JP3191648B2 - Manufacturing method of galvanized steel sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a galvanized steel sheet, and more particularly to a method for producing a galvanized steel sheet having excellent press formability, spot weldability and adhesiveness.

[0002]

2. Description of the Related Art Galvanized steel sheets are widely used as various kinds of rust-proof steel sheets because they have various excellent characteristics. In order to use this galvanized steel sheet as an anti-corrosion steel sheet for automobiles, in addition to corrosion resistance, paint compatibility, etc., it is required to have excellent press formability, spot weldability and adhesion as the performance required in the body manufacturing process. It is important that

[0003] However, galvanized steel sheets generally have a drawback that press formability is inferior to cold-rolled steel sheets.
This is because the sliding resistance between the galvanized steel sheet and the press mold,
The reason is that the sliding resistance is large as compared with the case of the cold-rolled steel sheet.If this sliding resistance is large, the galvanized steel sheet near the bead portion of the die hardly flows into the press die during pressing,
The steel sheet is likely to break.

[0004] As a method for improving the press formability of a zinc-based plated steel sheet, a method of applying a high-viscosity lubricating oil is generally widely used. However, in this method, since the lubricating oil has a high viscosity, there is a problem that a coating defect occurs due to poor degreasing in the next coating process, and there is a problem that press performance becomes unstable due to lack of oil, etc. There is a high demand for improved press formability of galvanized steel sheets.

On the other hand, in a zinc-based plated steel sheet, copper, which is an electrode, and molten zinc easily react during spot welding to form a brittle alloy layer. Therefore, the copper electrode is severely worn and its life is short. There is a problem that continuous hitting properties are inferior to cold-rolled steel sheets.

Further, in the manufacturing process of an automobile body,
Various adhesives are used for the purpose of rust prevention and vibration damping, etc., but it has recently become clear that galvanized steel sheets are inferior in adhesiveness to cold rolled steel sheets.

As a method for solving the above problem, Japanese Patent Laid-Open No.
JP-A-3-60332 and JP-A-2-190483 disclose electrolytic treatment, immersion treatment, coating oxidation treatment, or heat treatment on the surface of a galvanized steel sheet.
A technique for generating an oxide film mainly composed of ZnO to improve weldability or workability (hereinafter, referred to as “prior art 1”) is disclosed.

JP-A-4-88196 discloses that a galvanized steel sheet is immersed in an aqueous solution containing 5 to 60 g / l of sodium phosphate and having a pH of 2 to 6 on the surface of the galvanized steel sheet.
Electrolytic treatment and spraying of the above aqueous solution provide P
A technique for forming an oxide film mainly composed of an oxide to improve press formability and chemical conversion treatment (hereinafter referred to as “prior art 2”) is disclosed.

Japanese Patent Application Laid-Open No. Hei 3-190933 discloses a technique (hereinafter referred to as "prior art 3") for producing a Ni oxide to improve press formability and chemical conversion treatment (hereinafter referred to as "prior art 3"). JP-67885-A discloses a technique for improving the corrosion resistance by generating metals such as Ni and Fe by, for example, electroplating or chemical plating on the surface of a zinc-based plated steel sheet (hereinafter referred to as “prior art 4”). ").

[0010]

The prior art 1 described above has the following problems. That is, prior art 1
In this method, an oxide mainly composed of ZnO is generated on the surface of the plating layer by various treatments. Therefore, the effect of reducing the sliding resistance between the press die and the plated steel sheet is small, and the effect of improving the press formability is reduced. Is small. Further, an oxide mainly composed of ZnO deteriorates adhesiveness.

Prior Art 2 is a method of forming an oxide film mainly composed of P oxide on the surface of a zinc-based plated steel sheet, and therefore has a large effect of improving press formability and chemical conversion treatment. There is a problem that the adhesiveness is deteriorated.

Prior Art 3 is a single-phase Ni oxide film, so that press formability is improved, but there is a problem that adhesiveness is deteriorated.

Prior Art 4 is a method of producing only a metal such as Ni, so that the corrosion resistance is improved. However, since the metallic properties of the film are strong, the effects of improving press formability and spot weldability are not sufficient. Further, there is a problem that sufficient adhesiveness cannot be obtained because the wettability of the metal with respect to the adhesive is small.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a method for producing a zinc-based plated steel sheet having excellent press formability, spot weldability and adhesiveness.

[0015]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that an appropriate Fe-Ni-O-based film is formed on the surface of the plating layer of a zinc-based plated steel sheet. It has been found that press forming, spot weldability, and adhesion can be significantly improved by forming.

Here, the proper Fe—Ni—O-based coating is as follows: The amount of the coating is in the range of 10 to 1500 mg / m ^{2 in} terms of the total amount of metal elements in the coating. The sum of the Fe content and the Ni content (wt.
%) To the ratio of the Fe content (wt.%)
Also called "Fe ratio in film", "Fe / (Fe + N
i) ") is in the range of 0.05 to 0.9, preferably in the range of 0.1 to 0.5, and the oxygen content of this coating is 0.5 to 10 wt. % Was found to be satisfied.

The reason why the press formability of a zinc-based plated steel sheet is inferior to that of a cold-rolled steel sheet is that, under high surface pressure, the low melting point zinc and the mold cause an adhesion phenomenon, so that the sliding resistance is low. It is because it increases. In order to prevent this, it is effective to form a harder and higher melting point coating than the zinc or zinc alloy plating layer on the surface of the plating layer of the zinc-based plated steel sheet. The sliding resistance with the mold is reduced, the zinc-plated steel sheet is easily slid into the press mold, and the press formability is improved.

The reason why the continuous spotting property in spot welding of a zinc-based plated steel sheet is inferior to that of a cold-rolled steel sheet is that the molten zinc at the time of welding comes into contact with the copper of the electrode to form a brittle alloy layer. In addition, the deterioration of the electrodes becomes severe. Therefore, as a method of improving the continuous hitting property of a zinc-based plated steel sheet, it is effective to form a high-melting film on the plating surface. The present inventors have studied various coatings in order to improve the spot weldability of galvanized steel sheets, and have found that Ni metal is particularly effective. Although the details of this reason are not clear, it is considered that the reason is that Ni metal has a high melting point and high electric conductivity.

It has been known that the adhesion of a galvanized steel sheet is inferior to that of a cold-rolled steel sheet, but the cause has not been clarified. The present inventors have investigated the cause and found that the adhesiveness is controlled by the composition of the oxide film on the surface of the steel sheet. That is, in the case of a cold-rolled steel sheet, the oxide film on the surface of the steel sheet is mainly composed of Fe oxide, whereas in the case of a zinc-based plated steel sheet, the oxide film is mainly composed of Zn oxide. The adhesiveness differs depending on the composition of the oxide film.
Adhesion was inferior to oxide. Therefore, by forming a film containing Fe oxide on the surface of a galvanized steel sheet as in the present invention, it has become possible to improve the adhesiveness.

The present invention has been made on the basis of the above findings, and by appropriately forming a Fe—Ni—O-based coating on the surface of a plating layer of a zinc-based plated steel sheet, the press formability, This is a method for producing a galvanized steel sheet having excellent spot weldability and adhesiveness, as described below. Here, the microstructure and morphology of the Fe—Ni—O-based coating are at least metals of Ni and Fe,
Also, any film may be used as long as it is a film made of a mixture containing oxides of Ni and Fe, and the bonding state of the elements constituting the film is not limited.

The zinc-coated steel sheet according to the first aspect of the invention
The production methods are nickel sulfate, ferrous sulfate and
Using a galvanized steel sheet as a cathode in an aqueous solution containing iron
The surface of the plating layer of galvanized steel sheet by electrolysis
Nickel sulfate, ferrous sulfate and
And the total concentration of ferric sulfate is 0.3 to 2.0 mol / l
And within the range of²⁺And Fe³⁺Concentration sum (mo
l / l) ³⁺Of concentration (mol / l)
Is in the range of 0.5 to less than 1.0, and the pH is
Perform electrolysis in an aqueous solution within the range of 1.0 to 2.0
To form an Fe-Ni-O-based coating
It has a sign.

According to a second aspect of the present invention, there is provided the method for producing a zinc-based plated steel sheet according to the first aspect, wherein the plated layer of the zinc-based plated steel sheet has an iron content of 7 to 10. It is characterized in that it is an alloyed hot-dip galvanized layer within a range of 15 wt.%.

According to a third aspect of the present invention, there is provided a method for manufacturing a galvanized steel sheet according to the first aspect, wherein the galvanized steel sheet has an electrogalvanized layer or a hot-dip galvanized layer. It is characterized by being a galvanized layer.

[0024]

Next, the reason for limiting the manufacturing conditions of the present invention as described above will be described. In the present invention, Fe-Ni-
Nickel sulfate, ferrous sulfate, and ferric sulfate are used as components in an aqueous solution (hereinafter, also referred to as “electrolyte solution”) used to form an O-based film because Fe—Ni—O
Electrolytically using a zinc-based plated steel sheet on which a zinc-based coating is to be formed as a cathode, Fe, Ni and O
This is because they are suitable for containing and forming.

The reason why the total concentration of nickel sulfate, ferrous sulfate and ferric sulfate is 0.3 to 2.0 mol / l is as follows. The total concentration of the three compound components is
When the concentration is less than 0.3 mol / l, the electrolysis voltage is increased due to the low conductivity of the electrolytic bath. As a result, even if the current density is low, the burning of the plating proceeds excessively, and the oxygen content in the Fe—Ni—O-based film is reduced. When the amount is 10 wt. %, The spot weldability and the chemical conversion property are likely to decrease. On the other hand, when the above total concentration exceeds 2.0 mol / l, when the temperature is low, the solubility limit of nickel sulfate and / or ferrous sulfate is reached, and the precipitation of nickel sulfate and / or ferrous sulfate occurs. Is generated.

The reason for using an aqueous solution having a pH in the range of 1.0 to 2.0 as the electrolytic solution is as follows. If the pH of the electrolytic solution is less than 1.0, the generation of hydrogen during electrolysis is the main component of the cathode reaction, and the current efficiency is greatly reduced. On the other hand, when the pH of the electrolytic solution exceeds 2, a hydroxide of ferric oxide precipitates.

Fe in electrolyte²⁺And Fe³⁺Concentration sum of
(Mol / l)³⁺Concentration (mol / l)
A high ratio, where the ratio is in the range of 0.5 to less than 1.0
The reason for limiting to is as follows. Fe-Ni-
The main component of oxygen in the O-based coating is the acid in the eutectoid iron oxide.
It is considered to be elementary. Determine the oxygen content in this coating
In order to exceed the fixed value, Fe²⁺Precipitates at lower pH than
Fe³⁺The concentration ratio of Fe²⁺Higher than the concentration ratio of
Is more advantageous. Oxygen content in Fe-Ni-O based coating
The amount is 0.5 wt. % Or more, Fe²⁺And
And Fe³⁺To the sum of the concentrations (mol / l) of³⁺Concentration of
(Mol / l) ratio must be 0.5 or more
Absent. And Fe ³⁺High concentration (mol / l) ratio
Indeed, iron oxides were eutectoidized in Fe-Ni-O-based coatings.
It is efficient to make. This is Fe³⁺Is Fe²⁺than
Low pH (for example, when the concentration is 0.1 mol / l
Produces hydroxide at pH 2.2 and pH 7.5, respectively.
Oxidation due to surface pH rise due to electrolysis
This is because eutectoids are easily formed.

The temperature of the electrolytic bath is not particularly limited. If the temperature is lower than 30 ° C., the conductivity of the electrolytic bath is lowered and the electrolysis voltage is increased. Increases the amount of evaporation of nickel, making it difficult to control the concentration of nickel and iron ions.
It is desirably in the range of ° C.

Although the current density of the electrolytic plating is not particularly limited, if the current density is less than 1 A / dm ² , the generation of hydrogen becomes the main component of the cathode reaction, and the current efficiency is greatly reduced. However, if it exceeds 150 A / dm ² , burning of the plating proceeds and a large amount of hydroxide of nickel or iron is involved, resulting in deterioration of weldability. Therefore, it is desirable to limit the current density within the range of 1 to 150 A / dm ² .

In the present invention, the surface is made of Fe--Ni--O
The galvanized steel sheet used for forming the system coating includes a galvanized layer having an iron content of 7 to 15 wt.%, An electrogalvanized layer, And a hot-dip galvanized layer. The reason is that galvanized steel sheets having these plating layers are more workable than press-rolled steel sheets and zinc-nickel alloy-plated steel sheets, in particular press formability, and
Fe-N according to the present invention is inferior in spot weldability, etc.
This is because forming the i-O-based film on the surface of the plating layer greatly improves the press formability and spot weldability.

The electrolytic solution contains Z contained in the plating layer of the zinc-based plated steel sheet used in the present invention.
n, Co, Mn, Mo, Al, Ti, Sn, W, Si,
It may contain cations such as Pb, Nb and Ta, hydroxides and oxides, and further anions other than chloride ions.

Next, the zinc-based plated steel sheet used in the present invention is a steel sheet having a zinc-based plated layer formed on the surface of the steel sheet by a hot-dip plating method, an electroplating method, a vapor phase plating method or the like. The composition of the zinc-based plating layer is, in addition to pure zinc, Fe, Ni, Co, Mn, Cr, Al, Mo, T
Single-layer or multiple-layer plating layers containing one or two or more of metals such as i, Si, W, Sn, Pb, Nb and Ta (but Si is also treated as a metal) or an organic material Consists of Further, the plating layer is made of SiO.
Fine particles such as ₂ and Al ₂ O ₃ may be contained.
Further, as the zinc-based plated steel sheet, a multi-layer plated steel sheet having a different composition of a plating layer and a functionally graded plated steel sheet can be used.

The Fe—Ni—O-based film formed on the surface of the plating layer of the zinc-based plated steel sheet under the above-described limited conditions eliminates the adhesion phenomenon between the steel sheet and the mold during press forming, and reduces the sliding resistance. It becomes smaller, the sliding into the mold becomes better, the formation of a brittle alloy layer between the electrode copper and the electrode during spot welding is suppressed, and the continuous hitting property is improved.
The effect of improving the adhesiveness by the action of the film containing e-oxide is exhibited. However, Fe-N
Adhesion amount of i-O type film (total amount of metal elements in the film)
Is less than 10 mg / m ² , the effect of improving press formability is not obtained. On the other hand, if it exceeds 1500 mg / m ² , the effect of improving press formability is saturated. Therefore, Fe-Ni-
The amount of the O-based coating (converted to the total amount of metal elements in the coating) is
It is desirable to be within the range of 10 to 1500 mg / m ² .

The Fe content in the Fe—Ni—O based coating and the N content
i content (w.%) and the Fe content (w
t. %) (Fe / (Fe + Ni) in the film)
If it is less than 0.05, the effect of improving the adhesiveness is not exhibited.
On the other hand, if Fe / (Fe + Ni) in the coating exceeds 0.9, the Ni content in the coating decreases, so that
The ratio of the high melting point Zn—Ni alloy formed during welding is reduced, and as a result, the electrode is greatly deteriorated, and the effect of improving spot weldability is not exhibited. Therefore, it is desirable that Fe / (Fe + Ni) in the coating be in the range of 0.05 to 0.9, particularly in the range of 0.1 to 0.5.

The oxygen content in the Fe—Ni—O-based coating is
It is desirable to be within the range of 0.5 to 10 wt.%. When the oxygen content is less than 0.5 wt.%, The metallic properties of the film become strong, and the effect of improving press formability is reduced. On the other hand, when the oxygen content exceeds 10 wt.%, The amount of oxide is large. As a result, the electrical resistance of the surface is increased, the weldability is reduced, and the generation of phosphate crystals is suppressed, so that the chemical conversion property is deteriorated.

[0036]

Next, the present invention will be further described with reference to examples. The galvanized steel sheet before the electrolytic treatment according to the method of the present invention and the comparative method is one in which any of the following GA, GI and EG plating types is formed. GA: 10 wt. %, And the balance was Zn alloyed hot-dip galvanized layer, and the adhesion amount was 60 g / m ² on both sides. GI: A hot-dip galvanized layer was formed, and the adhesion amount was 90 g / m ² on both sides. EG: An electrogalvanized layer was formed, and the adhesion amount was 40 g / m ² on both sides.

The galvanized steel sheet is used as a cathode, and electrolytically treated with a mixed solution containing nickel sulfate, ferrous sulfate and ferric sulfate at a predetermined concentration to form a Fe—Ni—O-based coating on the surface of the galvanized steel sheet. A test specimen was prepared in which was formed. However, some were not subjected to electrolytic treatment. Table 1
In Examples 1 to 1 subjected to electrolytic treatment under the conditions within the scope of the present invention
20 and at least one of the electrolysis conditions of Comparative Examples 2, 3, and 5 in which electrolysis was performed outside the scope of the present invention. In addition, Comparative Examples 1, 4 and 6 in the same table were those immersed in the electrolytic solution but not subjected to the electrolytic treatment. The table shows the plating type of the steel sheet before electrolytic treatment, the component composition of the electrolytic solution, the pH, the temperature, the current density, and the energizing time.

[0038]

[Table 1]

The ratio between the ferrous sulfate concentration and the ferric sulfate concentration in the electrolytic solution was controlled by adjusting the concentration of each of the chemicals to be added. If the ratio to the iron ion concentration changes, an oxidizing agent such as hydrogen peroxide is added to the electrolyte to oxidize ferrous ions to ferric ions, or conversely, ferric ions. Was reduced to ferrous ions by contact with metallic iron to control the ratio.

With respect to the Fe—Ni—O-based film formed on each of the specimens subjected to the electrolytic treatment as described above, the amount of the film adhered (in terms of the total amount of metal elements in the film),
The ratio of the Fe content (wt.%) To the sum (wt.%) Of the Ni content and the Ni content, and the oxygen content of the coating were measured as follows.

[Measurement of Amount of Coating (Conversion of Total Metal Elements in Coating) and Fe / (Fe + Ni) in Coating]
For the specimens whose plating types are GI and EG, Fe
The Ni-O-based film is dissolved and peeled off with dilute hydrochloric acid together with the surface layer of a lower plating layer (Zn-based plating layer, the same applies hereinafter), and Fe and Ni are quantitatively analyzed by the ICP method to obtain Fe-Ni-O. The adhesion amount (in terms of the total amount of metal elements in the film) and the composition of the system film were measured. Next, Fe / (Fe + Ni) in the film was calculated. For specimens with a plating type of GA, Fe
Since it contains the component elements in the -Ni-O-based film, it is difficult to completely separate the component elements in the upper Fe-Ni-O-based film and the component elements in the lower plating layer by the ICP method.
Therefore, only the component elements of the Fe—Ni—O-based film not contained in the lower plating layer were quantitatively analyzed by the ICP method. Further, after Ar ion sputtering, the composition distribution of each component element with respect to the depth of the plating layer was measured by repeating the measurement of each component element in the Fe-Ni-O-based coating from the coating surface by the XPS method. In this measurement method, Fe—Ni—O not contained in the lower plating layer is used.
The distance between the depth at which the component element of the system coating has the maximum concentration and the position at half the depth where the element is no longer detected is defined as Fe
-The thickness of the Ni-O-based coating. Then, based on the result of the ICP method and the result of the XPS method, the adhesion amount (in terms of the total amount of metal elements in the film) and the composition of the Fe—Ni—O-based film were calculated. Next, Fe / (Fe + Ni) in the film was calculated.

[Measurement of the Oxygen Content of the Film] The oxygen content of the film was determined from the results of the Auger electron spectroscopy (AES) analysis in the depth direction.

Table 2 shows Examples 1 to 20 and Comparative Examples 1 to
7, that is, the specimen No. 7 of the present invention. 1-2
0 and the comparative specimen No. About 1-7, Fe-Ni
-Amount of O-based coating (converted to total amount of metal elements in the coating),
The measurement results of Fe / (Fe + Ni) in the film and the oxygen content of the film are shown.

[0044]

[Table 2]

Next, the test sample No. Nos. 1 to 20 and the comparative specimen Nos. For each of Nos. 1 to 7, in order to evaluate press formability, spot weldability, and adhesion, a coefficient of friction measurement, a continuous spot test in spot welding, and an adhesion test were performed by the following methods.

[Measurement of Coefficient of Friction] FIG. 1 is a schematic front view showing a friction coefficient measuring device. As shown in FIG. 1, a sample 1 for measuring a coefficient of friction collected from a specimen is fixed to a sample table 2, and the sample table 2 has a horizontally movable slide table 3.
It is fixed to the upper surface of. On the lower surface of the slide table 3, there is provided a vertically movable slide table support 5 having a roller 4 in contact with the slide table 3. By pushing up this, a sample for measuring a friction coefficient by a bead 6 is provided. A first load cell 7 for measuring a pressing load N on the first table 1 is mounted on the slide table support 5. With the pressing force applied, a second end for measuring the sliding resistance F for moving the slide table 3 in the horizontal direction is provided at one end of the slide table 3 in the horizontal movement direction. A load cell 8 is attached to one end of the slide table 3.

The coefficient of friction μ between the specimen and the bead is
Formula: Calculated by μ = F / N. However, pressing load N: 400
kgf, sample withdrawal speed (horizontal movement speed of slide table 3): 100 cm / min. The beads used had the following two dimensions and shapes.

FIG. 2 is a schematic perspective view showing the shape and dimensions of a first type bead (hereinafter referred to as "bead type A") used. The lower surface of the bead 6 slides while being pressed against the surface of the sample 1. The underside shape is 10m wide
m, a flat surface having a length of 3 mm in the sliding direction, and each line having a width of 10 mm on the front and rear surfaces thereof has a length of 4.5 mmR and is 1/4 of a cylindrical surface.
The cylindrical surfaces are in contact as shown in FIG.

FIG. 3 is a schematic perspective view showing the shape and dimensions of a second type bead (hereinafter referred to as "bead type B") used. In the bead type B, the length of the sliding surface of the bead type A in the sliding direction is increased from 3 mm to 60 mm, and the other parts are the same as the bead type A.
In both cases of the bead type A and the bead type B, Knoxlast 550HN manufactured by Nippon Parkalidging Co., Ltd. was provided on the upper surface of the friction coefficient measurement sample 1 as a lubricating oil.
Was tested.

[Continuous Dotting Test] Two specimens having the same NO.
Resistance welding (spot welding) in which the sheets were stacked, sandwiched between a pair of electrode tips of a spot welding machine from both sides, and energized under pressure to concentrate the current was continuously performed under the following welding conditions. -Electrode tip: dome type with a tip diameter of 6 mm-Pressure: 250 kgf-Welding time: 12 cycles (60 Hz)-Welding current: 11.0 KA-Welding speed: 1 point / sec. As the evaluation of the continuous hitting property, the diameter of the molten and solidified metal part (shape: goishi, hereinafter referred to as a nugget) generated at the joint of two superposed welding base materials (specimens) during spot welding was 4 points. The number of continuous dots welded until the thickness became less than × t ^1/2 (t: sheet thickness of one sheet) was used. The number of hit points is hereinafter referred to as electrode life.

[Adhesion Test] The following test specimens for adhesion test were prepared from the respective test specimens. FIG. 4 is a schematic perspective view illustrating the assembling process. As shown in FIG.
A test specimen 13 in which two test specimens 10 having a length of 200 mm and a length of 200 mm were overlapped and bonded via a spacer 11 having a diameter of 0.15 mm so that the thickness of the adhesive 12 became 0.15 mm.
And baking at 150 ° C. × 10 min. The test specimen thus prepared was bent into a T-shape as shown in FIG.
A tensile test was performed at a speed of m / min, and an average peel strength (n = 3 times) when the test piece was peeled was measured. The peel strength is
The average load was determined from the load chart of the tensile load curve at the time of peeling, and was expressed in the unit: kgf / 25 mm. In FIG.
Indicates a tensile load. The adhesive used was a PVC-based hemming adhesive.

Table 2 also shows the results of the coefficient of friction, the number of continuous hits, and the peel strength of each specimen obtained in the above test.
The following is clear from the table. Specimen No. 1 of the present invention
All of Nos. To 20 have small friction coefficients and good press moldability. Regarding the number of continuous hits, the test piece of the present invention N
o.1 to 20 are all comparative samples No.
It is 1000 points or more larger than 1, 4, and 6, and the electrode life is extended. Further, the test specimens of the present invention all have a peel strength of 12 kgf / 25 mm or more, and have very good adhesion. On the other hand, all of the comparative specimens Nos. 1 to 7, which are out of the scope of the present invention, have at least any one of the friction coefficient, the number of continuous hit points, and the peel strength which are poor, and have press formability and spot weldability. And poor adhesion.

[0053]

The present invention has been configured as described above.
Fe- formed on the surface of the plating layer of zinc-based plated steel sheet
Since the Ni-O-based coating is harder than the zinc or zinc alloy plating layer and has a high melting point, the presence of an appropriate amount of the Ni-O-based coating causes the surface of the plating layer and the pressing die during press forming of a zinc-based plated steel sheet to be formed. , The sliding resistance is reduced, and the zinc-based plated steel sheet easily slides into the press die. In addition, Fe-
The presence of the Ni-O-based high-melting film improves the continuous spotting property in spot welding. Further, the peel strength of the adhesive plate is improved by the presence of the Fe oxide in the Fe—Ni—O-based coating. Further, since the oxygen content of the coating can be adjusted so as not to be excessive, a galvanized steel sheet excellent in chemical conversion treatment can be obtained. Therefore, according to the present invention, it is possible to provide a galvanized steel sheet excellent in press formability, spot weldability, and adhesion, and an industrially extremely useful effect is provided.

[Brief description of the drawings]

FIG. 1 is a schematic front view showing a friction coefficient measuring device.

FIG. 2 shows a first type of bead in FIG. 1 (bead type A).
It is a schematic perspective view which shows the shape and dimension of.

FIG. 3 shows a bead of the second type in FIG. 1 (bead type B).
It is a schematic perspective view which shows the shape and dimension of.

FIG. 4 is a schematic perspective view illustrating a process of assembling a test piece for an adhesion test.

FIG. 5 is a schematic perspective view illustrating a load of a tensile load at the time of measuring a peel strength in an adhesion test.

[Explanation of symbols]

 1 Sample for friction coefficient measurement, 2 Sample table, 3 Slide table, 4 Roller, 5 Slide table support, 6 Bead, 7 First load cell, 8 Second load cell, 9 Ray 10 specimens, 11 spacers, 12 adhesives, 13 specimens for adhesion test, P tensile load, F sliding resistance, N pressing load.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Junichi Inagaki 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Masaaki Yamashita 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan (56) References JP-A-62-33795 (JP, A) JP-A-60-169587 (JP, A) JP-A-5-39588 (JP, A) JP-A-1-149990 (JP, A A) JP-A-7-258886 (JP, A) JP-A-4-176878 (JP, A) JP-A-3-191093 (JP, A) JP-A-8-158066 (JP, A) International publication 96 / 10103 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C25D 3/00-7/12 C23C 2/00-2/40 C23C 22/00-22/86 C23C 28/00 -30/00

Claims (3)

(57) [Claims] 1. A film is formed on a surface of a plating layer of a zinc-based plated steel sheet by performing electrolysis using a zinc-based plated steel sheet as a cathode in an aqueous solution containing nickel sulfate, ferrous sulfate, and ferric sulfate. In the method for producing a galvanized steel sheet, the total concentration of the nickel sulfate, the ferrous sulfate, and the ferric sulfate is 0.3 to 2.0 m.
be in the range of ol / l, the concentration of the Fe ³⁺ to the concentration sum of Fe ²⁺ and ^{Fe 3+ (mol / l) (} mol /
l) is in the range of 0.5 to less than 1.0 and the pH is in the range of 1.0 to 2.0 by performing the electrolysis in the aqueous solution to obtain Fe-Ni- A method for producing a zinc-based plated steel sheet, comprising forming an O-based film. 2. The method according to claim 1, wherein the plating layer of the galvanized steel sheet is an alloyed hot-dip galvanized layer having an iron content of 7 to 15 wt.%. 3. The method according to claim 1, wherein the plating layer of the galvanized steel sheet is an electrogalvanized layer or a hot-dip galvanized layer.