WO2015145722A1 - 準結晶含有めっき鋼板 - Google Patents
準結晶含有めっき鋼板 Download PDFInfo
- Publication number
- WO2015145722A1 WO2015145722A1 PCT/JP2014/059104 JP2014059104W WO2015145722A1 WO 2015145722 A1 WO2015145722 A1 WO 2015145722A1 JP 2014059104 W JP2014059104 W JP 2014059104W WO 2015145722 A1 WO2015145722 A1 WO 2015145722A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- coating layer
- metal coating
- phase
- steel sheet
- plated steel
- Prior art date
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 319
- 239000010959 steel Substances 0.000 title claims abstract description 319
- 239000013079 quasicrystal Substances 0.000 title claims abstract description 87
- 229910052751 metal Inorganic materials 0.000 claims abstract description 496
- 239000002184 metal Substances 0.000 claims abstract description 496
- 239000011247 coating layer Substances 0.000 claims abstract description 404
- 239000011701 zinc Substances 0.000 claims abstract description 196
- 239000011777 magnesium Substances 0.000 claims abstract description 160
- 239000000126 substance Substances 0.000 claims abstract description 57
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 49
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 48
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 17
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims abstract description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 6
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims abstract description 4
- 239000012071 phase Substances 0.000 claims description 437
- 238000001816 cooling Methods 0.000 claims description 99
- 239000013078 crystal Substances 0.000 claims description 75
- 238000007747 plating Methods 0.000 claims description 68
- 238000000034 method Methods 0.000 claims description 55
- 238000004519 manufacturing process Methods 0.000 claims description 41
- 239000000956 alloy Substances 0.000 claims description 37
- 238000007598 dipping method Methods 0.000 claims description 37
- 229910045601 alloy Inorganic materials 0.000 claims description 36
- 239000011575 calcium Substances 0.000 claims description 35
- 239000010410 layer Substances 0.000 claims description 31
- 239000007788 liquid Substances 0.000 claims description 30
- 229910017706 MgZn Inorganic materials 0.000 claims description 27
- 230000008569 process Effects 0.000 claims description 25
- 239000011651 chromium Substances 0.000 claims description 24
- 230000002902 bimodal effect Effects 0.000 claims description 22
- 229910052791 calcium Inorganic materials 0.000 claims description 22
- 239000010936 titanium Substances 0.000 claims description 21
- 229910052684 Cerium Inorganic materials 0.000 claims description 20
- 229910052746 lanthanum Inorganic materials 0.000 claims description 19
- 239000000203 mixture Substances 0.000 claims description 19
- 239000007790 solid phase Substances 0.000 claims description 18
- 229910052804 chromium Inorganic materials 0.000 claims description 16
- 229910052727 yttrium Inorganic materials 0.000 claims description 16
- 238000005520 cutting process Methods 0.000 claims description 15
- 229910052710 silicon Inorganic materials 0.000 claims description 15
- 229910052719 titanium Inorganic materials 0.000 claims description 13
- 239000010949 copper Substances 0.000 claims description 12
- 239000007791 liquid phase Substances 0.000 claims description 11
- 239000012535 impurity Substances 0.000 claims description 9
- 229910052760 oxygen Inorganic materials 0.000 claims description 9
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 8
- 239000001301 oxygen Substances 0.000 claims description 8
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 3
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 claims description 3
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims description 2
- 238000005260 corrosion Methods 0.000 description 136
- 230000007797 corrosion Effects 0.000 description 136
- 239000000470 constituent Substances 0.000 description 39
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 32
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 27
- 238000012360 testing method Methods 0.000 description 27
- 230000005496 eutectics Effects 0.000 description 25
- 239000011248 coating agent Substances 0.000 description 22
- 238000000576 coating method Methods 0.000 description 22
- 230000000694 effects Effects 0.000 description 22
- 238000011156 evaluation Methods 0.000 description 21
- 239000000463 material Substances 0.000 description 21
- 230000004580 weight loss Effects 0.000 description 16
- 229910052742 iron Inorganic materials 0.000 description 14
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 14
- 241001163841 Albugo ipomoeae-panduratae Species 0.000 description 12
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 12
- 238000010894 electron beam technology Methods 0.000 description 12
- 229910000765 intermetallic Inorganic materials 0.000 description 11
- 239000011572 manganese Substances 0.000 description 11
- 239000011135 tin Substances 0.000 description 11
- 238000006243 chemical reaction Methods 0.000 description 10
- 238000009826 distribution Methods 0.000 description 10
- 229910052759 nickel Inorganic materials 0.000 description 9
- 239000000523 sample Substances 0.000 description 9
- 230000015572 biosynthetic process Effects 0.000 description 8
- 229910052802 copper Inorganic materials 0.000 description 8
- 239000010955 niobium Substances 0.000 description 8
- 238000010587 phase diagram Methods 0.000 description 8
- 229910052718 tin Inorganic materials 0.000 description 8
- 230000001133 acceleration Effects 0.000 description 7
- 125000004429 atom Chemical group 0.000 description 7
- 238000002003 electron diffraction Methods 0.000 description 7
- 239000007789 gas Substances 0.000 description 7
- 229910052748 manganese Inorganic materials 0.000 description 7
- 229910000905 alloy phase Inorganic materials 0.000 description 6
- 239000007864 aqueous solution Substances 0.000 description 6
- 230000008018 melting Effects 0.000 description 6
- 238000002844 melting Methods 0.000 description 6
- 239000011780 sodium chloride Substances 0.000 description 6
- 229910007570 Zn-Al Inorganic materials 0.000 description 5
- 229910052787 antimony Inorganic materials 0.000 description 5
- 239000004566 building material Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 5
- 238000000227 grinding Methods 0.000 description 5
- 229910052758 niobium Inorganic materials 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- 150000003839 salts Chemical class 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 229910052712 strontium Inorganic materials 0.000 description 5
- 229910052720 vanadium Inorganic materials 0.000 description 5
- 238000007740 vapor deposition Methods 0.000 description 5
- 229910009369 Zn Mg Inorganic materials 0.000 description 4
- 229910007573 Zn-Mg Inorganic materials 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 4
- 230000008859 change Effects 0.000 description 4
- 239000010408 film Substances 0.000 description 4
- 230000001771 impaired effect Effects 0.000 description 4
- 229910052745 lead Inorganic materials 0.000 description 4
- 239000007921 spray Substances 0.000 description 4
- 238000007751 thermal spraying Methods 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 3
- 230000009471 action Effects 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 3
- 238000010411 cooking Methods 0.000 description 3
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 238000009713 electroplating Methods 0.000 description 3
- 239000010419 fine particle Substances 0.000 description 3
- 238000010191 image analysis Methods 0.000 description 3
- 238000009616 inductively coupled plasma Methods 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 230000000737 periodic effect Effects 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 230000037303 wrinkles Effects 0.000 description 3
- 229910018134 Al-Mg Inorganic materials 0.000 description 2
- 229910018467 Al—Mg Inorganic materials 0.000 description 2
- 229910000677 High-carbon steel Inorganic materials 0.000 description 2
- 229910000655 Killed steel Inorganic materials 0.000 description 2
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 229910021607 Silver chloride Inorganic materials 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 239000010953 base metal Substances 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000002524 electron diffraction data Methods 0.000 description 2
- 238000000635 electron micrograph Methods 0.000 description 2
- 238000010828 elution Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000007733 ion plating Methods 0.000 description 2
- 238000010409 ironing Methods 0.000 description 2
- 238000013507 mapping Methods 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 238000010422 painting Methods 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 2
- 239000010452 phosphate Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 238000000992 sputter etching Methods 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- -1 strictly speaking Substances 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 230000000007 visual effect Effects 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910001111 Fine metal Inorganic materials 0.000 description 1
- 229910001335 Galvanized steel Inorganic materials 0.000 description 1
- 229910000576 Laminated steel Inorganic materials 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 229910019018 Mg 2 Si Inorganic materials 0.000 description 1
- 229910000861 Mg alloy Inorganic materials 0.000 description 1
- 101000614615 Oryctolagus cuniculus Junctophilin-1 Proteins 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 238000000441 X-ray spectroscopy Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 230000003064 anti-oxidating effect Effects 0.000 description 1
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000007739 conversion coating Methods 0.000 description 1
- 238000005536 corrosion prevention Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000002848 electrochemical method Methods 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000007716 flux method Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 229910000803 frank kasper phase Inorganic materials 0.000 description 1
- 239000008397 galvanized steel Substances 0.000 description 1
- 125000005843 halogen group Chemical group 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000010884 ion-beam technique Methods 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 238000007750 plasma spraying Methods 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000004445 quantitative analysis Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000036647 reaction Effects 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000003252 repetitive effect Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000000550 scanning electron microscopy energy dispersive X-ray spectroscopy Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- GPPXJZIENCGNKB-UHFFFAOYSA-N vanadium Chemical compound [V]#[V] GPPXJZIENCGNKB-UHFFFAOYSA-N 0.000 description 1
- LRXTYHSAJDENHV-UHFFFAOYSA-H zinc phosphate Chemical compound [Zn+2].[Zn+2].[Zn+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O LRXTYHSAJDENHV-UHFFFAOYSA-H 0.000 description 1
- 229910000165 zinc phosphate Inorganic materials 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B15/00—Layered products comprising a layer of metal
- B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
- B32B15/013—Layered products comprising a layer of metal all layers being exclusively metallic one layer being formed of an iron alloy or steel, another layer being formed of a metal other than iron or aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C18/00—Alloys based on zinc
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C23/00—Alloys based on magnesium
- C22C23/04—Alloys based on magnesium with zinc or cadmium as the next major constituent
-
- 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
- C23C2/261—After-treatment in a gas atmosphere, e.g. inert or reducing atmosphere
-
- 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
- C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
- C23C2/29—Cooling or quenching
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
- C23C2/36—Elongated material
- C23C2/40—Plates; Strips
-
- 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
- C23C2/50—Controlling or regulating the coating processes
-
- 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
- C23C2/50—Controlling or regulating the coating processes
- C23C2/52—Controlling or regulating the coating processes with means for measuring or sensing
Definitions
- the present invention relates to a surface-treated steel sheet having excellent corrosion resistance, and more particularly to a plated steel sheet containing a quasicrystal.
- the quasicrystal is a crystal structure first discovered by Daniel Schuchman in 1982 and has an icosahedral atomic arrangement.
- This crystal structure is a non-periodic crystal structure with a unique rotational symmetry that cannot be obtained with ordinary metals and alloys, for example, a 5-fold symmetry, and is equivalent to an aperiodic structure represented by a three-dimensional Penrose pattern.
- Patent Documents 1 and 2 disclose a high-strength Mg-based alloy and a manufacturing method thereof. These Mg-based alloys are excellent in strength and elongation in which a hard quasicrystalline phase having a particle size of about several tens to several hundreds of nanometers is dispersed and precipitated in a metal structure. In these patent documents 1 and 2, the characteristic that a quasicrystal is hard is utilized.
- Patent Document 3 discloses a thermoelectric material using an Al reference crystal.
- the characteristic that a quasicrystal is excellent in a thermoelectric characteristic is utilized.
- Patent Document 4 discloses a heat-resistant catalyst using a quasicrystalline Al alloy (Al reference crystal) as a precursor and a method for producing the same. This patent document 4 utilizes the characteristic that a quasicrystal having no periodic crystal structure is brittle and easily crushed. As described above, in the inventions so far, the quasicrystals are often dispersed as fine particles, or the quasicrystals that are fine particles are often solidified and molded.
- Patent Document 8 discloses a metal coating for cooking utensils containing a quasicrystal.
- the coating powder which is excellent in abrasion resistance and the corrosion resistance to salt is provided to a cooking appliance by plasma spraying the alloy powder containing the quasicrystal excellent in corrosion resistance which consists of Al, Fe, and Cr.
- the Mg reference crystal is used as a material having excellent strength
- the Al reference crystal is used as a member having excellent strength, a thermoelectric material, a cooking utensil coating, and the like.
- these uses are limited, and quasicrystals are not necessarily used in many fields.
- Quasicrystals have excellent performance due to their unique crystal structure. However, its characteristics are only partially elucidated, and it cannot be said that it is a material that is currently widely used industrially. The present inventors tried to improve the corrosion resistance by applying a quasicrystal that has not been used almost industrially to the metal coating layer of the surface-treated steel sheet.
- the steel plate is given a certain anticorrosion function by performing a surface treatment such as metal coating, coating treatment, chemical conversion treatment, or organic coating lamination.
- a surface treatment such as metal coating, coating treatment, chemical conversion treatment, or organic coating lamination.
- Many steel materials used in the fields of automobiles, home appliances, building materials, etc. are mainly subjected to metal coating treatment.
- the metal coating layer By the metal coating layer, a barrier anticorrosive effect that shields the base iron (steel material) from the external environment and a sacrificial anticorrosive action that prevents the base iron by corroding preferentially over the base iron can be imparted at low cost.
- a thermal spraying method or a hot dipping method is suitable.
- a sputtering method, an ion plating method, a vapor deposition method, an electric method, A plating method is suitable.
- the hot dipping method is widely used because it can mass-produce a steel material having a metal coating layer at low cost.
- the deposited metal is limited, and the elements constituting the metal coating layer are limited.
- the method of forming a metal coating layer using metal melting, evaporation, precipitation, solidification reaction, etc. such as thermal spraying and vapor deposition, theoretically uses the same metal coating layer as the hot dipping method. Can be formed.
- the thermal spraying method and the vapor deposition method tend to cause separation between the chemical component of the alloy used and the chemical component of the formed metal coating layer.
- the hot dipping method capable of forming a metal coating layer having a chemical component substantially equivalent to the chemical component of the alloy used in the hot dipping bath is a method for forming a metal coating layer having a target chemical component. Better than any other method.
- the general surface-treated steel sheets that can be obtained on the market are mainly surface-treated steel sheets having a metal coating layer of a Zn-based alloy or a metal coating layer of an Al-based alloy.
- the metal coating layer of this Zn-based alloy is a metal coating layer containing a small amount of elements such as Al and Mg in the main component Zn.
- a metal structure of the metal coating layer in addition to the Zn phase, an Al phase, Mg 2 Zn phase and the like are contained.
- a metal coating layer of an Al-based alloy is a metal coating layer containing a small amount of elements such as Si and Fe in Al as a main component. Fe 2 Al 5 phase and the like are contained.
- the present inventors have disclosed Mg-based alloy-plated steel materials in Patent Documents 5 to 7 as plated steel materials having completely different plating alloy components from these general surface-treated steel sheets. Based on these plated steel materials, the present inventors have focused on quasicrystals that have hardly been considered for improving the corrosion resistance of plating layers (metal coating layers), and further improved the corrosion resistance. investigated.
- the quasicrystal is generally a non-periodic crystal structure having a specific rotational symmetry, for example, five-fold symmetry, which cannot be obtained with ordinary metals and alloys, and has a three-dimensional Penrose pattern. It is known as a crystal structure equivalent to a typical aperiodic structure.
- the problem to be solved by the present invention is to provide a plated steel sheet in which the corrosion resistance required when used in the field of building materials, automobiles, home appliances and the like is dramatically improved.
- the structure of the metal structure where the corrosion resistance is most improved is clarified, and as a result, excellent corrosion resistance and sacrificial corrosion resistance are achieved. It aims at providing the plated steel plate which combined. Specifically, regarding a quasicrystalline phase that is expected to improve the corrosion resistance but has not been studied so far, the preferred form in the metal coating layer (plating layer) is clarified, and the metal coating layer The purpose is to improve the corrosion resistance and sacrificial anticorrosion properties of the plated steel sheet by clarifying the method of preferably forming them.
- a quasi-crystal-containing plated steel sheet according to an aspect of the present invention is a plated steel sheet including a steel plate and a metal coating layer disposed on a surface of the steel plate, wherein the chemical component of the metal coating layer is an atom.
- the calcium content, the yttrium content, the lanthanum content, and the cerium content in the chemical component of the metal coating layer are 0% in atomic percent. .3% ⁇ Ca + Y + La + Ce ⁇ 3.5% may be satisfied.
- the silicon content, the titanium content, and the chromium content in the chemical component of the metal coating layer are 0% in atomic percent. 0.005% ⁇ Si + Ti + Cr ⁇ 0.5% may be satisfied.
- the zinc content and the aluminum content in the chemical component of the metal coating layer are atomic%, 30% ⁇ Zn + Al ⁇ 52% may be satisfied.
- the metal structure of the metal coating layer is a bimodal structure composed of a fine region composed of crystal grains having an equivalent circle diameter of 0.2 ⁇ m or less and a coarse region composed of crystal grains having an equivalent circle diameter of more than 0.2 ⁇ m.
- the coarse region includes the quasicrystalline phase and at least one of a Zn phase, an Al phase, and an MgZn phase
- the fine region includes an Mg 51 Zn 20 phase, a Zn phase, an amorphous phase, Mg 32 (Zn, Al) It may include at least one of 49 phases, and the average equivalent circle diameter of the quasicrystalline phase may be more than 0.2 ⁇ m to 1 ⁇ m.
- the metal structure of the metal coating layer is a bimodal structure composed of a fine region composed of crystal grains having an equivalent circle diameter of 0.2 ⁇ m or less and a coarse region composed of crystal grains having an equivalent circle diameter of more than 0.2 ⁇ m.
- the coarse region includes at least one of a Zn phase, an Al phase, and an MgZn phase
- the fine region includes the quasicrystalline phase, an Mg 51 Zn 20 phase, a Zn phase, an amorphous phase, Mg 32 (Zn, Al) including at least one of 49 phases, and the average equivalent circle diameter of the quasicrystalline phase may be 0.01 ⁇ m to 0.2 ⁇ m.
- the area fraction of the coarse region with respect to the metal structure is 5% to 50%
- the area fraction of the fine region may be 50% to 95%.
- the area fraction of the coarse region with respect to the metal structure is 5% to 50%
- the area fraction of the fine region with respect to the metal structure may be 50% to 95%.
- the area fraction of the quasicrystalline phase contained in the coarse region is in the coarse region.
- the total area fraction of the Mg 51 Zn 20 phase, the Zn phase, the amorphous phase, and the Mg 32 (Zn, Al) 49 phase contained in the fine region is 80% to less than 100%. Further, it may be 80% to less than 100% with respect to the fine region.
- the Zn phase, the Al phase, and the The total area fraction of the MgZn phase is 80% to less than 100% with respect to the coarse region, and the area fraction of the quasicrystalline phase contained in the fine region is more than 0% with respect to the fine region. It may be less than 10%.
- the thickness of the metal coating layer is determined when viewed in the cross section.
- a range of 0.05 ⁇ D from the surface of the metal coating layer toward the steel plate along the plate thickness direction is a metal coating layer outermost portion, and from the interface between the steel plate and the metal coating layer
- the range up to 0.05 ⁇ D toward the metal coating layer along the plate thickness direction is the deepest portion of the metal coating layer
- the area fraction of the coarse region with respect to the outermost surface portion of the metal coating layer is 7% to 100
- the area fraction of the coarse region with respect to the deepest part of the metal coating layer is less than 7% to less than 100%, other than the outermost surface part of the metal coating layer and the deepest part of the metal coating layer
- the range is the metal coating layer body
- the area fraction of the fine region may be 50% to less than 100%.
- the metal coating layer when viewed in the cross section.
- the thickness of the metal coating layer is 0.05 ⁇ D from the surface of the metal coating layer to the steel plate along the plate thickness direction as the metal coating layer outermost portion, and the steel plate and the metal coating layer
- the range from 0.05 to D along the plate thickness direction toward the metal coating layer is defined as the metal coating layer deepest part
- the area fraction of the coarse region with respect to the metal coating layer outermost part is 7% to less than 100%
- the area fraction of the coarse region with respect to the deepest part of the metal coating layer is 7% to less than 100%
- the metal coating layer outermost part of the metal coating layer and the metal coating When the range other than the deepest layer is the metal coating layer body, the metal coating layer book
- the area fraction of the fine region relative to the body part may be 50% to less than 100%.
- the metal structure of the metal coating layer may not contain an Mg phase.
- the quasicrystal-containing plated steel sheet according to any one of (1) to (13) further includes a Fe—Al-containing alloy layer, and the Fe—Al-containing alloy layer includes the steel sheet and the metal.
- the Fe—Al-containing alloy layer includes at least one of Fe 5 Al 2 or Al 3.2 Fe, and the Fe—Al-containing alloy layer has a thickness of 10 nm to 1000 nm. It may be.
- a method for producing a quasicrystal-containing plated steel sheet according to one aspect of the present invention is the method for producing a quasicrystal-containing plated steel sheet according to any one of (1) to (14) above, to form the metal coating layer on the surface, hot dipping process and is immersed in a molten plating bath the steel component has been adjusted; and T melt liquidus temperature of the metal coating layer in the unit ° C., wherein the metal coating When the temperature range in which the layer is in the coexistence state of the solid phase and the liquid phase and the volume ratio of the solid phase to the metal coating layer is 0.01 to 0.1 is T solid-liquid in units of ° C., In the temperature range of the metal coating layer from T melt + 10 ° C.
- the temperature of the metal coating layer is in a temperature range from the temperature at the end of cooling in the first cooling step to 250 ° C., and the average cooling rate of the metal coating layer is 100 ° C./second to 3000 ° C.
- the hot dipping step The oxygen concentration of the atmosphere when immersing the steel sheet is 100 ppm or less by volume, the plating tank holding the plating bath is made of steel, and T bath which is the temperature of the plating bath is from T melt The time during which the steel sheet is immersed in the plating bath may be 1 to 10 seconds higher by 10 to 100 ° C.
- FIG. 3 is an electron beam diffraction image obtained from a local region 2a1 in a coarse region 2a shown in FIG.
- FIG. 3 is an electron beam diffraction image obtained from a local region 2b1 in a fine region 2b shown in FIG. It is an electron beam diffraction image obtained from the local region 2a2 in the coarse region 2a shown in FIG. It is an electron beam diffraction image obtained from the local region 2b2 in the fine region 2b shown in FIG. It is a Zn-Mg binary equilibrium state diagram.
- FIG. 4 is a Zn, Al—Mg ternary liquid phase diagram.
- the plated steel plate according to the present embodiment includes a steel plate (ground iron) and a metal coating layer (plating layer) disposed on the surface of the steel plate.
- This metal coating layer is an alloy that shows a thin film shape and secures adhesion to a steel plate, and has a role of preventing corrosion and imparting functions to the steel.
- the material strength and rigidity of the steel Etc. The performance is not impaired. That is, the plated steel plate according to the present embodiment is a composite material in which two kinds of metal alloy materials, ie, a steel plate and a metal coating layer are combined.
- an interface alloy layer Fe—Al-containing alloy layer
- Interfacial adhesion due to metal atomic bonds can be obtained.
- the metal coating layer of the plated steel sheet is required to have excellent corrosion resistance. Corrosion resistance performance is divided into corrosion resistance and sacrificial corrosion resistance.
- the corrosion resistance of the metal coating layer is generally the corrosion resistance of the metal coating layer itself, and is often evaluated by the weight loss of the metal coating layer after a certain period of time in various corrosion tests.
- the corrosion weight loss is small, it means that the metal coating layer as a protective film for the steel plate (base metal) remains for a long period of time, that is, excellent corrosion resistance.
- the corrosion resistance generally tends to be higher for Zn than Mg and higher for Al than Zn.
- sacrificial anticorrosive property of the metal coating layer refers to the action of protecting the steel plate by corroding the surrounding metal coating layer instead of the steel plate when the steel plate (ground iron) is exposed to a corrosive environment for some reason. It is.
- the sacrificial anticorrosive property is high in the metal which is electrically base and easily corroded, and generally has a tendency that Zn is higher than Al and Mg is higher than Zn.
- the Zn—Mg alloy-plated steel sheet according to the present embodiment is excellent in sacrificial corrosion resistance because the metal coating layer contains a large amount of Mg.
- the problem is how to reduce the corrosion weight loss of the metal coating layer, that is, how to increase the corrosion resistance of the metal coating layer.
- the present inventors examined the constituent phase of the metal structure of the metal coating layer in order to minimize the corrosion weight loss of the metal coating layer in the Zn—Mg alloy plated steel sheet. As a result, it was found that the corrosion resistance is drastically improved when a quasicrystalline phase is contained in the metal coating layer.
- the main feature of the plated steel sheet according to this embodiment is the metal structure of the metal coating layer.
- a quasicrystalline phase is generated in the metal coating layer, and the corrosion resistance can be drastically improved.
- the average equivalent circle diameter (diameter) of the quasicrystalline phase generated in the metal coating layer is 0.01 ⁇ m to 1 ⁇ m.
- the corrosion resistance is improved as compared with the metal coating layer not containing the quasicrystalline phase.
- the metal coating layer of the plated steel sheet according to the present embodiment contains a large amount of Mg, it also has excellent sacrificial corrosion resistance for the steel sheet. That is, the plated steel sheet according to the present embodiment includes an ideal metal coating layer that is excellent in corrosion resistance and sacrificial corrosion resistance at the same time.
- the plated steel sheet according to the present embodiment will be described in detail in the order of chemical components of the metal coating layer, metal structure of the metal coating layer, and manufacturing conditions.
- an atomic ratio is used instead of a mass ratio when a structural formula of a metal phase such as Zn, Al, Mg 2 Zn, Fe 2 Al 5 or an intermetallic compound is displayed. Also in the description of the present embodiment, since attention is paid to the quasicrystalline phase, the atomic ratio is used. That is, in the following description, “%” indicating a chemical component means “atomic%” unless otherwise specified.
- the metal coating layer of the plated steel sheet according to the present embodiment contains Zn and Al as basic components, optionally contains optional components, and the balance consists of Mg and impurities.
- the Zn content of the metal coating layer is set to 28.5% to 52%.
- the Zn content is determined based on the eutectic composition (Mg72% -Zn28%) in the Zn—Mg binary equilibrium diagram shown in FIG. 6, and Zn is contained more than the Mg—Zn eutectic composition.
- the composition has a high concentration.
- Zn content of a metal coating layer shall be 28.5% or more. This makes it possible to preferentially disperse the Zn phase in the metal coating layer under appropriate manufacturing conditions.
- the lower limit of the Zn content may be 30%. As the area fraction of the Zn phase increases, the corrosion resistance also improves. However, if the Zn content exceeds 52%, the composition balance of the plating layer is lost, a large amount of intermetallic compounds such as Mg 4 Zn 7 and MgZn are formed, and the quasicrystalline phase is not formed, so the corrosion resistance is poor. Become. Therefore, the upper limit of the Zn content is set to 52%.
- the Zn content is preferably 33% or more. If it is 33% or more, the primary crystal has a composition range in which a Zn phase or a quasicrystalline phase easily grows, and the Mg phase becomes difficult to grow as a primary crystal. That is, the phase amount (area fraction) of the quasicrystalline phase in the metal coating layer can be increased, and the Mg phase that degrades the corrosion resistance can be reduced as much as possible. More preferably, the Zn content is 35% or more. Usually, if a plated steel sheet is manufactured by the manufacturing method according to this embodiment within this composition range, there is almost no Mg phase.
- Al 0.5% to 10%
- Al is an element that improves the corrosion resistance of the planar portion of the metal coating layer.
- Al is an element that promotes the formation of a quasicrystalline phase.
- the Al content of the metal coating layer is set to 0.5% or more.
- a Zn phase or an Al phase is generated in the metal coating layer in addition to the quasicrystalline phase.
- this Zn phase and Al phase form a eutectic structure, the corrosion resistance of the metal coating layer is preferably improved.
- the corrosion resistance is further preferably improved.
- the upper limit of the Al content of the metal coating layer is set to 10%.
- the Al content of the metal coating layer may be less than 5%.
- the corrosion resistance is not adversely affected, but the chemical conversion treatment property is somewhat inferior, and the corrosion resistance under coating (corrosion resistance after coating) tends to be deteriorated.
- Al is an element that is preferably contained when forming the Fe—Al interface alloy layer described later.
- the particle size of the quasicrystalline phase in the metal coating layer is small, it is preferable because the occurrence of red rust in the processed part is suppressed.
- a galvanized steel sheet is subjected to strong processing (drawing, ironing), etc.
- the quasicrystalline phase in the metal coating layer is coarse, the metal coating layer and the steel plate are partially separated starting from the quasicrystalline phase. Easy to peel. Since the steel sheet is peeled off at the peeling portion, red rust is likely to occur.
- the quasicrystalline phase in the metal coating layer is fine, the metal coating layer starting from the quasicrystalline phase hardly peels off from the steel plate.
- the metal coating layer and the steel plate are peeled off, the area is very small, and the occurrence of red rust at the peeled portion is suppressed.
- the occurrence of red rust is preferably suppressed when the average equivalent circle diameter of the quasicrystalline phase is 1 ⁇ m or less.
- the Zn content and the Al content in order to more preferably form a quasicrystalline phase in the metal coating layer, it is preferable to control the Zn content and the Al content as follows. That is, it is preferable that the Zn content and the Al content in the chemical component of the metal coating layer satisfy 30% ⁇ Zn + Al ⁇ 52% in atomic%.
- a quasicrystalline phase is generated in a preferred area fraction in the metal coating layer.
- the quasicrystalline phase is preferably formed in the metal coating layer in an area fraction of 5 to 12% with respect to the entire metal coating layer. The technical reason for this is not clear.
- the quasicrystalline phase in the present embodiment has a crystal structure mainly composed of Zn and Mg, the substitution of Al with Zn promotes the production of the quasicrystalline phase, and the amount of substitution of Al It is considered that the existence of an optimum value in
- Mg manganesium
- Zn and Al is a main element constituting the metal coating layer, and is an element that further improves sacrificial corrosion resistance.
- Mg is an important element that promotes the formation of a quasicrystalline phase.
- the Mg content in the balance is preferably 50% or more, and more preferably 55% or more. In the present embodiment, the Mg content is essential.
- the contained Mg is precipitated as an Mg phase in the metal coating layer. That is, since the Mg phase deteriorates the corrosion resistance, it is preferable that the contained Mg is a quasicrystalline phase or a constituent of other intermetallic compounds.
- the metal coating layer of the plated steel sheet according to the present embodiment contains impurities.
- an impurity refers to an element such as C, N, O, P, S, or Cd that is mixed from a raw material of steel and a plating alloy or a manufacturing environment when the plated steel plate is industrially manufactured. means. Even if these elements are contained as impurities in an amount of about 0.1%, the above effects are not impaired.
- the metal coating layer of the plated steel sheet according to the present embodiment is further replaced with a part of the remaining Mg, Ca, Y, La, Ce, Si, Ti, Cr, Fe, Co, Ni, V, Nb.
- At least one selected component selected from Cu, Sn, Mn, Sr, Sb, and Pb may be contained. These selective components may be contained depending on the purpose. Therefore, it is not necessary to limit the lower limit of these selection components, and the lower limit may be 0%. Moreover, even if these selective components are contained as impurities, the above effects are not impaired.
- Ca, Y, La, and Ce may be contained as necessary in order to improve the operability of hot dipping.
- a highly oxidized molten Mg alloy is hold
- Ca, Y, La, and Ce are more easily oxidized than Mg, and form a stable oxide film on the plating bath surface in a molten state to prevent oxidation of Mg in the bath.
- the Ca content of the metal coating layer is 0% to 3.5%
- the Y content is 0% to 3.5%
- the La content is 0% to 3.5%
- the Ce content is 0%. % To 3.5%. More preferably, regarding the Ca content, the Y content, the La content, and the Ce content, the lower limit may be set to 0.3% and the upper limit may be set to 2.0%.
- the upper limit of the content of Ca, Y, La, and Ce is preferably 3.5% in total. That is, it is preferable that the Ca content, the Y content, the La content, and the Ce content in the chemical component of the metal coating layer satisfy 0.3% ⁇ Ca + Y + La + Ce ⁇ 3.5% in atomic%.
- the total content of Ca, Y, La, and Ce is preferably 0.3% or more and 2.0% or less. These elements are considered to substitute for Mg constituting the quasicrystalline phase, but when these elements are contained in a large amount, the generation of the quasicrystalline phase may be inhibited. When these elements are contained in an appropriate content, the red rust suppressing effect of the quasicrystalline phase and other phases is improved. This effect is presumed to be caused by the elution timing of the quasicrystalline phase affecting the retention of white rust.
- the above effects can be obtained relatively large by containing Ca, La, and Ce.
- the above-mentioned effect obtained by the inclusion of Y is small as compared with Ca, La, and Ce. It is presumed that Ca, La, and Ce are more easily oxidized than Y and are related to highly reactive elements.
- EDX Electrode Dispersive X-ray Spectroscopy
- Y is often not detected, so it is presumed that Y is not easily incorporated into the quasicrystal.
- Ca, La, and Ce tend to be detected from the quasicrystal at a concentration higher than the concentration.
- Y it is not always necessary to include Y in the metal coating layer.
- 0.3% ⁇ Ca + La + Ce ⁇ 3.5% may be set, and 0.3% ⁇ Ca + La + Ce ⁇ 2.0% may be set.
- the Al content, the Ca content, the La content, the Y content, and the Ce content in the chemical component of the metal coating layer should satisfy 0.5% ⁇ Al + Ca + La + Y + Ce ⁇ 6% in atomic%.
- 0.5% ⁇ Al + Ca + La + Y + Ce ⁇ 5.5% is more preferably satisfied.
- the powdering characteristic (peeling resistance with respect to a compressive stress) of a plating layer can be improved.
- Si silicon: 0% to 0.5%
- Ti titanium
- Cr chromium
- Si titanium
- Ti, and Cr may be contained as necessary in order to preferably form a quasicrystalline phase in the metal coating layer.
- a quasicrystalline phase is easily generated, and the structure of the quasicrystalline phase is stabilized.
- Si is considered to be the starting point (nucleus) of the formation of the quasicrystalline phase by combining with Mg to form fine Mg 2 Si, and Ti and Cr having poor reactivity with Mg become fine metal phases. It is done.
- the generation of the quasicrystalline phase is generally affected by the cooling rate during production.
- the Si content of the metal coating layer may be 0% to 0.5%
- the Ti content may be 0% to 0.5%
- the Cr content may be 0% to 0.5%. More preferably, regarding the Si content, Ti content, and Cr content, the lower limit may be 0.005% and the upper limit may be 0.1%.
- the quasicrystal is preferably formed finely and in a large amount, so that the corrosion resistance of the surface of the metal coating layer is improved. Corrosion resistance in a wet environment is improved, and the occurrence of white rust is suppressed.
- the Co content is 0% to 0.5%
- the Ni content is 0% to 0.5%
- the V content is 0% to 0.5%
- the Nb content is It may be 0% to 0.5%.
- the lower limit may be 0.05% and the upper limit may be 0.1%, respectively.
- these elements are less effective in improving corrosion resistance than Si, Ti, and Cr.
- the element which comprises a steel plate may mix in the metal coating layer from the steel plate which is a base material.
- adhesion is enhanced by mutual diffusion of elements from the steel plate to the metal coating layer and from the metal coating layer to the steel plate. Therefore, a certain amount of Fe (iron) may be included in the metal coating layer.
- Fe iron
- the Fe content of the metal coating layer may be 0% to 2%.
- elements constituting the steel sheet diffused to the metal coating layer can affect the corrosion resistance of the metal coating layer. The nature is small.
- the metal coating layer may contain up to about 0.5% of these elements.
- Ni, Cu, and Sn Cu and Sn do not have the above-described effects that Ni has.
- the Cu content of the metal coating layer may be 0% to 0.5%, and the Sn content may be 0% to 0.5%. More preferably, regarding the Cu content and the Sn content, the lower limit may be 0.005% and the upper limit may be 0.4%.
- high-strength steel high-strength steel
- elements such as Si and Mn contained in the high-strength steel may diffuse into the metal coating layer.
- Si and Mn Mn does not have the above-described effects of Si.
- the Mn content of the metal coating layer may be 0% to 0.2%. More preferably, regarding the Mn content, the lower limit may be 0.005% and the upper limit may be 0.1%.
- Sr (Strontium): 0% to 0.5%
- Sb antimony
- Pb (lead): 0% to 0.5%
- Sr, Sb, and Pb are elements that improve the plating appearance and are effective in improving the antiglare property.
- the Sr content of the metal coating layer may be 0% to 0.5%
- the Sb content may be 0% to 0.5%
- the Pb content may be 0% to 0.5%.
- the lower limit may be 0.005% and the upper limit may be 0.4%.
- the chemical component of the above-mentioned metal coating layer is measured using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometer) or ICP-MS (Inductively Coupled Plasma Mass Spectrometer).
- ICP-AES Inductively Coupled Plasma Atomic Emission Spectrometer
- ICP-MS Inductively Coupled Plasma Mass Spectrometer
- the plated steel sheet is immersed in 10% hydrochloric acid to which an inhibitor is added for about 1 minute, the metal coating layer portion is peeled off, and a solution in which the metal coating layer is dissolved is prepared. This solution is analyzed by ICP-AES, ICP-MS or the like to obtain the chemical component as the overall average of the metal coating layer.
- a metal coating layer having a chemical component substantially equivalent to the chemical component of the hot dipping bath is formed. Therefore, regarding an element that can ignore the interdiffusion between the steel plate and the metal coating layer, the chemical component of the plating bath to be used may be measured, and the measured value may be substituted as the chemical component of the metal coating layer.
- a small ingot is collected from the plating bath, drill powder is collected, and a solution in which the drill powder is dissolved in an acid is prepared. This solution is analyzed by ICP or the like to obtain chemical components of the plating bath. You may use the measured value of the chemical component of this plating bath as a chemical component of a metal coating layer.
- the plated steel sheet according to the present embodiment includes a quasicrystalline phase as a metal structure in the metal coating layer.
- This quasicrystalline phase is a quasicrystalline phase in which Mg content, Zn content, and Al content in the quasicrystalline phase satisfy 0.5 ⁇ Mg / (Zn + Al) ⁇ 0.83 in atomic%.
- Mg: (Zn + Al) which is the ratio of Mg atoms to the sum of Zn atoms and Al atoms, is defined as a quasicrystalline phase of 3: 6 to 5: 6.
- Mg: (Zn + Al) is considered to be 4: 6.
- the chemical component of the quasicrystalline phase is determined by TEM-EDX (Transmission Electron Microscope-Energy Dispersive Dispersive X-ray Spectroscopy) or EPMA (Electron Probe Micro-Analyzer) preferably. Note that it is not easy to define a quasicrystal with an accurate chemical formula like an intermetallic compound. This is because the quasicrystalline phase cannot define a repetitive lattice unit like a unit cell of a crystal, and furthermore, it is difficult to specify the atomic positions of Zn and Mg.
- the average equivalent circle diameter of the quasicrystalline phase contained in the metal coating layer is 0.01 ⁇ m to 1 ⁇ m.
- a quasicrystalline phase a quasicrystalline phase having an average equivalent circle diameter of up to about 0.01 ⁇ m can be identified from an electron microscope image and an electron beam diffraction image by TEM.
- the metal coating layer also includes a quasicrystalline phase having an equivalent circle diameter of less than 0.01 ⁇ m, for the reasons described above, the lower limit of the average equivalent circle diameter of the quasicrystalline phase is set to 0.01 ⁇ m. .
- the upper limit of the average equivalent circle diameter of the quasicrystalline phase is not particularly limited, but the upper limit of the average equivalent circle diameter of the quasicrystalline phase is preferably 1 ⁇ m because of the structure of the metal structure of the metal coating layer described later.
- the upper limit of the average equivalent circle diameter of the quasicrystalline phase is preferably 0.8 ⁇ m, and the upper limit is 0.6 ⁇ m. Further preferred.
- the upper limit of the average equivalent circle diameter of the quasicrystalline phase is preferably 0.5 ⁇ m, and more preferably 0.4 ⁇ m.
- the metal structure of the metal coating layer is a coarse region composed of crystal grains having an equivalent circle diameter of more than 0.2 ⁇ m when viewed in a cross section in which the plate thickness direction and the cutting direction are parallel, and a circle A bimodal structure composed of fine regions composed of crystal grains having an equivalent diameter of 0.2 ⁇ m or less is preferable.
- the upper limit of the equivalent circle diameter of crystal grains included in the coarse region and the lower limit of the equivalent circle diameter of crystal grains included in the fine region are not particularly limited. However, if the coarse area becomes too large, the dispersion of the metal structure is biased, so the upper limit may be 10 ⁇ m, 5 ⁇ m, 2 ⁇ m, or 1 ⁇ m. Further, the lower limit of the fine region may be set to more than 0 ⁇ m or 0.01 ⁇ m as necessary.
- the coarse region is at least one of a quasicrystalline phase, a Zn phase, an Al phase, and an MgZn phase. It is preferable that the fine region includes at least one of Mg 51 Zn 20 phase, Zn phase, amorphous phase, and Mg 32 (Zn, Al) 49 phase.
- the coarse region includes at least one of Zn phase, Al phase, and MgZn phase.
- the fine region preferably includes a quasicrystalline phase and at least one of Mg 51 Zn 20 phase, Zn phase, amorphous phase, and Mg 32 (Zn, Al) 49 phase.
- the Zn phase and Al phase contained in the metal coating layer may form a eutectic structure.
- the average equivalent circle diameter of the block size of the eutectic structure is preferably more than 0.2 ⁇ m.
- Corrosion resistance is preferably improved by controlling the metal structure of the metal coating layer to a bimodal structure composed of the coarse region and the fine region as described above.
- a bimodal structure means a structure in which the frequency distribution such as the equivalent circle diameter of crystal grains included in the metal structure is a bimodal distribution. Also in the plated steel sheet according to the present embodiment, it is preferable that the frequency distribution of the equivalent circle diameter of the crystal grains included in the metal structure of the metal coating layer has a bimodal distribution. However, in the plated steel sheet according to the present embodiment, the frequency distribution does not necessarily need to be a bimodal distribution. For example, the above effect can be obtained even if the frequency distribution is a broad distribution.
- the bimodal structure in the present embodiment is that the frequency distribution of the equivalent circle diameter of the crystal grains included in the metal structure of the metal coating layer does not follow the normal distribution, and the metal structure of the metal coating layer is equivalent to a circle. It means that it consists of a fine region composed of crystal grains having a diameter of 0.2 ⁇ m or less and a coarse region composed of crystal grains having an equivalent circle diameter of more than 0.2 ⁇ m.
- the average equivalent circle diameter of the quasicrystalline phase contained in the metal structure of the metal coating layer of the plated steel sheet according to this embodiment is 0.01 ⁇ m to 1 ⁇ m. That is, when the crystal grains of the quasicrystalline phase are individually considered, the metal structure of the metal coating layer includes a quasicrystalline phase having an equivalent circle diameter of 0.2 ⁇ m or less and an equivalent circle diameter of more than 0.2 ⁇ m. A certain quasicrystalline phase. When the average equivalent circle diameter of the quasicrystalline phase is more than 0.2 ⁇ m to 1 ⁇ m, the quasicrystalline phase is mainly included in the coarse region of the metal coating layer. When the average equivalent circle diameter of the quasicrystalline phase is 0.01 ⁇ m to 0.2 ⁇ m, the quasicrystalline phase is mainly included in the fine region of the metal coating layer.
- the average equivalent circle diameter is preferably more than 0.2 ⁇ m.
- the metal structure of the metal coating layer includes those crystal grains having an equivalent circle diameter of 0.2 ⁇ m or less and those crystal grains having an equivalent circle diameter of more than 0.2 ⁇ m. The crystal grains are mainly included in the coarse region. Further, when the Zn phase and the Al phase form a eutectic structure, it is preferable that the average equivalent circle diameter of the block size of the eutectic structure is more than 0.2 ⁇ m.
- the metal structure of the metal coating layer includes a block having an equivalent circle diameter of 0.2 ⁇ m or less and a block having an equivalent circle diameter of more than 0.2 ⁇ m.
- the eutectic structure is mainly included in the coarse region.
- the upper limit of the average equivalent circle diameter of the constituent phase and eutectic structure included in the coarse region is not particularly limited. If necessary, the upper limit may be 10 ⁇ m, 5 ⁇ m, 2 ⁇ m, or 1 ⁇ m.
- the average equivalent circle diameter may be 0.01 ⁇ m to 0.2 ⁇ m. preferable.
- the metal structure of the metal coating layer includes those crystal grains having an equivalent circle diameter of 0.2 ⁇ m or less and those crystal grains having an equivalent circle diameter of more than 0.2 ⁇ m. The crystal grains are mainly included in the fine region.
- the average equivalent circle diameter of the Zn phase contained in the metal structure of the metal coating layer is not particularly limited. If necessary, the upper limit may be 10 ⁇ m, 5 ⁇ m, 2 ⁇ m, or 1 ⁇ m. If necessary, the lower limit may be set to more than 0 ⁇ m or 0.01 ⁇ m. That is, the Zn phase may be mainly included in the coarse region, or may be mainly included in the fine region.
- FIG. 1 is an electron micrograph of a plated steel sheet according to this embodiment, and is a metallographic photograph obtained by observing a cut surface whose cutting direction is parallel to the plate thickness direction of the plated steel sheet. This cross-sectional photograph is observed by SEM (Scanning Electron Microscope) and is a reflected electron composition image (COMPO image).
- 1 is a steel plate
- 2 is a metal coating layer.
- 2a shown in FIG. 1 is a coarse region
- 2b is a fine region.
- the coarse region 2a includes at least one of a quasicrystalline phase, a Zn phase, an Al phase, and a MgZn phase.
- the fine region 2b includes at least one of a quasicrystalline phase, an Mg 51 Zn 20 phase, a Zn phase, an amorphous phase, and an Mg 32 (Zn, Al) 49 phase.
- FIG. 1 shows that the metal structure of the metal coating layer is a bimodal structure.
- a fine intermetallic compound or metal phase having an equivalent circle diameter of 0.2 ⁇ m or less may be dispersed in the coarse region 2a.
- the fine grains present in the coarse area 2a are not the fine areas 2b.
- the fine region 2b is a region in which a plurality of fine particles having a circle equivalent diameter of 0.2 ⁇ m or less are continuously accumulated and observed in a considerable area in SEM level observation.
- FIG. 2 and FIG. 3 are electron micrographs of the metal coating layer of the plated steel sheet according to the embodiment, and the metal structure photograph obtained by observing a cut surface in which the cutting direction is parallel to the plate thickness direction of the plated steel sheet It is. This cross-sectional photograph is observed with a TEM and is a bright field image.
- FIG. 2 is a metal structure photograph near the surface of the metal coating layer
- FIG. 3 is a metal structure photograph near the interface between the metal coating layer and the steel plate. 2 and 3, for example, 2a is a coarse region and 2b is a fine region. 2 and 3, as in FIG. 1, it is shown that the metal structure of the metal coating layer is a bimodal structure.
- FIG. 4A is an electron beam diffraction image obtained from the local region 2a1 in the coarse region 2a shown in FIG.
- FIG. 4B is an electron beam diffraction image obtained from the local region 2b1 in the fine region 2b shown in FIG.
- FIG. 4A shows an electron beam diffraction image of a radial regular decagon resulting from a regular icosahedron structure.
- the electron diffraction image shown in FIG. 4A is obtained only from the quasicrystal, and cannot be obtained from any other crystal structure. It can be confirmed from the electron diffraction image shown in FIG. 4A that the coarse region 2a contains a quasicrystalline phase.
- FIG. 4B shows an electron diffraction image derived from the Mg 51 Zn 20 phase. From the electron diffraction image shown in FIG. 4B, it can be confirmed that the Mg 51 Zn 20 phase is contained in the fine region 2b.
- FIG. 5A is an electron beam diffraction image obtained from the local region 2a2 in the coarse region 2a shown in FIG.
- FIG. 5B is an electron beam diffraction image obtained from the local region 2b2 in the fine region 2b shown in FIG. From the electron diffraction image shown in FIG. 5A, it can be confirmed that the MgZn phase is contained in the coarse region 2a. Further, it can be confirmed from the electron diffraction pattern shown in FIG. 5B that the fine region 2b contains a Zn phase.
- the coarse region 2a may contain a Zn phase, an Al phase, or the like
- the fine region 2b contains a quasicrystalline phase, an amorphous phase, a Mg 32 (Zn, Al) 49 phase, or the like. Confirmed that there was a case.
- the quasicrystalline phase having an average equivalent circle diameter of 1 ⁇ m or less is very fine, depending on the irradiation position of the electron beam, diffraction patterns from a plurality of quasicrystalline phases may overlap. In that case, a clear regular decagonal electron beam diffraction image cannot be obtained, and a diffraction pattern similar to a halo pattern unique to the amorphous phase may be detected. Therefore, care must be taken in identifying the quasicrystalline phase.
- Mg 51 Zn 20 is observed when the Mg content is high
- Mg 32 (Zn, Al) 49 is observed when the Mg content is low.
- intermetallic compounds and metal phases such as Zn phase, Al phase, MgZn phase, Mg 51 Zn 20 phase, Mg 32 (Zn, Al) 49 phase, amorphous phase, etc. is the electron diffraction by TEM as described above. It can be confirmed by an image, or by XRD (X-Ray Diffractometer).
- Mg 51 Zn 20 phase is a JCPDS card: PDF # 00-008-0269 or # 00-065-4290, or a non-patent document of To et al. (Journal of solid state chemistry 36, 225-233 (1981). )) Is defined as the constituent phase that can be identified.
- the Mg 32 (Zn, Al) 49 phase is defined as a constituent phase that can be identified by JCPDS card: PDF # 00-019-0029 or # 00-039-0951.
- each crystal grain in the constituent phase is quasicrystalline phase, Mg 51 Zn 20 phase, Mg 32 (Zn, Al) 49 phase, Mg 4 Zn 7 phase, MgZn phase, Mg phase, Zn It is possible to easily identify whether it is a phase or another phase.
- Mg 51 Zn 20 has a unit cell close to a cubic crystal and is an icosahedron in the unit cell. It has been reported to have an atomic structure that forms Since the unit cell of Mg 51 Zn 20 is different from the icosahedral structure of the quasicrystal, strictly speaking, Mg 51 Zn 20 and the quasicrystal are in different phases. However, since the crystal structures of Mg 51 Zn 20 and the quasicrystal are similar, it is considered that the Mg 51 Zn 20 phase affects the generation of the quasicrystal phase.
- Mg 32 (Zn, Al) 49 is also called a Frank-Kasper phase, and this Mg 32 (Zn, Al) 49 also has a complicated arrangement of atoms (diamond 30-hedron).
- the Mg 32 (Zn, Al) 49 phase is also presumed to be closely related to the formation of a quasicrystalline phase, like the Mg 51 Zn 20 phase.
- the amorphous phase, the quasicrystalline phase, and the Mg 51 Zn 20 phase that may be included in the fine region 2b are almost different in chemical composition represented by the ratio of Zn and Mg, although the atomic arrangement (crystal structure) is different. There is no. Although not shown, it was confirmed by EDX mapping of the fine region 2b that there was no significant difference in the chemical components of the quasicrystalline phase, the Mg 51 Zn 20 phase, and the amorphous phase. These quasicrystalline phases, Mg 51 Zn 20 phase, and amorphous phase can be judged to be non-equilibrium phases that are generated by quenching before the equilibrium phase is precipitated during the production of the plated steel sheet.
- the corrosion resistance of the constituent phases of the metal coating layer tends to be excellent in the order of quasicrystalline phase> Mg 32 (Zn, Al) 49 phase> Mg 51 Zn 20 phase> MgZn phase> Al phase> Zn phase> amorphous phase >> Mg phase. It is in. When these constituent phases coexist, it is advantageous for the corrosion resistance of the metal coating layer to increase the fraction of the phase having high corrosion resistance and to uniformly disperse it.
- the corrosion resistance may be reduced due to the formation of the coupling cell as compared with the case where the metal coating layer is a single phase.
- the corrosion resistance decrease due to the coupling cell formation is hardly seen and can be ignored. Be looked at.
- the average equivalent circle diameter of each constituent phase included in the coarse region may be 2 ⁇ m or less, preferably 1 ⁇ m or less.
- an existing Zn-based chemical conversion treatment can be used.
- the Zn-based phosphate treatment used as a metal base coating treatment when the particle size of the constituent phase contained in the coarse region increases, phosphate crystals hardly grow on the coarse region. And this area
- the average equivalent circle diameter of each constituent phase included in the coarse region is controlled to 2 ⁇ m or less, preferably 1 ⁇ m or less, phosphoric acid crystals can be preferably grown.
- the intermetallic compound phase and the amorphous phase are poor in plastic deformability. Decreasing the fraction of coarse constituent phases with poor plastic workability will result in finer cracks in the metal coating layer during the processing of the plated steel sheet, and the exposed area of the steel sheet (base metal) will be reduced, which preferably improves the corrosion resistance. Is done. Moreover, since peeling of a metal coating layer is also suppressed, the period until red rust generation
- the quasicrystalline phase is a non-equilibrium phase and is thermally unstable. Therefore, phase decomposition occurs when exposed to a high temperature environment around 250 to 330 ° C. for a long time, and an Mg phase having poor corrosion resistance may be generated in addition to the Mg 51 Zn 20 phase. As a result, the corrosion resistance of the plated steel sheet as a whole may be deteriorated. Care must be taken when using a plated steel sheet in a high temperature environment.
- the Zn phase and the Al phase may form a eutectic structure.
- the Zn phase is a phase containing 95% or more of Zn, and Mg, Al, Ca, etc., which are elements constituting the metal coating layer, are dissolved in this Zn phase in less than 5%.
- the Al phase is a phase containing 33% or more of Al.
- This Al phase mainly contains Zn in addition to Al, and a small amount of Mg or Ca, which is an element constituting the metal coating layer, dissolves in a small amount.
- the eutectic structure of the Zn phase and the Al phase (Zn—Al eutectic) refers to a eutectic structure composed of a mixed phase of the Zn phase and the Al phase.
- the area fraction of the coarse region (the area of the coarse region ⁇ the area of the metal coating layer) with respect to the metal structure of the entire metal coating layer is preferably 5% to 50%.
- the area fraction of the fine region with respect to the metal structure of the entire metal coating layer (area of the fine region ⁇ area of the metal coating layer) is preferably 50% to 95%.
- the corrosion resistance of the metal coating layer is further improved. More preferably, the area fraction of the coarse region with respect to the metal structure of the entire metal coating layer may be 5% to 20%, and the area fraction of the coarse region may be 5% to 10%.
- the area fraction of the quasicrystalline phase contained in the coarse region is larger than that of the coarse region.
- (Area of quasicrystalline phase in coarse region ⁇ area of coarse region) is preferably 80% to less than 100%, and Mg 51 Zn 20 phase, Zn phase, amorphous phase, and Mg contained in the fine region
- the total area fraction of the 32 (Zn, Al) 49 phase is preferably 80% to less than 100% with respect to the fine region (total area of each constituent phase in the fine region / area of the fine region).
- the total area fraction of the Zn phase, Al phase, and MgZn phase contained in the coarse region is ( The total area of the above constituent phases in the coarse region ⁇ the area of the coarse region) is 80% to less than 100%, and the area fraction of the quasicrystalline phase contained in the fine region is smaller than that in the fine region (in the fine region)
- the area of the quasicrystalline phase / the area of the fine region) is preferably more than 0% and less than 10%.
- the metal phase of the metal coating layer does not contain an Mg phase. Since the Mg phase contained in the metal coating layer deteriorates the corrosion resistance regardless of whether it is in the coarse region or the fine region, it is preferable to reduce the precipitation of the Mg phase as much as possible.
- the determination of the presence or absence of the Mg phase may be confirmed by TEM-EDX or SEM-EDX, or may be confirmed by XRD.
- the number fraction of Mg phase crystal grains is 3% or less when arbitrary crystal grains are sampled at 100 or more, the metal structure of the metal coating layer does not contain Mg phase. It can be said.
- the number fraction of Mg phase crystal grains is more preferably less than 2%, and the number fraction of Mg phase crystal grains is most preferably less than 1%.
- the Mg phase is likely to be formed as an initial crystal immediately below the melting point. Whether the Mg phase is generated as the primary crystal is largely determined by the chemical composition of the metal coating layer and the manufacturing conditions. If the Mg content is higher than the eutectic composition (Mg 72% -Zn 28%) in the Mg-Zn binary equilibrium diagram, the Mg phase may crystallize as the primary crystal. On the other hand, when the Mg content is lower than this value, in principle, the possibility that the Mg phase crystallizes as the primary crystal is small.
- the manufacturing process according to the present embodiment since the manufacturing process according to the present embodiment generates a quasicrystal as the primary crystal, even if the Mg content is higher than the eutectic composition, the Mg phase is extremely difficult to generate and even if it can be confirmed.
- the possibility that an Mg phase exists as a main phase is small.
- the existence of Mg phase crystal grains is about 3% at the maximum in number fraction.
- the crystal grains of the Mg phase are in a number fraction with respect to the crystal grains contained in the metal structure of the metal coating layer. It tends to be less than 2%.
- the Mg phase crystal grains tend to be less than 1% in terms of the number fraction with respect to the crystal grains contained in the metal structure of the metal coating layer. If the Mg phase is present in the metal coating layer, the surface of the metal coating layer may change to black over time particularly in a wet environment, which may cause poor plating appearance. From this point, it is preferable to avoid mixing the Mg phase particularly in the surface layer of the metal coating layer.
- the appearance defect in which the surface of the metal coating layer changes to black can be determined by storing the plated steel sheet in a constant temperature and humidity chamber for a certain period.
- the thickness in the plate thickness direction of the metal coating layer is D in ⁇ m
- the metal coating layer The range of 0.05 ⁇ D from the surface of the layer toward the steel plate along the plate thickness direction is the metal coating layer outermost portion, and the metal coating layer is directed from the interface between the steel plate and the metal coating layer along the plate thickness direction.
- the area fraction of the coarse region relative to the outermost part of the metal coating layer (the area of the coarse region in the outermost part of the metal coating layer ⁇ the outermost surface of the metal coating layer
- the area fraction of the coarse area with respect to the deepest part of the metal coating layer (area of the coarse area in the deepest part of the metal coating layer / area of the deepest part of the metal coating layer) is 7% to less than 100%.
- the area fraction of the fine region with respect to the metal coating layer body (area of the fine region in the metal coating layer body ⁇ area of the metal coating layer body ) Is preferably 50% to less than 100%.
- the constituent phases contained in the metal coating layer are arranged in a preferable manner, so that the corrosion resistance of the metal coating layer is further improved.
- the adhesion of the metal coating layer tends to be improved.
- the above-mentioned area fraction may be calculated by using the area included in the metal coating layer outermost part or the metal coating layer deepest part of the crystal grains.
- the crystal grains in the fine region are present at a position straddling the outermost surface of the metal coating layer and the metal coating layer main body, or the crystal grains in the fine region are the deepest metal coating layer and the metal coating layer main body.
- the above-described area fraction may be calculated using the area included in the metal coating layer main body portion of the crystal grains.
- the plated steel sheet according to this embodiment further includes an Fe—Al-containing alloy layer, the Fe—Al-containing alloy layer is disposed between the steel sheet and the metal coating layer, and the Fe—Al-containing alloy layer is Fe 5 Al 2.
- the thickness of the Fe—Al-containing alloy layer is at least 10 nm to 1000 nm including at least one of Al 3.2 Fe.
- the thickness D of the metal coating layer of the plated steel sheet according to this embodiment is not particularly limited. This thickness D may be controlled as necessary. In general, the thickness D is often 35 ⁇ m or less.
- the metal structure of the metal coating layer is observed as follows.
- the plated steel sheet is cut and a sample is taken so that the cut surface in which the plate thickness direction and the cutting direction are parallel becomes the observation surface.
- the cut surface is polished or CP (Cross Section Polisher). In the case of polishing, this section is subjected to nital etching.
- This cross section is observed with an optical microscope or SEM, and a metallographic photograph is taken. Further, if the cross-section observed with the SEM is a COMPO image as shown in FIG. 1, the contrast is greatly different due to the difference in chemical composition between the coarse area and the fine area. The boundary is easy to distinguish.
- the chemical component of the constituent phase can be measured by analysis using EDX or EPMA.
- the constituent phase can be easily identified from the chemical component result.
- the area fraction of the constituent phase can be measured by binarizing the metal structure photograph by, for example, image analysis and measuring the area ratio of the white portion or the black portion of the metal coating layer. Further, the average equivalent circle diameter can be obtained by calculation from the obtained areas of the individual coarse regions.
- the metal structure of the metal coating layer may be observed by an EBSD (Electron Back Scattering Diffraction Pattern) method, the constituent phase may be identified, and the area fraction of the constituent phase and the average equivalent circle diameter may be obtained.
- EBSD Electro Back Scattering Diffraction Pattern
- the metal structure of the metal coating layer is observed as follows.
- the plated steel sheet is cut and a thin piece sample is taken so that the cut surface in which the plate thickness direction and the cutting direction are parallel becomes the observation surface.
- the thin sample is subjected to ion milling.
- a thin piece sample is collected by FIB (Focused Ion Beam) processing of the plated steel sheet so that the cut surface in which the plate thickness direction and the cutting direction are parallel becomes the observation surface.
- FIB Flucused Ion Beam
- the spatial existence state is not known, it is also simplest to confirm the presence of the constituent phase from the XRD diffraction peak of the metal coating layer.
- the diffraction peak positions of the quasicrystals, Mg 51 Zn 20 and Mg 32 (Zn, Al) 49 are overlapped with each other, the existence can be confirmed, but it is difficult to determine.
- the area fraction and average equivalent circle diameter of the constituent phases in the metal coating layer are 6 ⁇ m ⁇ 100 ⁇ m of the cross section of the metal coating layer. These areas may be obtained by photographing EPMA mapping images at three locations.
- the steel plate used as the base material of a plated steel plate is not specifically limited as a plated steel plate which concerns on this embodiment.
- the steel plate Al killed steel, extremely low carbon steel, high carbon steel, various high strength steels, Ni, Cr-containing steel, and the like can be used.
- the method for producing a plated steel sheet according to the present embodiment includes a hot dipping process in which the steel sheet is immersed in a hot dipping bath whose components are adjusted, and a liquid for the metal coating layer.
- the phase line temperature is T melt in ° C.
- the metal coating layer is in a coexisting state of the solid phase and the liquid phase
- the volume ratio of the solid phase to the metal coating layer (volume of the solid phase / volume of the metal coating layer).
- T solid-liquid the metal coating layer is in the temperature range from T melt + 10 ° C. to T solid-liquid.
- T melt that is the liquidus temperature of the metal coating layer
- Liang et al. Liang, P., Tarfa, T., Robinson, JA , Wagner, S., Ochin, P., Harmelin, MG, Seifert, HJ, Lukas, HL, Aldinger, F., “Experimental Investigation and Thermochemical Calfation-- System ", Thermochim. Acta, 314, 87-110 (1998)
- the value of T melt can be almost estimated from the ratio of Zn, Al, and Mg contained in the metal coating layer.
- the value of T solid-liquid can be uniquely determined from the alloy phase diagram. Specifically, using the alloy phase diagram corresponding to the chemical composition of the metal coating layer, the volume ratio (volume fraction) of each constituent phase coexisting with a plurality of phases can be obtained from the balance law. That is, using an alloy phase diagram, a temperature at which the volume ratio of the solid phase becomes 0.01 and a temperature at which the volume ratio of the solid phase becomes 0.1 may be obtained. In the method for manufacturing a plated steel sheet according to the present embodiment, the value of T solid-liquid may be obtained using an alloy phase diagram. At that time, a calculation state diagram based on a thermodynamic calculation system may be used as the alloy state diagram.
- the constituent phase ratio obtained from the alloy phase diagram does not exactly match the constituent phase ratio in the metal coating layer being cooled.
- the inventors of the present invention have a T solid in which the metal coating layer being cooled is in a coexistence state of a solid phase and a liquid phase, and the volume ratio of the solid phase to the metal coating layer is 0.01 to 0.1.
- T solid-liquid can be obtained empirically by the following equation: ⁇ 345 + 0.8 ⁇ (T melt -345) ⁇ -1 ⁇ T solid-liquid ⁇ T melt . Therefore, in the method for producing a plated steel sheet according to this embodiment, the value of T solid-liquid may be obtained from this equation.
- the chemical composition of the metal coating layer formed on the surface of the steel sheet is atomic%, Zn: 28.5% to 52%, Al: 0.5% to 10%, Ca: 0% to 3%. 0.5%, Y: 0% to 3.5%, La: 0% to 3.5%, Ce: 0% to 3.5%, Si: 0% to 0.5%, Ti: 0% to 0% 0.5%, Cr: 0% to 0.5%, Fe: 0% to 2%, Co: 0% to 0.5%, Ni: 0% to 0.5%, V: 0% to 0.5% %, Nb: 0% to 0.5%, Cu: 0% to 0.5%, Sn: 0% to 0.5%, Mn: 0% to 0.2%, Sr: 0% to 0.5% %, Sb: 0% to 0.5%, Pb: 0% to 0.5%, and the chemical composition of the plating bath is adjusted so that the balance is Mg and impurities.
- the hot dipping process is selected as an example.
- the method of forming the metal coating layer on the surface of the steel plate is not limited as long as the metal coating layer of the above chemical component can be formed on the surface of the steel plate.
- a thermal spraying method, a sputtering method, an ion plating method, a vapor deposition method, and an electroplating method may be applied.
- the metal coating layer formed on the surface of the steel sheet by the hot dipping process is in a molten state (liquid phase) immediately after being pulled up from the plating bath.
- the metal coating layer can be controlled to the above-described metal structure containing the quasicrystal. .
- the plated steel sheet on which the metal coating layer is formed is reheated in a heating furnace, and only the metal coating layer is melted.
- the metal coating layer can be controlled to the above-described metal structure containing the quasicrystal by cooling by the unique first cooling step and second cooling step.
- the melting point of the metal coating layer mainly composed of Mg and Zn is completely different from the melting point of the steel plate as the base material. Therefore, those skilled in the art can easily optimize and determine the temperature and time for melting only the metal coating layer.
- the metal coating layer is completely melted, and the steel plate as the base material is not melted.
- rapid heating in a high temperature atmosphere is preferable because it preferentially heats the metal coating layer of the plated steel sheet in contact with the atmosphere.
- the oxygen concentration of the atmosphere when the steel sheet is immersed is 0 ppm to 100 ppm in volume ratio
- the plating bath holding the plating bath is made of steel
- T is the temperature of the plating bath. It is preferable that the bath is 10 ° C. to 100 ° C. higher than T melt and the time during which the steel sheet is immersed in the plating bath is 1 second to 10 seconds.
- the oxygen concentration is 100 ppm or less by volume ratio
- oxidation of the plating bath can be preferably suppressed. More preferably, the oxygen concentration is 50 ppm or less by volume.
- the plating tank is made of steel, inclusions in the plating bath are reduced, so that quasicrystals are preferably generated in the metal structure of the metal coating layer.
- the said plating tank is steel, compared with the case where a plating tank is a product made from ceramic, the abrasion of the inner wall of a plating tank can be suppressed.
- T bath which is the temperature of the plating bath is 10 ° C. to 100 ° C.
- the metal coating layer is preferably formed on the surface of the steel plate, and the Fe—Al-containing alloy layer is formed between the steel plate and the metal coating layer. Is done.
- T bath which is the temperature of the plating bath is more preferably 30 ° C. to 50 ° C. higher than T melt .
- the metal coating layer is preferably formed on the steel plate, and the Fe—Al-containing alloy layer is formed between the steel plate and the metal coating layer.
- the time during which the steel sheet is immersed in the plating bath is more preferably 2 seconds to 4 seconds.
- the temperature of the metal coating layer is from T melt + 10 ° C., which is the liquidus temperature of the metal coating layer, and the volume ratio of the solid phase to the metal coating layer (liquid phase + solid phase) is 0.01. It is important to control the average cooling rate of the metal coating layer when reaching T solid-liquid which is a temperature range of ⁇ 0.1 .
- the steel sheet on which the metal coating layer is formed is cooled by controlling the average cooling rate to be 15 ° C./second to 50 ° C./second.
- the cooling in the first cooling step may be performed under the following conditions.
- the average cooling rate of the metal coating layer is 15 ° C./second to 50 ° C./second in the temperature range from T melt to T solid-liquid.
- the steel plate after the hot dipping process may be cooled.
- T melt ⁇ T solid-liquid + 10 ° C. the average cooling rate of the metal coating layer is 15 ° C./second to 50 ° C./second in the temperature range from T solid-liquid + 10 ° C. to T solid-liquid.
- the steel plate after the hot dipping process may be cooled.
- a Zn phase, a quasicrystalline phase, a MgZn phase, or an Al phase is formed as an initial crystal in the metal coating layer that is in a molten state (liquid phase) before the start of cooling.
- the seed crystallizes out.
- the crystallized Zn phase, quasicrystalline phase, MgZn phase, or Al phase finally becomes a constituent phase included in the coarse region.
- the Zn phase and the Al phase may form a eutectic structure.
- the average equivalent circle diameter of the block size of the eutectic structure is preferably more than 0.2 ⁇ m, and it is preferably a coarse region.
- the average cooling rate in the first cooling step is less than 15 ° C./second, the cooling rate of the quasicrystalline phase that is originally generated as a non-equilibrium phase is not reached, so that it is difficult to produce a quasicrystal. In addition, a coarse region mainly including a Zn phase, an Al phase, or a MgZn phase is hardly generated.
- the average cooling rate in the first cooling step exceeds 50 ° C./second, the average equivalent circle diameter of quasicrystalline phase, Zn phase, MgZn phase, Al phase, etc. does not reach 0.2 ⁇ m.
- a coarse region may not be formed, and the above-described bimodal structure may not be obtained.
- the upper limit of the average cooling rate in a 1st cooling process shall be 50 degrees C / sec.
- the first cooling step when the average cooling rate of the metal coating layer is controlled to the above condition from a temperature lower than T melt + 10 ° C. (when T melt ⁇ T solid-liquid + 10 ° C., control is performed from a temperature lower than T melt. If you, or T melt ⁇ when controlling from a temperature lower than T solid-liquid + 10 °C when the T solid-liquid + 10 °C) , Zn phase primary crystal crystallizing the metal coating layer, quasicrystalline phase, The MgZn phase or Al phase cannot be obtained.
- T when stop control in the solid-liquid temperature higher than the above condition of the average cooling rate, or if to a temperature below T solid-liquid the average cooling rate is controlled to the above condition, Zn phase,
- the average equivalent circle diameter and area fraction of the Al phase, quasicrystalline phase, MgZn phase, or Zn—Al eutectic are not preferably controlled.
- the average equivalent circle diameter and area fraction of the Al eutectic cannot be controlled preferably.
- the average cooling rate of the metal coating layer in the first cooling step is less than 15 ° C./second or more than 50 ° C./second, the Zn phase, Al phase, quasicrystalline phase, MgZn phase, or Zn—Al eutectic is formed. It may not be a coarse area.
- the second cooling step when the temperature of the metal coating layer reaches 250 ° C. from the temperature at the end of cooling in the first cooling step, that is, from the first cooling end temperature in T solid-liquid . It is important to control the average cooling rate.
- the steel sheet after the first cooling step is cooled by controlling the average cooling rate to be 100 ° C./second to 3000 ° C./second.
- the lower limit of the temperature range is preferably 200 ° C, more preferably 150 ° C, and most preferably 100 ° C.
- the Zn phase, the quasicrystalline phase, the MgZn phase, or the Al phase is crystallized as the primary crystal, and the finer in the metal coating layer in which the solid phase and the liquid phase coexist.
- At least one of a quasicrystalline phase, Mg 51 Zn 20 phase, Zn phase, amorphous phase, or Mg 32 (Zn, Al) 49 phase is crystallized. It is preferable that the crystallized quasicrystalline phase, the Mg 51 Zn 20 phase, the Zn phase, the amorphous phase, or the Mg 32 (Zn, Al) 49 phase finally becomes a constituent phase included in the fine region.
- the average cooling rate when the average cooling rate is controlled from the temperature higher than T solid-liquid or the temperature lower than T solid-liquid to the above conditions, Zn phase, Al phase, quasicrystalline phase, MgZn phase Alternatively, the average equivalent circle diameter and the area fraction of the Zn—Al eutectic cannot be controlled preferably. In addition, there is a case where it is impossible to control the bimodal structure including the above-described coarse region and fine region.
- the quasicrystalline phase, Mg 51 Zn 20 phase, and Mg 32 (Zn, Al) 49 phase which are non-equilibrium phases, are phase-decomposed. There are things to do.
- the bimodal structure including the above-described coarse region and fine region.
- the average cooling rate in the second cooling step is less than 100 ° C./second, a quasicrystalline phase, Mg 51 Zn 20 phase, Zn phase, amorphous phase, or Mg 32 (Zn, Al) 49 phase is not generated. Or it becomes a metal structure with much Mg phase.
- the quasicrystalline phase, the Mg 51 Zn 20 phase, the Zn phase, the amorphous phase, or the Mg 32 (Zn, Al) 49 phase may not be a fine region.
- the average cooling rate in the second cooling step exceeds 3000 ° C./second, an amorphous phase is excessively generated, and the above-described bimodal structure may not be controlled.
- T melt that is the liquidus temperature of the metal coating layer may be obtained from a Zn, Al—Mg ternary liquid phase diagram.
- T solid-liquid which is a temperature range in which the volume ratio of the solid phase to the metal coating layer is 0.01 to 0.1 is represented by the following equation: ⁇ 345 + 0.8 ⁇ (T melt ⁇ 345) ⁇ ⁇ 1 ⁇ T You may obtain
- the reason for terminating the cooling in the first cooling step within the temperature range where the volume ratio of the solid phase to the metal coating layer is 0.01 to 0.1 is that the solid phase explosively increases in the vicinity of this temperature range. Because.
- the average equivalent circle diameter and area fraction of the constituent phases can be preferably controlled.
- precise temperature control is required.
- a contact-type thermocouple (K-type) may be used as a method for actually measuring the temperature of the metal coating layer when manufacturing the plated steel sheet according to the present embodiment.
- K-type thermocouple By attaching a contact-type thermocouple to the original plate, the average temperature of the entire metal coating layer can always be monitored.
- By mechanically controlling the pulling speed and thickness and unifying the preheating temperature of the steel sheet, the hot dipping bath temperature, etc. it is possible to monitor the temperature of the entire metal coating layer at that point in the manufacturing conditions almost accurately. It becomes. Therefore, it becomes possible to precisely control the cooling in the first cooling process and the second cooling process.
- the surface temperature of the metal coating layer may be measured by a non-contact type radiation thermometer.
- the relationship between the surface temperature of the metal coating layer and the average temperature of the entire metal coating layer may be obtained by a cooling simulation in which heat conduction analysis is performed. Specifically, the preheating temperature of the steel plate, the hot dipping bath temperature, the pulling speed of the steel plate from the plating bath, the plate thickness of the steel plate, the layer thickness of the metal coating layer, the heat exchange heat quantity between the metal coating layer and the manufacturing equipment, the metal coating What is necessary is just to obtain
- the cooling method in the first cooling step and the second cooling step is not particularly limited.
- a cooling method rectified high pressure gas cooling, mist cooling, and submerged cooling may be performed.
- cooling with a rectified high-pressure gas is preferable. When H 2 and He are used, the cooling rate increases.
- all known plating methods such as Sendzimir method, pre-plating method, two-step plating method, flux method and the like can be applied.
- pre-plating displacement plating, electroplating, vapor deposition, or the like can be used.
- a steel material that is a base material of the plated steel sheet is not particularly limited.
- the above effects are not affected by the chemical composition of the steel material, and Al killed steel, extremely low carbon steel, high carbon steel, various high strength steels, Ni, Cr-containing steel, and the like can be used.
- each process such as a steel making process, a hot rolling process, a pickling process, and a cold rolling process before the hot dipping process is not particularly limited. That is, there are no particular limitations on the manufacturing conditions of the steel sheet used in the hot dipping process and the material of the steel sheet.
- the steel sheet subjected to the hot dipping process has a temperature difference between the surface and the inside.
- the surface temperature of the steel plate immediately before being immersed in the plating bath is higher than the internal temperature.
- the surface temperature of the steel sheet immediately before being immersed in the plating bath is preferably higher by 10 ° C. to 50 ° C. than the temperature at the center of the steel sheet in the thickness direction.
- the metal coating layer is extracted by the steel plate, so that the metal coating layer can be preferably controlled to the above-described metal structure containing the quasicrystal.
- the method for producing a temperature difference between the surface and the inside of the steel plate immediately before being immersed in the plating bath is not particularly limited.
- the steel plate immediately before being immersed in the plating bath is rapidly heated in a high-temperature atmosphere, and only the surface temperature of the steel plate may be controlled to a preferable temperature for hot-dip plating.
- only the surface region of the steel plate is preferentially heated, and the steel plate can be immersed in the plating bath with a temperature difference between the surface and the inside of the steel plate.
- an exposure test that can evaluate the corrosion resistance of the metal coating layer in an actual environment is most preferable. It is possible to evaluate the superiority or inferiority of the corrosion resistance by evaluating the corrosion weight loss of the metal coating layer during a certain period.
- a corrosion acceleration test such as a combined cycle corrosion tester or a salt spray test can be used. By evaluating the corrosion weight loss and red rust prevention period, the superiority or inferiority of the corrosion resistance can be determined.
- a corrosion acceleration test using a NaCl aqueous solution having a high concentration of about 5%.
- a NaCl aqueous solution having a low concentration (1% or less) is used, it is difficult to obtain superior or inferior corrosion resistance.
- An organic or inorganic chemical conversion treatment may be further performed on the metal coating layer. Since the metal coating layer which concerns on this embodiment contains Zn more than fixed content in a metal coating layer, it is possible to perform the chemical conversion treatment similar to a Zn-based plated steel plate. The same applies to the coating on the chemical conversion coating. It can also be used as an original sheet for laminated steel sheets.
- the plated steel sheet according to the present embodiment it is possible to use it in a place where the corrosive environment is particularly severe. It can be used as a substitute for various types of plated steel sheets used in the fields of building materials, automobiles, home appliances, and energy.
- the conditions in the examples are one example of conditions adopted to confirm the feasibility and effects of the present invention.
- the present invention is not limited to this one condition example.
- the present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.
- the quasicrystal-containing plated steel sheet was manufactured by the hot dipping process, the first cooling process, and the second cooling process under the manufacturing conditions shown in Tables 1 and 2.
- the plating bath was obtained by dissolving a predetermined amount of each pure metal ingot.
- the plating bath was covered with a sealing box, and Ar gas replacement was performed to control the plating bath to a predetermined oxygen concentration.
- a hot rolled steel sheet (carbon content: 0.2% by mass) having a thickness of 0.8 mm was used as a plating original sheet (steel sheet to be a base material of the plated steel sheet).
- the steel plate was cut into 100 mm ⁇ 200 mm.
- a batch type hot dipping test apparatus was used for the hot dipping. The temperature of the plated steel sheet during production was monitored at the center of the steel sheet.
- the surface of the steel sheet heated to 800 ° C. was reduced with N 2 -5% H 2 gas in a furnace with controlled oxygen concentration.
- the steel sheet was air-cooled with N 2 gas, and after the surface temperature of the steel sheet reached 20 ° C. higher than the bath temperature of the plating bath, the steel sheet was immersed in the plating bath for a predetermined time. After immersion in the plating bath, the steel sheet was pulled up at a pulling rate of 100 mm / sec. At the time of pulling up, high pressure N 2 gas or H 2 and N 2 mixed gas whose outlet is rectified by parallel slits is sprayed to control the plating adhesion amount (metal coating layer thickness) and cooling rate. It was.
- Samples of 20 (C direction: plate width direction) mm ⁇ 15 (L direction: rolling direction) mm were collected from arbitrary 10 locations in the produced plated steel sheet. These were immersed in an aqueous 10% HCl solution for 1 second to remove the oxide film. Observe the metallographic structure of the cut surface of each sample (the cutting direction and the plate thickness direction are parallel) with SEM, measure the equivalent circle diameter and area fraction of each constituent phase (each crystal grain), and calculate the average value did. The equivalent circle diameter and area fraction of each constituent phase were determined by image analysis. The chemical component of the constituent phase was measured by analysis with EPMA.
- Electron diffraction patterns of main crystal grains observed by TEM are analyzed, and constituent phases contained in the metal structure (quasicrystal, Zn, Al, MgZn, Mg 51 Zn 20 , Mg 32 (Zn, Al) 49 , Amorphous phase, etc.). Further, as necessary, the equivalent circle diameter and area fraction of each constituent phase were determined by image analysis, and the chemical components of each constituent phase were measured by analysis using EDX. The presence or absence of Mg phase was confirmed by XRD. When the diffraction intensity of the Mg phase was smaller than specified in the XRD diffraction pattern, it was judged that the Mg phase was not contained in the metal structure of the metal coating layer.
- the corrosion resistance, sacrificial anticorrosion, antiglare effect and appearance of the manufactured plated steel sheet were evaluated.
- corrosion resistance corrosion weight loss, occurrence of red rust, occurrence of white rust, occurrence of red rust in processed parts, and corrosion resistance after coating were evaluated.
- Corrosion weight loss was evaluated by a corrosion accelerated test (CCT: Combined cycle Corrosion Test) based on JASO (M609-91) cycle. Specifically, for the corrosion weight loss evaluation, a sample of 50 (C direction) mm ⁇ 100 (L direction) mm was cut out from the manufactured plated steel sheet and subjected to a corrosion acceleration test. A corrosion acceleration test (CCT) was performed using a 0.5% NaCl aqueous solution to evaluate the weight loss after 150 cycles.
- CCT corrosion acceleration test
- a plated steel sheet with a corrosion weight loss of less than 20 g / m 2 is “Excellent”
- a plated steel sheet with a corrosion weight loss of 20 g / m 2 to less than 30 g / m 2 is “Good”
- a corrosion weight loss is 30 g / m 2.
- the above plated steel sheet was judged as “Poor”. “Excellent” represents the most excellent corrosion weight loss evaluation.
- the occurrence of red rust was evaluated by the above-described corrosion acceleration test (CCT). Specifically, a corrosion acceleration test (CCT) using a 5% NaCl aqueous solution was performed using the manufactured plated steel sheet, and the number of test cycles in which a red rust of 5% or more in area% was generated on the flat portion of the plated steel sheet was investigated.
- CCT corrosion acceleration test
- Excellent is a plated steel sheet in which the red rust is not confirmed after 300 cycles
- “Very Good” is a plated steel sheet in which the red rust is not confirmed after 150 cycles
- “Good” is a plated steel sheet in which the red rust is not confirmed after 100 cycles.
- the plated steel plate in which the red rust was confirmed in less than 100 cycles was judged as “Poor”.
- “Excellent” represents the most excellent evaluation of occurrence of red rust.
- the occurrence of white rust was evaluated by a salt spray test (SST: Salt Spray Test) in accordance with JIS Z2371: 2000. Specifically, a salt spray test (SST) using a 5% NaCl aqueous solution was performed using the manufactured plated steel sheet, and the test elapsed time in which white rust exceeding 5% in area% was generated on the flat portion of the plated steel sheet was investigated. .
- SST Salt Spray Test
- Example 2 is the plated steel sheet in which the white rust is not confirmed after 120 hours
- Good is the plated steel sheet in which the white rust is not confirmed after 24 hours
- the white rust is confirmed in less than 24 hours
- the plated steel sheet was judged as “Poor”. “Excellent” represents the most excellent white rust evaluation.
- the occurrence of red rust in the processed part was evaluated by a corrosion accelerated test (CCT: Combined cycle Corrosion Test) based on JASO (M609-91) cycle using a deep-drawn plated steel sheet.
- CCT corrosion accelerated test
- JASO Combined cycle Corrosion Test
- a corrosion acceleration test was performed using this plated steel sheet, and the number of test cycles in which red rust exceeding 5% in area% was generated in the processed portion of the plated steel sheet was investigated.
- Excellent is a plated steel sheet in which the red rust is not confirmed after 60 cycles
- Good is a plated steel sheet in which the red rust is not confirmed after 30 cycles
- the steel plate was judged as “Poor”.
- Excellent represents that the red rust generation evaluation of a processed part is the most excellent.
- the corrosion resistance after painting was evaluated by a test under the following conditions. Specifically, the manufactured plated steel sheet is subjected to zinc phosphate conversion treatment (Surfdyne: SD5350, manufactured by Nippon Paint Co., Ltd.), and then electrodeposition-coated (PN110 gray: manufactured by Nippon Paint Co., Ltd.) The surface of the surface was cut with a cutter knife to reach a 10 mm long steel bar. The coated steel sheet having the cut wrinkles was corroded in 240 cycles in a combined cycle corrosion test (JASO M609-91), and the swollen width of the coating film around the cut wrinkles after 240 cycles was evaluated.
- zinc phosphate conversion treatment Sudfdyne: SD5350, manufactured by Nippon Paint Co., Ltd.
- PN110 gray manufactured by Nippon Paint Co., Ltd.
- the coated steel sheet having the cut wrinkles was corroded in 240 cycles in a combined cycle corrosion test (JASO M609-91), and the swollen
- “Excellent” is a plated steel sheet that has no blisters on the flat surface after 240 cycles and has a blister width of 2 mm or less from the cut surface. Plated steel sheet within 3mm is “Very Good”, and there is no blister and the coated steel sheet width is 5mm within “cut”, and one or more blisters are observed or A plated steel sheet having a coating bulge width of more than 5 mm was judged as “Poor”. “Excellent” represents the most excellent post-painting corrosion resistance evaluation.
- Sacrificial corrosion resistance was evaluated by an electrochemical method. Specifically, the manufactured plated steel sheet was immersed in a 0.5% NaCl aqueous solution, and the corrosion potential of the plated steel sheet manufactured using an Ag / AgCl reference electrode was measured. In this case, the corrosion potential of Fe is about ⁇ 0.62V.
- the plated steel sheet having a corrosion potential of ⁇ 1.0 to ⁇ 0.8 V is “Excellent” and the corrosion potential is ⁇ 1.0 to ⁇ 0.8 V with respect to the Ag / AgCl reference electrode.
- the plated steel sheet that should not be judged was “Poor”. “Excellent” indicates that the potential difference with iron is small and the sacrificial anticorrosive action is moderately effective.
- the antiglare effect was evaluated by a spectrocolorimetric method. Originally, visual evaluation is preferable, but after confirming in advance that there is a correlation between visual observation and the L * value by a colorimeter, SCI (regular reflection) using a spectrocolorimeter (D65 light source, 10 ° field of view). Evaluation was made by the method including light. Specifically, the L * value of the manufactured plated steel sheet was examined using a spectrocolorimeter CM2500d manufactured by Konica Minolta under the conditions of a measurement diameter of 8 ⁇ , a 10 ° field of view, and a D65 light source.
- CM2500d manufactured by Konica Minolta
- the plated steel sheet L * value is less than 75 "Excellent”, and a plated steel sheet L * value is not less than 75 judges as “Poor”.
- Excellent represents that it is excellent in the anti-glare effect.
- the appearance of the plated steel sheet was evaluated by a storage test in a constant temperature and humidity chamber. Specifically, the manufactured plated steel sheet was stored for 72 hours in a constant temperature and humidity chamber having a temperature of 40 ° C. and a humidity of 95%, and after storage, the area% of the blackened portion in the flat portion of the plated steel sheet was investigated.
- a plated steel sheet with an area% and a blackened portion of less than 1% is “Excellent”, and a plated steel plate with a blackened portion of less than 1% to 3% is “Good”
- a plated steel sheet having a blackened portion of 3% or more was judged as “Poor”. Note that “Excellent” represents the most excellent appearance evaluation.
- the powdering characteristics of the plated steel sheet were evaluated by the mass change of the plated steel sheet before and after the cylindrical drawing. Specifically, using the manufactured plated steel sheet, cylindrical drawing was performed from a ⁇ 90 blank with a ⁇ 50 punch drawing (drawing ratio 2.2, low clay oil coating). After cylindrical drawing, tape peeling was performed on the inner surface of the plated steel sheet, and the change in mass before and after the test was measured. For the evaluation of mass change, the average value of a total of 10 tests was used.
- a plated steel sheet having a powdering amount (g / m 2 ) of 1/2000 or less with respect to a coating adhesion amount (g / m 2 ) is “Excellent”, and a plated steel sheet having 1/1000 or less is “ “Good”, a plated steel sheet exceeding 1/1000 was judged as “Poor”.
- “Excellent” represents the most excellent powdering characteristic evaluation.
- Tables 1 to 12 show the manufacturing conditions, manufacturing results, and evaluation results described above.
- an underlined numerical value indicates that it is out of the scope of the present invention, and a blank indicates that an alloy element is not intentionally added.
- Example No. Each of Nos. 1 to 23 satisfies the scope of the present invention, and is a plated steel sheet excellent in corrosion resistance and sacrificial corrosion resistance. On the other hand, No. which is a comparative example. Since 1 to 16 did not satisfy the conditions of the present invention, the corrosion resistance or sacrificial corrosion resistance was not sufficient.
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Abstract
Description
(1)本発明の一態様に係る準結晶含有めっき鋼板は、鋼板と、前記鋼板の表面に配された金属被覆層とを備えるめっき鋼板であって、前記金属被覆層の化学成分が、原子%で、Zn:28.5%~52%、Al:0.5%~10%、Ca:0%~3.5%、Y:0%~3.5%、La:0%~3.5%、Ce:0%~3.5%、Si:0%~0.5%、Ti:0%~0.5%、Cr:0%~0.5%、Fe:0%~2%、Co:0%~0.5%、Ni:0%~0.5%、V:0%~0.5%、Nb:0%~0.5%、Cu:0%~0.5%、Sn:0%~0.5%、Mn:0%~0.2%、Sr:0%~0.5%、Sb:0%~0.5%、Pb:0%~0.5%を含有し、残部がMg及び不純物からなり、前記金属被覆層の金属組織が、準結晶相を含み、前記準結晶相に含まれるマグネシウム含有量と亜鉛含有量とアルミニウム含有量とが、原子%で、0.5≦Mg/(Zn+Al)≦0.83を満足し、前記準結晶相の平均円相当径が0.01μm~1μmである。
(2)上記(1)に記載の準結晶含有めっき鋼板では、前記金属被覆層の前記化学成分中のカルシウム含有量とイットリウム含有量とランタン含有量とセリウム含有量とが、原子%で、0.3%≦Ca+Y+La+Ce≦3.5%を満足してもよい。
(3)上記(1)または(2)に記載の準結晶含有めっき鋼板では、前記金属被覆層の前記化学成分中のシリコン含有量とチタニウム含有量とクロミウム含有量とが、原子%で、0.005%≦Si+Ti+Cr≦0.5%を満足してもよい。
(4)上記(1)~(3)のいずれか一項に記載の準結晶含有めっき鋼板では、前記金属被覆層の前記化学成分中の亜鉛含有量とアルミニウム含有量とが、原子%で、30%≦Zn+Al≦52%を満足してもよい。
(5)上記(1)~(4)のいずれか一項に記載の準結晶含有めっき鋼板では、板厚方向と切断方向とが平行となる断面で前記金属被覆層を見た場合に、前記金属被覆層の前記金属組織が、円相当径が0.2μm以下の結晶粒で構成される微細領域および円相当径が0.2μm超の結晶粒で構成される粗大領域からなるバイモーダル組織であり、前記粗大領域が前記準結晶相と、Zn相、Al相、MgZn相のうちの少なくとも1つとを含み、前記微細領域がMg51Zn20相、Zn相、アモルファス相、Mg32(Zn、Al)49相のうちの少なくとも1つを含み、前記準結晶相の前記平均円相当径が0.2μm超~1μmであってもよい。
(6)上記(1)~(4)のいずれか一項に記載の準結晶含有めっき鋼板では、板厚方向と切断方向とが平行となる断面で前記金属被覆層を見た場合に、前記金属被覆層の前記金属組織が、円相当径が0.2μm以下の結晶粒で構成される微細領域および円相当径が0.2μm超の結晶粒で構成される粗大領域からなるバイモーダル組織であり、前記粗大領域がZn相、Al相、MgZn相のうちの少なくとも1つを含み、前記微細領域が前記準結晶相と、Mg51Zn20相、Zn相、アモルファス相、Mg32(Zn、Al)49相のうちの少なくとも1つとを含み、前記準結晶相の前記平均円相当径が0.01μm~0.2μmであってもよい。
(7)上記(1)~(5)のいずれか一項に記載の準結晶含有めっき鋼板では、前記金属組織に対する前記粗大領域の面積分率が5%~50%であり、前記金属組織に対する前記微細領域の面積分率が50%~95%であってもよい。
(8)上記(1)~(4)、(6)のいずれか一項に記載の準結晶含有めっき鋼板では、前記金属組織に対する前記粗大領域の面積分率が5%~50%であり、前記金属組織に対する前記微細領域の面積分率が50%~95%であってもよい。
(9)上記(1)~(5)、(7)のいずれか一項に記載の準結晶含有めっき鋼板では、前記粗大領域に含まれる前記準結晶相の面積分率が、前記粗大領域に対して80%~100%未満であり、前記微細領域に含まれる前記Mg51Zn20相、前記Zn相、前記アモルファス相、および前記Mg32(Zn、Al)49相の合計の面積分率が、前記微細領域に対して80%~100%未満であってもよい。
(10)上記(1)~(4)、(6)、(8)のいずれか一項に記載の準結晶含有めっき鋼板では、前記粗大領域に含まれる前記Zn相、前記Al相、および前記MgZn相の合計の面積分率が、前記粗大領域に対して80%~100%未満であり、前記微細領域に含まれる前記準結晶相の面積分率が、前記微細領域に対して0%超~10%未満であってもよい。
(11)上記(1)~(5)、(7)、(9)のいずれか一項に記載の準結晶含有めっき鋼板では、前記断面で見た場合に、前記金属被覆層の厚さをDとし、前記金属被覆層の表面から前記板厚方向に沿って前記鋼板に向かう0.05×Dまでの範囲を金属被覆層最表部とし、前記鋼板と前記金属被覆層との界面から前記板厚方向に沿って前記金属被覆層に向かう0.05×Dまでの範囲を金属被覆層最深部とするとき、前記金属被覆層最表部に対する前記粗大領域の面積分率が7%~100%未満であり、および前記金属被覆層最深部に対する前記粗大領域の面積分率が7%~100%未満であり、前記金属被覆層の前記金属被覆層最表部および前記金属被覆層最深部以外の範囲を金属被覆層本体部とするとき、前記金属被覆層本体部に対する前記微細領域の面積分率が50%~100%未満であってもよい。
(12)上記(1)~(4)、(6)、(8)、(10)のいずれか一項に記載の準結晶含有めっき鋼板では、前記断面で見た場合に、前記金属被覆層の厚さをDとし、前記金属被覆層の表面から前記板厚方向に沿って前記鋼板に向かう0.05×Dまでの範囲を金属被覆層最表部とし、前記鋼板と前記金属被覆層との界面から前記板厚方向に沿って前記金属被覆層に向かう0.05×Dまでの範囲を金属被覆層最深部とするとき、前記金属被覆層最表部に対する前記粗大領域の面積分率が7%~100%未満であり、および前記金属被覆層最深部に対する前記粗大領域の面積分率が7%~100%未満であり、前記金属被覆層の前記金属被覆層最表部および前記金属被覆層最深部以外の範囲を金属被覆層本体部とするとき、前記金属被覆層本体部に対する前記微細領域の面積分率が50%~100%未満であってもよい。
(13)上記(1)~(12)のいずれか一項に記載の準結晶含有めっき鋼板では、前記金属被覆層の前記金属組織に、Mg相が含まれなくてもよい。
(14)上記(1)~(13)のいずれか一項に記載の準結晶含有めっき鋼板は、Fe-Al含有合金層をさらに有し、前記Fe-Al含有合金層が前記鋼板と前記金属被覆層との間に配され、前記Fe-Al含有合金層がFe5Al2またはAl3.2Feのうちの少なくとも1つを含み、前記Fe-Al含有合金層の厚さが10nm~1000nmであってもよい。
(15)本発明の一態様に係る準結晶含有めっき鋼板の製造方法は、上記(1)~(14)のいずれか一項に記載の準結晶含有めっき鋼板の製造方法であって、鋼板の表面に金属被覆層を形成するために、前記鋼板を成分が調整された溶融めっき浴に浸漬する溶融めっき工程と;前記金属被覆層の液相線温度を単位℃でTmeltとし、前記金属被覆層が固相と液相との共存状態でありかつ前記金属被覆層に対する前記固相の体積比が0.01~0.1となる温度範囲を単位℃でTsolid-liquidとするとき、前記金属被覆層の温度がTmelt+10℃からTsolid-liquidに至る温度範囲でかつ前記金属被覆層の平均冷却速度が15℃/秒~50℃/秒となる条件で、前記溶融めっき工程後の前記鋼板を冷却する第1冷却工程と;前記金属被覆層の温度が前記第1冷却工程の冷却終了時の温度から250℃に至る温度範囲でかつ前記金属被覆層の平均冷却速度が100℃/秒~3000℃/秒となる条件で、前記第1冷却工程後の前記鋼板を冷却する第2冷却工程と;を備える
(16)上記(15)に記載の準結晶含有めっき鋼板の製造方法では、前記溶融めっき工程で、前記鋼板を浸漬するときの雰囲気の酸素濃度が体積比で100ppm以下であり、前記めっき浴を保持するめっき槽が鋼製であり、前記めっき浴の温度であるTbathが前記Tmeltより10℃~100℃高く、前記鋼板が前記めっき浴中に浸漬される時間が1秒~10秒であってもよい。
金属被覆層の金属組織として準結晶相を得るためには、上記範囲のZnを含有することが必須である。このため、金属被覆層のZn含有量を28.5%~52%とする。また、このZn含有量は、図6に示すZn-Mg二元系平衡状態図の共晶組成(Mg72%-Zn28%)に基づいて決定されており、Mg-Zn共晶組成よりもZnが高濃度となる組成とする。共晶組成よりMg含有量が多くZn含有量が少ないと、耐食性に乏しいMg相が主体となる組織となり、金属被覆層の耐食性が劣化する。このため、金属被覆層のZn含有量を28.5%以上とする。これにより、適切な製造条件において、金属被覆層中にZn相を優先して分散させることが可能となる。Zn相をさらに高い面積分率で生成させるため、Zn含有量の下限を30%としてもよい。Zn相の面積分率が高まると耐食性も向上する。しかし、Zn含有量が52%を超えると、めっき層の組成バランスが崩れ、Mg4Zn7、MgZn等の金属間化合物が多量に生成し、準結晶相も形成しなくなることから、耐食性が悪くなる。そのため、Zn含有量の上限を52%とする。
Alは、金属被覆層の平面部の耐食性を向上させる元素である。また、Alは、準結晶相の生成を促進する元素である。これらの効果を得るために、金属被覆層のAl含有量を0.5%以上とする。また、Alが0.5%以上含有されると、上記の準結晶相に加えて、金属被覆層にZn相またはAl相が生成される。このZn相とAl相とが共晶組織を形成すると、金属被覆層の耐食性が好ましく向上する。準結晶相、Zn相、およびAl相の3相が共存することにより、耐食性がさらに好ましく向上する。ただし、Al含有量が10%を超えると、金属被覆層中でAl相の粒径が急激に粗大化して、Zn相とAl相との共晶組織が形成されなくなる。また、Zn相も形成されなくなる。そのため、耐食性が悪化する。よって、金属被覆層のAl含有量の上限を10%とする。準結晶相の平均円相当径を好ましく制御するためには、金属被覆層のAl含有量を5%未満としてもよい。準結晶相の平均円相当径が大きくなると、耐食性へ悪影響を与えることはないが、化成処理性がやや劣位になり、塗膜下耐食性(塗装後耐食性)が悪くなる傾向にある。また、Alは、後述するFe-Al界面合金層を形成する上で含有されることが好ましい元素である。
Y(イットリウム):0%~3.5%
La(ランタン):0%~3.5%
Ce(セリウム):0%~3.5%
Ca、Y、La、Ceは、溶融めっきの操業性を改善するために必要に応じて含有されてもよい。本実施形態に係るめっき鋼板を製造する場合、めっき浴として酸化性の高い溶融Mg合金を大気中で保持する。そのため、何らかのMgの酸化防止手段を取ることが好ましい。Ca、Y、La、CeはMgよりも酸化し易く、溶融状態でめっき浴面上に安定な酸化被膜を形成し浴中のMgの酸化を防止する。よって、金属被覆層のCa含有量を0%~3.5%とし、Y含有量を0%~3.5%とし、La含有量を0%~3.5%とし、Ce含有量を0%~3.5%としてもよい。さらに好ましくは、Ca含有量、Y含有量、La含有量、Ce含有量に関して、それぞれ、下限を0.3%とし、上限を2.0%としてもよい。
Ti(チタニウム):0%~0.5%
Cr(クロミウム):0%~0.5%
Si、Ti、Crは、金属被覆層に準結晶相を好ましく生成させるために必要に応じて含有されてもよい。微量のSi、Ti、Crが金属被覆層に含有されると、準結晶相が生成しやすくなり、準結晶相の構造が安定化する。SiはMgと結合して微細Mg2Siを形成することによって、またMgとの反応性が乏しいTiおよびCrは微細金属相となることによって、準結晶相の生成の起点(核)になると考えられる。また、準結晶相の生成は、一般に、製造時の冷却速度に影響を受ける。しかし、Si、Ti、Crが金属被覆層に含有されると、準結晶相の生成に対する冷却速度の依存性が小さくなる傾向にある。よって、金属被覆層のSi含有量を0%~0.5%とし、Ti含有量を0%~0.5%とし、Cr含有量を0%~0.5%としてもよい。さらに好ましくは、Si含有量、Ti含有量、Cr含有量に関して、それぞれ、下限を0.005%とし、上限を0.1%としてもよい。
Ni(ニッケル):0%~0.5%
V(バナジウム):0%~0.5%
Nb(ニオビウム):0%~0.5%
Co、Ni、V、Nbは、上述のSi、Ti、Crと同等の効果を有する。上記効果を得るために、Co含有量を0%~0.5%とし、Ni含有量を0%~0.5%とし、V含有量を0%~0.5%とし、Nb含有量を0%~0.5%としてもよい。さらに好ましくは、Co含有量、Ni含有量、V含有量、Nb含有量に関して、それぞれ、下限を0.05%とし、上限を0.1%としてもよい。ただし、これらの元素は、Si、Ti、Crと比較すると、耐食性を向上する効果が小さい。
Sn(スズ):0%~0.5%
鋼板と金属被覆層との密着性を向上させるために、溶融めっき工程前の鋼板にNi、Cu、Sn等のプレめっきを施す場合がある。プレめっきを施された鋼板を使用してめっき鋼板を製造した場合、金属被覆層中に、これらの元素が0.5%程度まで含まれることがある。Ni、Cu、Snのうち、Cu、Snは、Niが有する上述した効果を有さない。しかし、0.5%程度のCu、Snが金属被覆層に含有されても、準結晶の生成挙動や、金属被覆層の耐食性に対して影響を与える可能性は小さい。よって、金属被覆層のCu含有量を0%~0.5%とし、Sn含有量を0%~0.5%としてもよい。さらに好ましくは、Cu含有量、Sn含有量に関して、それぞれ、下限を0.005%とし、上限を0.4%としてもよい。
めっき鋼板の母材である鋼板として、近年、高張力鋼(高強度鋼)が使用されるようになってきた。高張力鋼を使用してめっき鋼板を製造した場合、高張力鋼に含まれるSi、Mn等の元素が、金属被覆層中に拡散することがある。SiおよびMnのうち、Mnは、Siが有する上述した効果を有さない。しかし、0.2%程度のMnが金属被覆層に含有されても、準結晶の生成挙動や、金属被覆層の耐食性に対して影響を与える可能性は小さい。よって、金属被覆層のMn含有量を0%~0.2%としてもよい。さらに好ましくは、Mn含有量に関して、下限を0.005%とし、上限を0.1%としてもよい。
Sb(アンチモン):0%~0.5%
Pb(鉛):0%~0.5%
Sr、Sb、Pbは、めっき外観を向上させる元素で、防眩性の向上に効果がある。この効果を得るために、金属被覆層のSr含有量を0%~0.5%とし、Sb含有量を0%~0.5%とし、Pb含有量を0%~0.5%としてもよい。Sr含有量、Sb含有量、およびPb含有量が上記範囲である場合、耐食性への影響はほとんどない。さらに好ましくは、Sr含有量、Sb含有量、およびPb含有量に関して、それぞれ、下限を0.005%とし、上限を0.4%としてもよい。
2 金属被覆層
2a 粗大領域
2b 微細領域
2a1、2a2、2b1、2b2 局所領域
Claims (16)
- 鋼板と、前記鋼板の表面に配された金属被覆層とを備えるめっき鋼板であって、
前記金属被覆層の化学成分が、原子%で、
Zn:28.5%~52%、
Al:0.5%~10%、
Ca:0%~3.5%、
Y :0%~3.5%、
La:0%~3.5%、
Ce:0%~3.5%、
Si:0%~0.5%、
Ti:0%~0.5%、
Cr:0%~0.5%、
Fe:0%~2%、
Co:0%~0.5%、
Ni:0%~0.5%、
V :0%~0.5%、
Nb:0%~0.5%、
Cu:0%~0.5%、
Sn:0%~0.5%、
Mn:0%~0.2%、
Sr:0%~0.5%、
Sb:0%~0.5%、
Pb:0%~0.5%
を含有し、残部がMg及び不純物からなり、
前記金属被覆層の金属組織が、準結晶相を含み、
前記準結晶相に含まれるマグネシウム含有量と亜鉛含有量とアルミニウム含有量とが、原子%で、0.5≦Mg/(Zn+Al)≦0.83を満足し、
前記準結晶相の平均円相当径が0.01μm~1μmである
ことを特徴とする準結晶含有めっき鋼板。 - 前記金属被覆層の前記化学成分中のカルシウム含有量とイットリウム含有量とランタン含有量とセリウム含有量とが、原子%で、
0.3%≦Ca+Y+La+Ce≦3.5%
を満足することを特徴とする請求項1に記載の準結晶含有めっき鋼板。 - 前記金属被覆層の前記化学成分中のシリコン含有量とチタニウム含有量とクロミウム含有量とが、原子%で、
0.005%≦Si+Ti+Cr≦0.5%
を満足することを特徴とする請求項1に記載の準結晶含有めっき鋼板。 - 前記金属被覆層の前記化学成分中の亜鉛含有量とアルミニウム含有量とが、原子%で、
30%≦Zn+Al≦52%
を満足することを特徴とする請求項1に記載の準結晶含有めっき鋼板。 - 板厚方向と切断方向とが平行となる断面で前記金属被覆層を見た場合に、前記金属被覆層の前記金属組織が、円相当径が0.2μm以下の結晶粒で構成される微細領域および円相当径が0.2μm超の結晶粒で構成される粗大領域からなるバイモーダル組織であり、
前記粗大領域が前記準結晶相と、Zn相、Al相、MgZn相のうちの少なくとも1つとを含み、
前記微細領域がMg51Zn20相、Zn相、アモルファス相、Mg32(Zn、Al)49相のうちの少なくとも1つを含み、
前記準結晶相の前記平均円相当径が0.2μm超~1μmである
ことを特徴とする請求項1に記載の準結晶含有めっき鋼板。 - 板厚方向と切断方向とが平行となる断面で前記金属被覆層を見た場合に、前記金属被覆層の前記金属組織が、円相当径が0.2μm以下の結晶粒で構成される微細領域および円相当径が0.2μm超の結晶粒で構成される粗大領域からなるバイモーダル組織であり、
前記粗大領域がZn相、Al相、MgZn相のうちの少なくとも1つを含み、
前記微細領域が前記準結晶相と、Mg51Zn20相、Zn相、アモルファス相、Mg32(Zn、Al)49相のうちの少なくとも1つとを含み、
前記準結晶相の前記平均円相当径が0.01μm~0.2μmである
ことを特徴とする請求項1に記載の準結晶含有めっき鋼板。 - 前記金属組織に対する前記粗大領域の面積分率が5%~50%であり、
前記金属組織に対する前記微細領域の面積分率が50%~95%である
ことを特徴とする請求項5に記載の準結晶含有めっき鋼板。 - 前記金属組織に対する前記粗大領域の面積分率が5%~50%であり、
前記金属組織に対する前記微細領域の面積分率が50%~95%である
ことを特徴とする請求項6に記載の準結晶含有めっき鋼板。 - 前記粗大領域に含まれる前記準結晶相の面積分率が、前記粗大領域に対して80%~100%未満であり、
前記微細領域に含まれる前記Mg51Zn20相、前記Zn相、前記アモルファス相、および前記Mg32(Zn、Al)49相の合計の面積分率が、前記微細領域に対して80%~100%未満である
ことを特徴とする請求項5に記載の準結晶含有めっき鋼板。 - 前記粗大領域に含まれる前記Zn相、前記Al相、および前記MgZn相の合計の面積分率が、前記粗大領域に対して80%~100%未満であり、
前記微細領域に含まれる前記準結晶相の面積分率が、前記微細領域に対して0%超~10%未満である
ことを特徴とする請求項6に記載の準結晶含有めっき鋼板。 - 前記断面で見た場合に、前記金属被覆層の厚さをDとし、前記金属被覆層の表面から前記板厚方向に沿って前記鋼板に向かう0.05×Dまでの範囲を金属被覆層最表部とし、前記鋼板と前記金属被覆層との界面から前記板厚方向に沿って前記金属被覆層に向かう0.05×Dまでの範囲を金属被覆層最深部とするとき、前記金属被覆層最表部に対する前記粗大領域の面積分率が7%~100%未満であり、および前記金属被覆層最深部に対する前記粗大領域の面積分率が7%~100%未満であり、
前記金属被覆層の前記金属被覆層最表部および前記金属被覆層最深部以外の範囲を金属被覆層本体部とするとき、前記金属被覆層本体部に対する前記微細領域の面積分率が50%~100%未満である
ことを特徴とする請求項5に記載の準結晶含有めっき鋼板。 - 前記断面で見た場合に、前記金属被覆層の厚さをDとし、前記金属被覆層の表面から前記板厚方向に沿って前記鋼板に向かう0.05×Dまでの範囲を金属被覆層最表部とし、前記鋼板と前記金属被覆層との界面から前記板厚方向に沿って前記金属被覆層に向かう0.05×Dまでの範囲を金属被覆層最深部とするとき、前記金属被覆層最表部に対する前記粗大領域の面積分率が7%~100%未満であり、および前記金属被覆層最深部に対する前記粗大領域の面積分率が7%~100%未満であり、
前記金属被覆層の前記金属被覆層最表部および前記金属被覆層最深部以外の範囲を金属被覆層本体部とするとき、前記金属被覆層本体部に対する前記微細領域の面積分率が50%~100%未満である
ことを特徴とする請求項6に記載の準結晶含有めっき鋼板。 - 前記金属被覆層の前記金属組織に、Mg相が含まれないことを特徴とする請求項1に記載の準結晶含有めっき鋼板。
- 前記めっき鋼板がFe-Al含有合金層をさらに有し、
前記Fe-Al含有合金層が前記鋼板と前記金属被覆層との間に配され、
前記Fe-Al含有合金層がFe5Al2またはAl3.2Feのうちの少なくとも1つを含み、
前記Fe-Al含有合金層の厚さが10nm~1000nmである
ことを特徴とする請求項1に記載の準結晶含有めっき鋼板。 - 請求項1~14のいずれか1項に記載の準結晶含有めっき鋼板の製造方法であって、
鋼板の表面に金属被覆層を形成するために、前記鋼板を成分が調整された溶融めっき浴に浸漬する溶融めっき工程と;
前記金属被覆層の液相線温度を単位℃でTmeltとし、前記金属被覆層が固相と液相との共存状態でありかつ前記金属被覆層に対する前記固相の体積比が0.01~0.1となる温度範囲を単位℃でTsolid-liquidとするとき、前記金属被覆層の温度がTmelt+10℃からTsolid-liquidに至る温度範囲でかつ前記金属被覆層の平均冷却速度が15℃/秒~50℃/秒となる条件で、前記溶融めっき工程後の前記鋼板を冷却する第1冷却工程と;
前記金属被覆層の温度が前記第1冷却工程の冷却終了時の温度から250℃に至る温度範囲でかつ前記金属被覆層の平均冷却速度が100℃/秒~3000℃/秒となる条件で、前記第1冷却工程後の前記鋼板を冷却する第2冷却工程と;
を備えることを特徴とする準結晶含有めっき鋼板の製造方法。 - 前記溶融めっき工程で、
前記鋼板を浸漬するときの雰囲気の酸素濃度が体積比で100ppm以下であり、
前記めっき浴を保持するめっき槽が鋼製であり、
前記めっき浴の温度であるTbathが前記Tmeltより10℃~100℃高く、
前記鋼板が前記めっき浴中に浸漬される時間が1秒~10秒である
ことを特徴とする請求項15に記載の準結晶含有めっき鋼板の製造方法。
Priority Applications (6)
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PCT/JP2014/059104 WO2015145722A1 (ja) | 2014-03-28 | 2014-03-28 | 準結晶含有めっき鋼板 |
EP14886792.2A EP3124642B1 (en) | 2014-03-28 | 2014-03-28 | Plated steel sheet with quasicrystal |
CN201480077517.9A CN106164323B (zh) | 2014-03-28 | 2014-03-28 | 含有准晶体的镀覆钢板 |
KR1020167025965A KR101807985B1 (ko) | 2014-03-28 | 2014-03-28 | 준결정 함유 도금 강판 |
JP2014542599A JP5785335B1 (ja) | 2014-03-28 | 2014-03-28 | 準結晶含有めっき鋼板 |
US15/127,994 US10232589B2 (en) | 2014-03-28 | 2014-03-28 | Plated steel sheet with quasicrystal |
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PCT/JP2014/059104 WO2015145722A1 (ja) | 2014-03-28 | 2014-03-28 | 準結晶含有めっき鋼板 |
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US (1) | US10232589B2 (ja) |
EP (1) | EP3124642B1 (ja) |
JP (1) | JP5785335B1 (ja) |
KR (1) | KR101807985B1 (ja) |
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Cited By (1)
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JP2017066459A (ja) * | 2015-09-29 | 2017-04-06 | 新日鐵住金株式会社 | めっき鋼材 |
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CA2959289C (en) | 2014-09-05 | 2018-05-22 | Nippon Steel & Sumitomo Metal Corporation | Quasicrystal-containing plated steel sheet and method for producing quasicrystal-containing plated steel sheet |
JP6569437B2 (ja) * | 2015-09-29 | 2019-09-04 | 日本製鉄株式会社 | 加工性と耐食性に優れるMg含有合金めっき鋼材 |
KR101775028B1 (ko) | 2016-09-26 | 2017-09-05 | 삼성전자주식회사 | 자기 공명 영상 장치 및 자기 공명 영상 획득 방법 |
KR101940885B1 (ko) * | 2016-12-26 | 2019-01-21 | 주식회사 포스코 | 점용접성 및 내식성이 우수한 단층 아연합금도금강재 및 그 제조방법 |
KR102043519B1 (ko) * | 2017-12-22 | 2019-11-12 | 주식회사 포스코 | 내식성 및 용접성이 우수한 용융 알루미늄 합금 도금강판 및 그 제조방법 |
CN108251677B (zh) * | 2018-01-24 | 2021-03-12 | 湖南创林新材料科技有限公司 | 一种铅合金冶炼用除渣剂及其制备方法 |
JP6680412B1 (ja) * | 2018-05-25 | 2020-04-15 | 日本製鉄株式会社 | 表面処理鋼板 |
KR102196210B1 (ko) * | 2018-12-11 | 2020-12-30 | 포스코강판 주식회사 | 용융도금강판 제조방법 |
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- 2014-03-28 KR KR1020167025965A patent/KR101807985B1/ko active IP Right Grant
- 2014-03-28 EP EP14886792.2A patent/EP3124642B1/en not_active Not-in-force
- 2014-03-28 JP JP2014542599A patent/JP5785335B1/ja active Active
- 2014-03-28 CN CN201480077517.9A patent/CN106164323B/zh active Active
- 2014-03-28 US US15/127,994 patent/US10232589B2/en active Active
- 2014-03-28 WO PCT/JP2014/059104 patent/WO2015145722A1/ja active Application Filing
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Also Published As
Publication number | Publication date |
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KR101807985B1 (ko) | 2017-12-11 |
KR20160123382A (ko) | 2016-10-25 |
US10232589B2 (en) | 2019-03-19 |
JP5785335B1 (ja) | 2015-09-30 |
US20170095995A1 (en) | 2017-04-06 |
CN106164323A (zh) | 2016-11-23 |
EP3124642A1 (en) | 2017-02-01 |
EP3124642B1 (en) | 2018-12-19 |
JPWO2015145722A1 (ja) | 2017-04-13 |
CN106164323B (zh) | 2019-01-11 |
EP3124642A4 (en) | 2017-10-25 |
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