JPH11310895A - Production of electrogalvanized steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrogalvanized steel sheet excellent in plating film adhesion and edge face corrosion resistance after coating. SOLUTION: In this method, a steel sheet subjected to pickling treatment is dipped into an electrogalvanizing bath contg. dextrin and/or 0.05 to 10 wt.% dextrin and metallic ions by the quantity sufficient for precipitating 0.01 to 10 wt.% Co, Ni, Cr and Fe in a plating film to form a galvanizing film on at least one side of the steel sheet. The sulfuric acid pickling treatment is executed in such a manner that a pickling soln. in which the concn. of sulfuric acid is regulated to 0.1 to 10% is used, the temp. is regulated to 20 to 70 deg.C, the dipping time is regulated to 1 to 5 sec, and the relative flow velocity is regulated to 1 to 3 m/sec, and it is preferable that, when the range of 1 mm×1 mm in the surface obtd. thereby is observed, the maximum area ratio of etch pits present in the range of 10 μm× 10 μm is regulated 0.1 to 10%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of galvanized steel sheets having excellent corrosion resistance after coating and excellent coating film adhesion as well as perforation resistance suitable for materials such as automobiles, home appliances and buildings. About the method.

[0002]

2. Description of the Related Art In the fields of automobiles, home appliances, buildings and the like, various surface-treated steel sheets, particularly plated steel sheets, are used as rust-preventive steel sheets. With the increase in its usage, the demand for performance is also increasing, especially for automobiles.
Long-term high corrosion resistance, such as "10-year puncture resistance" is required.

A general surface-treated steel sheet for rust prevention is a zinc-coated steel sheet having a zinc-plated film or a zinc-based alloy plating film such as Zn-Fe or Zn-Ni. These have already been put to practical use for automobile bodies and the like, but at present, it is inevitable to increase the amount of plating applied as the required rust-prevention ability becomes higher. This is due to the corrosion resistance of the plated surface (bare) with a small weight per unit area (hereinafter referred to as “perforation resistance”).
This is because it is difficult to achieve both the corrosion resistance after coating and the end face after coating. For example, it is known that galvanized steel sheet has good end face corrosion resistance after painting, but has poor puncture resistance, and zinc alloy plated steel sheet has good puncture resistance, but it is known that end face corrosion resistance after painting is poor. Have been.

[0004] The applicant of the present invention has proposed dextrin and / or dextran (hereinafter simply referred to as “dextrin etc.”) as a steel sheet which achieves both perforation resistance and corrosion resistance after coating.
Using a plating bath containing
A method for producing a zinc-based electroplated steel sheet in which one or more of o, Ni, and Cr are eutectoid has been proposed (see JP-A-8-209382).

[0005]

The zinc-based electroplated steel sheet proposed above has excellent paintability, press formability, spot weldability, low-temperature impact resistance, perforation resistance, and corrosion resistance after painting. However, when a molding process is performed, a phenomenon called powdering in which the plating film peels in a powder state may occur. Further, when used after being coated, when an impact force acts on the coating film, a phenomenon called chipping in which the coating film peels off may occur. These are all phenomena caused by the adhesion of the plating film.

An object of the present invention is to provide a method for producing a zinc-based electroplated steel sheet which does not generate powdering or chipping and has good perforation resistance and corrosion resistance after coating.

[0007]

Means for Solving the Problems The present inventors have manufactured a zinc-based electroplated steel sheet in which Co is codeposited by electroplating using a plating bath containing dextrin and the like, and variously examine the occurrence of powdering and chipping. After repeated studies, the following findings were obtained.

[0008] In a plating bath containing dextrin or the like, dextrin or the like is adsorbed on the surface of the steel sheet until the steel sheet is energized, and an adsorption layer is formed. Since this adsorption layer is very brittle, the adhesion of the plating film is reduced. Dextrin and the like are easily adsorbed to the sensitive points (activated points) of the steel plate exposed by the pickling, and the adhesion can be improved by adjusting the number of the sharp points (etch pits) generated by the pickling.

The present invention has been completed based on this finding, and the gist of the present invention lies in the following method for producing a zinc-based electroplated steel sheet.

A steel sheet in which the etch pits on the surface have been adjusted to an area ratio of 0.1 to 10% by pickling treatment is combined with a dextrin or the like in a total of 0.05 to 10% by weight and a plating film in a total of 0.01 to 10% by weight.
A method for producing a zinc-based electroplated steel sheet in which a plating film is formed by using a zinc plating bath containing a metal ion necessary for eutecting one or more of Co, Ni, Cr and Fe by weight.

The above pickling treatment is carried out using a pickling solution having a sulfuric acid concentration of 0.1 to 10%, at a temperature of 20 to 70 ° C. and for a dipping time of 1 to 1.
For 5 seconds, the relative flow rate with the steel sheet is set at 1 to 3 m / s, and the steel sheet before the pickling treatment is a low-carbon cold-rolled steel sheet or a cold-rolled steel sheet having a 1 to 50 mg / m ² Ni coating on one surface. It is desirable that

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The method of the present invention comprises the steps of finishing the surface of a steel sheet to a specific property by sulfuric acid pickling, and then adding a small amount of dextrin or the like and one or more of Co, Ni, Cr and Fe. This is a method for producing an electro-galvanized steel sheet in which these metals are eutectoid using a plating bath containing the metal, and is characterized in that the adhesion of the plating film and the corrosion resistance after painting are improved.

The inventors investigated the adhesion of the plating film of a zinc-based electroplated steel sheet in which one or more of Co, Ni, Cr and Fe were eutectoid using a plating bath containing dextrin or the like. As a result, it was clarified that the adhesion of the plating film was related to the pickling treatment conditions.

Usually, the pickling treatment of the steel sheet performed before the electroplating is performed for the purpose of improving the adhesion of the plating film in addition to the removal of the oxide film layer present on the surface.

[0015] It is said that a large number of fine sharp points (etch pits) are formed on the surface of the pickled steel sheet, which exerts an anchor effect to improve the adhesion of the plating film. However, in electrogalvanizing using a plating bath containing dextrin or the like, dextrin or the like is easily adsorbed to sharp points (activated points, that is, etch pits) of the steel sheet exposed by pickling, and the surface of the steel sheet is plated. Dextrin or the like is adsorbed before the film is deposited. This adsorbate was considered to be very brittle, so that the adhesion of the plating film was reduced.

Therefore, the relationship between the amount of etch pits and the adhesion of the plating film of a steel sheet with various conditions of the sulfuric acid pickling treatment was investigated.

FIGS. 1, 2 and 3 are diagrams showing sharp points (etch pits) generated by pickling. In this figure, the surface of the pickled steel sheet was observed with an SEM (scanning electron microscope), photographed, and tressed.

"Etch pit area ratio" in the present invention
Means that an arbitrary 1 mm x 1 mm area is observed with a SEM with a magnification of 5000, and 10 sites with many etch pits (10 µm x 10 µm
Range), a photograph was taken, and each etch pit was measured to determine the maximum value of the area ratio. The area ratio of the etch pit is 16.4% in FIG. 1, 4.9% in FIG. 2 and 0.05 in FIG.
The example of% is shown.

FIG. 4 is a diagram showing the relationship between the area ratio of etch pits and the plating film adhesion (L value). This figure is
It is a figure obtained from an example to be described later. As is clear from the figure, when the area ratio of the etch pit exceeds 10%, the adsorption amount of dextrin and the like is large, and the adhesion of the plating film is reduced. In addition, in the case of pickling in which the area ratio is less than 0.1%, the oxide film layer on the surface of the steel sheet cannot be removed, and the adhesion is deteriorated. Therefore, the amount of etch pits generated by sulfuric acid pickling was set to 0.1 to 10% in area ratio. If the area ratio of the etch pits is within this range, there is no particular limitation on the other steel sheet surface conditions. For example, a so-called dull finish steel plate may be used.

The composition or surface properties (roughness, dirt,
The etching rate differs depending on whether or not there is a Ni film, etc.
The area ratio of the etch pits generated by sulfuric acid pickling was 0.1
To achieve ~ 10%, it is desirable to satisfy the following conditions.

If the concentration of sulfuric acid is less than 1%, it is difficult to remove the oxide film layer on the surface of the steel sheet, and if it exceeds 10%, the area ratio of the etch pits may exceed 10%. Therefore, the concentration of sulfuric acid is 0.1 to 10% by weight. Further, the temperature of the pickling solution is 20 to 70 ° C., the immersion time is 1 to 5 seconds, and the relative flow rate is 1 to 3 seconds.
m / sec. It should be noted that the current supply to the steel sheet or the addition of the inhibitor to the bath during pickling may or may not be performed. When an inhibitor is added, a substance that does not adversely affect the adhesion of the plating is desirable. For example, urea and thiourea can be added in a concentration range of 1 to 500 ppm.

The steel sheet targeted by the method of the present invention is a hot-rolled steel sheet or a cold-rolled steel sheet to be subjected to ordinary electrogalvanizing.
In particular, a remarkable effect can be obtained when a low-carbon cold-rolled steel sheet that is easily etched or a cold-rolled steel sheet having an Ni film is used.

In the method of the present invention, a degreasing treatment is performed before pickling. In this degreasing treatment, it is sufficient that rust-preventive oil, temper rolling oil, and the like attached to the steel sheet can be removed, and electrolysis can be performed using an alkaline degreasing solution used in a normal electrogalvanizing line. After the degreasing treatment, it is desirable to completely remove the degreasing solution by washing with water.

In the method of the present invention, dextrin or the like is added to the surface of the steel sheet subjected to the above-mentioned sulfuric acid pickling in a total of 0.05 to 10% by weight.
And 0.01 to 10% by weight of Co, Ni, Cr and
This is performed using an electrogalvanizing bath containing a sufficient amount of metal ions to co-deposit one or more kinds of Fe. It is desirable that the coating amount of the plating film is 5 to 60 g / m ² .

Using a galvanized steel sheet containing a small amount of Co, Ni, Cr or Fe in an electrogalvanizing bath containing this dextrin or the like, a steel sheet coated with an organic coating has a perforation resistance and an end face after painting. Corrosion resistance is improved. If the total amount of dextrin or the like is less than 0.05% by weight, the effect cannot be obtained.
If it exceeds 10% by weight, uneven plating occurs. This effect can be obtained by electroplating in a plating bath containing dextrin or the like and one or more metal ions of Co, Ni, Cr and Fe. The reason why this effect can be obtained is unknown, but the electro-zinc plating film that satisfies both conditions is a uniform eutectoid state of Co, Ni, Cr or Fe, and the eutectoid of C derived from dextrin and the like Is presumed to be involved.

In the electro-zinc plating, the plating bath contains 0.05 to 10% by weight of dextrin and the like, and furthermore, the plating bath contains
Same as conventional electro-zinc plating except that it contains 0.01 to 10% by weight of Co, Ni, Cr and one or more of Co and more metal ions to coeutect Fe. Can be implemented.

The electro-zinc plating bath is an acid bath (for example,
Both a sulfate bath and a chloride bath and an alkaline bath (for example, a cyanide bath) are possible, but the use of an acidic bath, particularly a sulfate bath is preferred.

Although the molecular weight of dextrin and the like added to the plating bath is not particularly limited, the average molecular weight of dextran is generally in the range of 40,000 to 300,000. Dextrin is a mixture and it is difficult to display the molecular weight, but it may be a chain or a cyclic (so-called cyclodextrin). One or more dextrins or the like can be used. If the addition amount is less than 0.05% by weight, the adhesion to the coating film after coating is reduced, and if it exceeds 10% by weight, the viscosity of the plating bath is increased, the gas release property is deteriorated, and poor plating is caused. Therefore, the amount of dextrin or the like added to the plating bath is 0.05 to 10% by weight, preferably 0.1 to 10% by weight.
It is 5% by weight, more preferably 0.1 to 3% by weight.

In order to eutect one or more of Co, Ni, Cr and Fe into the plating film, a compound of Co, Ni, Cr or Fe is added to supply these metal ions to the plating bath. . These metal compounds dissolve in the plating bath,
And it is desirable not to adversely affect the electroplating,
In addition to the metal, the Co compound may be a divalent or trivalent compound such as an organic acid salt such as a sulfate or an acetate, a carbonate, a molybdate, an alkoxylate, or an organic metal vinegar. Similar salts may be used for Ni, Cr or Fe, and the valence of metal ions is not limited.

The amount of Co, Ni, Cr or Fe ions in the plating bath is selected according to the electroplating conditions so that 0.01 to 10% by weight of the total amount of these metals is eutectoid in the plating film. Is done.

When the total amount of eutectoids of Co, Ni, Cr and Fe in the plating film is less than 0.01% by weight, the corrosion resistance of the end face after coating is reduced, and when it exceeds 10% by weight, the effect of improving the corrosion resistance after coating is reduced. Saturation increases the cost. Therefore, the eutectoid amount of Co, Ni, Cr and Fe in the plating film is
0.05 to 10% by weight. Desirably, it is 0.1 to 5% by weight.

The eutectoid metal element contained in the zinc-based plating film obtained by electroplating is most preferably Co, but may be one or more metals such as Ni, Fe and Cr. However, the total amount of eutectoids of metals other than Co is desirably suppressed to 5% by weight or less.

The current supplied during the electroplating process may be a normal current, but a pulsed current, or a DC or pulsed current superimposed with an AC can also be used. The coating weight of the plating film is in the range of 5 to 60 g / m ² , preferably 10 to 45 g / m ² . When the amount is less than 5 g / m ² , the effect of improving the corrosion resistance of the end face after coating is hardly obtained, and when the amount exceeds 60 g / m ² , the cost is increased and peeling may occur in the plating film layer.

[0034]

[Example] Cold rolled steel sheet with a thickness of 0.8 mm (about 15 g / m ² of Ni on the surface)
After the alkaline electrolytic degreasing is applied to
The following test was performed.

The concentration and temperature of sulfuric acid in the pickling solution, immersion time,
Test materials were manufactured by changing the relative speed with respect to the steel sheet as shown in Tables 1 and 2.

[0036]

[Table 1]

[0037]

[Table 2]

Urea was added as an inhibitor to the pickling solutions treated with test materials Nos. 3, 15 and 18, and test materials Nos. 7 to 15 were added.
Thiourea was added to the pickling solutions treated with 9, 12, 19 to 24, 34, 36 and 37. Test material No. 6 was indirectly energized during pickling.

After the pickled test material was washed with water, a portion of the test material was dried and used for investigating etch pits, and the remaining test materials were subjected to electrogalvanizing without drying.

In the investigation of the etch pits, the "area ratio of the etch pits" was measured, and the results are shown in Tables 1 and 2.

The electrogalvanizing was performed under the plating bath composition and plating conditions shown in Tables 3 and 4. The plating current was performed by 10-cycle pulse current with an on / off ratio (current ratio) of 0.5.

[0042]

[Table 3]

[0043]

[Table 4]

The contents of Co, Ni, Cr and Fe in the plating film were determined by dissolving the film in hydrochloric acid containing an inhibitor and analyzing the film by an atomic absorption method. The results are shown in Tables 5 and 6.

[0045]

[Table 5]

[0046]

[Table 6]

The adhesion of the plating film was evaluated by the DuPont impact test method. In this test method, a 1000-gram weight having a 1 / 4-inch diameter hemisphere at its tip is dropped onto a plated steel sheet from a position at a height of 50 cm. An adhesive tape is attached to the bulging convex portion on the back surface where the weight has fallen, peeled off and adhered to white paper, and a color difference (L
Value) was measured with a color difference meter (Handy color difference meter manufactured by Minolta). Tables 5 and 6 show the obtained color differences (L values). An L value of 85 or more was defined as a range defined by the present invention.

A plate having a size of 70 mm × 150 mm is cut out from a plated steel sheet, the surface is degreased with a degreasing agent (FC4366, manufactured by Nippon Parker Rising Co., Ltd.), and the surface is adjusted with a surface modifier (PZT, manufactured by Nippon Parker Rising Co., Ltd.) After that, a chemical conversion treatment was performed using a phosphate chemical conversion treatment solution (PB-L3080, manufactured by Nippon Parker Rising Co., Ltd.). Next, a cationic electrodeposition coating having a thickness of 20 ± 1 μm was applied with a paint (U-80, manufactured by Nippon Paint Co., Ltd.), and baked at 175 ° C. for 25 minutes. Thereafter, a middle coat (40 μm) of an alkyd paint for automobiles and baking, a top coat (40 μm) of a melamine / polyester paint, and baking were performed.

The corrosion resistance test was performed on the above-mentioned 70 mm × 150 mm plated steel sheet and painted plated steel sheet (organic composite steel sheet).
Was degreased with a degreasing agent (FC4366, manufactured by Nippon Parker Rising Co., Ltd.), washed and dried, and the former was used as a plating film corrosion resistance test piece, and the latter was used as a paint corrosion resistance test piece. Seal 10 mm around these test pieces, the end face and the back face with polyester tape, and conduct a composite corrosion cycle test on the plating film corrosion resistance test pieces.
Thirty cycles were performed, and 300 cycles were performed for painted corrosion resistance test pieces. The composite corrosion cycle test was performed by spraying a solution of 5% NaCl at 35 ° C for 7 hours (salt spray test) → drying at 60 ° C for 2 hours →
85% humidity, 50 ° C. for 15 hours ”as one cycle.

After the test, the corrosion products were removed, and the maximum erosion depth was measured. The results are shown in Tables 5 and 6. Maximum erosion depth
A range of less than 0.2 mm was defined as the range defined in the present invention.

The corrosion resistance of the end face after coating is determined by press-molding a test piece and coating the same as in the manufacture of an automobile body.
The corrosion resistance was evaluated.

A test piece (50 mm × 100 mm) was punched out by using a 70 mm × 150 mm plated steel sheet and adjusting the clearance of a press die so that the “burr” on the end face was 10% of the sheet thickness. The punched test specimen was degreased with a degreasing agent (FC4336, manufactured by Nippon Parker Rising Co., Ltd.), and a surface conditioner (PZ
T, manufactured by Nippon Parker Rising Co., Ltd.), and then subjected to phosphate conversion treatment using a phosphate conversion solution (PB-L3080, manufactured by Nippon Parker Rising Co., Ltd.). Next, a cationic electrodeposition coating having a thickness of 20 ± 1 μm was applied with a paint (U-80, manufactured by Nippon Paint Co., Ltd.), and baked at 175 ° C. for 25 minutes. After that, middle coat (40μm) of alkyd paint for automobile, baking, top coat of melamine polyester paint (40μm)
m), baking was performed to prepare a sample in which the plating surface or the organic composite coating surface was painted.

The sample was subjected to the above-described composite corrosion cycle test, and after 60 cycles had elapsed, the occurrence rate of red rust on the end face was visually determined and is shown in Tables 4 and 5. 5 occurrence rate of red rust
% Or less was defined as the range defined by the present invention.

As is clear from Tables 1, 3 and 5, the test materials No. 1 to No. 24 of the invention examples have a sulfuric acid concentration of 1 to 10%.
Weight percent, using a pickling solution with a bath temperature of 21 to 65 ° C.
Since the pickling treatment was performed at 2.0 to 3.5 m / sec and the immersion time was 1 to 5 seconds, etch pits having an area ratio of 0.1 to 9.9% were formed on the surface. The adhesion of the plating film of the steel sheet obtained by plating them is 86 to 97 in L value, which is good. Also,
The plated steel sheet has a maximum erosion depth of 0.05 to 0.15 mm in a composite corrosion cycle test, and has good corrosion resistance. further,
The end face corrosion resistance after coating is good, with the occurrence rate of red rust being 3% or less in 60 cycles of the composite corrosion cycle test.

On the other hand, as is clear from Table 2, Table 4 and Table 6, the test material No. 25 of the comparative example was subjected to the plating treatment without performing the sulfuric acid pickling, so that an etch pit was formed on the steel sheet surface. Not present, the L value of the plating film is 55, and the adhesion is poor.

In Test Material No. 26, since the temperature of the sulfuric acid bath was 18 ° C., which was lower than the range specified in the present invention, the area ratio of the etch pit was as small as 0.05%, and the L value of the plating film was 79. Poor adhesion.

Test material No. 27 has a high sulfuric acid concentration of 15% by weight, so the area ratio of etch pits is as large as 11.3%, the L value of the plating film is 83, and the adhesion is slightly poor.

Test materials No. 28 and No. 29 were soaked in the pickling solution for as long as 10 seconds, so that the area ratio of the etch pits was large at 16.4% and 12.7%, and the L of the plating film was large. The values are 76 and 72, and both have poor adhesion.

Test material No. 30 was soaked in the pickling solution for 0.5 seconds, so that the area ratio of the etch pit was 0.05%.
And the L value of the plating film was 70, and the adhesion was poor.

Test material No. 31 has a very high pickling bath temperature of 72 ° C., and therefore has a very high etch pit area ratio of 54.7%.
The L value of the plating film is 55, and the adhesion is poor.

In the test material No. 32, since the relative speed between the pickling liquid and the steel plate was as high as 3.5 m / s, the area ratio of the etch pit was 12.7%.
The L value of the plating film was 77, and the adhesion was poor.

No. 33 to No. 38 are test materials in which the pickling treatment was performed under the conditions within the range defined by the invention, but the composition of the plating bath was out of the range defined by the invention.

As shown in Table 4, the ratio of CoSO ₄ .7H ₂ O in the plating bath was as low as 2% by weight.
As shown in the figure, the Co content in the plating film is 0.006% by weight.
And less. Therefore, as shown in Table 6, the maximum depth of the plating film is as large as 0.50 mm, and the plating film is inferior in corrosion resistance.
Also, 25% red rust is generated on the end face after painting, and the corrosion resistance after painting is poor.

For test material No. 34, Co, Ni, Cr, Fe was contained in the plating film because no metal ions were added to the plating bath.
Does not contain any metal. For this reason, the maximum depth of the plating film is as large as 0.35 mm, and the corrosion resistance of the plating film is inferior, and 20% red rust is generated on the end face after painting, and the corrosion resistance after painting is poor.

In Test Material No. 35, since the ratio of dextran added to the plating bath was as low as 0.03% by weight, 20% red rust was generated on the coated end face of the coated steel sheet, and the corrosion resistance after coating was poor.

In Test Material No. 36, since dextran and the like were not added to the plating bath, 20% red rust was generated on the coated end face of the coated steel sheet, and the corrosion resistance after coating was poor.

In the test material No. 37, since the ratio of the equivalent mixture of dextrin and dextran in the plating bath was as high as 15% by weight, the plating film was uneven. For this reason, adhesion and corrosion resistance tests were not performed.

No. 38 of the test material was NiSO ₄ .6H ₂ O of the plating bath.
Is as high as 20% by weight, and as shown in Table 6, the Ni content in the plating film is as high as 5.2% by weight. For this reason, the L value of the plating film is 75, and the adhesion is poor.

[0069]

According to the method of the present invention, the steel sheet is pickled by a predetermined method and then electrogalvanized with a plating solution containing dextrin or the like and metal ions. Not only is the adhesion of the plating film significantly improved compared to the plated steel sheet, but it also has good corrosion resistance. Further, the composite steel sheet in which the plating surface is coated with an organic paint has excellent end face corrosion resistance and can be widely used as a material for automobiles, household products, buildings and the like.

[Brief description of the drawings]

FIG. 1 is a view showing a state in which a sharp point (etch pit: area ratio 16.4%) generated by pickling is observed from above a steel sheet surface by a scanning electron microscope (SEM).

FIG. 2 is a diagram showing a state in which a sharp point (etch pit: area ratio of 4.9%) generated by pickling is observed from above a steel sheet surface with a scanning electron microscope (SEM).

FIG. 3 is a diagram showing a state in which a sharp point (etch pit: area ratio 0.05%) generated by pickling is observed from above a steel sheet surface with a scanning electron microscope (SEM).

FIG. 4 shows the area ratio of etch pit plating film adhesion (L
FIG.

Claims (3)

[Claims] 1. A steel sheet whose surface etch pits have been adjusted to an area ratio of 0.1 to 10% by pickling treatment, a dextrin and / or dextran totaling 0.05 to 10% by weight, and a plating film having a total of 0.01 to 10% by weight. Wt% Co, Ni, Cr and Fe
A method for producing a zinc-based electroplated steel sheet, comprising forming a plating film using a zinc plating bath containing a metal ion necessary for coeutecting one or more of the above. 2. The pickling treatment is carried out using a solution having a sulfuric acid concentration of 0.1 to 10%, a bath temperature of 20 to 70.degree.
2. The method for producing a zinc-based electroplated steel sheet according to claim 1, wherein the relative flow speed with respect to the steel sheet is set to 1 to 3 m / sec. 3. The steel sheet according to claim 1, wherein the steel sheet before the pickling treatment is a low-carbon cold-rolled steel sheet or a cold-rolled steel sheet having a Ni coating of 1 to 50 mg / m ^{2 on} one surface. Manufacturing method of zinc-based electroplated steel sheet.