CA1064786A - Low tin terne coating - Google Patents
Low tin terne coatingInfo
- Publication number
- CA1064786A CA1064786A CA231,055A CA231055A CA1064786A CA 1064786 A CA1064786 A CA 1064786A CA 231055 A CA231055 A CA 231055A CA 1064786 A CA1064786 A CA 1064786A
- Authority
- CA
- Canada
- Prior art keywords
- terne
- coating
- tin
- bath
- lead
- 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
Links
Classifications
-
- 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
- C23C2/10—Lead or alloys based thereon
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Coating With Molten Metal (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The application discloses a method of terne coating, and a terne coated product, wherein the tin content of the terne is substantially lower than in conventional terne, without the need for other alloying elements in substitution for tin, such as zinc, antimony, silver, and phosphorus. The tin content of the terne bath is lowered to between about 2%
and about 6% and the terne coated product, upon emerging from the coating bath, is jet finished. Such a terne coat has improved solderability and appearance with no change in pinhole frequency. Coating weight control is easier than with a terne coat having 9% or more tin in the bath.
The application discloses a method of terne coating, and a terne coated product, wherein the tin content of the terne is substantially lower than in conventional terne, without the need for other alloying elements in substitution for tin, such as zinc, antimony, silver, and phosphorus. The tin content of the terne bath is lowered to between about 2%
and about 6% and the terne coated product, upon emerging from the coating bath, is jet finished. Such a terne coat has improved solderability and appearance with no change in pinhole frequency. Coating weight control is easier than with a terne coat having 9% or more tin in the bath.
Description
-1647~36 This invention relates to a terne coated steel article, the coating containing about 2% to about 6% tin and balance lead, and to a method for production thereof.
The generally accepted and published composition range for terne coating is 8% to 20% by weight tin, with the balance commercially pure lead ~ASTM 3Q8). According to Federal Specification QQ-T-19lB, the impurity level for ele-ments other than lead and tin is 1%. When tin became scarce during World War II about 1944, work was done on low-tin terne (about 2%) but zinc, antimony, silver, and phosphorus had to be added to the bath in order to produce a sound coating. At that time a minimum of 9% tin was required in the terne to make an acceptable hot dip coating without the addition of tin substitution elements.
With the high price of tin relative to the pric0 of lead, it has become very desirable to provide a low-tin terne, provided the qualities of the high tin terne can be maintained or enhanced.
The object of terne coating is to provide an inex-pensive, corrosion resistant coating of lead on a steel base, and the percentage of the tin in the terne need only be suffi-cient to obtain a smooth continuous coating. Furthermore, since lead does not alloy with iron, the tin addition is ; necessary in order to alloy with the stael base and form a metallurgical bond between coating and base metal.
In prior terne coating procedures the coating was finished by means of exit rolls turning in an oil bath in order to obtain a good finished appearance. If the tin content of the bath was below about 9%, the exit rolls, normally coated with molten metal, would de-wet and imprint the finished ....~,.....
~064~t~6 product. This would cause rejection and scrap.
- Recently jet nozzles have come into use in the finishing of zinc and aluminum coatings on steel strip, as well as terne coating. By the use of jet nozzles in the finishing of terne coated steel, much lower tin levels have become possible, since the high tin levels needed to keep the exit rolls wetted are no longer needed.
Thus, with the tin content between about 2~ and about ~ by weight, and using jet finishing rather than the conventional exit rolls, in accordance with the present invention, it is possible to produce a low tin terne coating having improved solderability with no change in pinhole frequency, and improved appearance, and with greater ease of coating weight control.
`15 As mentioned above, a lead coating on steel is ; useful for many purposes. Terne coated sheets are exten-sively used in the manufacture of gasoline tanks, for the ~ractor, truck, automotive and marine industries. They are also used in radiator parts, mufflers, oil pans, and air cleaners in those industries. Terne coated steel also finds uses in such areas as roofing, hand fire extinguishers, ; electronic chassis and burial caskets.
The basic problem with putting a lead coating onto a steel base is that the lead does not alloy with iron. It is therefore necessary to add an ingredient which will alloy with iron and cause the lead coating to wet and bond metallur-- gically to the steel base. Long ago it was found that a very suitable alloying ingredient was tin which alloys readily with the steel base and forms a solid solution with the lead. This lead-tin coating alloy became known as terne coating.
.
6~
According to the invention there is provided a hot dipped terne coated steel article having improved solderability and appearance, the coating consisting of about 2% to about 6% by weight tin, and the balance lead plus impurities.
The method of this invention is characterized by passing a steel article through a bath containing from about 2% to about 6% by weight tin, and the balance lead plus impurities, and immediately upon its issuance from the bath subjecting it to a jet finishing operation.
Various attempts have been made over the years to provide a low-tin terne coating but it was always found necessary to add other elements such as zinc, antimony, silver, or phosphorus or combinations of these in order to obtain a reasonably satisfactory and saleable product.
Jet finishing has recently come into use with zinc coating.
The j et finishing process and apparatus is described in detail in United States of America Patent No. 3,314,163 issued to J.B. Kohler. By applying ; the jet finishing procedures to the terne coating process, it is possible to greatly reduce the tin content of the te~ne coat to between about 2%
and about 6% with a consequent reduction in cost, and while maintaining, and ev en enhancing the qualities of the terne coating.
In the preferred practice of the present invention strip is preannealed forming a blue oxide surface. Surface preparation o the ; base metal may be more or less standard. By way of example, it may include the usual steps of pickling, scrubbing, prefluxing and bath entry through a flux cover. Preferably the pickling solution will contain from 8% to 15%
sulfuric acid and from 4% to 15% ferrous sulfate. Sodium chlorate may be added as a pickle accelèrator. The temperature of the pickling bath is generally from 85C to about 100C.
The pickling step removes the surface oxides resulting from prior annealing. Pickling may also be accomplished in a hydrochloric acid bath. It will be understood that the pre-flux and flux steps may be combined in a single flux treàtment.
After pickllng~ the plckler smùdge may be removedby brushing in a water rinse. Prefluxing may ba accomplished by a high speed tinning flux such as is manufactured by duPont, maintained at between about 7 and about 15 Baume, and agitated and suspended in the solution by air or steam. The preflux acids aid in removing iron salts and acid radicals from the strip surface. A commercially available bath cover ~ -such as duPont's ZACLON A galvanizing flux may be used. This is a molten zinc chloride flux with ammonium bromide or ammonium chloride dissolved it it. This would be added to a flux box which immediately precedes the terne pot.
The conventional terne coatlng bath has the ~ollowing analysis.
Antimony .5 to .9%
Aluminum .005% Max.
Arsenic .02% Max.
Bismuth .10% Max.
Copper .05% Max.
Iron ~ .02% Max.
Silver .05% Max.
Zinc - .01% Max.
Tin 12~ - 15%
Total Others .l~ Max.
Lead Balance ~ e ~rk ,, .
10647~6 `
Only tin is purposely addedO Other elements are lmpurities. Relatively large amoun*s of antimony for example result from the reclamation of storage battery lead for terne use and is neither a hindrance nor a significant help in terne coating.
According to the present invention, the tin content of the terne coating bath may be from about 2~ to about ~
and other alloying ingredients may be eliminated. The lead and impurity content will therefore be from about 98% to about ~ . The terne coated metal emerging from the coa~ing bath is subjected to jet finishing as taught in Kohler U.S. Patent No.
3,314,163. The jet finishing apparatus will not be described since it does not per se form a part of the present invention;
and reference may be had to said patent for detailed descrip-tion thereof.
~ The terne coated steel according to the presentinvention has improved solderability over the conventional higher tin terne coating, and an improved appearance because ~ a smoother coating is produced by jet finishing and the coating can be more easily burnished to a uniform sheen. Furthermore, the ~ost is reduced with refèxence to the conventional terne coating. The pinhole frequency remains unchanged. As far as - coating weight is concerned, control is easier than with the high tin terne bath; and it is-possible to produce, with much greate-r ease,"very light coating weights such as 0.05 oz./ft.2 (,15.25 g/l2) as-against 0.18 oz./ft.2 (61 g/m ~
which was àbout the lightest which could be produced consis-tently heretofore.
It should be understood that with a reduction in tin content, the temperature of the coating bath must be increased slightly. This additional cost is nominal, and is far more than compensated for by the savings in tin.
Minor modifications may of course be.made without departing from the spirit of the invention; and therefore no limitation except as set forth in the claims is intended, and no such limitation should be implied~
'' ~`, ' ` ' ' ',' , ' " ' , , .
The generally accepted and published composition range for terne coating is 8% to 20% by weight tin, with the balance commercially pure lead ~ASTM 3Q8). According to Federal Specification QQ-T-19lB, the impurity level for ele-ments other than lead and tin is 1%. When tin became scarce during World War II about 1944, work was done on low-tin terne (about 2%) but zinc, antimony, silver, and phosphorus had to be added to the bath in order to produce a sound coating. At that time a minimum of 9% tin was required in the terne to make an acceptable hot dip coating without the addition of tin substitution elements.
With the high price of tin relative to the pric0 of lead, it has become very desirable to provide a low-tin terne, provided the qualities of the high tin terne can be maintained or enhanced.
The object of terne coating is to provide an inex-pensive, corrosion resistant coating of lead on a steel base, and the percentage of the tin in the terne need only be suffi-cient to obtain a smooth continuous coating. Furthermore, since lead does not alloy with iron, the tin addition is ; necessary in order to alloy with the stael base and form a metallurgical bond between coating and base metal.
In prior terne coating procedures the coating was finished by means of exit rolls turning in an oil bath in order to obtain a good finished appearance. If the tin content of the bath was below about 9%, the exit rolls, normally coated with molten metal, would de-wet and imprint the finished ....~,.....
~064~t~6 product. This would cause rejection and scrap.
- Recently jet nozzles have come into use in the finishing of zinc and aluminum coatings on steel strip, as well as terne coating. By the use of jet nozzles in the finishing of terne coated steel, much lower tin levels have become possible, since the high tin levels needed to keep the exit rolls wetted are no longer needed.
Thus, with the tin content between about 2~ and about ~ by weight, and using jet finishing rather than the conventional exit rolls, in accordance with the present invention, it is possible to produce a low tin terne coating having improved solderability with no change in pinhole frequency, and improved appearance, and with greater ease of coating weight control.
`15 As mentioned above, a lead coating on steel is ; useful for many purposes. Terne coated sheets are exten-sively used in the manufacture of gasoline tanks, for the ~ractor, truck, automotive and marine industries. They are also used in radiator parts, mufflers, oil pans, and air cleaners in those industries. Terne coated steel also finds uses in such areas as roofing, hand fire extinguishers, ; electronic chassis and burial caskets.
The basic problem with putting a lead coating onto a steel base is that the lead does not alloy with iron. It is therefore necessary to add an ingredient which will alloy with iron and cause the lead coating to wet and bond metallur-- gically to the steel base. Long ago it was found that a very suitable alloying ingredient was tin which alloys readily with the steel base and forms a solid solution with the lead. This lead-tin coating alloy became known as terne coating.
.
6~
According to the invention there is provided a hot dipped terne coated steel article having improved solderability and appearance, the coating consisting of about 2% to about 6% by weight tin, and the balance lead plus impurities.
The method of this invention is characterized by passing a steel article through a bath containing from about 2% to about 6% by weight tin, and the balance lead plus impurities, and immediately upon its issuance from the bath subjecting it to a jet finishing operation.
Various attempts have been made over the years to provide a low-tin terne coating but it was always found necessary to add other elements such as zinc, antimony, silver, or phosphorus or combinations of these in order to obtain a reasonably satisfactory and saleable product.
Jet finishing has recently come into use with zinc coating.
The j et finishing process and apparatus is described in detail in United States of America Patent No. 3,314,163 issued to J.B. Kohler. By applying ; the jet finishing procedures to the terne coating process, it is possible to greatly reduce the tin content of the te~ne coat to between about 2%
and about 6% with a consequent reduction in cost, and while maintaining, and ev en enhancing the qualities of the terne coating.
In the preferred practice of the present invention strip is preannealed forming a blue oxide surface. Surface preparation o the ; base metal may be more or less standard. By way of example, it may include the usual steps of pickling, scrubbing, prefluxing and bath entry through a flux cover. Preferably the pickling solution will contain from 8% to 15%
sulfuric acid and from 4% to 15% ferrous sulfate. Sodium chlorate may be added as a pickle accelèrator. The temperature of the pickling bath is generally from 85C to about 100C.
The pickling step removes the surface oxides resulting from prior annealing. Pickling may also be accomplished in a hydrochloric acid bath. It will be understood that the pre-flux and flux steps may be combined in a single flux treàtment.
After pickllng~ the plckler smùdge may be removedby brushing in a water rinse. Prefluxing may ba accomplished by a high speed tinning flux such as is manufactured by duPont, maintained at between about 7 and about 15 Baume, and agitated and suspended in the solution by air or steam. The preflux acids aid in removing iron salts and acid radicals from the strip surface. A commercially available bath cover ~ -such as duPont's ZACLON A galvanizing flux may be used. This is a molten zinc chloride flux with ammonium bromide or ammonium chloride dissolved it it. This would be added to a flux box which immediately precedes the terne pot.
The conventional terne coatlng bath has the ~ollowing analysis.
Antimony .5 to .9%
Aluminum .005% Max.
Arsenic .02% Max.
Bismuth .10% Max.
Copper .05% Max.
Iron ~ .02% Max.
Silver .05% Max.
Zinc - .01% Max.
Tin 12~ - 15%
Total Others .l~ Max.
Lead Balance ~ e ~rk ,, .
10647~6 `
Only tin is purposely addedO Other elements are lmpurities. Relatively large amoun*s of antimony for example result from the reclamation of storage battery lead for terne use and is neither a hindrance nor a significant help in terne coating.
According to the present invention, the tin content of the terne coating bath may be from about 2~ to about ~
and other alloying ingredients may be eliminated. The lead and impurity content will therefore be from about 98% to about ~ . The terne coated metal emerging from the coa~ing bath is subjected to jet finishing as taught in Kohler U.S. Patent No.
3,314,163. The jet finishing apparatus will not be described since it does not per se form a part of the present invention;
and reference may be had to said patent for detailed descrip-tion thereof.
~ The terne coated steel according to the presentinvention has improved solderability over the conventional higher tin terne coating, and an improved appearance because ~ a smoother coating is produced by jet finishing and the coating can be more easily burnished to a uniform sheen. Furthermore, the ~ost is reduced with refèxence to the conventional terne coating. The pinhole frequency remains unchanged. As far as - coating weight is concerned, control is easier than with the high tin terne bath; and it is-possible to produce, with much greate-r ease,"very light coating weights such as 0.05 oz./ft.2 (,15.25 g/l2) as-against 0.18 oz./ft.2 (61 g/m ~
which was àbout the lightest which could be produced consis-tently heretofore.
It should be understood that with a reduction in tin content, the temperature of the coating bath must be increased slightly. This additional cost is nominal, and is far more than compensated for by the savings in tin.
Minor modifications may of course be.made without departing from the spirit of the invention; and therefore no limitation except as set forth in the claims is intended, and no such limitation should be implied~
'' ~`, ' ` ' ' ',' , ' " ' , , .
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A hot dipped terne coated steel article having improved solder-ability and appearance, the coating consisting of from about 2% to about 6%
by weight tin, the balance being lead plus impurities, wherein the weight of coating is from 0.05 oz/ft2 (15.25 g/m2), through the entire range of commercial coating weights.
by weight tin, the balance being lead plus impurities, wherein the weight of coating is from 0.05 oz/ft2 (15.25 g/m2), through the entire range of commercial coating weights.
2. A method of producing a low-tin terne coated steel article, according to claim 1, characterized by the steps of passing the article through a bath containing from about 2% to about 6% by weight tin, the balance being lead plus impurities, and immediately upon its issuance from said bath subjecting it to a jet finishing operation.
3. The method of claim 2, wherein the article, prior to being in-troduced into the bath of coating metal is oxide annealed, pickled, scrubbed prefluxed and fluxed.
4. The method of claim 3, wherein the pickling solution contains from 8% to 15% sulfuric acid and from 4% to 15% ferrous sulfate and is maintained at a temperature between 85°C and 100°C.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US49091774A | 1974-07-22 | 1974-07-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1064786A true CA1064786A (en) | 1979-10-23 |
Family
ID=23950045
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA231,055A Expired CA1064786A (en) | 1974-07-22 | 1975-07-08 | Low tin terne coating |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS5135633A (en) |
| AR (1) | AR207781A1 (en) |
| BR (1) | BR7504590A (en) |
| CA (1) | CA1064786A (en) |
| DE (1) | DE2532044A1 (en) |
| FR (1) | FR2279859A1 (en) |
| GB (1) | GB1513002A (en) |
| IT (1) | IT1045562B (en) |
| ZA (1) | ZA754382B (en) |
Families Citing this family (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0008706B1 (en) * | 1978-08-29 | 1982-05-05 | Joh. Vaillant GmbH u. Co. | Lead-alloy coated heat exchanger for a fuel-heated heat source, and process for coating such an exchanger with lead |
| JPS63127032A (en) * | 1986-11-18 | 1988-05-30 | Matsushita Electric Ind Co Ltd | Electric stove |
| KR930019848A (en) * | 1992-01-04 | 1993-10-19 | 존 알. 코렌 | Weatherproof flaky roofing material and manufacturing method |
| US5314758A (en) * | 1992-03-27 | 1994-05-24 | The Louis Berkman Company | Hot dip terne coated roofing material |
| US5455122A (en) * | 1993-04-05 | 1995-10-03 | The Louis Berkman Company | Environmental gasoline tank |
| US6080497A (en) | 1992-03-27 | 2000-06-27 | The Louis Berkman Company | Corrosion-resistant coated copper metal and method for making the same |
| US5397652A (en) * | 1992-03-27 | 1995-03-14 | The Louis Berkman Company | Corrosion resistant, colored stainless steel and method of making same |
| US5489490A (en) * | 1993-04-05 | 1996-02-06 | The Louis Berkman Company | Coated metal strip |
| US5597656A (en) * | 1993-04-05 | 1997-01-28 | The Louis Berkman Company | Coated metal strip |
| US5491036A (en) * | 1992-03-27 | 1996-02-13 | The Louis Berkman Company | Coated strip |
| US5491035A (en) * | 1992-03-27 | 1996-02-13 | The Louis Berkman Company | Coated metal strip |
| US6794060B2 (en) | 1992-03-27 | 2004-09-21 | The Louis Berkman Company | Corrosion-resistant coated metal and method for making the same |
| US6652990B2 (en) | 1992-03-27 | 2003-11-25 | The Louis Berkman Company | Corrosion-resistant coated metal and method for making the same |
| US5429882A (en) * | 1993-04-05 | 1995-07-04 | The Louis Berkman Company | Building material coating |
| US5401586A (en) * | 1993-04-05 | 1995-03-28 | The Louis Berkman Company | Architectural material coating |
| US5354624A (en) * | 1992-07-15 | 1994-10-11 | The Louis Berkman Company | Coated copper roofing material |
| GB2337057B (en) * | 1993-12-10 | 1999-12-15 | Berkman Louis Co | Coated substrate |
-
1975
- 1975-01-01 AR AR259598A patent/AR207781A1/en active
- 1975-07-08 ZA ZA00754382A patent/ZA754382B/en unknown
- 1975-07-08 CA CA231,055A patent/CA1064786A/en not_active Expired
- 1975-07-15 IT IT50531/75A patent/IT1045562B/en active
- 1975-07-17 DE DE19752532044 patent/DE2532044A1/en active Pending
- 1975-07-17 GB GB30052/75A patent/GB1513002A/en not_active Expired
- 1975-07-18 BR BR7504590*A patent/BR7504590A/en unknown
- 1975-07-21 JP JP50088445A patent/JPS5135633A/en active Granted
- 1975-07-21 FR FR7522703A patent/FR2279859A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| ZA754382B (en) | 1976-06-30 |
| AR207781A1 (en) | 1976-10-29 |
| FR2279859A1 (en) | 1976-02-20 |
| JPS5629744B2 (en) | 1981-07-10 |
| JPS5135633A (en) | 1976-03-26 |
| DE2532044A1 (en) | 1976-02-05 |
| IT1045562B (en) | 1980-06-10 |
| GB1513002A (en) | 1978-06-01 |
| FR2279859B1 (en) | 1977-12-09 |
| BR7504590A (en) | 1976-07-06 |
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