (en) | 2011-09-21 |
| CA2742354A1 (en) | 2010-06-24 |
| TW201024461A (en) | 2010-07-01 |
| EP2366812A4 (en) | 2012-04-25 |
| EP2366812B1 (en) | 2019-08-14 |
| KR20110073573A (en) | 2011-06-29 |
| TWI516638B (en) | 2016-01-11 |
| CA2742354C (en) | 2014-02-25 |
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