CA1279031C - Method for producing a thin tin and nickel plated steel sheet for welded can material - Google Patents
Method for producing a thin tin and nickel plated steel sheet for welded can materialInfo
- Publication number
- CA1279031C CA1279031C CA000490827A CA490827A CA1279031C CA 1279031 C CA1279031 C CA 1279031C CA 000490827 A CA000490827 A CA 000490827A CA 490827 A CA490827 A CA 490827A CA 1279031 C CA1279031 C CA 1279031C
- Authority
- CA
- Canada
- Prior art keywords
- tin
- steel sheet
- nickel
- plated steel
- nickel plated
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 title claims abstract description 212
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 115
- 239000010959 steel Substances 0.000 title claims abstract description 115
- 229910052759 nickel Inorganic materials 0.000 title claims abstract description 106
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 title claims abstract description 105
- 238000004519 manufacturing process Methods 0.000 title abstract description 14
- 239000000463 material Substances 0.000 title abstract description 5
- 239000003792 electrolyte Substances 0.000 claims abstract description 35
- 229910000990 Ni alloy Inorganic materials 0.000 claims abstract description 26
- PYWICZIXLIWNGZ-UHFFFAOYSA-N [Sn].[Ni].[Fe] Chemical compound [Sn].[Ni].[Fe] PYWICZIXLIWNGZ-UHFFFAOYSA-N 0.000 claims abstract description 20
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 claims abstract description 12
- 238000010791 quenching Methods 0.000 claims abstract description 7
- 230000000171 quenching effect Effects 0.000 claims abstract description 7
- 238000009713 electroplating Methods 0.000 claims abstract description 5
- 238000009826 distribution Methods 0.000 claims abstract description 4
- 238000000034 method Methods 0.000 claims description 22
- 238000007747 plating Methods 0.000 claims description 22
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 17
- 229910052804 chromium Inorganic materials 0.000 claims description 17
- 239000011651 chromium Substances 0.000 claims description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 16
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 14
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 claims description 11
- 229910000423 chromium oxide Inorganic materials 0.000 claims description 11
- 230000005611 electricity Effects 0.000 claims description 9
- 239000002253 acid Substances 0.000 claims description 8
- KRVSOGSZCMJSLX-UHFFFAOYSA-L chromic acid Substances O[Cr](O)(=O)=O KRVSOGSZCMJSLX-UHFFFAOYSA-L 0.000 claims description 8
- AWJWCTOOIBYHON-UHFFFAOYSA-N furo[3,4-b]pyrazine-5,7-dione Chemical compound C1=CN=C2C(=O)OC(=O)C2=N1 AWJWCTOOIBYHON-UHFFFAOYSA-N 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 7
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 6
- 229910019142 PO4 Inorganic materials 0.000 claims description 5
- 229910052783 alkali metal Inorganic materials 0.000 claims description 5
- 150000003868 ammonium compounds Chemical class 0.000 claims description 5
- WHOZNOZYMBRCBL-OUKQBFOZSA-N (2E)-2-Tetradecenal Chemical compound CCCCCCCCCCC\C=C\C=O WHOZNOZYMBRCBL-OUKQBFOZSA-N 0.000 claims description 4
- 150000001340 alkali metals Chemical class 0.000 claims description 4
- 239000004327 boric acid Substances 0.000 claims description 4
- SOCTUWSJJQCPFX-UHFFFAOYSA-N dichromate(2-) Chemical compound [O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O SOCTUWSJJQCPFX-UHFFFAOYSA-N 0.000 claims description 4
- 238000007654 immersion Methods 0.000 claims description 4
- KERTUBUCQCSNJU-UHFFFAOYSA-L nickel(2+);disulfamate Chemical compound [Ni+2].NS([O-])(=O)=O.NS([O-])(=O)=O KERTUBUCQCSNJU-UHFFFAOYSA-L 0.000 claims description 4
- 229940044654 phenolsulfonic acid Drugs 0.000 claims description 4
- 229910021586 Nickel(II) chloride Inorganic materials 0.000 claims description 3
- 150000001875 compounds Chemical class 0.000 claims description 3
- QMMRZOWCJAIUJA-UHFFFAOYSA-L nickel dichloride Chemical compound Cl[Ni]Cl QMMRZOWCJAIUJA-UHFFFAOYSA-L 0.000 claims description 3
- 229910000375 tin(II) sulfate Inorganic materials 0.000 claims description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical class OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 claims description 2
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 claims description 2
- 150000001447 alkali salts Chemical class 0.000 claims description 2
- LGQLOGILCSXPEA-UHFFFAOYSA-L nickel sulfate Chemical compound [Ni+2].[O-]S([O-])(=O)=O LGQLOGILCSXPEA-UHFFFAOYSA-L 0.000 claims description 2
- 229910000363 nickel(II) sulfate Inorganic materials 0.000 claims description 2
- 229940044652 phenolsulfonate Drugs 0.000 claims description 2
- RCIVOBGSMSSVTR-UHFFFAOYSA-L stannous sulfate Chemical compound [SnH2+2].[O-]S([O-])(=O)=O RCIVOBGSMSSVTR-UHFFFAOYSA-L 0.000 claims description 2
- 150000008044 alkali metal hydroxides Chemical class 0.000 claims 1
- 150000001642 boronic acid derivatives Chemical class 0.000 claims 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 claims 1
- PYRZPBDTPRQYKG-UHFFFAOYSA-N cyclopentene-1-carboxylic acid Chemical compound OC(=O)C1=CCCC1 PYRZPBDTPRQYKG-UHFFFAOYSA-N 0.000 claims 1
- 235000011180 diphosphates Nutrition 0.000 claims 1
- 239000000203 mixture Substances 0.000 claims 1
- 235000021317 phosphate Nutrition 0.000 claims 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 claims 1
- 150000004760 silicates Chemical class 0.000 claims 1
- 230000007797 corrosion Effects 0.000 abstract description 23
- 238000005260 corrosion Methods 0.000 abstract description 23
- 229940073644 nickel Drugs 0.000 description 84
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- 238000003466 welding Methods 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 10
- 239000005028 tinplate Substances 0.000 description 9
- 230000015572 biosynthetic process Effects 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- 239000000243 solution Substances 0.000 description 8
- 239000011248 coating agent Substances 0.000 description 7
- 238000000576 coating method Methods 0.000 description 7
- 239000004922 lacquer Substances 0.000 description 7
- 230000007423 decrease Effects 0.000 description 6
- ZPUCINDJVBIVPJ-LJISPDSOSA-N cocaine Chemical compound O([C@H]1C[C@@H]2CC[C@@H](N2C)[C@H]1C(=O)OC)C(=O)C1=CC=CC=C1 ZPUCINDJVBIVPJ-LJISPDSOSA-N 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 238000005238 degreasing Methods 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- CLDVQCMGOSGNIW-UHFFFAOYSA-N nickel tin Chemical compound [Ni].[Sn] CLDVQCMGOSGNIW-UHFFFAOYSA-N 0.000 description 4
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 4
- 239000010452 phosphate Substances 0.000 description 4
- 238000005554 pickling Methods 0.000 description 4
- 239000003513 alkali Substances 0.000 description 3
- 239000012670 alkaline solution Substances 0.000 description 3
- 235000013305 food Nutrition 0.000 description 3
- NNIPDXPTJYIMKW-UHFFFAOYSA-N iron tin Chemical compound [Fe].[Sn] NNIPDXPTJYIMKW-UHFFFAOYSA-N 0.000 description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 229910001128 Sn alloy Inorganic materials 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 230000032683 aging Effects 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 229960002050 hydrofluoric acid Drugs 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000004826 seaming Methods 0.000 description 2
- 235000011149 sulphuric acid Nutrition 0.000 description 2
- 239000005029 tin-free steel Substances 0.000 description 2
- TXUICONDJPYNPY-UHFFFAOYSA-N (1,10,13-trimethyl-3-oxo-4,5,6,7,8,9,11,12,14,15,16,17-dodecahydrocyclopenta[a]phenanthren-17-yl) heptanoate Chemical compound C1CC2CC(=O)C=C(C)C2(C)C2C1C1CCC(OC(=O)CCCCCC)C1(C)CC2 TXUICONDJPYNPY-UHFFFAOYSA-N 0.000 description 1
- JHWIEAWILPSRMU-UHFFFAOYSA-N 2-methyl-3-pyrimidin-4-ylpropanoic acid Chemical compound OC(=O)C(C)CC1=CC=NC=N1 JHWIEAWILPSRMU-UHFFFAOYSA-N 0.000 description 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- KRKNYBCHXYNGOX-UHFFFAOYSA-K Citrate Chemical compound [O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O KRKNYBCHXYNGOX-UHFFFAOYSA-K 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 description 1
- 229910020212 Na2SnO3 Inorganic materials 0.000 description 1
- 229910005911 NiSO4-6H2O Inorganic materials 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229910021626 Tin(II) chloride Inorganic materials 0.000 description 1
- 229910001297 Zn alloy Inorganic materials 0.000 description 1
- DXUDJFADLQCQMZ-UHFFFAOYSA-N [Sn+4].[O-2].[Fe+2].[O-2].[O-2] Chemical compound [Sn+4].[O-2].[Fe+2].[O-2].[O-2] DXUDJFADLQCQMZ-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000000443 aerosol Substances 0.000 description 1
- -1 alkali metal salt Chemical class 0.000 description 1
- DQSGVVGOPRWTKI-QVFAWCHISA-N atazanavir sulfate Chemical compound [H+].[H+].[O-]S([O-])(=O)=O.C([C@H](NC(=O)[C@@H](NC(=O)OC)C(C)(C)C)[C@@H](O)CN(CC=1C=CC(=CC=1)C=1N=CC=CC=1)NC(=O)[C@@H](NC(=O)OC)C(C)(C)C)C1=CC=CC=C1 DQSGVVGOPRWTKI-QVFAWCHISA-N 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- ZZUFCTLCJUWOSV-UHFFFAOYSA-N furosemide Chemical compound C1=C(Cl)C(S(=O)(=O)N)=CC(C(O)=O)=C1NCC1=CC=CO1 ZZUFCTLCJUWOSV-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- LNOPIUAQISRISI-UHFFFAOYSA-N n'-hydroxy-2-propan-2-ylsulfonylethanimidamide Chemical compound CC(C)S(=O)(=O)CC(N)=NO LNOPIUAQISRISI-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 238000005476 soldering Methods 0.000 description 1
- 229940071182 stannate Drugs 0.000 description 1
- 125000005402 stannate group Chemical group 0.000 description 1
- 239000001119 stannous chloride Substances 0.000 description 1
- 235000011150 stannous chloride Nutrition 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 235000015193 tomato juice Nutrition 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Abstract
ABSTRACT OF THE DISCLOSURE
A method for producing a thin tin and nickel plated steel sheet having a surface structure in which the distribution of numerous nodules of metallic tin axe observed by using an electron microscope on an iron-tin-nickel alloy layer farmed on a steel sheet which comprises electroplating nickel on the steel sheet which has been anodically treated in an alkaline electrolyte with a pH of above 10 followed by electrotinplating the nickel plated steel sheet, reflowing, quenching, and then chromate treating the tin and nickel plated steel sheet. This tin and nickel plated steel sheet is suitable for welded can materials since it is excellent in corrosion resistance after lacquering and weld-ability.
A method for producing a thin tin and nickel plated steel sheet having a surface structure in which the distribution of numerous nodules of metallic tin axe observed by using an electron microscope on an iron-tin-nickel alloy layer farmed on a steel sheet which comprises electroplating nickel on the steel sheet which has been anodically treated in an alkaline electrolyte with a pH of above 10 followed by electrotinplating the nickel plated steel sheet, reflowing, quenching, and then chromate treating the tin and nickel plated steel sheet. This tin and nickel plated steel sheet is suitable for welded can materials since it is excellent in corrosion resistance after lacquering and weld-ability.
Description
~,7~J;~
FIELD OF THE INVENTION
The present invention relates to a method for producing a thin tin and nickel plated steel sheet having excellent corrosion resistance after lac~uering and excellent weldability. In detail, the inv~ntion relates to a method for producing a thin tin and nickel plated steel sheet which is characterized by an anodic treatment of a pickled steel sheet in an àlkaline electrol~te with a pH of above 10 before plating with a small amount of nickel, plating with a small amount of tin on the ni~kel plated steel sheet, reflowing, quenching, and chromate treating the tin and nickel plated steel sheet.
By using this tin and nickel plated steel sheet, a welded can body can be easily produced at high speed in spite of the small amount of the plated tin and nickel without removing the plated layer in the welded part.
, .
BACKGROU~D AND OBJECTIVE
Recently, electric welding has been widely used for the seaming of tinplate can bodies in the field of food cans, aerosol cans, and miscellaneous cans, instead of soldering. In the seaming of the tinplate can body, it is desirable to decrease the tin coating weight in the tinplate because tin used for electrotinplate is very,expensive and there is concern over the exhaustion of tin resources. However, the weldability of the tinplate becomes gradually poor with a decrease of the tin , coating weight.
From the background described above, the development of a welded can material which is cheaper than conventional electrotinplate clcc~ eC-, is easily welded at high speed without the removal `' : ' , . ` ` ' .
.
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of the plated layer and i5.. excellent in corrosion resistance after lacquering, has been required in the field of food cans. Over the past few years, various surface treated steel sheets have been prop~sed for welded can materials which can be easily welded at high speed without the removal of the plated layer and are cheaper than tinplate. For instance, the followins surface treated steel sheets have been proposed: (a) Lightly tin plated steel sheet ~LTS) with below about 1.0 g/m2 of tin which is reflowed or unreflowed after tinplating (Japanese Patent Publication Nos. Sho.56-3440 (Jan. 24, 1981;
Applicant: Toyo Kohan Co., Ltd.), Sho.56-54070 tDec.
23, 1981; Applicant: Toyo Kohan Co., Ltd.), Sho.
57-55800 (Nov. 26, 1982; Applicant: Nihon Kokan ,:
- Corporation) and Laid Open Japanese Patent Applica-. .
~ tion Nos. Sho.56-75589 (June 22, 1981; Applicant;
, ~
Nihon Kokan Corporation), Sho.56-130487 (Oct. 13, 1981i Applicant: Toyo Kohan Co., Ltd.), Sho.56-156788 (Dec. 3, 1981; Applicant: Nlhon Kokan Corporation), Sho.57-101694 (June 24, 1982; Applicant: Toyo Kohan Co., Ltd.), Sho.57-185997 (Nov. 16, 1982; Applicant:
Toyo Kohan Co., Ltd.), Sho.57-192294 tNov. 26, 1982;
Applicant: Nihon Kokan Corporation), Sho.57-192295 . ': :~ :
Nov. 26, 1982; Applicant: Nihon Kokan Corporation) and Sho.55-69297 (May 24, 1980; Applicant: Nippon Steel Corporation)); (b) Nickel preplated LTS with , ~." ~
, ,'-, - , ,:,- . - .: , : :
.: ~ . ' - . -' ~ ' '' :` ` ' below about 1 g/m of tin ~Laid Open Japanese Patent Application Nos. Sho.57-23091 (Feb. 6, 1982;
Applicant: Nippon Steel Corporation), Sho.57-67196 (Apr 23, 1982; Applicant: Nippon Steel Corporation), Sho.57-110685 (Jul. 9, 1982; Applicant: Nippon Steel Corporation), Sho. 57-177991 (Nov. 1, 1982;
Applicant: Nippon Steel Corporation), Sho.57-200592 (Dec. 8, 1982; Applicant: Kawasaki Steel Corpora-tion), Sho.57-203797 (Dec. 14, 1982i Applicant:
Kawasaki Steel Corporation), Sho. 60-33362 (Fe~. 20, 1985; Applicant: Nippon Steel Corporation) and Sho.60-56074 (Apr. 1. 1985; Applicant: Nippon Steel Corporation)); (c) Nickel plated steel sheet with chromate film or phosphate film (Laid Open Japanese Patent Application Nos. Sho.56-116885 (Sept. 12, 1981; Applicant: Nippon Steel Corporation), Sho.56-169788 (Dec. 26, 1981; Applicant: Nippon Steel Corporation), Sho.57-2892 (Jan. 8, lg82; Applicant:
Nippon Steel Corporation), shO.57-2895 (Jan. 8, 1982;
Applicant: Nippon Steel Corporation), Sho.57-2896 (Jan. 8, 1982; Applicant: Nippon Steel Corporation), Sho.57-2897 (Jan. 8, 1982; Applicant: Nippon Steel Corporation), Sho.57-35697 (~eb. 26, 1982; Applicant:
Nippon Steel Corporation) and Sho.57-35698 (Feb. 26, 1982; Applicant: Mippon Steel Corporation)).
~' . ' .
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However, LTS and nickel preplated LTS above identified as (a) and ~b) have a narrower current range for sound welding than that in tinplate, although these can be welded without the removal of the plated layer. The reason why the current range for sound welding in LTS and nickel preplated LTS is narrower than in tinplate is considered to be that the amount of free metallic tin in these is smaller than that in tinplate and also further decreases because of the change of plated free metallic tin to iron-tin alloy or iron-tin-nickel alloy by heating for lacquer curing or reflowing after tinplating.
Although the weldability -and the corrosion resistance after lacquering are improved with an increase of coating tin, it is difficult to increase the expensive tin coating weight in LTS and nickel preplated LTS in view of increase in production cost.
.~, An increase in the amount of nickel in nickel preplated LTS lmproves the corrosion resistance after lacquering, but does not improve the weldability, beoause the amount of free metallic tin decreases by the formation of tin-nickel alloy during aging at room temperature or by the formation of iron tin-nickel alloy during reflowing nickel preplated , ,,. ~ .
~ LTS.
r~
, :,~: . -.. . . .
. -' : ~ ' . , ~
. -.
.
. -- . ~ -- .
: - .. .
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~.~,7~0;~
Nickel plated steel sheet with chromate film or phosphate film identi~ied ~bove as (c) also has a narrower current range for sound welding than that in tinplate, LTS, or nickel preplated LTS.
Furthermore, the corrosion resistance of nickel plated steel sheet is poor, although the lacquer adhesion is good. Particularly, pitting corrosion in the defective part of the lacquered nickel plate steel sheet may occur easily in acidic foods such as tomato juice because the electric potential of nickel is more noble than that of steel sheet.
As described above, the various surface treated steel sheets proposed in ~a), ~b) and (c) have various problems in production cost and characteristics as a welded can material which can be easily welded without the removal of the plated layer at high speed.
It is therefore an object of the present ~ invention to provide a thin tin and nickel plated - steel sheet having excellent corrosion resistance after lacquering and excellent weldability.
It is another object of the present invention to provide a method for the continuous production of a thin tin and nickel plated steel `,~ sheet having excellent characteristics as described ~ ~ above.
`1~
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', ~r~' ~ 5a -, . . . .
: . ': ' ' ' ~ ' -: : , , - , . ~ ~ .
! In accordance with the invention, there is provided a method of producing a tin and nickel plated steel sheet having a surface structure in which the distribution of numerous nodules of metallic tin can be observed by using an electron microscope (1000 magnifications) on an iron-tin-. nickel alloy layer formed on a steel sheet, which comprises the steps of:
a) anodically treating a substantially clean steel sheet in an alkaline electrolyte having a pH
above 10 under a quantity of electricity ranging from 3 to 50 coulombs/dm2;
b) electroplating the steel sheet treated in step (a) with nickel in an amount of S to 20 mg/m i c) electroplating the nickel plated steel :~ sheet obtained in step (b) with tin in an amount of ::
400 to 900 mg/m2;
: : d) reflowing and quenching the tin and nickel plated steel sheet obtained in step (c); and e) chromate treating the tin and nickel plated steel sheet to form thereon a film containing ::, hydrated chromium oxide in an amount of 3 to 20 mg/m2 as chromium.
The tin and nickel plated steel sheet produced according to the method of the present invention is clearly different from the nickel preplated LTS, which has already been disclosed in 5b -. ~ - ..... - - . . - .:
~ . . -. . :
~, "- ~: ' ' -' : . , ' ' : .
:. :- . - . . .
.. . . .
~ t)~
various Laid-Open Japaneses Patent Applications, in the surface structure, particularly in the form of metallic tin on the iron-tin-nickel alloy layer formed on the steel sheet, although it nevertheless is a nickel preplated LTS. Namely, in the tin and nickel plated steel sheet according to the present invention, numerous nodules of metallic tin are present on the iron-tin-nickel alloy layer formed on : the steel sheet. On the other hand, it is considered that a uniform and thin metallic tin layer is formed on the ,,~ .
;, ., , . ~.', ~
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~-~ ` . . ` . , , . ` -. . .
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~ ~, `. ` - ` ` . ' -~.~79()~i ixon tin-nickel alloy layer or the tin-nickel alloy layer ~ormed on the steel sheet in the known nickel preplated LTS.
DETAILED DESCRIPTION OF THE INVENTION
The steel sheet used for the production of the tin and nickel plated steel sheet according to the present invention can be any cold rolled steel sheet customarily used in manufacturing electro-tin plated and tin-free steel. Preferably the thickness of the steel sheet is from about Q.l to about 0.35mm.
The tin and nlckel plated steel sheet according to the present invention is produced by the following process:
degreasing with an alkali and pickling with an acid ~ water rinslng ~ an anodic treatment in an alkaline electrolyte ~ ~ater rinsing ~ nickel plating ~ water rinsing ~ tinplating ~ water rinslng ~ drying ~ reflowing ~ quenching . chromate treatment ~ water rinsing ~ drying.
:, In this process, it is possible that the anodically treated s~tee~l sheet is plated with tin-nicke~l alloy, nickel-iron alloy, nickél-~zinc alloy, or nickel containing boron and phosphorus instead of plating with nickel. In the present invention, an anodic treatment of a pickled steel sheet in an alkaline electrolyte wlth a pH of above 10 is indispensable in order to obtain the thin tin and nickel plated steel sheet having a surface~seructure~ln whlch the distribution of numerous nodules Qf`mëta`lllC~`till lS observed by uslng an electron microscope on the~iron-tin-nic-kel alloy layer formed on the steel sheet after !
reflowlnq~of~the tin and nickel plated steel sheet. The alkaline e1ectrolyte having a pH of above 10 used for the anodic treatment of the pickled steel sheet is made up by the dissolution of at least one alkallne compound selected from the group cansisting of ;.. - . . . .
~ ~ 7~3~
- ~ydroxide, a carbonate, a bicarbonate, a silicate, a phosphate, anl a borate of an alkali metal and ammonium compounds in water.
Furthermore, the effect of the anodic treatment o~ the pickled steel sheet in the alkaline electrolyte is not reduced as long as the pH of the alkaline elèctrolyte is maintained above lO, even if at least one compound such as an acidic phosphate, an oxalate, a citrate, and an acetate of an alkali metal, and an ammonium compound is added , if the surface active agent which is usually added t~ tAe alkaline solution for degreasing of the steel sheet is added or a small amount of sulfuric acid or hydrochloric acid is brought into the alkaline electrolyte of the present invention because of insufficient rinsing after pickling.
It is an essential condition that the alkaline electrolyte used for the anodic treatment of the pickled steel sheet be maintained above a pH of lO, although it is not necessary to strictly control the concentration of hydroxide, carbonate, etc., salts of an alkal~ m~tal and ammonium compounds. If the concentration of the alkaline electrolyte is restricted, it is . " , , preferably in the range of lO to lOO g/l. At below lO g/l, a waste of electric power resul~s because of tne higher electric resistance of the alkaline electrolyte. The concentration is ". ~
~ limited to lOO g/l from the viewpoint of economy, although the . .
effect of the anodic treatment in the alkaline electrolyte is not increased even if the concentration is above lOO g/l. Although it :
is not necessary that the temperature of the alkaline electrolyte ,~
be strictly controlled, it is preferably below 90C from the ; viewpoint of energy savings.
rn order to obtain the effect of the anodic treatment in the aIkaline electrolyte, it is necessary that the quantity of . ~
~ electricity for the anodic trea~ment be in the range of 3 to 50 ., ~ . . ~.
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coulom~s/dm2, more preferably 5 to 30 coulombsldm2. If the q~_ntity o~ electricity is below 3 coulombs~dm2,,the effect o~ -the anodic treatment is not obtained because thin and dense iron oxide film is not uni~ormly formed on the surface of the pickled steel sheet The quantity of electricity is limited to 50 coulombs/dm ~rom the viewpoint of the high speed production of the tin and nickel plated steel sheet and from the viewpoint of ener5y savings, although the effect of the anodic treatment in the al~31ine electrolyte is not reduced.
In the case o~ the alkaline electrolyte having a pH of below , a large quantity of electricity is necessary in order to obtain the effect of the anodic treatment in the present invention. Therefore, a 12rge qùantity of electricity for the .
:, anodic treatment is not desirahie from the viewpoint of the high speed production of the tin and nickel plated steel sheet : accarding to the present invention~
~ ,;
For the high speed production of tin and nickel plated steel sheet:~according to the presen~ invention, it is reasonable ~hat the~electrolytic time be 0.1 to S seconds, and the range of ' ~r ~ current density be 1 to 50 A/dm in the anodic treatment of the pickled~steel sheet, The amount o~ nickeI plated on.the'steel sheet which, is anodically treated beforehand in the al~aline electrolyte with a pH~of ;above 10 lS one of the lmportant factors in the present inventlon. The:amount of.plated nic~el should be controlled in .` ,'~the~range of~5 to 20 mg/'m2.
i, ~, ~, - .. . .
5.~,7~
BRIEF DESCRIPTION OF THE DRAWINGS
. . . _ .
Figure 1 shows the magnified photograph wherein numerous nodules of metallic tin 1 are distributed on the uniform iron-tin-nickel alloy layer 2 in the surface of the tin and nickel plated steel sheet according to the present invention.
Figure 2 shows the effectof the amount of plated nickel on the-disbribution of nodular metallic tin on the iron-tin-nickel alloy layer formed on the steel sheet after tinplating and then reflowing.
Figure 3 shows the effect of the amount of plated nickel on the electric contact resistance of the tin and nickel plated steel sheet after heating at 2LOC for 20 minutes.
:.
Figure 4 shows the effect of the amount of plated nickel on the filiform corrosion resistance after lacquering of the tin and nickel plated steel sheet.
In Figure 2 to Figure 4, Curve A shows examples wherein nickel plating, tinplating, and then reflowing were carried out after the anodic treatment of the pickled steel sheet in an alkaline electro-lyte, and Curve s shows examples without the anodic treatment before nickel plating. Samples used for Example A and s in Figure 2 to Figure 4 were produced by the following same conditions in each step except "",~
~ for the anodic treatment of samples for Example A.
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Furthermore, samples shown--in Figure 4 were cathodically treated in chromic acid electrolyte after reflowing.
Degreasing...Cathodic electrolysis in 70 g/l of NaOH under 5 A/dm for 2 seconds at 70 C.
Pickling...Immersion into 100 g/l of H2SO4 for 2 seconds at 25C.
Anodic treatment...Anodic treatment in 70 g/l of NaOH (pH 14~ at 5 A/dm for 2 seconds at 70 C.
(Only samples for Example A) Nickel plating...Plating with various amounts of nickel under 3 A/dm at 40C by using Watts bath.
Tinplating...Plating with 700 mg/m2 of tin under 10 A/dm at 40 C by using a phenolsulfonic acid bath.
Reflowing...Raising the temperature of the tin and nickel plated steel sheet up to 28QC during 1.6 seconds by using resistance heating.
Quenching...Rapid immersion into water after reflowing.
Chromate treatment...Cathodic treatment in chromic acid electrolyte containing 30 g/l of CrO
and 0.3 g/l of H2SO4 under 10 A/dm for 0.5 seconds at 50C.
Water rinsing was carried out between succeeding steps.
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As shown ln Flgure-2, in the case of Ex~mple --A with ~r~odic treatment in alkaline solution, numerous nodules of metallic tin were observed by an electron microscope on the iron-tin-nickel alloy layer Eormed on -the steel sheet in the range of S to 20 mq/m2 of plated nickel, but nodular metallic tin is almost not present at above 20 mg/m and at below 5 mg/m2 of plated nickel.
On the other hand, in the case of Example B
without anodic treatment in alkaline solution, almost all of the deposited tin forms a uniform iron-tin-nickel alloy layer irrespective of the amount of nickel prior to tinplating.
Generally, tne weldability is evaluated by an available range of secondary current in welding as shown in the report by N.T. Williams (Metal Construction, April 19?7, pages 157-160), that is to say, the wider the secondary current range in . welding, the better the weldability. The upper limit . ~ . . .
~ in the available secondary current range corresponds .:
~ to the welding conditions in which some defect such ~ ..
as splashing is found and the lower limit corresponds - to the welding conditions in which the breakage ~ occurs in the welded part by the tearing test.
-~ ~ However, in order to obtain data wherein the available range of secondary current in welding is ;-` decided for each sample, a large amount of samples ....
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are necessary. Therefore, the weldability is evaluated by electric contact resistance, because electric contact resistance has an apparent correlation with the available range of secondary current in welding as shown in the report by T. Fu~imura (Journal of The Iron and Steel Institute of Japan, Vol. 69, No. 13, September 1983, page 181), that is, the lower the electric contact resistance, the wider the secondary current range in welding Accordingly, ~f the electric contact resistance is lower, the weldability is better.
It is found from Figure 3 that the electric contact than resistance of samples for Example A is lower that in the sample for Example B at below 20 mg/m2 of plated nickel wherein nodular metallic tin is observed on the iron-tin-nickel alloy layer formed on the steel sheet in the sample for Example A. At below 5 mglm2 plated nickel, the electric contact resistance becomes slLghtly high because of the decrease in the amount of metallic t~in by the formation of an alloy consisting mainly of iron-tin alloy. The electric contact resistance increases with an increase in the amount of plated nickel because of the decrease Ln the amount of metallic tin caused by the formation of an alloy consisting mainly of tin-nickel alloy during aging at ordlnary tèmpérature-As shown in Figure 4, the filiform corrosion resistance is lmproved with an increa$e in the amount of plated nickel. In the range of~5 to ~30 mg/m2 of plated nickel, the filiform corrosion resi~stance after laoquering of samples for Example A is excellent compared with that of Example B because the iron-tin-nickel alloy having excellent lacquer adhesion is present with numerous nodules of metallic tin on the surface of samples for Example A, ,, . ~,, "
~:i`, ~
,,.~.. ~ ~ . -:: ... .. . .................................... .
~, ~ . . -- . ~ ., : ' :~ . .. . .
7~
~-t the surface of the samples for Example ~ is covered with uniform metallic tin layer having poor lac~uer adhesion.
As described above, the anodic treatment of the pickled steel sheet in an alkaline electrolyte and the plating with the limited amount of nickel are indispensible factors in the present invention.
The reason why the anodic treatment of the pickled steel sheet in an alkaline electrolyte and the plating with the limited amount of~ni~ckel is necessary in order to produce the tin and nickel plate steel sheet having numerous nodules of metallic tin on ~he iron-tin-nickel alloy layer formed on the steel sheet is not clear. However, it is assumed that the reason is the formation of numerous nodules of metallic tin by dewetting of ~ .~
:~j metallic tin electrodeposited in the part wherein iron oxide is : formed on the pickled steel sheet by the anodic treatment in an . :~
~alkaline electrolyte and the concentration of.metallic tin to the ~part wherein nickel is electrodeposited during the formation of an iron-tin-nickel alloy layer by reflowing after tinplating.
Furthermore, it is assumed that the reason why the tin and nickel plat:ed steel sheet having numerous nodules of metallic tin on the iron-tin-nickel alloy layer formed on the steel sheet is excellent in welda~ility and corrosion resistance after laequering, particularly filiform corrosion resistance, is that excellent weldability is maintained in the area having a large amount~of metallic tin in noduIar form compared with an average amount~ of plated metallic tin and that excellent corrosion rcsistance after lacquering is maintained in the area where iron-tin-nickel alloy having excellent lacquer adhesion is exposed~on the surface without being covered by a uniform metallic tin làyer.
.. : , -r , Therefore, an amount of nickel above 20 mg/m2 is not desirable in the present lnvention becaus~ the tin iron oxide coating formed on the steel sheet substrate by the anodic treatment in the alkaline electrolyte p~ior to nickel plating is almost completely removed during nickel plating. In the present invention, a known nickel plating electrolyte such as a Watts bath containing 200 to 300 g/l of nickel sulfate, 20 to 50 g/l of nickel chloride, and 20 to 40 g/l of boric acid or a nickel sulfamate bath containing 300 to 500 g/l of nickel sulfamate, and 20 to 40 g/l of boric acid is used for nickel plating of the steel sheet treated anodically in an alkaline electrolyte. The plating 5 to 20 mg/m2 which is required in the present invention is carried out by using these electrolytes described above under 2 to 30 A/dm2, 30 to 70C of the electrolyte temperature,-and 1 to 10 coulombs~dm2 of a quantity of electricity.
In the present invention, the amount of tin plated on the nickel plated steel sheet is also one of the important factors. The amount of plated tin should be controlled in the range of 400 to 900 mg/m2.
If the amount of plated tin is below ,.
400 mg/mG number of nodules of metallic tin is not :.
enough to improve the weldability after reflowing because a large part of electrodeposited metallic ,~,::: : :
tin readily changes to an iron-tin-nickel alloy on reflowing. At above 900 mg/m2 of plated tin, few .' - . . . .
.
'7't();~1 nodules o~ metall-Lc tin are obtained on re~lowing bcc~use the iron tin-nic~el alloy layer formed on reflowi.ng is uniformly covered with a large amount of metallic tin.
Tinplating on the nickel plated steel sheet : in the present invention is carried out by using a known tinplating electrolyte ~:' . .
,' ~ - 13a -'~; ''"' - :
.
, ~` ~ .: ` ` ' ; ' . ' ` ' - ' ~ .~,7<3();~1 uc~ rQr ~h~ production of electrotinplate. For instance, a phenolsulfonic acicl ~ath colltailling 10 to 30 g/l of phenolsulfonic acicl as ~ulfuric acid, 10 to 40 g/l of stannous sulfate or stannous phenolsulfonate and 0.5 to 10 gtl of et.hoxylated a-naphthol sulronic acid, halo5enide ba~h containing stannous chloride, alkali haloserlide, and additives or an alkaline bath containing al~ali stannate ~nd alkali hydro~ide is used in the present invention.
The conditions for tinplating in the present invention are also almost the same as that for the production of conventional electrotinplate. For instance, tinplating by using a FERROSTAN
(trade ~ark; phenolsulfonic acid bath) bath is carried out under 5 to 50 A/dm2 of current density at 30 to 55C of electrol~e t~erature.
Reflowing, that is flow melting of elect~odeposited metallic tin after nickel and tin plating, is also indispensible in order ;~ to form numerous nodules of metallic tin on the iron-tin-nickel alloy layer which is an inventive feature in the present invention.
The known method in which a temperature above the melting point of tin is maintained for a short time by resistance neating and induction heating can be used for reflowing of the tin and nickel plated steel sheet in the presen~ invention.
It is suitable in the present invention that the tin and ~; nlc~el plated steel sheet is heated from 235 to 350C for 0.5 ~o 3 seconds and then immediately quenched into water.
Reflowing at a higher temperature for a lon~er time is not desirable because of the poor welda~ility caused by the change :
of a large part of plated metallic tin to iron-tin-nickel alloy, particularly in the case of a lower amount of plated metallic tin. Furthermore, reflowing at lower temperature for a short r 1 4 . ~ - ' ,', . ` - . ' .
~ .~79(~1 time is not also desirable because of the poor corrosion resistance after lacquering caused by insufficient formation of the iron-tin-nickel alloy layer, particularly in the case of a higher amount of plated metallic tin.
After reflowing, the tin and nickel plated steel sheet according to the present invention is cathodically treated in a known electrolyte such as a sodium dichromate solution which is used for conventional post-treatment of an electrotinplated, or a chromic~`acid solution containing a small amount of sulfuric acid, fluoric acid, fluoboric acid, fluosilicic acid, an alkali salt thereof, and a combination thereof which is used for the production of conventional tin free steel having a upper layer of hydrated chromium oxide and a lower layer of metallic chromium, in order to ensure excellent characteristics in lacquer adhesion, corrosion resistance before Qr after lacquering. For instance, the tin and nickel plated steel sheet according to the present invention is cathodically treated in 20 to 100 g/l of a dichromate of an alkali metal or ammonium or chromic acid ;, solution containing 0.01 to 5% of sulfuric acid, fluoric acid, fluoboric acid, fluosilicic acid, an alkali metal salt thereof, or a combination thereof based on the amount of chromic acid under 5 to 40 A/dm2 of a eurrent density for 0.1 to 5 seconds of a treating time at 30 to 70C of electrolyte temperature.
The amount of total chromium in the film formed on the tin and~nickel plated steel sheet by cathodic treatment in dichromate or chromic acid solution described above should be limited to 3 to~20~mg/m2, preferably 5 to 15 mg~ . If the amount of total chromium is below 3 mg~m2, the excellent corrosion resistance bsfore or after lacguering is not obtained, althou~h the weldability does not change.
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At above 20 mg/m2 of total chromium in the film formed by cathodic treatment in dichromate or chromic acid solution, the current-range for sound welding becomes narrow because of the formation of thic~er chromium oxide having high electric resistance by the dehydration of the formed hydrated chromium oxide or the oxidation of metallic chromium during heating for lacquer curing.
In the present invention, the presence of hvdrated chromium oxide is indispensable in order to obtain the excellent corrosion resistance before or after lacquerin5. Moreover, the presence of metallic chromium is desirable for the improvement of filiform corrosion resistance after lacquering. Thèrefore, in the case : ~
- w~ere the film formed by chromate treatment consists of an u??er iayer of hydrated chromium oxide and a lower layer of metallic chromium, the amount of metallic chromium should be limited to 2 to 17 mg/m and the amount of hydrated chromium oxide should be limited to 3 to 18 mg/m as chromium~
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~ . ' . , , , , : ' ,,. . . ., . - . -. . .
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U:~l The present invention is illustrated by the rollowing examples.
In Example 1 to Example 4 and comparative Example 1 to ` Comparative Example 4, a cold rolled stèeI sheet having a - thickness of 0.2 mm was basically treated by the following process after electroiytically degreasing in a solution of 70 g/l of sodium hydroxide, water rinsing, pickling by an immersion into :, .
100 g/l of sulfuric acid, and then water rinsing.
Anodic treatment in an alkaline electrolyte ~ water rinsing -~ nickel plating , water rinsing ~ tinplating . water rinsing drying ~ reflowing . ~uenching I chromate treatment :
water rinsing ~ drying.
In Comparative Example 1, anodic treatment in an alXaline ~ . .
electrolyte was omitted in the present scheme as described above.
In Comparative Example 2, reflowing after tinplating was omitted.
In~Comparative Example 3, the anodically treated steel sheet was plated with nickel above the upper limited amount in the present :
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invention. In Comparative Example 4, the nickel plated steel sheet was plated with tin below the lower limited a~ount in the present invention.
In Example l to Example 4 and Comparative Example 1 to comparative Example 4, a watts bath containing 250 g/l of NiSO4-6H2O, 30 g/l of NiCl2 6H2O, and 40 g/l of H3BO3 or sulfamic acid bath containing 350 q/l of nickel sulfamate and 40 g~l of H3BO3 was ~sed for nickel plating. Furthermore, a Ferrostan bath containing 60 g/l of SnSO4, 3~ g/l of phenolsulfonic acid and 5 g/1 of ethoxylated a-naphthol sulfonic acid or alkaline bath containing 80 g/l of Na2SnO3 and 15 g/l of NaOH was used for tinplating after nickel plating.
The tin and nickel plated steel sheet was immediately reflowing quenched in water after ~ ~or~, and the temperature of the tin and nickel plated steel sheet dropped to 280C over 1.6 seconds except in Comparative Example 2. The other conditions in every Example are shown in the attached table.
:
The weldability, and corrosion resistance after lacquering of the tin and nickel plated steel sheet in~the above described Examples and Comparative Examples were evaluated by the following te;stinq methods after the measurement of the amounts nickel, tin, metalIic chromium, and chromium in a hydrated chromium oxide by ~:, ~ the~fluorescent X-ray methodj and the results were shown in the :~ attached TabIe.
~ ~ -18-,.. .~, . . . . . . .
~ . . . : . . - .
:- , . , - .. :: , . , . . ~ .: ., , -:,, . - . : -~': :: ' ` ,: - -(1) Weldability 1~ 7 9~
The weldability was evaluated by electric contact resistance for the reason already described.
At first, the sample plated on both sides was cut to a size of 20mm x lOOmm after heating at 210C for 20 minutes. The electric contact resistance was calculated from the change of voltage in a pair of copper disk electrodes tdiameter: 65mm, thickness: 2mm) to which 5 amperes of direct current were supplied'~and SOkg of load was added, when two sample pieces were inserted between a pair of the copper disk electrodes rotating at.5m/min.
~ (2) Filiform corrosion resistance ~after lacquering (Test l) -~ The sample was baked at 200C for 10 minutes after coating with ;- ~ 75 mg/dm2 of a vinyl organosol. The coated-sample was immersed into 3%~sodium chloride solution for 1 hour and then was left in a chamber having 85% of relative humidity at 45C for lO days àter the~surface of the coated samplé was cross-hatched by a razor~and ~then expanded for Smm by an ~richsen~tester.
resùIt~of filiform~rusting spread from the scratched part~of~the coated sample was divided i~nto 5 ranks, namely, excellent,~ goad, f~air, poor,~and bad.
3~ Underoutting corrosion resistance after lacquering (Test The sample was baked at 210C for 10 minutes after coating ~-w~l-;th `6~5~mg~m2~of~an epoxy-phenolic type of lacquer. The coated immersed into the deaerated solution containing 1.5 -id -nd l.S~ of sodium chlorlde for lS days at 37C
fber~thé~sùrfaae of the coated sample was cross-hatched by a zo~r.~
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The result of corrosion in the scratched part of the coated sample was divided into S ranks, namely, excellent, good, fair, poor, and bad.
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FIELD OF THE INVENTION
The present invention relates to a method for producing a thin tin and nickel plated steel sheet having excellent corrosion resistance after lac~uering and excellent weldability. In detail, the inv~ntion relates to a method for producing a thin tin and nickel plated steel sheet which is characterized by an anodic treatment of a pickled steel sheet in an àlkaline electrol~te with a pH of above 10 before plating with a small amount of nickel, plating with a small amount of tin on the ni~kel plated steel sheet, reflowing, quenching, and chromate treating the tin and nickel plated steel sheet.
By using this tin and nickel plated steel sheet, a welded can body can be easily produced at high speed in spite of the small amount of the plated tin and nickel without removing the plated layer in the welded part.
, .
BACKGROU~D AND OBJECTIVE
Recently, electric welding has been widely used for the seaming of tinplate can bodies in the field of food cans, aerosol cans, and miscellaneous cans, instead of soldering. In the seaming of the tinplate can body, it is desirable to decrease the tin coating weight in the tinplate because tin used for electrotinplate is very,expensive and there is concern over the exhaustion of tin resources. However, the weldability of the tinplate becomes gradually poor with a decrease of the tin , coating weight.
From the background described above, the development of a welded can material which is cheaper than conventional electrotinplate clcc~ eC-, is easily welded at high speed without the removal `' : ' , . ` ` ' .
.
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of the plated layer and i5.. excellent in corrosion resistance after lacquering, has been required in the field of food cans. Over the past few years, various surface treated steel sheets have been prop~sed for welded can materials which can be easily welded at high speed without the removal of the plated layer and are cheaper than tinplate. For instance, the followins surface treated steel sheets have been proposed: (a) Lightly tin plated steel sheet ~LTS) with below about 1.0 g/m2 of tin which is reflowed or unreflowed after tinplating (Japanese Patent Publication Nos. Sho.56-3440 (Jan. 24, 1981;
Applicant: Toyo Kohan Co., Ltd.), Sho.56-54070 tDec.
23, 1981; Applicant: Toyo Kohan Co., Ltd.), Sho.
57-55800 (Nov. 26, 1982; Applicant: Nihon Kokan ,:
- Corporation) and Laid Open Japanese Patent Applica-. .
~ tion Nos. Sho.56-75589 (June 22, 1981; Applicant;
, ~
Nihon Kokan Corporation), Sho.56-130487 (Oct. 13, 1981i Applicant: Toyo Kohan Co., Ltd.), Sho.56-156788 (Dec. 3, 1981; Applicant: Nlhon Kokan Corporation), Sho.57-101694 (June 24, 1982; Applicant: Toyo Kohan Co., Ltd.), Sho.57-185997 (Nov. 16, 1982; Applicant:
Toyo Kohan Co., Ltd.), Sho.57-192294 tNov. 26, 1982;
Applicant: Nihon Kokan Corporation), Sho.57-192295 . ': :~ :
Nov. 26, 1982; Applicant: Nihon Kokan Corporation) and Sho.55-69297 (May 24, 1980; Applicant: Nippon Steel Corporation)); (b) Nickel preplated LTS with , ~." ~
, ,'-, - , ,:,- . - .: , : :
.: ~ . ' - . -' ~ ' '' :` ` ' below about 1 g/m of tin ~Laid Open Japanese Patent Application Nos. Sho.57-23091 (Feb. 6, 1982;
Applicant: Nippon Steel Corporation), Sho.57-67196 (Apr 23, 1982; Applicant: Nippon Steel Corporation), Sho.57-110685 (Jul. 9, 1982; Applicant: Nippon Steel Corporation), Sho. 57-177991 (Nov. 1, 1982;
Applicant: Nippon Steel Corporation), Sho.57-200592 (Dec. 8, 1982; Applicant: Kawasaki Steel Corpora-tion), Sho.57-203797 (Dec. 14, 1982i Applicant:
Kawasaki Steel Corporation), Sho. 60-33362 (Fe~. 20, 1985; Applicant: Nippon Steel Corporation) and Sho.60-56074 (Apr. 1. 1985; Applicant: Nippon Steel Corporation)); (c) Nickel plated steel sheet with chromate film or phosphate film (Laid Open Japanese Patent Application Nos. Sho.56-116885 (Sept. 12, 1981; Applicant: Nippon Steel Corporation), Sho.56-169788 (Dec. 26, 1981; Applicant: Nippon Steel Corporation), Sho.57-2892 (Jan. 8, lg82; Applicant:
Nippon Steel Corporation), shO.57-2895 (Jan. 8, 1982;
Applicant: Nippon Steel Corporation), Sho.57-2896 (Jan. 8, 1982; Applicant: Nippon Steel Corporation), Sho.57-2897 (Jan. 8, 1982; Applicant: Nippon Steel Corporation), Sho.57-35697 (~eb. 26, 1982; Applicant:
Nippon Steel Corporation) and Sho.57-35698 (Feb. 26, 1982; Applicant: Mippon Steel Corporation)).
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However, LTS and nickel preplated LTS above identified as (a) and ~b) have a narrower current range for sound welding than that in tinplate, although these can be welded without the removal of the plated layer. The reason why the current range for sound welding in LTS and nickel preplated LTS is narrower than in tinplate is considered to be that the amount of free metallic tin in these is smaller than that in tinplate and also further decreases because of the change of plated free metallic tin to iron-tin alloy or iron-tin-nickel alloy by heating for lacquer curing or reflowing after tinplating.
Although the weldability -and the corrosion resistance after lacquering are improved with an increase of coating tin, it is difficult to increase the expensive tin coating weight in LTS and nickel preplated LTS in view of increase in production cost.
.~, An increase in the amount of nickel in nickel preplated LTS lmproves the corrosion resistance after lacquering, but does not improve the weldability, beoause the amount of free metallic tin decreases by the formation of tin-nickel alloy during aging at room temperature or by the formation of iron tin-nickel alloy during reflowing nickel preplated , ,,. ~ .
~ LTS.
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Nickel plated steel sheet with chromate film or phosphate film identi~ied ~bove as (c) also has a narrower current range for sound welding than that in tinplate, LTS, or nickel preplated LTS.
Furthermore, the corrosion resistance of nickel plated steel sheet is poor, although the lacquer adhesion is good. Particularly, pitting corrosion in the defective part of the lacquered nickel plate steel sheet may occur easily in acidic foods such as tomato juice because the electric potential of nickel is more noble than that of steel sheet.
As described above, the various surface treated steel sheets proposed in ~a), ~b) and (c) have various problems in production cost and characteristics as a welded can material which can be easily welded without the removal of the plated layer at high speed.
It is therefore an object of the present ~ invention to provide a thin tin and nickel plated - steel sheet having excellent corrosion resistance after lacquering and excellent weldability.
It is another object of the present invention to provide a method for the continuous production of a thin tin and nickel plated steel `,~ sheet having excellent characteristics as described ~ ~ above.
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! In accordance with the invention, there is provided a method of producing a tin and nickel plated steel sheet having a surface structure in which the distribution of numerous nodules of metallic tin can be observed by using an electron microscope (1000 magnifications) on an iron-tin-. nickel alloy layer formed on a steel sheet, which comprises the steps of:
a) anodically treating a substantially clean steel sheet in an alkaline electrolyte having a pH
above 10 under a quantity of electricity ranging from 3 to 50 coulombs/dm2;
b) electroplating the steel sheet treated in step (a) with nickel in an amount of S to 20 mg/m i c) electroplating the nickel plated steel :~ sheet obtained in step (b) with tin in an amount of ::
400 to 900 mg/m2;
: : d) reflowing and quenching the tin and nickel plated steel sheet obtained in step (c); and e) chromate treating the tin and nickel plated steel sheet to form thereon a film containing ::, hydrated chromium oxide in an amount of 3 to 20 mg/m2 as chromium.
The tin and nickel plated steel sheet produced according to the method of the present invention is clearly different from the nickel preplated LTS, which has already been disclosed in 5b -. ~ - ..... - - . . - .:
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various Laid-Open Japaneses Patent Applications, in the surface structure, particularly in the form of metallic tin on the iron-tin-nickel alloy layer formed on the steel sheet, although it nevertheless is a nickel preplated LTS. Namely, in the tin and nickel plated steel sheet according to the present invention, numerous nodules of metallic tin are present on the iron-tin-nickel alloy layer formed on : the steel sheet. On the other hand, it is considered that a uniform and thin metallic tin layer is formed on the ,,~ .
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DETAILED DESCRIPTION OF THE INVENTION
The steel sheet used for the production of the tin and nickel plated steel sheet according to the present invention can be any cold rolled steel sheet customarily used in manufacturing electro-tin plated and tin-free steel. Preferably the thickness of the steel sheet is from about Q.l to about 0.35mm.
The tin and nlckel plated steel sheet according to the present invention is produced by the following process:
degreasing with an alkali and pickling with an acid ~ water rinslng ~ an anodic treatment in an alkaline electrolyte ~ ~ater rinsing ~ nickel plating ~ water rinsing ~ tinplating ~ water rinslng ~ drying ~ reflowing ~ quenching . chromate treatment ~ water rinsing ~ drying.
:, In this process, it is possible that the anodically treated s~tee~l sheet is plated with tin-nicke~l alloy, nickel-iron alloy, nickél-~zinc alloy, or nickel containing boron and phosphorus instead of plating with nickel. In the present invention, an anodic treatment of a pickled steel sheet in an alkaline electrolyte wlth a pH of above 10 is indispensable in order to obtain the thin tin and nickel plated steel sheet having a surface~seructure~ln whlch the distribution of numerous nodules Qf`mëta`lllC~`till lS observed by uslng an electron microscope on the~iron-tin-nic-kel alloy layer formed on the steel sheet after !
reflowlnq~of~the tin and nickel plated steel sheet. The alkaline e1ectrolyte having a pH of above 10 used for the anodic treatment of the pickled steel sheet is made up by the dissolution of at least one alkallne compound selected from the group cansisting of ;.. - . . . .
~ ~ 7~3~
- ~ydroxide, a carbonate, a bicarbonate, a silicate, a phosphate, anl a borate of an alkali metal and ammonium compounds in water.
Furthermore, the effect of the anodic treatment o~ the pickled steel sheet in the alkaline electrolyte is not reduced as long as the pH of the alkaline elèctrolyte is maintained above lO, even if at least one compound such as an acidic phosphate, an oxalate, a citrate, and an acetate of an alkali metal, and an ammonium compound is added , if the surface active agent which is usually added t~ tAe alkaline solution for degreasing of the steel sheet is added or a small amount of sulfuric acid or hydrochloric acid is brought into the alkaline electrolyte of the present invention because of insufficient rinsing after pickling.
It is an essential condition that the alkaline electrolyte used for the anodic treatment of the pickled steel sheet be maintained above a pH of lO, although it is not necessary to strictly control the concentration of hydroxide, carbonate, etc., salts of an alkal~ m~tal and ammonium compounds. If the concentration of the alkaline electrolyte is restricted, it is . " , , preferably in the range of lO to lOO g/l. At below lO g/l, a waste of electric power resul~s because of tne higher electric resistance of the alkaline electrolyte. The concentration is ". ~
~ limited to lOO g/l from the viewpoint of economy, although the . .
effect of the anodic treatment in the alkaline electrolyte is not increased even if the concentration is above lOO g/l. Although it :
is not necessary that the temperature of the alkaline electrolyte ,~
be strictly controlled, it is preferably below 90C from the ; viewpoint of energy savings.
rn order to obtain the effect of the anodic treatment in the aIkaline electrolyte, it is necessary that the quantity of . ~
~ electricity for the anodic trea~ment be in the range of 3 to 50 ., ~ . . ~.
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coulom~s/dm2, more preferably 5 to 30 coulombsldm2. If the q~_ntity o~ electricity is below 3 coulombs~dm2,,the effect o~ -the anodic treatment is not obtained because thin and dense iron oxide film is not uni~ormly formed on the surface of the pickled steel sheet The quantity of electricity is limited to 50 coulombs/dm ~rom the viewpoint of the high speed production of the tin and nickel plated steel sheet and from the viewpoint of ener5y savings, although the effect of the anodic treatment in the al~31ine electrolyte is not reduced.
In the case o~ the alkaline electrolyte having a pH of below , a large quantity of electricity is necessary in order to obtain the effect of the anodic treatment in the present invention. Therefore, a 12rge qùantity of electricity for the .
:, anodic treatment is not desirahie from the viewpoint of the high speed production of the tin and nickel plated steel sheet : accarding to the present invention~
~ ,;
For the high speed production of tin and nickel plated steel sheet:~according to the presen~ invention, it is reasonable ~hat the~electrolytic time be 0.1 to S seconds, and the range of ' ~r ~ current density be 1 to 50 A/dm in the anodic treatment of the pickled~steel sheet, The amount o~ nickeI plated on.the'steel sheet which, is anodically treated beforehand in the al~aline electrolyte with a pH~of ;above 10 lS one of the lmportant factors in the present inventlon. The:amount of.plated nic~el should be controlled in .` ,'~the~range of~5 to 20 mg/'m2.
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BRIEF DESCRIPTION OF THE DRAWINGS
. . . _ .
Figure 1 shows the magnified photograph wherein numerous nodules of metallic tin 1 are distributed on the uniform iron-tin-nickel alloy layer 2 in the surface of the tin and nickel plated steel sheet according to the present invention.
Figure 2 shows the effectof the amount of plated nickel on the-disbribution of nodular metallic tin on the iron-tin-nickel alloy layer formed on the steel sheet after tinplating and then reflowing.
Figure 3 shows the effect of the amount of plated nickel on the electric contact resistance of the tin and nickel plated steel sheet after heating at 2LOC for 20 minutes.
:.
Figure 4 shows the effect of the amount of plated nickel on the filiform corrosion resistance after lacquering of the tin and nickel plated steel sheet.
In Figure 2 to Figure 4, Curve A shows examples wherein nickel plating, tinplating, and then reflowing were carried out after the anodic treatment of the pickled steel sheet in an alkaline electro-lyte, and Curve s shows examples without the anodic treatment before nickel plating. Samples used for Example A and s in Figure 2 to Figure 4 were produced by the following same conditions in each step except "",~
~ for the anodic treatment of samples for Example A.
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Furthermore, samples shown--in Figure 4 were cathodically treated in chromic acid electrolyte after reflowing.
Degreasing...Cathodic electrolysis in 70 g/l of NaOH under 5 A/dm for 2 seconds at 70 C.
Pickling...Immersion into 100 g/l of H2SO4 for 2 seconds at 25C.
Anodic treatment...Anodic treatment in 70 g/l of NaOH (pH 14~ at 5 A/dm for 2 seconds at 70 C.
(Only samples for Example A) Nickel plating...Plating with various amounts of nickel under 3 A/dm at 40C by using Watts bath.
Tinplating...Plating with 700 mg/m2 of tin under 10 A/dm at 40 C by using a phenolsulfonic acid bath.
Reflowing...Raising the temperature of the tin and nickel plated steel sheet up to 28QC during 1.6 seconds by using resistance heating.
Quenching...Rapid immersion into water after reflowing.
Chromate treatment...Cathodic treatment in chromic acid electrolyte containing 30 g/l of CrO
and 0.3 g/l of H2SO4 under 10 A/dm for 0.5 seconds at 50C.
Water rinsing was carried out between succeeding steps.
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As shown ln Flgure-2, in the case of Ex~mple --A with ~r~odic treatment in alkaline solution, numerous nodules of metallic tin were observed by an electron microscope on the iron-tin-nickel alloy layer Eormed on -the steel sheet in the range of S to 20 mq/m2 of plated nickel, but nodular metallic tin is almost not present at above 20 mg/m and at below 5 mg/m2 of plated nickel.
On the other hand, in the case of Example B
without anodic treatment in alkaline solution, almost all of the deposited tin forms a uniform iron-tin-nickel alloy layer irrespective of the amount of nickel prior to tinplating.
Generally, tne weldability is evaluated by an available range of secondary current in welding as shown in the report by N.T. Williams (Metal Construction, April 19?7, pages 157-160), that is to say, the wider the secondary current range in . welding, the better the weldability. The upper limit . ~ . . .
~ in the available secondary current range corresponds .:
~ to the welding conditions in which some defect such ~ ..
as splashing is found and the lower limit corresponds - to the welding conditions in which the breakage ~ occurs in the welded part by the tearing test.
-~ ~ However, in order to obtain data wherein the available range of secondary current in welding is ;-` decided for each sample, a large amount of samples ....
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are necessary. Therefore, the weldability is evaluated by electric contact resistance, because electric contact resistance has an apparent correlation with the available range of secondary current in welding as shown in the report by T. Fu~imura (Journal of The Iron and Steel Institute of Japan, Vol. 69, No. 13, September 1983, page 181), that is, the lower the electric contact resistance, the wider the secondary current range in welding Accordingly, ~f the electric contact resistance is lower, the weldability is better.
It is found from Figure 3 that the electric contact than resistance of samples for Example A is lower that in the sample for Example B at below 20 mg/m2 of plated nickel wherein nodular metallic tin is observed on the iron-tin-nickel alloy layer formed on the steel sheet in the sample for Example A. At below 5 mglm2 plated nickel, the electric contact resistance becomes slLghtly high because of the decrease in the amount of metallic t~in by the formation of an alloy consisting mainly of iron-tin alloy. The electric contact resistance increases with an increase in the amount of plated nickel because of the decrease Ln the amount of metallic tin caused by the formation of an alloy consisting mainly of tin-nickel alloy during aging at ordlnary tèmpérature-As shown in Figure 4, the filiform corrosion resistance is lmproved with an increa$e in the amount of plated nickel. In the range of~5 to ~30 mg/m2 of plated nickel, the filiform corrosion resi~stance after laoquering of samples for Example A is excellent compared with that of Example B because the iron-tin-nickel alloy having excellent lacquer adhesion is present with numerous nodules of metallic tin on the surface of samples for Example A, ,, . ~,, "
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~-t the surface of the samples for Example ~ is covered with uniform metallic tin layer having poor lac~uer adhesion.
As described above, the anodic treatment of the pickled steel sheet in an alkaline electrolyte and the plating with the limited amount of nickel are indispensible factors in the present invention.
The reason why the anodic treatment of the pickled steel sheet in an alkaline electrolyte and the plating with the limited amount of~ni~ckel is necessary in order to produce the tin and nickel plate steel sheet having numerous nodules of metallic tin on ~he iron-tin-nickel alloy layer formed on the steel sheet is not clear. However, it is assumed that the reason is the formation of numerous nodules of metallic tin by dewetting of ~ .~
:~j metallic tin electrodeposited in the part wherein iron oxide is : formed on the pickled steel sheet by the anodic treatment in an . :~
~alkaline electrolyte and the concentration of.metallic tin to the ~part wherein nickel is electrodeposited during the formation of an iron-tin-nickel alloy layer by reflowing after tinplating.
Furthermore, it is assumed that the reason why the tin and nickel plat:ed steel sheet having numerous nodules of metallic tin on the iron-tin-nickel alloy layer formed on the steel sheet is excellent in welda~ility and corrosion resistance after laequering, particularly filiform corrosion resistance, is that excellent weldability is maintained in the area having a large amount~of metallic tin in noduIar form compared with an average amount~ of plated metallic tin and that excellent corrosion rcsistance after lacquering is maintained in the area where iron-tin-nickel alloy having excellent lacquer adhesion is exposed~on the surface without being covered by a uniform metallic tin làyer.
.. : , -r , Therefore, an amount of nickel above 20 mg/m2 is not desirable in the present lnvention becaus~ the tin iron oxide coating formed on the steel sheet substrate by the anodic treatment in the alkaline electrolyte p~ior to nickel plating is almost completely removed during nickel plating. In the present invention, a known nickel plating electrolyte such as a Watts bath containing 200 to 300 g/l of nickel sulfate, 20 to 50 g/l of nickel chloride, and 20 to 40 g/l of boric acid or a nickel sulfamate bath containing 300 to 500 g/l of nickel sulfamate, and 20 to 40 g/l of boric acid is used for nickel plating of the steel sheet treated anodically in an alkaline electrolyte. The plating 5 to 20 mg/m2 which is required in the present invention is carried out by using these electrolytes described above under 2 to 30 A/dm2, 30 to 70C of the electrolyte temperature,-and 1 to 10 coulombs~dm2 of a quantity of electricity.
In the present invention, the amount of tin plated on the nickel plated steel sheet is also one of the important factors. The amount of plated tin should be controlled in the range of 400 to 900 mg/m2.
If the amount of plated tin is below ,.
400 mg/mG number of nodules of metallic tin is not :.
enough to improve the weldability after reflowing because a large part of electrodeposited metallic ,~,::: : :
tin readily changes to an iron-tin-nickel alloy on reflowing. At above 900 mg/m2 of plated tin, few .' - . . . .
.
'7't();~1 nodules o~ metall-Lc tin are obtained on re~lowing bcc~use the iron tin-nic~el alloy layer formed on reflowi.ng is uniformly covered with a large amount of metallic tin.
Tinplating on the nickel plated steel sheet : in the present invention is carried out by using a known tinplating electrolyte ~:' . .
,' ~ - 13a -'~; ''"' - :
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, ~` ~ .: ` ` ' ; ' . ' ` ' - ' ~ .~,7<3();~1 uc~ rQr ~h~ production of electrotinplate. For instance, a phenolsulfonic acicl ~ath colltailling 10 to 30 g/l of phenolsulfonic acicl as ~ulfuric acid, 10 to 40 g/l of stannous sulfate or stannous phenolsulfonate and 0.5 to 10 gtl of et.hoxylated a-naphthol sulronic acid, halo5enide ba~h containing stannous chloride, alkali haloserlide, and additives or an alkaline bath containing al~ali stannate ~nd alkali hydro~ide is used in the present invention.
The conditions for tinplating in the present invention are also almost the same as that for the production of conventional electrotinplate. For instance, tinplating by using a FERROSTAN
(trade ~ark; phenolsulfonic acid bath) bath is carried out under 5 to 50 A/dm2 of current density at 30 to 55C of electrol~e t~erature.
Reflowing, that is flow melting of elect~odeposited metallic tin after nickel and tin plating, is also indispensible in order ;~ to form numerous nodules of metallic tin on the iron-tin-nickel alloy layer which is an inventive feature in the present invention.
The known method in which a temperature above the melting point of tin is maintained for a short time by resistance neating and induction heating can be used for reflowing of the tin and nickel plated steel sheet in the presen~ invention.
It is suitable in the present invention that the tin and ~; nlc~el plated steel sheet is heated from 235 to 350C for 0.5 ~o 3 seconds and then immediately quenched into water.
Reflowing at a higher temperature for a lon~er time is not desirable because of the poor welda~ility caused by the change :
of a large part of plated metallic tin to iron-tin-nickel alloy, particularly in the case of a lower amount of plated metallic tin. Furthermore, reflowing at lower temperature for a short r 1 4 . ~ - ' ,', . ` - . ' .
~ .~79(~1 time is not also desirable because of the poor corrosion resistance after lacquering caused by insufficient formation of the iron-tin-nickel alloy layer, particularly in the case of a higher amount of plated metallic tin.
After reflowing, the tin and nickel plated steel sheet according to the present invention is cathodically treated in a known electrolyte such as a sodium dichromate solution which is used for conventional post-treatment of an electrotinplated, or a chromic~`acid solution containing a small amount of sulfuric acid, fluoric acid, fluoboric acid, fluosilicic acid, an alkali salt thereof, and a combination thereof which is used for the production of conventional tin free steel having a upper layer of hydrated chromium oxide and a lower layer of metallic chromium, in order to ensure excellent characteristics in lacquer adhesion, corrosion resistance before Qr after lacquering. For instance, the tin and nickel plated steel sheet according to the present invention is cathodically treated in 20 to 100 g/l of a dichromate of an alkali metal or ammonium or chromic acid ;, solution containing 0.01 to 5% of sulfuric acid, fluoric acid, fluoboric acid, fluosilicic acid, an alkali metal salt thereof, or a combination thereof based on the amount of chromic acid under 5 to 40 A/dm2 of a eurrent density for 0.1 to 5 seconds of a treating time at 30 to 70C of electrolyte temperature.
The amount of total chromium in the film formed on the tin and~nickel plated steel sheet by cathodic treatment in dichromate or chromic acid solution described above should be limited to 3 to~20~mg/m2, preferably 5 to 15 mg~ . If the amount of total chromium is below 3 mg~m2, the excellent corrosion resistance bsfore or after lacguering is not obtained, althou~h the weldability does not change.
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At above 20 mg/m2 of total chromium in the film formed by cathodic treatment in dichromate or chromic acid solution, the current-range for sound welding becomes narrow because of the formation of thic~er chromium oxide having high electric resistance by the dehydration of the formed hydrated chromium oxide or the oxidation of metallic chromium during heating for lacquer curing.
In the present invention, the presence of hvdrated chromium oxide is indispensable in order to obtain the excellent corrosion resistance before or after lacquerin5. Moreover, the presence of metallic chromium is desirable for the improvement of filiform corrosion resistance after lacquering. Thèrefore, in the case : ~
- w~ere the film formed by chromate treatment consists of an u??er iayer of hydrated chromium oxide and a lower layer of metallic chromium, the amount of metallic chromium should be limited to 2 to 17 mg/m and the amount of hydrated chromium oxide should be limited to 3 to 18 mg/m as chromium~
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U:~l The present invention is illustrated by the rollowing examples.
In Example 1 to Example 4 and comparative Example 1 to ` Comparative Example 4, a cold rolled stèeI sheet having a - thickness of 0.2 mm was basically treated by the following process after electroiytically degreasing in a solution of 70 g/l of sodium hydroxide, water rinsing, pickling by an immersion into :, .
100 g/l of sulfuric acid, and then water rinsing.
Anodic treatment in an alkaline electrolyte ~ water rinsing -~ nickel plating , water rinsing ~ tinplating . water rinsing drying ~ reflowing . ~uenching I chromate treatment :
water rinsing ~ drying.
In Comparative Example 1, anodic treatment in an alXaline ~ . .
electrolyte was omitted in the present scheme as described above.
In Comparative Example 2, reflowing after tinplating was omitted.
In~Comparative Example 3, the anodically treated steel sheet was plated with nickel above the upper limited amount in the present :
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invention. In Comparative Example 4, the nickel plated steel sheet was plated with tin below the lower limited a~ount in the present invention.
In Example l to Example 4 and Comparative Example 1 to comparative Example 4, a watts bath containing 250 g/l of NiSO4-6H2O, 30 g/l of NiCl2 6H2O, and 40 g/l of H3BO3 or sulfamic acid bath containing 350 q/l of nickel sulfamate and 40 g~l of H3BO3 was ~sed for nickel plating. Furthermore, a Ferrostan bath containing 60 g/l of SnSO4, 3~ g/l of phenolsulfonic acid and 5 g/1 of ethoxylated a-naphthol sulfonic acid or alkaline bath containing 80 g/l of Na2SnO3 and 15 g/l of NaOH was used for tinplating after nickel plating.
The tin and nickel plated steel sheet was immediately reflowing quenched in water after ~ ~or~, and the temperature of the tin and nickel plated steel sheet dropped to 280C over 1.6 seconds except in Comparative Example 2. The other conditions in every Example are shown in the attached table.
:
The weldability, and corrosion resistance after lacquering of the tin and nickel plated steel sheet in~the above described Examples and Comparative Examples were evaluated by the following te;stinq methods after the measurement of the amounts nickel, tin, metalIic chromium, and chromium in a hydrated chromium oxide by ~:, ~ the~fluorescent X-ray methodj and the results were shown in the :~ attached TabIe.
~ ~ -18-,.. .~, . . . . . . .
~ . . . : . . - .
:- , . , - .. :: , . , . . ~ .: ., , -:,, . - . : -~': :: ' ` ,: - -(1) Weldability 1~ 7 9~
The weldability was evaluated by electric contact resistance for the reason already described.
At first, the sample plated on both sides was cut to a size of 20mm x lOOmm after heating at 210C for 20 minutes. The electric contact resistance was calculated from the change of voltage in a pair of copper disk electrodes tdiameter: 65mm, thickness: 2mm) to which 5 amperes of direct current were supplied'~and SOkg of load was added, when two sample pieces were inserted between a pair of the copper disk electrodes rotating at.5m/min.
~ (2) Filiform corrosion resistance ~after lacquering (Test l) -~ The sample was baked at 200C for 10 minutes after coating with ;- ~ 75 mg/dm2 of a vinyl organosol. The coated-sample was immersed into 3%~sodium chloride solution for 1 hour and then was left in a chamber having 85% of relative humidity at 45C for lO days àter the~surface of the coated samplé was cross-hatched by a razor~and ~then expanded for Smm by an ~richsen~tester.
resùIt~of filiform~rusting spread from the scratched part~of~the coated sample was divided i~nto 5 ranks, namely, excellent,~ goad, f~air, poor,~and bad.
3~ Underoutting corrosion resistance after lacquering (Test The sample was baked at 210C for 10 minutes after coating ~-w~l-;th `6~5~mg~m2~of~an epoxy-phenolic type of lacquer. The coated immersed into the deaerated solution containing 1.5 -id -nd l.S~ of sodium chlorlde for lS days at 37C
fber~thé~sùrfaae of the coated sample was cross-hatched by a zo~r.~
:`.~ , , : ~ `:
~v~ ~9~3 :.
The result of corrosion in the scratched part of the coated sample was divided into S ranks, namely, excellent, good, fair, poor, and bad.
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Claims (14)
1. A method of producing a tin and nickel plated steel sheet having a surface structure in which the distribution of numerous nodules of metallic tin can be observed by using an electron microscope (1000 magnifications) on an iron-tin-nickel alloy layer formed on a steel sheet, which comprises the steps of:
a) anodically treating a substantially clean steel sheet in an alkaline electrolyte having a pH
above 10 under a quantity of electricity ranging from 3 to 50 coulombs/dm2;
b) electroplating the steel sheet treated in step (a) with nickel in an amount of 5 to 20 mg/m ;
c) electroplating the nickel plated steel sheet obtained in step (b) with tin in an amount of 400 to 900 mg/m2;
d) reflowing and quenching the tin and nickel plated steel sheet obtained in step (c); and e) chromate treating the tin and nickel plated steel sheet to form thereon a film containing hydrated chromium oxide in an amount of 3 to 20 mg/m2 as chromium.
a) anodically treating a substantially clean steel sheet in an alkaline electrolyte having a pH
above 10 under a quantity of electricity ranging from 3 to 50 coulombs/dm2;
b) electroplating the steel sheet treated in step (a) with nickel in an amount of 5 to 20 mg/m ;
c) electroplating the nickel plated steel sheet obtained in step (b) with tin in an amount of 400 to 900 mg/m2;
d) reflowing and quenching the tin and nickel plated steel sheet obtained in step (c); and e) chromate treating the tin and nickel plated steel sheet to form thereon a film containing hydrated chromium oxide in an amount of 3 to 20 mg/m2 as chromium.
2. A method according to claim 1, wherein the film formed by chromate treatment comprises an upper layer of hydrated chromium oxide and a lower layer of metallic chromium, and wherein the amounts of total chromium, hydrated chromium oxide as chromium and metallic chromium range from 3 to 20 mg/m2, from 3 to 18 mg/m2 and from 2 to 17 mg/m2, respectively.
3. A method according to claim 1, wherein the anodic treatment of step (a) is carried out under a current density of 1 to 50 A/dm2 and a treating time of 0.1 to 5 seconds at a temperature of 20 to 90°C in an alkaline electrolyte containing 10 to 100 g/l of at least one alkaline compound selected from the group consisting of alkali metal hydroxides, carbonates, bicarbonates, silicates, phosphates, pyrophosphates and borates, and ammonium compounds.
4. The method according to claim 1, wherein the nickel plating of step (b) is carried out under a quantity of electricity of 1 to 10 coulombs/dm2, a current density of 2 to 30 A/dm2 at a temperature of 30 to 70°C in a nickel plating electrolyte containing 200 to 300 g/l of nickel sulfate, 20 to 50 g/l of nickel chloride, and 20 to 40 g/l of boric acid or containing 300 to 500 g/l of nickel sulfamate, and 20 to 40 g/l or boric acid.
5. A method according to claim 1, wherein the tinplating of step (c) is carried out under a current density of 5 to 50 A/dm2 at a temperature of 30 to 55°C in a tinplating electrolyte containing 10 to 40 g/l of stannous sulfate or stannous phenolsulfonate, 10 to 30 g/l of phenolsulfonic acid as sulfuric acid, and 0.5 to 10 g/l of ethoxylated .alpha.-naphtol sulfonic acid or ethoxylated .alpha.-naphtol.
6. A method according to claim 1, wherein the reflowing and quenching of the tin and nickel plated steel sheet in step (d) is carried out by an immediate immersion into water, and heating said tin and nickel plated steel sheet to 235 to 350°C during 0.5 to 3 seconds.
7. A method according to claim 1, wherein the chromate treatment of step (e) is carried out under a cathodic current density of 5 to 40 A/dm2 and a treating time of 0.1 to 5 seconds at a temperature of 30 to 70°C in a solution containing 20 to 100 g/l of a dichromate of an alkali metal or ammonium compound, and 20 to 100 g/l of chromic acid having 0.01 to 5%
of sulfuric acid, fluoboric acid, fluosilic acid or an alkali salt thereof, or a mixture thereof, based on the amount of chromic acid.
of sulfuric acid, fluoboric acid, fluosilic acid or an alkali salt thereof, or a mixture thereof, based on the amount of chromic acid.
8. The tin an nickel plated steel sheet produced by a method according to claim 1.
9. The tin and nickel plated steel sheet produced by a method according to claim 2.
10. The tin and nickel plated steel sheet produced by a method according to claim 3.
11. The tin and nickel plated steel sheet produced by a method according to claim 4.
12. The tin and nickel plated steel sheet produced by a method according to claim 5.
13. The tin and nickel plated steel sheet produced by a method according to claim 6.
14. The tin and nickel plated steel sheet produced by a method according to claim 7.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000490827A CA1279031C (en) | 1985-09-16 | 1985-09-16 | Method for producing a thin tin and nickel plated steel sheet for welded can material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000490827A CA1279031C (en) | 1985-09-16 | 1985-09-16 | Method for producing a thin tin and nickel plated steel sheet for welded can material |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1279031C true CA1279031C (en) | 1991-01-15 |
Family
ID=4131392
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000490827A Expired - Lifetime CA1279031C (en) | 1985-09-16 | 1985-09-16 | Method for producing a thin tin and nickel plated steel sheet for welded can material |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1279031C (en) |
-
1985
- 1985-09-16 CA CA000490827A patent/CA1279031C/en not_active Expired - Lifetime
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