WO2013022118A1 - Molten zn-al alloy-plated steel sheet and manufacturing method thereof - Google Patents
Molten zn-al alloy-plated steel sheet and manufacturing method thereof Download PDFInfo
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- WO2013022118A1 WO2013022118A1 PCT/JP2012/070719 JP2012070719W WO2013022118A1 WO 2013022118 A1 WO2013022118 A1 WO 2013022118A1 JP 2012070719 W JP2012070719 W JP 2012070719W WO 2013022118 A1 WO2013022118 A1 WO 2013022118A1
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- steel sheet
- plating layer
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- based alloy
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 97
- 239000010959 steel Substances 0.000 title claims abstract description 97
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 16
- 238000007747 plating Methods 0.000 claims abstract description 150
- 229910007570 Zn-Al Inorganic materials 0.000 claims abstract description 66
- 239000000126 substance Substances 0.000 claims abstract description 52
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 45
- 239000000956 alloy Substances 0.000 claims abstract description 45
- 238000006243 chemical reaction Methods 0.000 claims abstract description 43
- 229910018134 Al-Mg Inorganic materials 0.000 claims abstract description 30
- 229910018467 Al—Mg Inorganic materials 0.000 claims abstract description 30
- 230000005496 eutectics Effects 0.000 claims abstract description 23
- 239000000203 mixture Substances 0.000 claims abstract description 22
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 14
- 239000012535 impurity Substances 0.000 claims abstract description 12
- MEFBJEMVZONFCJ-UHFFFAOYSA-N molybdate Chemical compound [O-][Mo]([O-])(=O)=O MEFBJEMVZONFCJ-UHFFFAOYSA-N 0.000 claims description 17
- 238000001816 cooling Methods 0.000 claims description 13
- 238000007739 conversion coating Methods 0.000 claims description 10
- 239000007788 liquid Substances 0.000 claims description 9
- 238000007598 dipping method Methods 0.000 claims 1
- 238000005260 corrosion Methods 0.000 abstract description 42
- 230000007797 corrosion Effects 0.000 abstract description 42
- 239000000463 material Substances 0.000 abstract description 2
- 229910052725 zinc Inorganic materials 0.000 abstract description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 22
- 238000000034 method Methods 0.000 description 16
- 239000000758 substrate Substances 0.000 description 9
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 7
- 238000000576 coating method Methods 0.000 description 6
- 150000003839 salts Chemical class 0.000 description 6
- 238000004381 surface treatment Methods 0.000 description 6
- 229910052719 titanium Inorganic materials 0.000 description 6
- 239000010936 titanium Substances 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 229910052726 zirconium Inorganic materials 0.000 description 5
- 239000011248 coating agent Substances 0.000 description 4
- 238000011156 evaluation Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 229910052748 manganese Inorganic materials 0.000 description 4
- 230000009257 reactivity Effects 0.000 description 4
- 229910052720 vanadium Inorganic materials 0.000 description 4
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 238000002845 discoloration Methods 0.000 description 3
- 238000010191 image analysis Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 238000000465 moulding Methods 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- 238000010998 test method Methods 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 2
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 239000002738 chelating agent Substances 0.000 description 2
- KRVSOGSZCMJSLX-UHFFFAOYSA-L chromic acid Substances O[Cr](O)(=O)=O KRVSOGSZCMJSLX-UHFFFAOYSA-L 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000011651 chromium Substances 0.000 description 2
- 150000001869 cobalt compounds Chemical class 0.000 description 2
- 239000010960 cold rolled steel Substances 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000004453 electron probe microanalysis Methods 0.000 description 2
- 239000011737 fluorine Substances 0.000 description 2
- 229910052731 fluorine Inorganic materials 0.000 description 2
- AWJWCTOOIBYHON-UHFFFAOYSA-N furo[3,4-b]pyrazine-5,7-dione Chemical compound C1=CN=C2C(=O)OC(=O)C2=N1 AWJWCTOOIBYHON-UHFFFAOYSA-N 0.000 description 2
- 239000002932 luster Substances 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 239000010452 phosphate Substances 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 2
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 241001163841 Albugo ipomoeae-panduratae Species 0.000 description 1
- 229910018571 Al—Zn—Mg Inorganic materials 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 229910018605 Ni—Zn Inorganic materials 0.000 description 1
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- VLAPMBHFAWRUQP-UHFFFAOYSA-L molybdic acid Chemical compound O[Mo](O)(=O)=O VLAPMBHFAWRUQP-UHFFFAOYSA-L 0.000 description 1
- 150000002816 nickel compounds Chemical class 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 229910002059 quaternary alloy Inorganic materials 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 229910000077 silane Inorganic materials 0.000 description 1
- -1 silane compound Chemical class 0.000 description 1
- 150000004756 silanes Chemical class 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 230000002195 synergetic effect Effects 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
- 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
-
- 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
-
- 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
- C23C22/40—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing molybdates, tungstates or vanadates
- C23C22/42—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing molybdates, tungstates or vanadates containing also phosphates
-
- 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
- C23C22/40—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing molybdates, tungstates or vanadates
- C23C22/44—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing molybdates, tungstates or vanadates containing also fluorides or complex fluorides
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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
- C23C28/321—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer with at least one metal alloy 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
- C23C28/3455—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 with a refractory ceramic layer, e.g. refractory metal oxide, ZrO2, rare earth oxides or a thermal barrier system comprising at least one refractory oxide layer
Definitions
- the present invention relates to a molten Zn-Al alloy-plated steel sheet excellent in corrosion resistance and suitable for use in members of buildings, civil engineering, home appliances and the like, and a method for producing the same, and more particularly, molten Zn- with improved workability and corrosion resistance of a plating layer
- the present invention relates to an Al-based alloy plated steel sheet.
- hot-dip Zn-based plated steel sheets used in fields such as architecture, civil engineering, and home appliances are required to have excellent corrosion resistance.
- a hot dip Zn-based plated steel sheet is formed into a predetermined shape and used as a structural member such as a roof, wall, or other structure.
- it is required to be excellent in workability, and further in the corrosion resistance of the processed part, and the corrosion resistance of the material including the processed part enhances the durability of the structural member. It is an important factor to decide. For this reason, from the viewpoint of improving the durability of structural members, there is a strong demand for improving the corrosion resistance of hot-dip Zn-based plated steel sheets used as raw materials.
- blackening refers to a phenomenon in which a dark gray discoloration occurs on a part or the whole of the plating surface.
- the hot-dip Zn-based plated steel sheet is often used without coating in the construction field because it is excellent in corrosion resistance even in a severe environment with a lot of incoming salt such as a coastal area.
- Patent Document 1 describes a continuous molten Zn—Al—Mg plated steel sheet.
- the technique described in Patent Document 1 is a continuous molten Zn in which a plating layer comprising Al: 4.0 to 10%, Mg: 1.0 to 4.0%, the balance being Zn and unavoidable impurities is formed on the steel sheet surface.
- a plating layer comprising Al: 4.0 to 10%, Mg: 1.0 to 4.0%, the balance being Zn and unavoidable impurities is formed on the steel sheet surface.
- the cooling rate after plating is controlled to 0.5 ° C / s or more, and the plated layer is primary Al in the substrate of the ternary eutectic structure of Al / Zn / Zn 2 Mg.
- Patent Document 2 describes a hot-dip Zn-Al alloy-plated steel sheet having a beautiful plating appearance with metallic luster and excellent blackening resistance.
- a steel sheet is immersed in a molten Zn-Al alloy plating bath, then pulled up from the plating bath, and cooled at a cooling rate of up to 250 ° C in a range of 1 to 15 ° C / s.
- the concentration of Ni in the plating outermost layer portion is promoted by the synergistic action of Mg and Ni. It is said.
- the molten Zn—Al-based alloy plating layer preferably contains 10 to 30 area% of a ternary eutectic of an Al—Zn—Mg intermetallic compound in a cross section of the plating layer. It is preferable.
- a chemical conversion treatment layer, a primer layer, and a resin layer may be formed as an upper layer of the plating layer, and the chemical conversion treatment layer may be a titanium-based or zirconium-based treatment that does not contain chromium. It is said that a chromium-free treatment with a liquid may be applied.
- Patent Document 3 discloses a molten Zn-Al alloy formed by forming a molten Zn-Al-based alloy plating layer on at least one surface of a steel sheet and further forming a surface treatment film on the surface of the plating layer.
- a plated steel sheet is described.
- a molten Zn—Al-based alloy plating layer is formed by mass%, Al: 1.0 to 10%, Mg: 0.2 to 1.0%, Ni: 0.005.
- a surface treatment film formed on the surface of the plating layer containing a Zn-Al alloy plating layer containing Zn and unavoidable impurities, including a specific titanium-containing aqueous liquid and nickel By forming a surface treatment film with a surface treatment composition containing a compound and / or a cobalt compound and a fluorine-containing compound at a predetermined ratio, excellent blackening resistance can be obtained in combination with optimization of the plating composition.
- the reactivity is increased by the action of the fluorine-containing compound, a dense reaction layer is formed on the plating surface, and a high barrier property is imparted by the surface treatment film itself, thereby obtaining excellent corrosion resistance.
- the plated steel sheet manufactured by the technique described in Patent Document 1 contains a large amount of Al or Mg, which has higher oxidizing power than Zn, in the plating layer.
- a dark gray discoloration black discoloration phenomenon
- the technique described in Patent Document 1 contains a large amount of Mg in the plating layer, the plating layer is hardened, cracks are generated in the portions subjected to the forming process, and corrosion of the plating layer base ( There is a problem that red rust) progresses.
- the blackening resistance is mainly improved by adopting a Zn—Al—Mg-based composition containing Ni in the plating layer, but Al—Mg—Ni—Zn.
- the chemical conversion treatment film is formed on the surface of the plating layer, the chemical conversion treatment reaction may become insufficient, and the effect of suppressing blackening becomes unstable. There was a problem.
- the object of the present invention is to solve the problems of the prior art and to provide a hot-dip Zn-Al alloy-plated steel sheet excellent in blackening resistance and corrosion resistance and a method for producing the same.
- the present inventors diligently studied various factors affecting blackening resistance and corrosion resistance of a hot-dip Zn-Al alloy-plated steel sheet.
- the plating layer formed on the surface of the steel sheet has a Zn—Al—Mg-based composition containing an appropriate amount of Ni, and the surface structure of the plating layer is the area of the Zn—Al—Mg-based ternary eutectic.
- the present inventors form a chemical conversion film containing molybdate as an upper layer of the plating layer after forming the Zn—Al—Mg alloy plating layer having the composition as described above.
- the present invention has been completed based on such findings and further studies. That is, the gist of the present invention is as follows.
- a molten Zn-Al alloy obtained by forming a molten Zn-Al alloy plating layer on at least one surface of a steel plate and further forming a chemical conversion coating as an upper layer of the molten Zn-Al alloy plating layer A plated steel sheet,
- the molten Zn—Al-based alloy plating layer is in mass%, Al: 3.0 to 6.0%, Mg: 0.2-1.0% and Ni: 0.01-0.10%
- the surface structure of the plating layer contains Zn—Al—Mg ternary eutectic in an area ratio of 1 to 50%, and the chemical conversion coating film has a composition comprising the balance Zn and inevitable impurities.
- a molten Zn-Al alloy-plated steel sheet excellent in blackening resistance and corrosion resistance characterized by containing molybdate.
- the temperature of the steel sheet immersed in the molten Zn—Al based alloy plating bath is 420 to 600 ° C., and the temperature of the steel plate is melted. Adjust the temperature above the temperature of the Zn-Al based plating bath, immerse in the molten Zn-Al based alloy plating bath, Furthermore, after pulling up the steel sheet from the molten Zn-Al plating bath, the steel sheet is subjected to cooling at an average cooling rate of 1 to 100 ° C./s up to 350 ° C.
- the chemical conversion solution has a pH of 2 to 6.
- the present invention it is possible to easily and inexpensively manufacture a hot-dip Zn-Al alloy-plated steel sheet having stable blackening resistance, and achieve a remarkable industrial effect.
- the present invention as a result of improving the workability of the plating layer, cracking of the plating layer during molding processing is suppressed, and corrosion of the plating base is effectively suppressed. It is possible to provide a hot-dip Zn—Al-based alloy-plated steel sheet having excellent corrosion resistance.
- the hot-dip Zn—Al-based alloy-plated steel sheet (hereinafter, also referred to as “the present invention-coated steel sheet”) of the present invention is formed on at least one surface of the steel sheet by mass%, Al: 3.0 to 6.0%, Mg: It has 0.2 to 1.0%, Ni: 0.01 to 0.1%, and has a molten Zn-Al alloy plating layer composed of the balance Zn and unavoidable impurities, and further has molybdic acid as an upper layer. It has a chemical conversion treatment film containing salt.
- the mass% in the composition is simply expressed as%.
- Al 3.0 to 6.0% If the Al contained in the plating layer is less than 3.0%, the Fe—Al-based alloy layer is formed thick at the interface between the plating layer and the underlying steel plate, and therefore the workability is lowered. On the other hand, when Al is contained in a large amount exceeding 6.0%, the sacrificial anticorrosive action of Zn is reduced, the corrosion resistance is lowered, and the blackening resistance is lowered.
- Al in the plating layer is limited to a range of 3.0 to 6.0%. Further, it is preferably in the range of 4.0 to 5.5%.
- Mg 0.2 to 1.0% Mg is contained in the plating layer to improve corrosion resistance. However, if Mg contained in the plating layer is less than 0.2%, the effect of improving corrosion resistance is small, while Mg exceeds 1.0% and a large amount. When contained in Zn, the formation of Zn—Al—Mg ternary eutectic increases, and the workability of the plating layer decreases. Therefore, Mg in the plating layer is limited to the range of 0.2 to 1.0%. Furthermore, it is preferably in the range of 0.3 to 0.8%.
- Ni 0.01 to 0.10% Ni is included in the plating layer to improve corrosion resistance and blackening resistance. However, if Ni contained in the plating layer is less than 0.01%, the effect of improving corrosion resistance and blackening resistance is small. If it is contained in a large amount exceeding 0.10%, the surface of the plating layer is excessively activated and easily corroded, and white rust is likely to appear at the initial stage. For this reason, Ni in the plating layer is limited to a range of 0.01 to 0.10%.
- the balance other than the above consists of Zn and unavoidable impurities. Examples of impurities include Si, Ca, Ti, V, Cr, Mn, Fe, Co, Cu, Sr, Zr, Nb, and Mo, and each may be included with an upper limit of 0.01%.
- the plating layer formed on the surface of the plated steel sheet of the present invention has the above-described composition, and further has a structure containing 1 to 50% of Zn—Al—Mg ternary eutectic by area ratio on the surface of the plating layer.
- the plated layer of the plated steel sheet of the present invention has a surface structure in which Zn—Al—Mg ternary eutectic is exposed on the surface in an area ratio of 1 to 50%.
- the Zn—Al—Mg ternary eutectic on the surface of the plating layer is less than 1% in terms of the area ratio on the same surface, the effect of improving the corrosion resistance is small, while the Zn—Al—Mg ternary eutectic has an area on the surface. If the rate exceeds 50%, the reactivity with the plating layer surface of the chemical conversion treatment decreases, it becomes difficult to obtain a good chemical conversion coating film, the blackening resistance becomes unstable, and the surface of the plating layer becomes hard. Thus, cracks are likely to occur during the molding process. Therefore, the Zn—Al—Mg ternary eutectic in the surface structure of the plating layer is limited to the range of 1 to 50% in terms of area ratio. Note that the content is preferably 5 to 40%.
- the area ratio of the Zn—Al—Mg ternary eutectic on the surface of the plating layer can be determined by, for example, observing the surface of the plating layer with a scanning electron microscope (magnification: about 1000 times) and randomizing the surface structure of the plating layer. It is preferable to obtain several fields of view and obtain the field of view (photograph) using image processing software. In the present invention, the area ratio obtained in each field of view is arithmetically averaged to obtain the area ratio of the Zn—Al—Mg ternary eutectic in the plating layer. In FIG. 1, an example of the plating layer surface structure of this invention plated steel plate is shown.
- FIG. 2 is an image analysis diagram showing the result of analyzing the result of analyzing Mg on the surface of the plating layer shown in FIG. 1 by EPMA and showing the surface distribution of the Zn—Al—Mg ternary eutectic.
- the surface area ratio of the Zn—Al—Mg ternary eutectic may be obtained by a method of making two gradations in black and white and calculating from a histogram.
- a black part is a Zn-Al-Mg ternary eutectic.
- the adhesion amount of the hot-dip Zn—Al—Mg alloy plating layer in the plated steel sheet of the present invention may be set according to the usage as usual, and is not particularly limited, but is about 30 to 300 g / m 2 per side. It is preferable to do.
- the adhesion amount of the plating layer is 30 g / m 2 or more, the plating layer thickness is not insufficient, and desired corrosion resistance can be maintained. On the other hand, if it is 300 g / m 2 or less, the plating layer thickness will not be too thick and the plating layer will not peel off.
- the plated steel sheet of the present invention has a chemical conversion treatment film containing molybdate as an upper layer of the molten Zn—Al—Mg alloy plating layer.
- the chemical conversion film formed as the upper layer of the plating layer contains molybdate, and the combination of this molybdate and Zn-Al-Mg ternary eutectic improves blackening resistance and corrosion resistance.
- the molybdate is not particularly limited as long as it dissolves during the chemical conversion treatment. Examples of the molybdate include salts such as ammonium and sodium.
- the content of molybdate in the chemical conversion coating is not particularly limited, but from the viewpoint of blackening resistance and corrosion resistance, it is advantageous to contain it in the range of 0.3 to 3% by mass in terms of molybdenum. It is.
- the chemical conversion film includes chromic acid, phosphate, fluoride or salt such as Ti, Zr, V, Mn, Ni, Co, silane compound, metal chelating agent, aqueous You may contain oxide sols, such as resin and a silica sol.
- the adhesion amount per one side of the chemical conversion coating may be appropriately determined according to the use and is not particularly limited. However, if it is 0.05 g / m 2 or more, the blackening resistance and the corrosion resistance are not lowered. On the other hand, if it is 1.5 g / m 2 or less, the amount of film formation will not increase, and the production cost will not increase. For this reason, the amount of adhesion per one side of the chemical conversion film is preferably 0.05 to 1.5 g / m 2 . Below, the preferable manufacturing method of this invention plated steel plate is demonstrated.
- the steel plate used as a substrate is immersed in a molten Zn-Al alloy plating bath using, for example, a continuous hot-dip Zn plating production facility, and then pulled up and cooled, and a molten Zn-Al alloy on the steel plate surface. A plating layer is formed.
- the type and composition of the steel plate used as the substrate are not particularly limited, and can be appropriately selected from known hot-rolled steel plates and cold-rolled steel plates according to the application.
- a steel plate as a substrate is heated to a desired heating temperature using, for example, a continuous hot-dip Zn plating manufacturing facility.
- the heating temperature may be appropriately determined according to the steel plate to be used, and is not particularly limited.
- the steel plate temperature (plate temperature) is adjusted to a desired temperature when immersed in the plating bath. It is necessary to set the heating temperature to ensure a desired steel plate temperature (plate temperature) when immersed in the plating bath.
- the steel sheet heated to a predetermined temperature is immersed in a molten Zn—Al alloy plating bath maintained at a predetermined composition and bath temperature.
- the composition of the hot-dip Zn-Al alloy plating bath in which the steel sheet is immersed is as follows: mass: Al: 3-6%, Mg: 0.2-1.0%, Ni: 0.01-0.10% And a composition comprising the balance Zn and inevitable impurities.
- the bath temperature of the plating bath is 420 ° C. to 520 ° C. When the bath temperature of the plating bath is lower than 420 ° C., the bath temperature is too low and the plating bath may partially solidify, and the predetermined plating treatment cannot be performed.
- the bath temperature of the plating bath is limited to a temperature in the range of 420 ° C. to 520 ° C. Furthermore, the bath temperature of the plating bath is preferably in the range of 450 to 500 ° C.
- the temperature (plate temperature) of the steel sheet immersed in the plating bath is adjusted to a temperature in the range of 420 to 600 ° C. and higher than the bath temperature of the plating bath.
- the bath temperature gradually decreases, so that the viscosity of the plating bath increases and the operation is hindered.
- the temperature exceeds 600 ° C. the bath temperature gradually increases and the plating fixability decreases. For this reason, the temperature (plate temperature) of the steel sheet immersed in the plating bath is limited to a temperature in the range of 420 to 600 ° C. and higher than the bath temperature of the plating bath.
- the temperature of the steel sheet immersed in the plating bath (plate temperature) is adjusted to a temperature in the range of 420 to 600 ° C., and further immersed in the plating bath.
- the temperature (plate temperature) of the steel sheet to be adjusted is adjusted to be equal to or higher than the bath temperature of the plating bath.
- the steel plate immersed in the plating bath is then lifted from the plating bath and cooled.
- the cooling after the pulling is performed at a surface temperature of the steel sheet at an average cooling rate of up to 350 ° C. at 1 to 100 ° C./s.
- the average cooling rate up to 350 ° C. is less than 1 ° C./s, the time required for cooling becomes long, so that productivity is lowered.
- the Zn—Al—Mg ternary crystal exceeds 50% in terms of the surface area ratio, and the reactivity of the chemical conversion treatment and the workability of the plating layer are lowered.
- the cooling rate after pulling the steel plate up from the plating bath was limited to 1 to 100 ° C./s on average up to 350 ° C. It is preferably 2 to 70 ° C./s.
- chemical conversion treatment solution used in the chemical conversion treatment according to the present invention a solution prepared by adding molybdate to a solvent such as water and preferably adjusted to pH: 2 to 6 is used.
- chemical conversion treatment liquid includes fluoride such as chromic acid, phosphate, Ti, Zr, V, Mn, Ni, Co, Ti, Zr, V, Mn, Ni, Co, etc. It goes without saying that any one or more of sols, silane compounds, metal chelating agents, aqueous resins and oxide sols such as silica sol may be contained.
- the pH of a chemical conversion liquid is 2 or more, the solubility to a plating layer surface is moderate, a chemical conversion treatment film will be formed normally, and fixability and corrosion resistance will not fall.
- the pH is 6 or less, the stability of the chemical conversion solution does not deteriorate, and adhesion and corrosion resistance do not deteriorate.
- it is preferable to adjust the pH of the chemical conversion solution to a range of 2-6. More preferably, it is 4-5.
- the coating method is not particularly limited, but any of the generally known coating methods such as roll coating, shower ringer, dip gas squeezing, etc. can be applied.
- any one of conventionally known methods such as a hot air furnace, an electric heating furnace, induction heating and the like can be applied.
- Cold-rolled steel plate (plate thickness: 0.8 mm, unannealed) was used as a substrate, and the substrate was heated to the steel plate temperature (plate temperature) during immersion shown in Table 1, and then various compositions shown in Table 1 were obtained. It was immersed in a molten Zn—Al based alloy plating bath having a bath temperature, pulled up and cooled to form a molten Zn—Al based alloy plating layer having the composition and adhesion amount shown in Table 2 on the substrate surface. In addition, it cooled at the cooling rate shown in Table 1 by the average after the raising shown in Table 1 to 350 degreeC after raising.
- a chemical conversion treatment liquid (liquid temperature: 25 ° C.) is applied to the surface of the plated layer of the obtained plated steel sheet by roll coating, followed by drying in a hot air oven at 220 ° C. for 3 seconds, and 0.6 g / m 2.
- a chemical conversion treatment was performed to form a chemical conversion treatment film.
- the used chemical conversion liquid has 10 mass% of any one of molybdate, a zirconate, and a titanate by mass ratio to a solvent (water), and has pH shown in Table 1. A liquid was used.
- the test method was as follows. (1) Structure observation on the surface of the plating layer A specimen for structure observation was collected from the obtained molten Zn-Al alloy-plated steel sheet, and the structure on the surface of the plating layer was obtained using a scanning electron microscope (magnification: 1000 times). Observed. In addition, Mg is analyzed on the surface of the plating layer using EPMA, and the analysis result is image-analyzed to be converted into black and white, and the area ratio of the Zn—Al—Mg ternary eutectic is calculated from the histogram. did. Next, the obtained hot-dip Zn-Al alloy-plated steel sheet was subjected to a blackening resistance test to evaluate blackening resistance. The test method is as follows.
- Score 3 ⁇ L: 8 or less (a state in which blackening hardly occurs)
- Evaluation 2 ⁇ L: More than 8 to less than 15 (a state where slight blackening occurs)
- Score 1 ⁇ L: 15 or more (a state in which significant blackening has occurred)
- the test method was as follows.
- the examples of the present invention are all hot-dip Zn-Al alloy-plated steel sheets that are excellent in blackening resistance and excellent in corrosion resistance of processed parts.
- the blackening resistance is reduced, the corrosion resistance of the processed part is reduced, or both are reduced.
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Abstract
A molten Zn-Al alloy-plated steel sheet with excellent blackening resistance and corrosion resistance, and a manufacturing method thereof are provided. On at least one surface of the steel sheet, a molten Zn-Al alloy plating layer is formed having a composition comprising, in mass%, Al: 3.0-6.0%, Mg: 0.2-1.0% and Ni: 0.01-0.10%, the remainder consisting of Zn and unavoidable impurities, and further, a chemical conversion film containing molybdates is formed as the upper layer of said molten Zn-Al alloy plating layer. By this means, the surface of the plating layer has a structure containing, by surface area ratio, 1-50% of a Zn-Al-Mg ternary eutectic, and, by means of the material / structure of the plating layer and also the chemical conversion film containing molybdates formed on the upper layer of said plating layer, this molten Zn-Al alloy plated steel sheet has excellent blackening resistance and corrosion resistance.
Description
本発明は、建築、土木、家電等の部材用として好適な、耐食性に優れた溶融Ｚｎ−Ａｌ系合金めっき鋼板およびその製造方法に係り、とくにめっき層の加工性および耐食性を向上した溶融Ｚｎ−Ａｌ系合金めっき鋼板に関する。
The present invention relates to a molten Zn-Al alloy-plated steel sheet excellent in corrosion resistance and suitable for use in members of buildings, civil engineering, home appliances and the like, and a method for producing the same, and more particularly, molten Zn- with improved workability and corrosion resistance of a plating layer The present invention relates to an Al-based alloy plated steel sheet.
従来、建築、土木、家電等の分野で使用される溶融Ｚｎ系めっき鋼板には、耐食性に優れることが要求されている。
例えば、建築分野では、溶融Ｚｎ系めっき鋼板を所定形状に成形加工して、屋根、壁、あるいはその他構造体などの構造部材として使用している。このような用途では、耐食性に優れていることに加えて、加工性に優れること、さらには加工部の耐食性に優れることが要求され、加工部を含む素材の耐食性がその構造部材の耐久性を決定する重要な要素となっている。このため、構造部材の耐久性向上の観点から、素材として使用される溶融Ｚｎ系めっき鋼板の耐食性向上が強く要望されている。この場合には、外観の均一性や耐黒変性にも優れることが要求されている。ここで、黒変とは、めっき表面の一部もしくは全面にくすんだ灰黒色の変色が発生する現象をいう。
また、溶融Ｚｎ系めっき鋼板は、例えば、海岸部など飛来塩分が多い厳しい環境下においても耐食性に優れることから、建築分野では、無塗装で使用されることも多い。 Conventionally, hot-dip Zn-based plated steel sheets used in fields such as architecture, civil engineering, and home appliances are required to have excellent corrosion resistance.
For example, in the construction field, a hot dip Zn-based plated steel sheet is formed into a predetermined shape and used as a structural member such as a roof, wall, or other structure. In such applications, in addition to being excellent in corrosion resistance, it is required to be excellent in workability, and further in the corrosion resistance of the processed part, and the corrosion resistance of the material including the processed part enhances the durability of the structural member. It is an important factor to decide. For this reason, from the viewpoint of improving the durability of structural members, there is a strong demand for improving the corrosion resistance of hot-dip Zn-based plated steel sheets used as raw materials. In this case, it is required to have excellent appearance uniformity and blackening resistance. Here, blackening refers to a phenomenon in which a dark gray discoloration occurs on a part or the whole of the plating surface.
Further, the hot-dip Zn-based plated steel sheet is often used without coating in the construction field because it is excellent in corrosion resistance even in a severe environment with a lot of incoming salt such as a coastal area.
例えば、建築分野では、溶融Ｚｎ系めっき鋼板を所定形状に成形加工して、屋根、壁、あるいはその他構造体などの構造部材として使用している。このような用途では、耐食性に優れていることに加えて、加工性に優れること、さらには加工部の耐食性に優れることが要求され、加工部を含む素材の耐食性がその構造部材の耐久性を決定する重要な要素となっている。このため、構造部材の耐久性向上の観点から、素材として使用される溶融Ｚｎ系めっき鋼板の耐食性向上が強く要望されている。この場合には、外観の均一性や耐黒変性にも優れることが要求されている。ここで、黒変とは、めっき表面の一部もしくは全面にくすんだ灰黒色の変色が発生する現象をいう。
また、溶融Ｚｎ系めっき鋼板は、例えば、海岸部など飛来塩分が多い厳しい環境下においても耐食性に優れることから、建築分野では、無塗装で使用されることも多い。 Conventionally, hot-dip Zn-based plated steel sheets used in fields such as architecture, civil engineering, and home appliances are required to have excellent corrosion resistance.
For example, in the construction field, a hot dip Zn-based plated steel sheet is formed into a predetermined shape and used as a structural member such as a roof, wall, or other structure. In such applications, in addition to being excellent in corrosion resistance, it is required to be excellent in workability, and further in the corrosion resistance of the processed part, and the corrosion resistance of the material including the processed part enhances the durability of the structural member. It is an important factor to decide. For this reason, from the viewpoint of improving the durability of structural members, there is a strong demand for improving the corrosion resistance of hot-dip Zn-based plated steel sheets used as raw materials. In this case, it is required to have excellent appearance uniformity and blackening resistance. Here, blackening refers to a phenomenon in which a dark gray discoloration occurs on a part or the whole of the plating surface.
Further, the hot-dip Zn-based plated steel sheet is often used without coating in the construction field because it is excellent in corrosion resistance even in a severe environment with a lot of incoming salt such as a coastal area.
このような要望に対して、例えば、特許文献１には、連続溶融Ｚｎ−Ａｌ−Ｍｇめっき鋼板が記載されている。特許文献１に記載された技術は、Ａｌ：４．０~１０％、Ｍｇ：１．０~４．０％、残部がＺｎおよび不可避的不純物からなるめっき層を鋼板表面に形成した連続溶融Ｚｎ−Ａｌ−Ｍｇめっき鋼板であり、めっき後の冷却速度を０．５℃／ｓ以上に制御して、めっき層をＡｌ／Ｚｎ／Ｚｎ２Ｍｇの三元共晶組織の素地中に初晶Ａｌ相が混在した金属組織を有する層とすることにより、良好な耐食性と表面外観を有するめっき鋼板になる、としている。
In response to such a demand, for example, Patent Document 1 describes a continuous molten Zn—Al—Mg plated steel sheet. The technique described in Patent Document 1 is a continuous molten Zn in which a plating layer comprising Al: 4.0 to 10%, Mg: 1.0 to 4.0%, the balance being Zn and unavoidable impurities is formed on the steel sheet surface. -Al-Mg plated steel sheet, the cooling rate after plating is controlled to 0.5 ° C / s or more, and the plated layer is primary Al in the substrate of the ternary eutectic structure of Al / Zn / Zn 2 Mg. By forming a layer having a metal structure in which phases are mixed, a plated steel sheet having good corrosion resistance and surface appearance is obtained.
また、特許文献２には、金属光沢をもつ美麗なめっき外観と、優れた耐黒変性を有する溶融Ｚｎ−Ａｌ系合金めっき鋼板が記載されている。この特許文献２に記載された技術では、鋼板を溶融Ｚｎ−Ａｌ系合金めっき浴に浸漬した後、該めっき浴から引き上げて、２５０℃までの冷却速度で１~１５℃／ｓの範囲で冷却し、鋼板表面に、Ａｌ：１．０~１０％、Ｍｇ：０．２~１．０％、Ｎｉ：０．００５~０．１％を含み、残部がＺｎおよび不可避的不純物からなる溶融Ｚｎ−Ａｌ系合金めっき層を形成することによって、金属光沢をもつ美麗なめっき外観と、優れた耐黒変性を有する溶融Ｚｎ−Ａｌ系合金めっき鋼板が得られる、としている。そして、特許文献２に記載された技術では、めっき後の冷却速度を上記した特定の範囲に制御すれば、ＭｇとＮｉの相乗作用によりめっき最表層部へのＮｉの濃化が促進される、としている。また、特許文献２に記載された技術では、溶融Ｚｎ−Ａｌ系合金めっき層が、めっき層断面で、Ａｌ−Ｚｎ−Ｍｇ金属間化合物の３元共晶を好ましくは１０~３０面積％含有することが好ましい、としている。さらに、特許文献２に記載された技術では、めっき層の上層として化成処理層、プライマー層、樹脂層を形成してもよく、化成処理層として、クロムを含まないチタン系やジルコニウム系等の処理液によるクロムフリー処理を適用してもよい、としている。
Patent Document 2 describes a hot-dip Zn-Al alloy-plated steel sheet having a beautiful plating appearance with metallic luster and excellent blackening resistance. In the technique described in Patent Document 2, a steel sheet is immersed in a molten Zn-Al alloy plating bath, then pulled up from the plating bath, and cooled at a cooling rate of up to 250 ° C in a range of 1 to 15 ° C / s. In addition, molten steel containing Al: 1.0 to 10%, Mg: 0.2 to 1.0%, Ni: 0.005 to 0.1% on the steel plate surface, the balance being Zn and inevitable impurities -By forming an Al-based alloy plating layer, a beautiful plated appearance with metallic luster and a hot-dip Zn-Al-based alloy-plated steel sheet having excellent blackening resistance can be obtained. And in the technique described in Patent Document 2, if the cooling rate after plating is controlled within the specific range described above, the concentration of Ni in the plating outermost layer portion is promoted by the synergistic action of Mg and Ni. It is said. In the technique described in Patent Document 2, the molten Zn—Al-based alloy plating layer preferably contains 10 to 30 area% of a ternary eutectic of an Al—Zn—Mg intermetallic compound in a cross section of the plating layer. It is preferable. Furthermore, in the technique described in Patent Document 2, a chemical conversion treatment layer, a primer layer, and a resin layer may be formed as an upper layer of the plating layer, and the chemical conversion treatment layer may be a titanium-based or zirconium-based treatment that does not contain chromium. It is said that a chromium-free treatment with a liquid may be applied.
次に、特許文献３には、鋼板の少なくとも一方の表面に、溶融Ｚｎ−Ａｌ系合金めっき層を形成し、さらに該めっき層の表面に表面処理皮膜を形成してなる溶融Ｚｎ−Ａｌ系合金めっき鋼板が記載されている。この特許文献３に記載された技術では、溶融Ｚｎ−Ａｌ系合金めっき層を、質量％で、Ａｌ：１．０~１０％、Ｍｇ：０．２~１．０％、Ｎｉ：０．００５~０．１％を含み、残部がＺｎおよび不可避的不純物からなる溶融Ｚｎ−Ａｌ系合金めっき層とし、さらに該めっき層の表面に形成する表面処理皮膜を、特定のチタン含有水性液と、ニッケル化合物及び／又はコバルト化合物と、弗素含有化合物とを所定の割合で含有する表面処理組成物による表面処理皮膜とすることにより、めっき組成の最適化と相俟って、優れた耐黒変性が得られるとともに、弗素含有化合物の作用により反応性が高まり、めっき表面に緻密な反応層が形成され、さらに表面処理皮膜自体により高いバリア性が付与されて、優れた耐食性が得られる、としている。
Next, Patent Document 3 discloses a molten Zn-Al alloy formed by forming a molten Zn-Al-based alloy plating layer on at least one surface of a steel sheet and further forming a surface treatment film on the surface of the plating layer. A plated steel sheet is described. In the technique described in Patent Document 3, a molten Zn—Al-based alloy plating layer is formed by mass%, Al: 1.0 to 10%, Mg: 0.2 to 1.0%, Ni: 0.005. A surface treatment film formed on the surface of the plating layer containing a Zn-Al alloy plating layer containing Zn and unavoidable impurities, including a specific titanium-containing aqueous liquid and nickel By forming a surface treatment film with a surface treatment composition containing a compound and / or a cobalt compound and a fluorine-containing compound at a predetermined ratio, excellent blackening resistance can be obtained in combination with optimization of the plating composition. In addition, the reactivity is increased by the action of the fluorine-containing compound, a dense reaction layer is formed on the plating surface, and a high barrier property is imparted by the surface treatment film itself, thereby obtaining excellent corrosion resistance.
しかしながら、特許文献１に記載された技術で製造されためっき鋼板は、めっき層中に、Ｚｎよりも酸化力の強いＡｌやＭｇを多量に含有させており、かようなめっき鋼板をコイルやシート状態で倉庫などにて長期間保管すると、めっき表面の一部もしくは全面にくすんだ灰黒色の変色（黒変現象）が発生する場合があり、商品価値が低下するという問題がある。また、特許文献１に記載された技術は、めっき層中にＭｇを多量に含有させるため、めっき層が硬質化して、成形加工を施された箇所にクラックが発生し、めっき層下地の腐食（赤錆）が進行するという問題がある。
However, the plated steel sheet manufactured by the technique described in Patent Document 1 contains a large amount of Al or Mg, which has higher oxidizing power than Zn, in the plating layer. When stored in a warehouse or the like for a long period of time, a dark gray discoloration (black discoloration phenomenon) may occur on a part or the whole of the plating surface, resulting in a problem that the commercial value is lowered. Moreover, since the technique described in Patent Document 1 contains a large amount of Mg in the plating layer, the plating layer is hardened, cracks are generated in the portions subjected to the forming process, and corrosion of the plating layer base ( There is a problem that red rust) progresses.
また、特許文献２に記載された技術では、めっき層中にＮｉを含有するＺｎ−Ａｌ−Ｍｇ系組成とすることにより、主として耐黒変性を向上させるとしているが、Ａｌ−Ｍｇ−Ｎｉ−Ｚｎ系という４元系では、めっき層組成によっては、めっき層表面に化成処理皮膜を形成する際に、化成処理反応が不十分となる場合があり、黒変を抑止する効果が不安定になるという問題があった。
Moreover, in the technique described in Patent Document 2, the blackening resistance is mainly improved by adopting a Zn—Al—Mg-based composition containing Ni in the plating layer, but Al—Mg—Ni—Zn. In the quaternary system, depending on the plating layer composition, when the chemical conversion treatment film is formed on the surface of the plating layer, the chemical conversion treatment reaction may become insufficient, and the effect of suppressing blackening becomes unstable. There was a problem.
さらに、特許文献３に記載された技術では、めっき層をＮｉを含有するＺｎ−Ａｌ−Ｍｇ系組成としたうえで、さらにめっき層の上層として特殊な表面処理皮膜を形成し、耐黒変性を向上させているが、ニッケル化合物および／又はコバルト化合物を多くすると、耐食性が低下することから、耐黒変性との両立が難しいところに問題を残していた。
本発明は、かかる従来技術の問題を解決し、耐黒変性および耐食性に優れる溶融Ｚｎ−Ａｌ系合金めっき鋼板およびその製造方法を提供することを目的とする。 Furthermore, in the technique described in Patent Document 3, after the plating layer has a Zn-Al-Mg-based composition containing Ni, a special surface treatment film is formed as an upper layer of the plating layer, and blackening resistance is reduced. However, when the nickel compound and / or the cobalt compound is increased, the corrosion resistance is lowered, so that there remains a problem in that it is difficult to achieve both blackening resistance.
The object of the present invention is to solve the problems of the prior art and to provide a hot-dip Zn-Al alloy-plated steel sheet excellent in blackening resistance and corrosion resistance and a method for producing the same.
本発明は、かかる従来技術の問題を解決し、耐黒変性および耐食性に優れる溶融Ｚｎ−Ａｌ系合金めっき鋼板およびその製造方法を提供することを目的とする。 Furthermore, in the technique described in Patent Document 3, after the plating layer has a Zn-Al-Mg-based composition containing Ni, a special surface treatment film is formed as an upper layer of the plating layer, and blackening resistance is reduced. However, when the nickel compound and / or the cobalt compound is increased, the corrosion resistance is lowered, so that there remains a problem in that it is difficult to achieve both blackening resistance.
The object of the present invention is to solve the problems of the prior art and to provide a hot-dip Zn-Al alloy-plated steel sheet excellent in blackening resistance and corrosion resistance and a method for producing the same.
本発明者らは、上記した目的を達成するために、溶融Ｚｎ−Ａｌ系合金めっき鋼板の耐黒変性および耐食性に及ぼす各種要因について、鋭意検討した。その結果、鋼板表面に形成するめっき層を、Ｎｉを適正量含有するＺｎ−Ａｌ−Ｍｇ系組成としたうえで、めっき層の表面組織を、Ｚｎ−Ａｌ−Ｍｇ系の３元共晶が面積率で１~５０％存在する組織とすることにより、その後の化成処理において反応性に優れるめっき層表面上に、良好な化成処理皮膜を形成でき、安定して耐黒変性を向上することができるとともに、成形加工に際し、めっき層のクラック発生を有効に抑制でき、成形加工部の耐食性が顕著に向上することを見出した。
In order to achieve the above-mentioned object, the present inventors diligently studied various factors affecting blackening resistance and corrosion resistance of a hot-dip Zn-Al alloy-plated steel sheet. As a result, the plating layer formed on the surface of the steel sheet has a Zn—Al—Mg-based composition containing an appropriate amount of Ni, and the surface structure of the plating layer is the area of the Zn—Al—Mg-based ternary eutectic. By making the structure present at a rate of 1 to 50%, a good chemical conversion film can be formed on the surface of the plating layer that is excellent in reactivity in the subsequent chemical conversion treatment, and the blackening resistance can be stably improved. At the same time, it has been found that the cracking of the plating layer can be effectively suppressed during the molding process, and the corrosion resistance of the molded part is significantly improved.
また、本発明者らは、上記したような組成のＺｎ−Ａｌ−Ｍｇ系合金めっき層としたうえで、さらに、該めっき層の上層として、モリブデン酸塩を含有する化成処理皮膜を形成することにより、めっき層組成と相俟って黒変が顕著に抑止され、耐黒変性が格段に向上することを知見した。
本発明は、このような知見に基づき、さらに検討を加えて完成されたものである。すなわち、本発明の要旨は次のとおりである。
（１）鋼板の少なくとも一方の表面に、溶融Ｚｎ−Ａｌ系合金めっき層を形成し、さらに該溶融Ｚｎ−Ａｌ系合金めっき層の上層として化成処理被膜を形成してなる溶融Ｚｎ−Ａｌ系合金めっき鋼板であって、
前記溶融Ｚｎ−Ａｌ系合金めっき層は、質量％で、
Ａｌ：３．０~６．０％、
Ｍｇ：０．２~１．０％および
Ｎｉ：０．０１~０．１０％
を含有し、残部Ｚｎおよび不可避的不純物からなる組成を有し、該めっき層の表面組織が、Ｚｎ−Ａｌ−Ｍｇ系三元共晶を面積率で１~５０％含み、前記化成処理被膜が、モリブデン酸塩を含有することを特徴とする耐黒変性と耐食性に優れた溶融Ｚｎ−Ａｌ系合金めっき鋼板。
（２）前記モリブデン酸塩を含有する化成処理皮被膜の片面当たりの付着量が、０．０５~１．５ｇ／ｍ２であることを特徴とする請求項１に記載の溶融Ｚｎ−Ａｌ系合金めっき鋼板。
（３）鋼板を、質量％で、Ａｌ：３~６％、Ｍｇ：０．２~１．０％およびＮｉ：０．０１~０．１０％を含み、残部Ｚｎおよび不可避的不純物からなる組成の溶融Ｚｎ−Ａｌ系合金めっき浴中に浸漬したのち、同めっき浴から鋼板を引き上げて冷却して、該鋼板表面に溶融Ｚｎ−Ａｌ系合金めっき層を形成し、さらに化成処理を施して、該溶融Ｚｎ−Ａｌ系合金めっき層の上層として、化成処理皮被膜を形成する、溶融Ｚｎ−Ａｌ系合金めっき鋼板の製造方法であって、
前記溶融Ｚｎ−Ａｌ系合金めっき浴の温度を４２０℃~５２０℃、前記溶融Ｚｎ−Ａｌ系合金めっき浴中に浸漬する前記鋼板の温度を４２０~６００℃で、かつ前記鋼板の温度を前記溶融Ｚｎ−Ａｌ系めっき浴の温度以上に調整して、前記溶融Ｚｎ−Ａｌ系合金めっき浴中に浸漬し、
さらに前記溶融Ｚｎ−Ａｌ系めっき浴から鋼板を引き上げたのち、前記鋼板の表面温度で、３５０℃までの平均冷却速度が１~１００℃／ｓである冷却を前記鋼板に施し、
前記化成処理を、モリブデン酸塩を含有する化成処理液を用いて行うことを特徴とする耐黒変性と耐食性に優れた溶融Ｚｎ−Ａｌ系合金めっき鋼板の製造方法。
（４）前記化成処理液のｐＨが２~６であることを特徴とする請求項３に記載の溶融Ｚｎ−Ａｌ系めっき鋼板の製造方法。 Moreover, the present inventors form a chemical conversion film containing molybdate as an upper layer of the plating layer after forming the Zn—Al—Mg alloy plating layer having the composition as described above. Thus, it was found that blackening is remarkably suppressed in combination with the plating layer composition, and the blackening resistance is remarkably improved.
The present invention has been completed based on such findings and further studies. That is, the gist of the present invention is as follows.
(1) A molten Zn-Al alloy obtained by forming a molten Zn-Al alloy plating layer on at least one surface of a steel plate and further forming a chemical conversion coating as an upper layer of the molten Zn-Al alloy plating layer A plated steel sheet,
The molten Zn—Al-based alloy plating layer is in mass%,
Al: 3.0 to 6.0%,
Mg: 0.2-1.0% and Ni: 0.01-0.10%
The surface structure of the plating layer contains Zn—Al—Mg ternary eutectic in an area ratio of 1 to 50%, and the chemical conversion coating film has a composition comprising the balance Zn and inevitable impurities. A molten Zn-Al alloy-plated steel sheet excellent in blackening resistance and corrosion resistance, characterized by containing molybdate.
(2) The molten Zn—Al system according to claim 1, wherein the amount of adhesion per one side of the chemical conversion coating containing the molybdate is 0.05 to 1.5 g / m 2. Alloy-plated steel sheet.
(3) A composition containing, by mass%, Al: 3 to 6%, Mg: 0.2 to 1.0% and Ni: 0.01 to 0.10%, the balance being Zn and inevitable impurities After being immersed in the molten Zn-Al-based alloy plating bath, the steel plate is pulled up from the plating bath and cooled to form a molten Zn-Al-based alloy plating layer on the steel plate surface, and further subjected to chemical conversion treatment, A method for producing a molten Zn-Al-based alloy-plated steel sheet, which forms a chemical conversion treatment coating as an upper layer of the molten Zn-Al-based alloy plating layer,
The temperature of the molten Zn—Al based alloy plating bath is 420 ° C. to 520 ° C., the temperature of the steel sheet immersed in the molten Zn—Al based alloy plating bath is 420 to 600 ° C., and the temperature of the steel plate is melted. Adjust the temperature above the temperature of the Zn-Al based plating bath, immerse in the molten Zn-Al based alloy plating bath,
Furthermore, after pulling up the steel sheet from the molten Zn-Al plating bath, the steel sheet is subjected to cooling at an average cooling rate of 1 to 100 ° C./s up to 350 ° C. at the surface temperature of the steel sheet,
A method for producing a hot-dip Zn-Al alloy-plated steel sheet having excellent blackening resistance and corrosion resistance, wherein the chemical conversion treatment is performed using a chemical conversion treatment solution containing molybdate.
(4) The method for producing a hot-dip Zn—Al-based plated steel sheet according to claim 3, wherein the chemical conversion solution has a pH of 2 to 6.
本発明は、このような知見に基づき、さらに検討を加えて完成されたものである。すなわち、本発明の要旨は次のとおりである。
（１）鋼板の少なくとも一方の表面に、溶融Ｚｎ−Ａｌ系合金めっき層を形成し、さらに該溶融Ｚｎ−Ａｌ系合金めっき層の上層として化成処理被膜を形成してなる溶融Ｚｎ−Ａｌ系合金めっき鋼板であって、
前記溶融Ｚｎ−Ａｌ系合金めっき層は、質量％で、
Ａｌ：３．０~６．０％、
Ｍｇ：０．２~１．０％および
Ｎｉ：０．０１~０．１０％
を含有し、残部Ｚｎおよび不可避的不純物からなる組成を有し、該めっき層の表面組織が、Ｚｎ−Ａｌ−Ｍｇ系三元共晶を面積率で１~５０％含み、前記化成処理被膜が、モリブデン酸塩を含有することを特徴とする耐黒変性と耐食性に優れた溶融Ｚｎ−Ａｌ系合金めっき鋼板。
（２）前記モリブデン酸塩を含有する化成処理皮被膜の片面当たりの付着量が、０．０５~１．５ｇ／ｍ２であることを特徴とする請求項１に記載の溶融Ｚｎ−Ａｌ系合金めっき鋼板。
（３）鋼板を、質量％で、Ａｌ：３~６％、Ｍｇ：０．２~１．０％およびＮｉ：０．０１~０．１０％を含み、残部Ｚｎおよび不可避的不純物からなる組成の溶融Ｚｎ−Ａｌ系合金めっき浴中に浸漬したのち、同めっき浴から鋼板を引き上げて冷却して、該鋼板表面に溶融Ｚｎ−Ａｌ系合金めっき層を形成し、さらに化成処理を施して、該溶融Ｚｎ−Ａｌ系合金めっき層の上層として、化成処理皮被膜を形成する、溶融Ｚｎ−Ａｌ系合金めっき鋼板の製造方法であって、
前記溶融Ｚｎ−Ａｌ系合金めっき浴の温度を４２０℃~５２０℃、前記溶融Ｚｎ−Ａｌ系合金めっき浴中に浸漬する前記鋼板の温度を４２０~６００℃で、かつ前記鋼板の温度を前記溶融Ｚｎ−Ａｌ系めっき浴の温度以上に調整して、前記溶融Ｚｎ−Ａｌ系合金めっき浴中に浸漬し、
さらに前記溶融Ｚｎ−Ａｌ系めっき浴から鋼板を引き上げたのち、前記鋼板の表面温度で、３５０℃までの平均冷却速度が１~１００℃／ｓである冷却を前記鋼板に施し、
前記化成処理を、モリブデン酸塩を含有する化成処理液を用いて行うことを特徴とする耐黒変性と耐食性に優れた溶融Ｚｎ−Ａｌ系合金めっき鋼板の製造方法。
（４）前記化成処理液のｐＨが２~６であることを特徴とする請求項３に記載の溶融Ｚｎ−Ａｌ系めっき鋼板の製造方法。 Moreover, the present inventors form a chemical conversion film containing molybdate as an upper layer of the plating layer after forming the Zn—Al—Mg alloy plating layer having the composition as described above. Thus, it was found that blackening is remarkably suppressed in combination with the plating layer composition, and the blackening resistance is remarkably improved.
The present invention has been completed based on such findings and further studies. That is, the gist of the present invention is as follows.
(1) A molten Zn-Al alloy obtained by forming a molten Zn-Al alloy plating layer on at least one surface of a steel plate and further forming a chemical conversion coating as an upper layer of the molten Zn-Al alloy plating layer A plated steel sheet,
The molten Zn—Al-based alloy plating layer is in mass%,
Al: 3.0 to 6.0%,
Mg: 0.2-1.0% and Ni: 0.01-0.10%
The surface structure of the plating layer contains Zn—Al—Mg ternary eutectic in an area ratio of 1 to 50%, and the chemical conversion coating film has a composition comprising the balance Zn and inevitable impurities. A molten Zn-Al alloy-plated steel sheet excellent in blackening resistance and corrosion resistance, characterized by containing molybdate.
(2) The molten Zn—Al system according to claim 1, wherein the amount of adhesion per one side of the chemical conversion coating containing the molybdate is 0.05 to 1.5 g / m 2. Alloy-plated steel sheet.
(3) A composition containing, by mass%, Al: 3 to 6%, Mg: 0.2 to 1.0% and Ni: 0.01 to 0.10%, the balance being Zn and inevitable impurities After being immersed in the molten Zn-Al-based alloy plating bath, the steel plate is pulled up from the plating bath and cooled to form a molten Zn-Al-based alloy plating layer on the steel plate surface, and further subjected to chemical conversion treatment, A method for producing a molten Zn-Al-based alloy-plated steel sheet, which forms a chemical conversion treatment coating as an upper layer of the molten Zn-Al-based alloy plating layer,
The temperature of the molten Zn—Al based alloy plating bath is 420 ° C. to 520 ° C., the temperature of the steel sheet immersed in the molten Zn—Al based alloy plating bath is 420 to 600 ° C., and the temperature of the steel plate is melted. Adjust the temperature above the temperature of the Zn-Al based plating bath, immerse in the molten Zn-Al based alloy plating bath,
Furthermore, after pulling up the steel sheet from the molten Zn-Al plating bath, the steel sheet is subjected to cooling at an average cooling rate of 1 to 100 ° C./s up to 350 ° C. at the surface temperature of the steel sheet,
A method for producing a hot-dip Zn-Al alloy-plated steel sheet having excellent blackening resistance and corrosion resistance, wherein the chemical conversion treatment is performed using a chemical conversion treatment solution containing molybdate.
(4) The method for producing a hot-dip Zn—Al-based plated steel sheet according to claim 3, wherein the chemical conversion solution has a pH of 2 to 6.
本発明によれば、優れた耐黒変性を安定して有する溶融Ｚｎ−Ａｌ系合金めっき鋼板を、容易にかつ安価に製造でき、産業上格段の効果を奏する。また、本発明によれば、めっき層の加工性が向上した結果、成形加工時のめっき層のクラック発生が抑制されて、めっき下地の腐食が効果的に抑制されることから、成形加工後の耐食性に優れた溶融Ｚｎ−Ａｌ系合金めっき鋼板を提供することができる。
According to the present invention, it is possible to easily and inexpensively manufacture a hot-dip Zn-Al alloy-plated steel sheet having stable blackening resistance, and achieve a remarkable industrial effect. In addition, according to the present invention, as a result of improving the workability of the plating layer, cracking of the plating layer during molding processing is suppressed, and corrosion of the plating base is effectively suppressed. It is possible to provide a hot-dip Zn—Al-based alloy-plated steel sheet having excellent corrosion resistance.
本発明の溶融Ｚｎ−Ａｌ系合金めっき鋼板（以下、「本発明めっき鋼板」ともいう）は、鋼板の少なくとも一方の表面に、質量％で、Ａｌ：３．０~６．０％、Ｍｇ：０．２~１．０％、Ｎｉ：０．０１~０．１％を含有し、残部Ｚｎおよび不可避的不純物からなる溶融Ｚｎ−Ａｌ系合金めっき層を有し、さらにその上層として、モリブデン酸塩を含有する化成処理皮膜を有する。
The hot-dip Zn—Al-based alloy-plated steel sheet (hereinafter, also referred to as “the present invention-coated steel sheet”) of the present invention is formed on at least one surface of the steel sheet by mass%, Al: 3.0 to 6.0%, Mg: It has 0.2 to 1.0%, Ni: 0.01 to 0.1%, and has a molten Zn-Al alloy plating layer composed of the balance Zn and unavoidable impurities, and further has molybdic acid as an upper layer. It has a chemical conversion treatment film containing salt.
まず、溶融Ｚｎ−Ａｌ系合金めっき層の組成限定理由について説明する。なお、以下、組成における質量％は単に％で記す。
Ａｌ：３．０~６．０％
めっき層中に含まれるＡｌが、３．０％未満では、めっき層と下地鋼板との界面にＦｅ−Ａｌ系合金層が厚く形成するため、加工性が低下する。一方、Ａｌが６．０％を超えて多量に含有されると、Ｚｎの犠牲防食作用が小さくなり、耐食性が低下するとともに、耐黒変性が低下する。また、Ｚｎ−Ａｌ−Ｍｇの３元共晶の形成が多くなり、化成処理性が不安定となるうえ、めっき層の加工性も低下する。このため、めっき層中のＡｌは３．０~６．０％の範囲に限定した。さらに、４．０~５．５％の範囲であることが好ましい。 First, the reason for limiting the composition of the molten Zn—Al-based alloy plating layer will be described. Hereinafter, the mass% in the composition is simply expressed as%.
Al: 3.0 to 6.0%
If the Al contained in the plating layer is less than 3.0%, the Fe—Al-based alloy layer is formed thick at the interface between the plating layer and the underlying steel plate, and therefore the workability is lowered. On the other hand, when Al is contained in a large amount exceeding 6.0%, the sacrificial anticorrosive action of Zn is reduced, the corrosion resistance is lowered, and the blackening resistance is lowered. In addition, the formation of Zn—Al—Mg ternary eutectic increases, the chemical conversion property becomes unstable, and the workability of the plating layer also decreases. For this reason, Al in the plating layer is limited to a range of 3.0 to 6.0%. Further, it is preferably in the range of 4.0 to 5.5%.
Ａｌ：３．０~６．０％
めっき層中に含まれるＡｌが、３．０％未満では、めっき層と下地鋼板との界面にＦｅ−Ａｌ系合金層が厚く形成するため、加工性が低下する。一方、Ａｌが６．０％を超えて多量に含有されると、Ｚｎの犠牲防食作用が小さくなり、耐食性が低下するとともに、耐黒変性が低下する。また、Ｚｎ−Ａｌ−Ｍｇの３元共晶の形成が多くなり、化成処理性が不安定となるうえ、めっき層の加工性も低下する。このため、めっき層中のＡｌは３．０~６．０％の範囲に限定した。さらに、４．０~５．５％の範囲であることが好ましい。 First, the reason for limiting the composition of the molten Zn—Al-based alloy plating layer will be described. Hereinafter, the mass% in the composition is simply expressed as%.
Al: 3.0 to 6.0%
If the Al contained in the plating layer is less than 3.0%, the Fe—Al-based alloy layer is formed thick at the interface between the plating layer and the underlying steel plate, and therefore the workability is lowered. On the other hand, when Al is contained in a large amount exceeding 6.0%, the sacrificial anticorrosive action of Zn is reduced, the corrosion resistance is lowered, and the blackening resistance is lowered. In addition, the formation of Zn—Al—Mg ternary eutectic increases, the chemical conversion property becomes unstable, and the workability of the plating layer also decreases. For this reason, Al in the plating layer is limited to a range of 3.0 to 6.0%. Further, it is preferably in the range of 4.0 to 5.5%.
Ｍｇ：０．２~１．０％
Ｍｇは、耐食性向上のためにめっき層中に含有させるが、めっき層中に含まれるＭｇが、０．２％未満では耐食性の向上効果が少なく、一方、Ｍｇが１．０％を超えて多量に含有されると、Ｚｎ−Ａｌ−Ｍｇ系３元共晶の形成が多くなり、めっき層の加工性が低下する。このようなことから、めっき層中のＭｇは０．２~１．０％の範囲に限定した。さらに、０．３~０．８％の範囲であることが好ましい。 Mg: 0.2 to 1.0%
Mg is contained in the plating layer to improve corrosion resistance. However, if Mg contained in the plating layer is less than 0.2%, the effect of improving corrosion resistance is small, while Mg exceeds 1.0% and a large amount. When contained in Zn, the formation of Zn—Al—Mg ternary eutectic increases, and the workability of the plating layer decreases. Therefore, Mg in the plating layer is limited to the range of 0.2 to 1.0%. Furthermore, it is preferably in the range of 0.3 to 0.8%.
Ｍｇは、耐食性向上のためにめっき層中に含有させるが、めっき層中に含まれるＭｇが、０．２％未満では耐食性の向上効果が少なく、一方、Ｍｇが１．０％を超えて多量に含有されると、Ｚｎ−Ａｌ−Ｍｇ系３元共晶の形成が多くなり、めっき層の加工性が低下する。このようなことから、めっき層中のＭｇは０．２~１．０％の範囲に限定した。さらに、０．３~０．８％の範囲であることが好ましい。 Mg: 0.2 to 1.0%
Mg is contained in the plating layer to improve corrosion resistance. However, if Mg contained in the plating layer is less than 0.2%, the effect of improving corrosion resistance is small, while Mg exceeds 1.0% and a large amount. When contained in Zn, the formation of Zn—Al—Mg ternary eutectic increases, and the workability of the plating layer decreases. Therefore, Mg in the plating layer is limited to the range of 0.2 to 1.0%. Furthermore, it is preferably in the range of 0.3 to 0.8%.
Ｎｉ：０．０１~０．１０％
Ｎｉは、耐食性と耐黒変性向上のためにめっき層中に含有させるが、めっき層中に含まれるＮｉが、０．０１％未満では耐食性と耐黒変性の向上効果が少なく、一方、Ｎｉが０．１０％を超えて多量に含有されると、めっき層の表面が過剰に活性化され、腐食しやすくなり、初期に白錆が出やすくなる。このため、めっき層中のＮｉは０．０１~０．１０％の範囲に限定した。
上記した以外の残部は、Ｚｎおよび不可避的不純物からなる。なお、不純物としては、Ｓｉ、Ｃａ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｃｕ、Ｓｒ、Ｚｒ、Ｎｂ、Ｍｏ等があり、それぞれ０．０１％を上限として含まれていてもよい。 Ni: 0.01 to 0.10%
Ni is included in the plating layer to improve corrosion resistance and blackening resistance. However, if Ni contained in the plating layer is less than 0.01%, the effect of improving corrosion resistance and blackening resistance is small. If it is contained in a large amount exceeding 0.10%, the surface of the plating layer is excessively activated and easily corroded, and white rust is likely to appear at the initial stage. For this reason, Ni in the plating layer is limited to a range of 0.01 to 0.10%.
The balance other than the above consists of Zn and unavoidable impurities. Examples of impurities include Si, Ca, Ti, V, Cr, Mn, Fe, Co, Cu, Sr, Zr, Nb, and Mo, and each may be included with an upper limit of 0.01%.
Ｎｉは、耐食性と耐黒変性向上のためにめっき層中に含有させるが、めっき層中に含まれるＮｉが、０．０１％未満では耐食性と耐黒変性の向上効果が少なく、一方、Ｎｉが０．１０％を超えて多量に含有されると、めっき層の表面が過剰に活性化され、腐食しやすくなり、初期に白錆が出やすくなる。このため、めっき層中のＮｉは０．０１~０．１０％の範囲に限定した。
上記した以外の残部は、Ｚｎおよび不可避的不純物からなる。なお、不純物としては、Ｓｉ、Ｃａ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｃｕ、Ｓｒ、Ｚｒ、Ｎｂ、Ｍｏ等があり、それぞれ０．０１％を上限として含まれていてもよい。 Ni: 0.01 to 0.10%
Ni is included in the plating layer to improve corrosion resistance and blackening resistance. However, if Ni contained in the plating layer is less than 0.01%, the effect of improving corrosion resistance and blackening resistance is small. If it is contained in a large amount exceeding 0.10%, the surface of the plating layer is excessively activated and easily corroded, and white rust is likely to appear at the initial stage. For this reason, Ni in the plating layer is limited to a range of 0.01 to 0.10%.
The balance other than the above consists of Zn and unavoidable impurities. Examples of impurities include Si, Ca, Ti, V, Cr, Mn, Fe, Co, Cu, Sr, Zr, Nb, and Mo, and each may be included with an upper limit of 0.01%.
さらに、本発明めっき鋼板の表面に形成されるめっき層は、上記した組成を有し、さらにめっき層表面で、Ｚｎ−Ａｌ−Ｍｇ系三元共晶を面積率で１~５０％含む組織を有する。
本発明めっき鋼板のめっき層は、表面に、Ｚｎ−Ａｌ−Ｍｇ系３元共晶が面積率で１~５０％露出した、表面組織を有する。めっき層表面に所定量のＺｎ−Ａｌ−Ｍｇ系３元共晶を存在（露出）させることにより、耐食性と加工性を兼備させることができる。 Furthermore, the plating layer formed on the surface of the plated steel sheet of the present invention has the above-described composition, and further has a structure containing 1 to 50% of Zn—Al—Mg ternary eutectic by area ratio on the surface of the plating layer. Have.
The plated layer of the plated steel sheet of the present invention has a surface structure in which Zn—Al—Mg ternary eutectic is exposed on the surface in an area ratio of 1 to 50%. By allowing a predetermined amount of Zn—Al—Mg ternary eutectic to be present (exposed) on the surface of the plating layer, both corrosion resistance and workability can be provided.
本発明めっき鋼板のめっき層は、表面に、Ｚｎ−Ａｌ−Ｍｇ系３元共晶が面積率で１~５０％露出した、表面組織を有する。めっき層表面に所定量のＺｎ−Ａｌ−Ｍｇ系３元共晶を存在（露出）させることにより、耐食性と加工性を兼備させることができる。 Furthermore, the plating layer formed on the surface of the plated steel sheet of the present invention has the above-described composition, and further has a structure containing 1 to 50% of Zn—Al—Mg ternary eutectic by area ratio on the surface of the plating layer. Have.
The plated layer of the plated steel sheet of the present invention has a surface structure in which Zn—Al—Mg ternary eutectic is exposed on the surface in an area ratio of 1 to 50%. By allowing a predetermined amount of Zn—Al—Mg ternary eutectic to be present (exposed) on the surface of the plating layer, both corrosion resistance and workability can be provided.
すなわち、めっき層表面のＺｎ−Ａｌ−Ｍｇ系三元共晶が同表面における面積率で１％未満では耐食性の向上効果が少なく、一方、Ｚｎ−Ａｌ−Ｍｇ系三元共晶が表面における面積率で５０％を超えると、化成処理のめっき層表面との反応性が低下し、良好な化成処理皮膜が得られ難くなり、耐黒変性が不安定となるとともに、めっき層の表面が固くなりすぎて、成形加工時にクラックが発生しやすくなる。このため、めっき層の表面組織におけるＺｎ−Ａｌ−Ｍｇ系三元共晶を、面積率で１~５０％の範囲に限定した。なお、好ましくは５~４０％である。
That is, when the Zn—Al—Mg ternary eutectic on the surface of the plating layer is less than 1% in terms of the area ratio on the same surface, the effect of improving the corrosion resistance is small, while the Zn—Al—Mg ternary eutectic has an area on the surface. If the rate exceeds 50%, the reactivity with the plating layer surface of the chemical conversion treatment decreases, it becomes difficult to obtain a good chemical conversion coating film, the blackening resistance becomes unstable, and the surface of the plating layer becomes hard. Thus, cracks are likely to occur during the molding process. Therefore, the Zn—Al—Mg ternary eutectic in the surface structure of the plating layer is limited to the range of 1 to 50% in terms of area ratio. Note that the content is preferably 5 to 40%.
なお、めっき層表面におけるＺｎ−Ａｌ−Ｍｇ系三元共晶の面積率は、例えば、走査型電子顕微鏡（倍率：１０００倍程度）でめっき層表面を観察し、めっき層の表面組織を無作為に数視野撮像し、その視野（写真）ごとに画像処理ソフトを用いて求めることが好ましい。本発明では、各視野で得られた面積率を算術平均し、そのめっき層におけるＺｎ−Ａｌ−Ｍｇ系三元共晶の面積率とする。図１に、本発明めっき鋼板のめっき層表面組織の一例を示す。縞模様を有する結晶が、Ｚｎ−Ａｌ−Ｍｇ系三元共晶である。そして、図２は、図１に示しためっき層表面をＥＰＭＡでＭｇを分析した結果を画像解析し、Ｚｎ−Ａｌ−Ｍｇ系三元共晶の表面分布状況として示す画像解析図である。この画像解析図を利用して、白黒に２階調化し、ヒストグラムから算出する方法で、Ｚｎ−Ａｌ−Ｍｇ系三元共晶の表面面積率を求めてもよい。黒い部分がＺｎ−Ａｌ−Ｍｇ系三元共晶である。
In addition, the area ratio of the Zn—Al—Mg ternary eutectic on the surface of the plating layer can be determined by, for example, observing the surface of the plating layer with a scanning electron microscope (magnification: about 1000 times) and randomizing the surface structure of the plating layer. It is preferable to obtain several fields of view and obtain the field of view (photograph) using image processing software. In the present invention, the area ratio obtained in each field of view is arithmetically averaged to obtain the area ratio of the Zn—Al—Mg ternary eutectic in the plating layer. In FIG. 1, an example of the plating layer surface structure of this invention plated steel plate is shown. A crystal having a stripe pattern is a Zn—Al—Mg ternary eutectic. FIG. 2 is an image analysis diagram showing the result of analyzing the result of analyzing Mg on the surface of the plating layer shown in FIG. 1 by EPMA and showing the surface distribution of the Zn—Al—Mg ternary eutectic. By using this image analysis diagram, the surface area ratio of the Zn—Al—Mg ternary eutectic may be obtained by a method of making two gradations in black and white and calculating from a histogram. A black part is a Zn-Al-Mg ternary eutectic.
本発明めっき鋼板における溶融Ｚｎ−Ａｌ−Ｍｇ系合金めっき層の付着量は、通常通り、使途に応じて設定すればよく、とくに限定する必要はないが、片面あたり３０~３００ｇ／ｍ２程度とすることが好ましい。めっき層の付着量が３０ｇ／ｍ２以上では、めっき層厚さが不足せず、所望の耐食性を維持できる。一方、３００ｇ／ｍ２以下であれば、めっき層厚さが厚くなりすぎることがなく、めっき層が剥離しない。
The adhesion amount of the hot-dip Zn—Al—Mg alloy plating layer in the plated steel sheet of the present invention may be set according to the usage as usual, and is not particularly limited, but is about 30 to 300 g / m 2 per side. It is preferable to do. When the adhesion amount of the plating layer is 30 g / m 2 or more, the plating layer thickness is not insufficient, and desired corrosion resistance can be maintained. On the other hand, if it is 300 g / m 2 or less, the plating layer thickness will not be too thick and the plating layer will not peel off.
本発明めっき鋼板では、溶融Ｚｎ−Ａｌ−Ｍｇ系合金めっき層の上層として、モリブデン酸塩を含有する化成処理皮膜を有する。
めっき層の上層として形成される化成処理皮膜は、モリブデン酸塩を含有するものであり、このモリブデン酸塩とＺｎ−Ａｌ−Ｍｇ系三元共晶との組み合わせにより、耐黒変性と耐食性をよくするものである。なお、モリブデン酸塩としては、化成処理中に溶解するものであればよく、特に限定されるものではない。モリブデン酸塩の種類としては、例えばアンモニウム、ナトリウム等の塩が例示できる。化成処理皮膜中のモリブデン酸塩の含有量は、特に限定されるものではないが、耐黒変性と耐食性の観点からは、モリブデン換算で０．３~３質量％の範囲で含有することが有利である。 The plated steel sheet of the present invention has a chemical conversion treatment film containing molybdate as an upper layer of the molten Zn—Al—Mg alloy plating layer.
The chemical conversion film formed as the upper layer of the plating layer contains molybdate, and the combination of this molybdate and Zn-Al-Mg ternary eutectic improves blackening resistance and corrosion resistance. To do. The molybdate is not particularly limited as long as it dissolves during the chemical conversion treatment. Examples of the molybdate include salts such as ammonium and sodium. The content of molybdate in the chemical conversion coating is not particularly limited, but from the viewpoint of blackening resistance and corrosion resistance, it is advantageous to contain it in the range of 0.3 to 3% by mass in terms of molybdenum. It is.
めっき層の上層として形成される化成処理皮膜は、モリブデン酸塩を含有するものであり、このモリブデン酸塩とＺｎ−Ａｌ−Ｍｇ系三元共晶との組み合わせにより、耐黒変性と耐食性をよくするものである。なお、モリブデン酸塩としては、化成処理中に溶解するものであればよく、特に限定されるものではない。モリブデン酸塩の種類としては、例えばアンモニウム、ナトリウム等の塩が例示できる。化成処理皮膜中のモリブデン酸塩の含有量は、特に限定されるものではないが、耐黒変性と耐食性の観点からは、モリブデン換算で０．３~３質量％の範囲で含有することが有利である。 The plated steel sheet of the present invention has a chemical conversion treatment film containing molybdate as an upper layer of the molten Zn—Al—Mg alloy plating layer.
The chemical conversion film formed as the upper layer of the plating layer contains molybdate, and the combination of this molybdate and Zn-Al-Mg ternary eutectic improves blackening resistance and corrosion resistance. To do. The molybdate is not particularly limited as long as it dissolves during the chemical conversion treatment. Examples of the molybdate include salts such as ammonium and sodium. The content of molybdate in the chemical conversion coating is not particularly limited, but from the viewpoint of blackening resistance and corrosion resistance, it is advantageous to contain it in the range of 0.3 to 3% by mass in terms of molybdenum. It is.
また、化成処理皮膜には、モリブデン酸塩に加えて、クロム酸、リン酸塩、あるいは、Ｔｉ、Ｚｒ、Ｖ、Ｍｎ、Ｎｉ、Ｃｏなどのフッ化物もしくは塩、シラン化合物、金属キレート剤、水性樹脂、シリカゾルなどの酸化物ゾルなどを含有してもよい。
さらに、化成処理皮膜の片面当たりの付着量は、用途に応じて適宜決定すればよく、とくに限定する必要はないが、０．０５ｇ／ｍ２以上であれば耐黒変性および耐食性が低下せず、一方、１．５ｇ／ｍ２以下であれば、皮膜形成量が多くなることがなく、製造コストは高騰しない。このようなことから、化成処理皮膜の片面当たりの付着量は、０．０５~１．５ｇ／ｍ２とすることが好ましい。
つぎに、本発明めっき鋼板の好ましい製造方法について説明する。 In addition to the molybdate, the chemical conversion film includes chromic acid, phosphate, fluoride or salt such as Ti, Zr, V, Mn, Ni, Co, silane compound, metal chelating agent, aqueous You may contain oxide sols, such as resin and a silica sol.
Furthermore, the adhesion amount per one side of the chemical conversion coating may be appropriately determined according to the use and is not particularly limited. However, if it is 0.05 g / m 2 or more, the blackening resistance and the corrosion resistance are not lowered. On the other hand, if it is 1.5 g / m 2 or less, the amount of film formation will not increase, and the production cost will not increase. For this reason, the amount of adhesion per one side of the chemical conversion film is preferably 0.05 to 1.5 g / m 2 .
Below, the preferable manufacturing method of this invention plated steel plate is demonstrated.
さらに、化成処理皮膜の片面当たりの付着量は、用途に応じて適宜決定すればよく、とくに限定する必要はないが、０．０５ｇ／ｍ２以上であれば耐黒変性および耐食性が低下せず、一方、１．５ｇ／ｍ２以下であれば、皮膜形成量が多くなることがなく、製造コストは高騰しない。このようなことから、化成処理皮膜の片面当たりの付着量は、０．０５~１．５ｇ／ｍ２とすることが好ましい。
つぎに、本発明めっき鋼板の好ましい製造方法について説明する。 In addition to the molybdate, the chemical conversion film includes chromic acid, phosphate, fluoride or salt such as Ti, Zr, V, Mn, Ni, Co, silane compound, metal chelating agent, aqueous You may contain oxide sols, such as resin and a silica sol.
Furthermore, the adhesion amount per one side of the chemical conversion coating may be appropriately determined according to the use and is not particularly limited. However, if it is 0.05 g / m 2 or more, the blackening resistance and the corrosion resistance are not lowered. On the other hand, if it is 1.5 g / m 2 or less, the amount of film formation will not increase, and the production cost will not increase. For this reason, the amount of adhesion per one side of the chemical conversion film is preferably 0.05 to 1.5 g / m 2 .
Below, the preferable manufacturing method of this invention plated steel plate is demonstrated.
基板とする鋼板を、例えば、連続式溶融Ｚｎめっき製造設備を利用して、溶融Ｚｎ−Ａｌ系合金めっき浴中に浸漬させたのち、引き上げ、冷却して、鋼板表面に溶融Ｚｎ−Ａｌ系合金めっき層を形成する。
基板として使用する鋼板は、その種類、組成について、とくに限定する必要はなく、用途に応じて、公知の熱延鋼板、冷延鋼板のなかから適宜選択することができる。 The steel plate used as a substrate is immersed in a molten Zn-Al alloy plating bath using, for example, a continuous hot-dip Zn plating production facility, and then pulled up and cooled, and a molten Zn-Al alloy on the steel plate surface. A plating layer is formed.
The type and composition of the steel plate used as the substrate are not particularly limited, and can be appropriately selected from known hot-rolled steel plates and cold-rolled steel plates according to the application.
基板として使用する鋼板は、その種類、組成について、とくに限定する必要はなく、用途に応じて、公知の熱延鋼板、冷延鋼板のなかから適宜選択することができる。 The steel plate used as a substrate is immersed in a molten Zn-Al alloy plating bath using, for example, a continuous hot-dip Zn plating production facility, and then pulled up and cooled, and a molten Zn-Al alloy on the steel plate surface. A plating layer is formed.
The type and composition of the steel plate used as the substrate are not particularly limited, and can be appropriately selected from known hot-rolled steel plates and cold-rolled steel plates according to the application.
まず、基板である鋼板は、例えば、連続式溶融Ｚｎめっき製造設備を用いて、所望の加熱温度まで加熱される。加熱温度は、使用する鋼板に応じて、適宜決定すればよく、とくに限定する必要はないが、本発明では、めっき浴に浸漬する際に、鋼板温度（板温）を所望の温度に調整する必要があり、少なくともめっき浴に浸漬する際の、所望の鋼板温度（板温）を確保できる加熱温度とする必要がある。
First, a steel plate as a substrate is heated to a desired heating temperature using, for example, a continuous hot-dip Zn plating manufacturing facility. The heating temperature may be appropriately determined according to the steel plate to be used, and is not particularly limited. However, in the present invention, the steel plate temperature (plate temperature) is adjusted to a desired temperature when immersed in the plating bath. It is necessary to set the heating temperature to ensure a desired steel plate temperature (plate temperature) when immersed in the plating bath.
所定の温度に加熱された鋼板は、所定の組成、浴温に保持された溶融Ｚｎ−Ａｌ系合金めっき浴に浸漬する。
鋼板が浸漬する、溶融Ｚｎ−Ａｌ系合金めっき浴の組成は、質量％で、Ａｌ：３~６％、Ｍｇ：０．２~１．０％、Ｎｉ：０．０１~０．１０％を含み、残部Ｚｎおよび不可避的不純物からなる組成とする。また、めっき浴の浴温は、４２０℃~５２０℃とする。めっき浴の浴温が４２０℃未満では、浴温が低すぎて、めっき浴が一部凝固する場合があり、所定のめっき処理ができなくなる。一方、５２０℃を超えて高温となると、めっき浴の酸化が著しくなり、ドロスの発生が増加する。このため、めっき浴の浴温は４２０℃~５２０℃の範囲の温度に限定した。さらに、めっき浴の浴温は、４５０~５００℃の範囲であることが好ましい。 The steel sheet heated to a predetermined temperature is immersed in a molten Zn—Al alloy plating bath maintained at a predetermined composition and bath temperature.
The composition of the hot-dip Zn-Al alloy plating bath in which the steel sheet is immersed is as follows: mass: Al: 3-6%, Mg: 0.2-1.0%, Ni: 0.01-0.10% And a composition comprising the balance Zn and inevitable impurities. The bath temperature of the plating bath is 420 ° C. to 520 ° C. When the bath temperature of the plating bath is lower than 420 ° C., the bath temperature is too low and the plating bath may partially solidify, and the predetermined plating treatment cannot be performed. On the other hand, when the temperature is higher than 520 ° C., oxidation of the plating bath becomes remarkable and dross generation increases. Therefore, the bath temperature of the plating bath is limited to a temperature in the range of 420 ° C. to 520 ° C. Furthermore, the bath temperature of the plating bath is preferably in the range of 450 to 500 ° C.
鋼板が浸漬する、溶融Ｚｎ−Ａｌ系合金めっき浴の組成は、質量％で、Ａｌ：３~６％、Ｍｇ：０．２~１．０％、Ｎｉ：０．０１~０．１０％を含み、残部Ｚｎおよび不可避的不純物からなる組成とする。また、めっき浴の浴温は、４２０℃~５２０℃とする。めっき浴の浴温が４２０℃未満では、浴温が低すぎて、めっき浴が一部凝固する場合があり、所定のめっき処理ができなくなる。一方、５２０℃を超えて高温となると、めっき浴の酸化が著しくなり、ドロスの発生が増加する。このため、めっき浴の浴温は４２０℃~５２０℃の範囲の温度に限定した。さらに、めっき浴の浴温は、４５０~５００℃の範囲であることが好ましい。 The steel sheet heated to a predetermined temperature is immersed in a molten Zn—Al alloy plating bath maintained at a predetermined composition and bath temperature.
The composition of the hot-dip Zn-Al alloy plating bath in which the steel sheet is immersed is as follows: mass: Al: 3-6%, Mg: 0.2-1.0%, Ni: 0.01-0.10% And a composition comprising the balance Zn and inevitable impurities. The bath temperature of the plating bath is 420 ° C. to 520 ° C. When the bath temperature of the plating bath is lower than 420 ° C., the bath temperature is too low and the plating bath may partially solidify, and the predetermined plating treatment cannot be performed. On the other hand, when the temperature is higher than 520 ° C., oxidation of the plating bath becomes remarkable and dross generation increases. Therefore, the bath temperature of the plating bath is limited to a temperature in the range of 420 ° C. to 520 ° C. Furthermore, the bath temperature of the plating bath is preferably in the range of 450 to 500 ° C.
また、めっき浴に浸漬する鋼板の温度（板温）は、４２０~６００℃の範囲でかつめっき浴の浴温以上の温度に調整する。浸漬する鋼板の板温が、４２０℃未満又は浴温未満では浴温が次第に低下していくため、めっき浴の粘性が大きくなり、操業に支障をきたす。一方、６００℃を超えると、浴温が次第に上昇し、めっき定着性が低下する。このため、めっき浴に浸漬する鋼板の温度（板温）は、４２０~６００℃の範囲の温度で、かつめっき浴の浴温以上に限定した。
本発明では、上記しためっき浴を上記した範囲の浴温とし、さらにめっき浴に浸漬する鋼板の温度（板温）を、４２０~６００℃の範囲の温度に調整したうえ、さらにめっき浴に浸漬する鋼板の温度（板温）を、めっき浴の浴温以上となるように調整する。これにより、めっき浴と鋼板表面との界面で合金元素の拡散が生じ、めっき層と鋼板（基板）との界面にＮｉ濃化層の形成が促進される。Ｎｉ濃化層の形成により、めっき層に基板に到達するような傷が生じた場合にも、あるいは加工によりめっき層にクラックが生じた場合にも、耐食性を確保できる。 The temperature (plate temperature) of the steel sheet immersed in the plating bath is adjusted to a temperature in the range of 420 to 600 ° C. and higher than the bath temperature of the plating bath. When the plate temperature of the steel plate to be immersed is less than 420 ° C. or less than the bath temperature, the bath temperature gradually decreases, so that the viscosity of the plating bath increases and the operation is hindered. On the other hand, when the temperature exceeds 600 ° C., the bath temperature gradually increases and the plating fixability decreases. For this reason, the temperature (plate temperature) of the steel sheet immersed in the plating bath is limited to a temperature in the range of 420 to 600 ° C. and higher than the bath temperature of the plating bath.
In the present invention, the temperature of the steel sheet immersed in the plating bath (plate temperature) is adjusted to a temperature in the range of 420 to 600 ° C., and further immersed in the plating bath. The temperature (plate temperature) of the steel sheet to be adjusted is adjusted to be equal to or higher than the bath temperature of the plating bath. Thereby, diffusion of the alloy element occurs at the interface between the plating bath and the steel sheet surface, and the formation of the Ni concentrated layer is promoted at the interface between the plating layer and the steel sheet (substrate). Corrosion resistance can be ensured even when a scratch that reaches the substrate occurs in the plated layer due to the formation of the Ni concentrated layer or when a crack occurs in the plated layer due to processing.
本発明では、上記しためっき浴を上記した範囲の浴温とし、さらにめっき浴に浸漬する鋼板の温度（板温）を、４２０~６００℃の範囲の温度に調整したうえ、さらにめっき浴に浸漬する鋼板の温度（板温）を、めっき浴の浴温以上となるように調整する。これにより、めっき浴と鋼板表面との界面で合金元素の拡散が生じ、めっき層と鋼板（基板）との界面にＮｉ濃化層の形成が促進される。Ｎｉ濃化層の形成により、めっき層に基板に到達するような傷が生じた場合にも、あるいは加工によりめっき層にクラックが生じた場合にも、耐食性を確保できる。 The temperature (plate temperature) of the steel sheet immersed in the plating bath is adjusted to a temperature in the range of 420 to 600 ° C. and higher than the bath temperature of the plating bath. When the plate temperature of the steel plate to be immersed is less than 420 ° C. or less than the bath temperature, the bath temperature gradually decreases, so that the viscosity of the plating bath increases and the operation is hindered. On the other hand, when the temperature exceeds 600 ° C., the bath temperature gradually increases and the plating fixability decreases. For this reason, the temperature (plate temperature) of the steel sheet immersed in the plating bath is limited to a temperature in the range of 420 to 600 ° C. and higher than the bath temperature of the plating bath.
In the present invention, the temperature of the steel sheet immersed in the plating bath (plate temperature) is adjusted to a temperature in the range of 420 to 600 ° C., and further immersed in the plating bath. The temperature (plate temperature) of the steel sheet to be adjusted is adjusted to be equal to or higher than the bath temperature of the plating bath. Thereby, diffusion of the alloy element occurs at the interface between the plating bath and the steel sheet surface, and the formation of the Ni concentrated layer is promoted at the interface between the plating layer and the steel sheet (substrate). Corrosion resistance can be ensured even when a scratch that reaches the substrate occurs in the plated layer due to the formation of the Ni concentrated layer or when a crack occurs in the plated layer due to processing.
めっき浴に浸漬した鋼板はついで、めっき浴から引き上げられ、冷却される。引き上げたのちの冷却は、鋼板の表面温度で、３５０℃までの平均冷却速度で、１~１００℃／ｓにて行う。３５０℃までの平均冷却速度が１℃／ｓ未満では、冷却に必要な時間が長くなるため、生産性が低下する。一方、１００℃／ｓを超えて急冷すると、Ｚｎ−Ａｌ−Ｍｇ系三元結晶が表面の面積率で５０％を超え、化成処理の反応性とめっき層の加工性が低下する。このようなことから、鋼板をめっき浴から引き上げたのちの冷却速度は、３５０℃までの平均で、１~１００℃／ｓに限定した。なお、好ましくは２~７０℃／ｓである。
The steel plate immersed in the plating bath is then lifted from the plating bath and cooled. The cooling after the pulling is performed at a surface temperature of the steel sheet at an average cooling rate of up to 350 ° C. at 1 to 100 ° C./s. When the average cooling rate up to 350 ° C. is less than 1 ° C./s, the time required for cooling becomes long, so that productivity is lowered. On the other hand, when it is rapidly cooled above 100 ° C./s, the Zn—Al—Mg ternary crystal exceeds 50% in terms of the surface area ratio, and the reactivity of the chemical conversion treatment and the workability of the plating layer are lowered. For this reason, the cooling rate after pulling the steel plate up from the plating bath was limited to 1 to 100 ° C./s on average up to 350 ° C. It is preferably 2 to 70 ° C./s.
表面にめっき層が形成された鋼板には、ついで、化成処理が施され、めっき層の上層として、化成処理皮膜が形成される。
本発明で行う化成処理で使用する化成処理液は、水等の溶媒に、モリブデン酸塩を添加して、好ましくはｐＨ：２~６に調整した液を用いる。なお、化成処理液には、モリブデン酸塩に加えて、クロム酸、リン酸塩、Ｔｉ、Ｚｒ、Ｖ、Ｍｎ、Ｎｉ、Ｃｏなどのフッ化物、Ｔｉ、Ｚｒ、Ｖ、Ｍｎ、Ｎｉ、Ｃｏなどの塩、シラン化合物、金属キレート剤、水性樹脂およびシリカゾルなどの酸化物ゾルのいずれか１種または２種以上を含有してもよいことは言うまでもない。 The steel sheet having the plating layer formed on the surface is then subjected to chemical conversion treatment, and a chemical conversion treatment film is formed as an upper layer of the plating layer.
As the chemical conversion treatment solution used in the chemical conversion treatment according to the present invention, a solution prepared by adding molybdate to a solvent such as water and preferably adjusted to pH: 2 to 6 is used. In addition to molybdate, chemical conversion treatment liquid includes fluoride such as chromic acid, phosphate, Ti, Zr, V, Mn, Ni, Co, Ti, Zr, V, Mn, Ni, Co, etc. It goes without saying that any one or more of sols, silane compounds, metal chelating agents, aqueous resins and oxide sols such as silica sol may be contained.
本発明で行う化成処理で使用する化成処理液は、水等の溶媒に、モリブデン酸塩を添加して、好ましくはｐＨ：２~６に調整した液を用いる。なお、化成処理液には、モリブデン酸塩に加えて、クロム酸、リン酸塩、Ｔｉ、Ｚｒ、Ｖ、Ｍｎ、Ｎｉ、Ｃｏなどのフッ化物、Ｔｉ、Ｚｒ、Ｖ、Ｍｎ、Ｎｉ、Ｃｏなどの塩、シラン化合物、金属キレート剤、水性樹脂およびシリカゾルなどの酸化物ゾルのいずれか１種または２種以上を含有してもよいことは言うまでもない。 The steel sheet having the plating layer formed on the surface is then subjected to chemical conversion treatment, and a chemical conversion treatment film is formed as an upper layer of the plating layer.
As the chemical conversion treatment solution used in the chemical conversion treatment according to the present invention, a solution prepared by adding molybdate to a solvent such as water and preferably adjusted to pH: 2 to 6 is used. In addition to molybdate, chemical conversion treatment liquid includes fluoride such as chromic acid, phosphate, Ti, Zr, V, Mn, Ni, Co, Ti, Zr, V, Mn, Ni, Co, etc. It goes without saying that any one or more of sols, silane compounds, metal chelating agents, aqueous resins and oxide sols such as silica sol may be contained.
また、化成処理液のｐＨが２以上であれば、めっき層表面への溶解性が適度であり、化成処理皮膜が正常に形成され、定着性、耐食性が低下しない。一方、ｐＨが６以下であれば、化成処理液の安定性が悪くなることがなく、密着性、耐食性が低下しない。このため、化成処理液のｐＨを２~６の範囲に調整することが好ましい。より好ましくは、４~５である。
上記した化成処理液を、常温で、めっき層表面に塗布したのち、好ましくは鋼板温度として６０~１２０℃に加熱し乾燥して溶媒を蒸発させ、めっき層の上層である化学処理皮膜を形成する。塗布方法は、とくに限定されないが、通常公知の塗布方法である、ロールコート、シャワーリンガー、ディップ気体絞りなど連続的に処理する方法がいずれも適用できる。また、乾燥方法は、通常公知の方法である、熱風炉、電熱炉、誘導加熱等がいずれも適用できる。 Moreover, if the pH of a chemical conversion liquid is 2 or more, the solubility to a plating layer surface is moderate, a chemical conversion treatment film will be formed normally, and fixability and corrosion resistance will not fall. On the other hand, if the pH is 6 or less, the stability of the chemical conversion solution does not deteriorate, and adhesion and corrosion resistance do not deteriorate. For this reason, it is preferable to adjust the pH of the chemical conversion solution to a range of 2-6. More preferably, it is 4-5.
After the above chemical conversion treatment solution is applied to the surface of the plating layer at room temperature, it is preferably heated to a steel plate temperature of 60 to 120 ° C. and dried to evaporate the solvent, thereby forming a chemical treatment film as an upper layer of the plating layer. . The coating method is not particularly limited, but any of the generally known coating methods such as roll coating, shower ringer, dip gas squeezing, etc. can be applied. In addition, as a drying method, any one of conventionally known methods such as a hot air furnace, an electric heating furnace, induction heating and the like can be applied.
上記した化成処理液を、常温で、めっき層表面に塗布したのち、好ましくは鋼板温度として６０~１２０℃に加熱し乾燥して溶媒を蒸発させ、めっき層の上層である化学処理皮膜を形成する。塗布方法は、とくに限定されないが、通常公知の塗布方法である、ロールコート、シャワーリンガー、ディップ気体絞りなど連続的に処理する方法がいずれも適用できる。また、乾燥方法は、通常公知の方法である、熱風炉、電熱炉、誘導加熱等がいずれも適用できる。 Moreover, if the pH of a chemical conversion liquid is 2 or more, the solubility to a plating layer surface is moderate, a chemical conversion treatment film will be formed normally, and fixability and corrosion resistance will not fall. On the other hand, if the pH is 6 or less, the stability of the chemical conversion solution does not deteriorate, and adhesion and corrosion resistance do not deteriorate. For this reason, it is preferable to adjust the pH of the chemical conversion solution to a range of 2-6. More preferably, it is 4-5.
After the above chemical conversion treatment solution is applied to the surface of the plating layer at room temperature, it is preferably heated to a steel plate temperature of 60 to 120 ° C. and dried to evaporate the solvent, thereby forming a chemical treatment film as an upper layer of the plating layer. . The coating method is not particularly limited, but any of the generally known coating methods such as roll coating, shower ringer, dip gas squeezing, etc. can be applied. In addition, as a drying method, any one of conventionally known methods such as a hot air furnace, an electric heating furnace, induction heating and the like can be applied.
冷延鋼板（板厚：０．８ｍｍ、未焼鈍）を基板とし、該基板を、表１に示す浸漬時の鋼板温度（板温）となるように加熱したのち、表１に示す各種組成、浴温の溶融Ｚｎ−Ａｌ系合金めっき浴に浸漬させ、引き上げ、冷却して、基板表面に、表２に示す組成、付着量の溶融Ｚｎ−Ａｌ系合金めっき層を形成した。なお、引き上げ後、表１に示す引き上げ後から３５０℃までの平均で、表１に示す冷却速度で冷却した。
Cold-rolled steel plate (plate thickness: 0.8 mm, unannealed) was used as a substrate, and the substrate was heated to the steel plate temperature (plate temperature) during immersion shown in Table 1, and then various compositions shown in Table 1 were obtained. It was immersed in a molten Zn—Al based alloy plating bath having a bath temperature, pulled up and cooled to form a molten Zn—Al based alloy plating layer having the composition and adhesion amount shown in Table 2 on the substrate surface. In addition, it cooled at the cooling rate shown in Table 1 by the average after the raising shown in Table 1 to 350 degreeC after raising.
ついで、得られためっき鋼板のめっき層表面に、化成処理液（液温：２５℃）をロールコートで塗布し、続いて２２０℃の熱風炉で３秒間、乾燥し、０．６ｇ／ｍ２の化成処理皮膜を形成する化成処理を施した。なお、使用した化成処理液は、溶媒（水）に、モリブデン酸塩、ジルコン酸塩、チタン酸塩のうちのいずれか１種を質量比で１０質量％添加し、表１に示すｐＨを有する液とした。
Next, a chemical conversion treatment liquid (liquid temperature: 25 ° C.) is applied to the surface of the plated layer of the obtained plated steel sheet by roll coating, followed by drying in a hot air oven at 220 ° C. for 3 seconds, and 0.6 g / m 2. A chemical conversion treatment was performed to form a chemical conversion treatment film. In addition, the used chemical conversion liquid has 10 mass% of any one of molybdate, a zirconate, and a titanate by mass ratio to a solvent (water), and has pH shown in Table 1. A liquid was used.
得られた溶融Ｚｎ−Ａｌ系合金めっき鋼板について、まず、めっき層表面の組織観察、腐食試験を実施した。試験方法は次のとおりとした。
（１）めっき層表面の組織観察
得られた溶融Ｚｎ−Ａｌ系合金めっき鋼板から組織観察用試験片を採取し、走査型電子顕微鏡（倍率：１０００倍）を用いて、めっき層表面の組織を観察した。また、ＥＰＭＡを用いて、めっき層表面についてＭｇを分析し、その分析結果を画像解析して白黒の２階調化して、ヒストグラムより、Ｚｎ−Ａｌ−Ｍｇ系三元共晶の面積率を算出した。
ついで、得られた溶融Ｚｎ−Ａｌ系合金めっき鋼板について、耐黒変性試験を実施し、耐黒変性を評価した。試験方法は次のとおりである。 About the obtained hot-dip Zn—Al-based alloy-plated steel sheet, first, the observation of the structure of the plating layer surface and the corrosion test were performed. The test method was as follows.
(1) Structure observation on the surface of the plating layer A specimen for structure observation was collected from the obtained molten Zn-Al alloy-plated steel sheet, and the structure on the surface of the plating layer was obtained using a scanning electron microscope (magnification: 1000 times). Observed. In addition, Mg is analyzed on the surface of the plating layer using EPMA, and the analysis result is image-analyzed to be converted into black and white, and the area ratio of the Zn—Al—Mg ternary eutectic is calculated from the histogram. did.
Next, the obtained hot-dip Zn-Al alloy-plated steel sheet was subjected to a blackening resistance test to evaluate blackening resistance. The test method is as follows.
（１）めっき層表面の組織観察
得られた溶融Ｚｎ−Ａｌ系合金めっき鋼板から組織観察用試験片を採取し、走査型電子顕微鏡（倍率：１０００倍）を用いて、めっき層表面の組織を観察した。また、ＥＰＭＡを用いて、めっき層表面についてＭｇを分析し、その分析結果を画像解析して白黒の２階調化して、ヒストグラムより、Ｚｎ−Ａｌ−Ｍｇ系三元共晶の面積率を算出した。
ついで、得られた溶融Ｚｎ−Ａｌ系合金めっき鋼板について、耐黒変性試験を実施し、耐黒変性を評価した。試験方法は次のとおりである。 About the obtained hot-dip Zn—Al-based alloy-plated steel sheet, first, the observation of the structure of the plating layer surface and the corrosion test were performed. The test method was as follows.
(1) Structure observation on the surface of the plating layer A specimen for structure observation was collected from the obtained molten Zn-Al alloy-plated steel sheet, and the structure on the surface of the plating layer was obtained using a scanning electron microscope (magnification: 1000 times). Observed. In addition, Mg is analyzed on the surface of the plating layer using EPMA, and the analysis result is image-analyzed to be converted into black and white, and the area ratio of the Zn—Al—Mg ternary eutectic is calculated from the histogram. did.
Next, the obtained hot-dip Zn-Al alloy-plated steel sheet was subjected to a blackening resistance test to evaluate blackening resistance. The test method is as follows.
（２）耐黒変性試験
得られた溶融Ｚｎ−Ａｌ系合金めっき鋼板から試験片（平板：５０×５０ｍｍ）を採取し、該試験片を、温度：８０℃、相対湿度：９５％の恒温恒湿槽内に２４時間保持する試験を実施し、試験片表面の明度Ｌを試験の前後で測定し、明度Ｌの差ΔＬを求め、耐黒変性を評価した。評価基準は、下記のとおりとした。
評点３：ΔＬ：８以下（黒変発生がほとんどない状態）
評価２：ΔＬ：８超~１５未満（若干の黒変が発生している状態）
評点１：ΔＬ：１５以上（著しい黒変が発生している状態）
また、得られた溶融Ｚｎ−Ａｌ系合金めっき鋼板について、加工後の耐食性試験を実施し、加工部の耐食性を評価した。試験方法は次のとおりとした。 (2) Blackening resistance test A test piece (flat plate: 50 × 50 mm) was taken from the obtained molten Zn—Al-based alloy-plated steel sheet, and the test piece was kept at a constant temperature and a constant temperature of 80 ° C. and a relative humidity of 95%. A test for holding in a wet tank for 24 hours was carried out, the brightness L of the surface of the test piece was measured before and after the test, the difference ΔL of the brightness L was determined, and blackening resistance was evaluated. The evaluation criteria were as follows.
Score 3: ΔL: 8 or less (a state in which blackening hardly occurs)
Evaluation 2: ΔL: More than 8 to less than 15 (a state where slight blackening occurs)
Score 1: ΔL: 15 or more (a state in which significant blackening has occurred)
Moreover, about the obtained hot-dip Zn-Al type alloy plating steel plate, the corrosion resistance test after a process was implemented, and the corrosion resistance of the process part was evaluated. The test method was as follows.
得られた溶融Ｚｎ−Ａｌ系合金めっき鋼板から試験片（平板：５０×５０ｍｍ）を採取し、該試験片を、温度：８０℃、相対湿度：９５％の恒温恒湿槽内に２４時間保持する試験を実施し、試験片表面の明度Ｌを試験の前後で測定し、明度Ｌの差ΔＬを求め、耐黒変性を評価した。評価基準は、下記のとおりとした。
評点３：ΔＬ：８以下（黒変発生がほとんどない状態）
評価２：ΔＬ：８超~１５未満（若干の黒変が発生している状態）
評点１：ΔＬ：１５以上（著しい黒変が発生している状態）
また、得られた溶融Ｚｎ−Ａｌ系合金めっき鋼板について、加工後の耐食性試験を実施し、加工部の耐食性を評価した。試験方法は次のとおりとした。 (2) Blackening resistance test A test piece (flat plate: 50 × 50 mm) was taken from the obtained molten Zn—Al-based alloy-plated steel sheet, and the test piece was kept at a constant temperature and a constant temperature of 80 ° C. and a relative humidity of 95%. A test for holding in a wet tank for 24 hours was carried out, the brightness L of the surface of the test piece was measured before and after the test, the difference ΔL of the brightness L was determined, and blackening resistance was evaluated. The evaluation criteria were as follows.
Score 3: ΔL: 8 or less (a state in which blackening hardly occurs)
Evaluation 2: ΔL: More than 8 to less than 15 (a state where slight blackening occurs)
Score 1: ΔL: 15 or more (a state in which significant blackening has occurred)
Moreover, about the obtained hot-dip Zn-Al type alloy plating steel plate, the corrosion resistance test after a process was implemented, and the corrosion resistance of the process part was evaluated. The test method was as follows.
（３）加工部の耐食性試験
得られた溶融Ｚｎ−Ａｌ系合金めっき鋼板から曲げ試験片を採取し、ＪＩＳ Ｇ ３３１７の規定に準拠して、内１．６ｍｍＲ−１８０°曲げを付与したのち、ＪＩＳ Ｚ ２３７１の規定に準拠して塩水噴霧試験を実施した。塩水噴霧条件は、噴霧液：５質量％食塩水、温度：３５℃、試験時間：２０００ｈとした。試験後、試験片表面をデジタルカメラで観察し、撮像して、画像処理により、赤錆発生率（面積率）を求め、加工部の耐食性を評価した。評価の基準は次のとおりとした。
評点３：赤錆発生なし
評価２：赤錆発生あり、赤錆発生率５０％以下
評点１：赤錆発生あり、赤錆発生率５０％超
得られた結果を表２に示す。 (3) Corrosion resistance test of processed part After collecting a bending test piece from the obtained molten Zn-Al-based alloy-plated steel sheet and applying a 1.6 mm R-180 ° bending in accordance with JIS G 3317, A salt spray test was performed in accordance with the provisions of JIS Z 2371. The salt spray conditions were: spray solution: 5% by mass saline, temperature: 35 ° C., test time: 2000 h. After the test, the surface of the test piece was observed with a digital camera, imaged, and the red rust occurrence rate (area rate) was determined by image processing, and the corrosion resistance of the processed part was evaluated. The evaluation criteria were as follows.
Rating 3: No red rust generated Evaluation 2: Red rust generated, red rust generation rate of 50% or less Rating 1: Red rust generated, red rust generation rate exceeding 50% is shown in Table 2.
得られた溶融Ｚｎ−Ａｌ系合金めっき鋼板から曲げ試験片を採取し、ＪＩＳ Ｇ ３３１７の規定に準拠して、内１．６ｍｍＲ−１８０°曲げを付与したのち、ＪＩＳ Ｚ ２３７１の規定に準拠して塩水噴霧試験を実施した。塩水噴霧条件は、噴霧液：５質量％食塩水、温度：３５℃、試験時間：２０００ｈとした。試験後、試験片表面をデジタルカメラで観察し、撮像して、画像処理により、赤錆発生率（面積率）を求め、加工部の耐食性を評価した。評価の基準は次のとおりとした。
評点３：赤錆発生なし
評価２：赤錆発生あり、赤錆発生率５０％以下
評点１：赤錆発生あり、赤錆発生率５０％超
得られた結果を表２に示す。 (3) Corrosion resistance test of processed part After collecting a bending test piece from the obtained molten Zn-Al-based alloy-plated steel sheet and applying a 1.6 mm R-180 ° bending in accordance with JIS G 3317, A salt spray test was performed in accordance with the provisions of JIS Z 2371. The salt spray conditions were: spray solution: 5% by mass saline, temperature: 35 ° C., test time: 2000 h. After the test, the surface of the test piece was observed with a digital camera, imaged, and the red rust occurrence rate (area rate) was determined by image processing, and the corrosion resistance of the processed part was evaluated. The evaluation criteria were as follows.
Rating 3: No red rust generated Evaluation 2: Red rust generated, red rust generation rate of 50% or less Rating 1: Red rust generated, red rust generation rate exceeding 50% is shown in Table 2.
本発明例はいずれも、耐黒変性に優れ、かつ加工部の耐食性にも優れた、溶融Ｚｎ−Ａｌ系合金めっき鋼板となっている。一方、本発明の範囲を外れる比較例は、耐黒変性が低下しているか、加工部の耐食性が低下しているか、あるいは両方とも低下している。
The examples of the present invention are all hot-dip Zn-Al alloy-plated steel sheets that are excellent in blackening resistance and excellent in corrosion resistance of processed parts. On the other hand, in the comparative examples outside the scope of the present invention, the blackening resistance is reduced, the corrosion resistance of the processed part is reduced, or both are reduced.
Claims (4)
- 鋼板の少なくとも一方の表面に、溶融Ｚｎ−Ａｌ系合金めっき層を形成し、さらに該溶融Ｚｎ−Ａｌ系合金めっき層の上層として化成処理被膜を形成してなる溶融Ｚｎ−Ａｌ系合金めっき鋼板であって、
前記溶融Ｚｎ−Ａｌ系合金めっき層は、質量％で、
Ａｌ：３．０~６．０％、
Ｍｇ：０．２~１．０％および
Ｎｉ：０．０１~０．１０％
を含有し、残部Ｚｎおよび不可避的不純物からなる組成を有し、該めっき層の表面組織が、Ｚｎ−Ａｌ−Ｍｇ系三元共晶を面積率で１~５０％含み、前記化成処理被膜が、モリブデン酸塩を含有することを特徴とする溶融Ｚｎ−Ａｌ系合金めっき鋼板。 A molten Zn-Al alloy-plated steel sheet in which a molten Zn-Al-based alloy plating layer is formed on at least one surface of the steel sheet, and a chemical conversion coating is formed as an upper layer of the molten Zn-Al-based alloy plating layer. There,
The molten Zn—Al-based alloy plating layer is in mass%,
Al: 3.0 to 6.0%,
Mg: 0.2-1.0% and Ni: 0.01-0.10%
The surface structure of the plating layer contains Zn—Al—Mg ternary eutectic in an area ratio of 1 to 50%, and the chemical conversion coating film has a composition comprising the balance Zn and inevitable impurities. And a hot-dip Zn-Al alloy-plated steel sheet containing molybdate. - 前記モリブデン酸塩を含有する化成処理皮被膜の片面当たりの付着量が、０．０５~１．５ｇ／ｍ２であることを特徴とする請求項１に記載の溶融Ｚｎ−Ａｌ系合金めっき鋼板。 2. The hot-dip Zn—Al-based alloy-plated steel sheet according to claim 1, wherein an adhesion amount per side of the chemical conversion coating containing the molybdate is 0.05 to 1.5 g / m 2. .
- 鋼板を、質量％で、Ａｌ：３~６％、Ｍｇ：０．２~１．０％およびＮｉ：０．０１~０．１０％を含み、残部Ｚｎおよび不可避的不純物からなる組成の溶融Ｚｎ−Ａｌ系合金めっき浴中に浸漬したのち、同めっき浴から鋼板を引き上げて冷却して、該鋼板表面に溶融Ｚｎ−Ａｌ系合金めっき層を形成し、さらに化成処理を施して、該溶融Ｚｎ−Ａｌ系合金めっき層の上層として、化成処理被膜を形成する、溶融Ｚｎ−Ａｌ系合金めっき鋼板の製造方法であって、
前記溶融Ｚｎ−Ａｌ系合金めっき浴の温度を４２０℃~５２０℃、前記溶融Ｚｎ−Ａｌ系合金めっき浴中に浸漬する前記鋼板の温度を４２０~６００℃で、かつ前記鋼板の温度を前記溶融Ｚｎ−Ａｌ系めっき浴の温度以上に調整して、前記溶融Ｚｎ−Ａｌ系合金めっき浴中に浸漬し、
さらに前記溶融Ｚｎ−Ａｌ系めっき浴から鋼板を引き上げたのち、前記鋼板の表面温度で、３５０℃までの平均冷却速度が１~１００℃／ｓである冷却を前記鋼板に施し、
前記化成処理を、モリブデン酸塩を含有する化成処理液を用いて行うことを特徴とする溶融Ｚｎ−Ａｌ系合金めっき鋼板の製造方法。 Molten Zn having a composition containing, by mass%, Al: 3 to 6%, Mg: 0.2 to 1.0% and Ni: 0.01 to 0.10%, the balance being Zn and inevitable impurities -After dipping in the Al-based alloy plating bath, the steel plate is pulled up from the plating bath and cooled to form a molten Zn-Al-based alloy plating layer on the surface of the steel plate, further subjected to chemical conversion treatment, and the molten Zn -A method for producing a hot-dip Zn-Al-based alloy-plated steel sheet, which forms a chemical conversion coating as an upper layer of an Al-based alloy plating layer,
The temperature of the molten Zn—Al based alloy plating bath is 420 ° C. to 520 ° C., the temperature of the steel sheet immersed in the molten Zn—Al based alloy plating bath is 420 to 600 ° C., and the temperature of the steel plate is melted. Adjust the temperature above the temperature of the Zn-Al based plating bath, immerse in the molten Zn-Al based alloy plating bath,
Furthermore, after pulling up the steel sheet from the molten Zn-Al plating bath, the steel sheet is subjected to cooling at an average cooling rate of 1 to 100 ° C./s up to 350 ° C. at the surface temperature of the steel sheet,
The said chemical conversion treatment is performed using the chemical conversion liquid containing a molybdate, The manufacturing method of the hot-dip Zn-Al type alloy plating steel plate characterized by the above-mentioned. - 前記化成処理液のｐＨが２~６であることを特徴とする請求項３に記載の溶融Ｚｎ−Ａｌ系めっき鋼板の製造方法。 4. The method for producing a hot-dip Zn—Al-based plated steel sheet according to claim 3, wherein the chemical conversion solution has a pH of 2 to 6.
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| CN201280038542.7A CN103732780B (en) | 2011-08-09 | 2012-08-08 | Melting Zn-Al alloy coated steel sheet and manufacture method thereof |
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| SG2014007579A SG2014007579A (en) | 2011-08-09 | 2012-08-08 | Molten zn-al alloy-plated steel sheet and manufacturing method thereof |
| KR1020147002993A KR101615459B1 (en) | 2011-08-09 | 2012-08-08 | ZnAl MOLTEN ZNAL ALLOYPLATED STEEL SHEET AND MANUFACTURING METHOD THEREOF |
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| JP2018062710A (en) * | 2016-10-11 | 2018-04-19 | Ｊｆｅスチール株式会社 | Surface treatment liquid for galvanized steel sheet, method for manufacturing galvanized steel sheet having surface treatment film and galvanized steel sheet having surface treatment film |
| WO2021038102A1 (en) * | 2019-08-30 | 2021-03-04 | Rijksuniversiteit Groningen | Characterization method of formability properties of zinc alloy coating on a metal substrate |
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| JP6165529B2 (en) * | 2013-07-12 | 2017-07-19 | 日新製鋼株式会社 | Method and apparatus for producing chemical conversion steel sheet |
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| CN111155044B (en) * | 2019-12-13 | 2021-09-21 | 首钢集团有限公司 | Method for improving surface quality of zinc-aluminum-magnesium coated steel and zinc-aluminum-magnesium coating |
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