JPH09170086A - Galvanized steel sheet excellent in press formability and adhesion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a film to be formed on the surface of a galvanized steel sheet, minimal in sliding resistance to a press die and increased in the peeling strength after adhesion by the use of various adhesives. SOLUTION: This film is an Ni-O film 23 having a composition containing Ni hydroxide, Ni oxide, and metallic Ni and having a form of mixture film. An oxidic layer 24, consisting of Ni oxide and Ni hydroxide, is formed in the surface layer part of the Ni-O film 23, and the thickness of this oxidic layer 24 is regulated to 0.5-5nm. This film can be obtained by subjecting a steel sheet to immersion in an aqueous solution of hydrochloric acid, in which Ni ion concentration, temp., and pH value are regulated to >=0.1mol/l, 40-70 deg.C, and 2.0-4.0, respectively, for 5-50sec and then to oxidation in a mixed atmosphere of air and ozone to regulate the thickness of the oxidic layer in the surface layer part of the Ni-O film. By this method, the galvanized steel sheet, excellent in press formability and adhesion, can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved zinc-based plated steel sheet, and more particularly to a zinc-based plated steel sheet excellent in press formability 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 zinc-based plated steel sheet as an anticorrosive steel sheet for automobiles, not only performance such as corrosion resistance is required, but also excellent press formability and adhesiveness are required in the body manufacturing process. It

However, zinc-based plated steel sheets generally have a drawback that they are inferior in press formability to cold-rolled steel sheets. This is because the zinc-based plated steel sheet has a larger sliding resistance with the press die than the cold-rolled steel sheet.
That is, if this sliding resistance is large, the zinc-based plated steel sheet is less likely to flow into the press die at the portion where the bead and the zinc-based plated steel sheet slide violently, and the steel sheet is likely to break.

As a method of improving the press formability of a zinc-based plated steel sheet, a method of applying a high-viscosity lubricating oil to the steel sheet is generally widely used. But with this method,
Due to the high viscosity of the lubricating oil, coating defects due to poor degreasing may occur in the coating process, and oil shortage during pressing may cause
There are problems such as unstable press performance. Accordingly, there is a strong demand for improving the press formability of a zinc-based plated steel sheet.

[0005] In the manufacturing process of an automobile body,
Various kinds of adhesives are used for the purpose of rust prevention and damping of car bodies, but in recent years it has become clear that the adhesion of zinc-based plated steel sheets is inferior to that of cold-rolled steel sheets. Came.

As a method for solving the above-mentioned problems, Japanese Patent Laid-Open Nos. 53-60332 and 2-19048 are known.
No. 3 publication improves the weldability or workability by producing an oxide film mainly composed of ZnO by subjecting the surface of a zinc-based plated steel sheet to electrolytic treatment, dipping treatment, coating oxidation treatment, or heat treatment. The technology (hereinafter referred to as "prior art 1") is disclosed.

Japanese Unexamined Patent Publication (Kokai) No. 4-88196 discloses that the surface of a zinc-based plated steel sheet is immersed in an aqueous solution of pH 2 to 6 containing 5 to 60 g / l of sodium phosphate, or
Disclosed is a technique (hereinafter referred to as "Prior Art 2") for improving press moldability and chemical conversion treatability by electrolytic treatment or by spraying the above aqueous solution to form an oxide film mainly containing P oxide. doing.

Japanese Unexamined Patent Publication (Kokai) No. 3-191093 discloses press-formability and chemical conversion treatment by producing Ni oxide on the surface of a zinc-based plated steel sheet by electrolytic treatment, dipping treatment, coating treatment, coating oxidation treatment or heat treatment. The technology (hereinafter, referred to as "Prior Art 3") for improving the property is disclosed.

Japanese Unexamined Patent Publication (Kokai) No. 58-67885 does not limit the method on the surface of a zinc-based plated steel sheet. For example, by electroplating or chemical plating, Ni is used.
And a technique for improving corrosion resistance by generating a metal such as Fe (hereinafter referred to as Prior Art 4).

[0010]

However, the above-mentioned prior art has the following problems. Prior art 1 is a method of producing an oxide mainly composed of ZnO on the surface of the plating layer by the above-mentioned various treatments, and therefore the usual weldability and workability are improved, but the press die and the plated steel sheet are Since the sliding resistance does not become sufficiently small, the effect of improving press formability is small. Furthermore, it has been revealed that the presence of ZnO-based oxide on the surface of the steel sheet further deteriorates the adhesiveness.

Prior art 2 is a method of forming an oxide film mainly composed of P oxide on the surface of a zinc-plated steel sheet, so that the press forming property and the chemical conversion processability are largely improved, but the adhesive property is deteriorated. Have the problem of doing.

It is possible to form a film having excellent adhesiveness on the surface of the plating film by paying attention to the adhesive property, but since Prior Art 3 is a method of forming a Ni oxide single phase film. Although the press moldability is improved, there is a problem that the adhesiveness is still insufficient.

The prior art 4 is a method of producing only a metal such as Ni, so that the corrosion resistance is improved, but the wettability to the adhesive is low due to the strong metallic property of the film, and sufficient adhesion is obtained. There is a problem that you can not.

Therefore, an object of the present invention is to solve the above-mentioned problems, to reduce the sliding resistance with the press die, and to increase the peel strength by using various adhesives, thereby improving the press formability. Another object is to provide a zinc-based plated steel sheet having excellent adhesiveness.

[0015]

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a mixed film containing Ni hydroxide, Ni oxide and metallic Ni (hereinafter referred to as A "Ni-O-based coating" is formed on the surface, and the surface layer portion of the Ni-O-based coating is a layer composed of Ni oxide and Ni hydroxide (in this specification, "oxide-based coating"). It has been found that a zinc-based plated steel sheet in which the thickness of the oxide-based layer is controlled to an appropriate thickness exhibits excellent press formability and adhesiveness.

That is, the conventional galvanized steel sheet is inferior in press formability to the cold rolled steel sheet. That is, the zinc-based plated steel sheet has a larger sliding resistance with the press die than the cold-rolled steel sheet. The reason is that in a zinc-based plated steel sheet, zinc having a low melting point causes an adhesion phenomenon with a die under high surface pressure. In order to prevent this, it was considered effective to form a film harder and higher in melting point than the zinc or zinc alloy plated layer on the surface of the plated layer of the zinc-based plated steel sheet. As a result of further research based on the above consideration, the present inventors formed an appropriate Ni-O-based coating on the surface of the plating layer of a zinc-based plated steel sheet, thereby forming a surface of the plating layer during press forming. It has been found that the sliding resistance with the press die can be reduced, so that the zinc-based plated steel sheet easily slips into the press die and the press formability is improved.

It has been known that the adhesiveness of the conventional zinc-based plated steel sheet is inferior to that of the cold-rolled steel sheet, but the cause has not been clarified. Therefore, as a result of researches to clarify the reason, the present inventors have revealed that the adhesiveness is governed by the composition of the oxide film on the surface of the steel sheet. That is, in the case of cold rolled steel sheet,
The oxide film on the surface of the steel sheet is mainly Fe oxide, whereas in the case of a zinc-based plated steel sheet, Zn oxide is mainly. On the other hand, it became clear that Zn oxide was inferior in adhesiveness to Fe oxide. Further, it has been clarified that the adhesiveness of the zinc-based plated steel sheet varies depending on the composition of the oxide film on the surface, and the more Zn oxide in the oxide film, the poorer the adhesiveness. Furthermore, Ni-O is applied to the surface of the zinc-based plated steel sheet.
It has been clarified that the adhesiveness is further improved when a system film is formed and metal Ni is not exposed on the surface of the film.

The present invention has been made on the basis of the above-mentioned findings, and the zinc-based plated steel sheet of the present invention has at least one surface of the plating layer on which Ni oxide, Ni
A zinc-based plated steel sheet having a Ni-O-based coating film containing a hydroxide and metallic Ni, the Ni-O
The surface layer portion of the system-based coating is composed of an oxide-based layer composed of Ni oxide and Ni hydroxide, and the thickness of the oxide-based layer is in the range of 0.5 to 5 nm. I have.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the surface of the plating layer of the zinc-plated steel sheet of the present invention is formed on the composition of the Ni-O coating and the surface layer portion of the Ni-O coating. The reason for limiting the thickness of the oxide-based layer made of Ni oxide and Ni hydroxide as described above will be described. FIG. 1 shows the structure of the zinc-based plated steel sheet of the present invention in a cross section in a direction perpendicular to the surface. Reference numeral 21 is a steel plate, 22 is a zinc-based plating layer, 23 is a Ni—O-based coating, and 24 is an oxide-based layer composed of Ni oxide and Ni hydroxide.

As described above, the Ni—O based film 23 made of Ni oxide, Ni hydroxide and metallic Ni is formed on the surface of the plated layer 22 of the zinc plated steel sheet.
When the oxide-based layer 24 made of Ni oxide and Ni hydroxide having an appropriate thickness is present in the surface layer portion of the i-O-based coating 23, press formability and adhesiveness are improved. here,
As described above, the Ni—O-based coating 23 should include not only Ni oxide and metallic Ni, but also Ni hydroxide.
When forming a film composed of an i oxide and metallic Ni, the Ni hydroxide is unavoidably formed along with the above film regardless of the forming method. Although FIG. 1 shows a zinc-based plated steel sheet having Ni—O based coating 23 formed on both surfaces, the coating may be formed on only one surface depending on the application.

The Ni--O type coating in this invention is Ni
In the zinc-based plating film below the —O-based film, a component element inevitably contained in the lower zinc-based plating layer, namely Zn,
Co, Fe, Mn, Mo, Al, Ti, Si, W, S
Component elements such as n, Pb, Nb and Ta may be inevitably incorporated in the form of oxide, hydroxide and / or metal simple substance. Even in such a case, the above N
This is because the effect of the i-O-based film is exhibited.

However, if the thickness of the oxide-based layer in the surface layer portion of the Ni—O-based coating is less than 0.5 nm, metallic Ni will partially exist on the surface of the above-mentioned coating, resulting in adhesiveness. No improvement effect is observed. On the other hand, when the thickness of the oxide-based layer exceeds 5 nm, cohesive failure of the oxide-based layer occurs, so that the effect of improving press moldability cannot be obtained, and further, phosphate crystals are formed. Is suppressed and the chemical conversion processability also deteriorates. Therefore, the thickness of the oxide-based layer in the surface layer portion of the Ni—O-based coating formed on the surface of the plating layer of the zinc-based plated steel sheet should be limited to the range of 0.5 to 5 nm.

As described above, a Ni—O type coating is formed on the surface, and the thickness of 0.5 to 5 n is formed on the surface layer of the coating.
By forming the oxide layer within the range of m, the press formability and the adhesiveness of the zinc-plated steel sheet are improved, but more desirably, the adhesion amount of the Ni-O-based coating is determined by the amount of metal in the coating. When the total amount is 10 mg / m ² or more, press moldability and adhesiveness are further improved, and
Spot weldability is secured. On the other hand, when the adhered amount exceeds 1500 mg / m ^{2 in} terms of the total amount, the press formability and adhesiveness of the zinc-plated steel sheet are saturated, and the formation of phosphate crystals is suppressed during the chemical conversion treatment, resulting in chemical conversion. Since the processability is poor, it is desirable that the amount of the Ni—O-based coating adhered is 1500 mg / m ² or less in terms of the total amount of metals in the coating.

The method of forming the Ni--O type coating of the present invention is as follows.
It is not particularly limited, displacement plating using an aqueous solution having a predetermined chemical component composition, a method by immersion in an oxidizing agent-containing aqueous solution, cathodic electrolysis treatment and anodic electrolytic treatment in an oxidizing agent-containing aqueous solution, a predetermined Spraying of an aqueous solution, roll coating and the like, and vapor phase plating methods such as laser CVD, photo CVD, vacuum vapor deposition and sputter vapor deposition can be employed.

The present inventors have completed the following method by displacement plating for forming the Ni—O type coating of the present invention. That is, the ion concentration of Ni ions is 0.1 mol /
The thickness of the Ni-O-based film after being immersed in a hydrochloric acid aqueous solution having a temperature of 40 to 70 ° C. and a pH of 2.0 to 4.0 for 5 to 50 seconds and then oxidizing in a mixed atmosphere of air and ozone. Is the method of adjusting.

The thickness of the oxide-based layer in the surface layer of the Ni-O-based coating formed by the various methods described above, Ni
The method for measuring the chemical component composition and electronic state of the —O-based film is not particularly limited, and examples thereof include the following methods. That is, a method of performing a depth direction analysis from the surface of a subject by X-ray photoelectron spectroscopy (XPS) combined with Ar ion sputtering, a method of performing a depth direction analysis from the surface of a subject by angle-resolved XPS, and a synchrotron. By changing the energy of incident X-rays by synchrotron radiation (SOR) and performing depth direction analysis from the surface of the subject using XPS, Auger electron spectroscopy (AES) or secondary ion mass spectrometry (SIMS) Examples include a method of performing depth direction analysis from the surface of the subject.

For example, in the case of measurement by XPS combined with Ar ion sputtering, the composition at that depth can be obtained by performing relative sensitivity factor correction from the spectral intensity of each element to be measured after sputtering to a predetermined depth. . By repeating this analysis from the surface, the composition distribution in the depth direction in the plating film can be measured. In this measuring method, hydroxide or Ni as an oxide reaches a maximum concentration at a certain depth and then decreases and becomes constant. At the position where the hydroxide or Ni as the oxide is deeper than the maximum concentration, the sum of the maximum concentration and the constant concentration is 1
The depth of / 2 is the thickness of the oxide-based layer in the surface layer of the Ni—O-based coating.

The zinc-based plated steel sheet used in the present invention is a steel sheet obtained by forming a plated layer on a base steel sheet by a method such as hot dipping, electroplating or vapor phase plating. In addition to pure zinc, the chemical composition of the zinc-based plating layer is Co, Ni, Fe, Mn, Mo, A.
Metals or oxides such as l, Ti, Si, W, Sn, Pb, Nb and Ta, or organic substances, etc., which are composed of a single-layer or multi-layer plating layer containing a predetermined amount of one or more of them. If In addition, the plating layer is made of Si
Fine particles such as O ₂ and Al ₂ O ₃ may be contained. In addition, as a zinc-based plated steel sheet, a multi-layer plated steel sheet having a plurality of layers having the same composition element of the plating layer but different compositions, and a composition element of the plating layer having the same composition element in the thickness direction of the plating layer It is also possible to use a functionally graded plated steel sheet having a different value.

Since the above-mentioned Ni-O-based coating is formed on at least one surface of the plated layer of the zinc-based plated steel sheet, it is used for any vehicle body part in any step of the vehicle body manufacturing process. Depending on whether it is a steel plate
The film formed on one surface or both surfaces can be appropriately selected.

[0030]

Next, the present invention will be described in more detail with reference to examples. First, a zinc-based plated steel sheet (hereinafter referred to as an original plate) before forming the Ni—O-based coating was prepared. The prepared original plate consisted of the following 7 plating species, and the following symbols were given according to the plating method, the plating composition, and the amount of plating adhered.

GA: Alloyed hot-dip galvanized steel sheet (10w
t. % Fe, the balance Zn), and the adhesion amount is 60 on both sides.
It is g / m ² . GI: Hot-dip galvanized steel sheet, adhesion amount is 9 on both sides
0 g / m ² . EG: Electrogalvanized steel sheet, the adhesion amount is 40 on both sides
g / m ² . Zn-Fe: Electric Zn-Fe alloy plated steel plate (15w
t. % Fe), and the adhesion amount is 40 g / m ² on both sides. Zn-Ni: Electric Zn-Ni alloy plated steel plate (12w
t. % Ni), and the adhesion amount is 30 g / m ² on both surfaces. Zn-Cr: Electric Zn-Cr alloy plated steel sheet (4 wt.
% Cr), and the adhesion amount is 20 g / m ² on both sides. Zn-Al: hot-dip Zn-Al alloy plated steel sheet (5 wt.
% Al), and the adhesion amount is 60 g / m ² on both sides.

A Ni-O based film was formed on the plated surface of the zinc based plated steel sheet thus prepared by the following method. That is, the ion concentration of Ni ions is 0.1 mol / l
As described above, the substrate is immersed in a hydrochloric acid aqueous solution having a temperature of 40 to 70 ° C. and a pH of 2.0 to 4.0 for 5 to 50 seconds. By adjusting the dipping time, the amount of Ni—O-based coating adhered was changed to a predetermined value.
Further, it is oxidized in a mixed atmosphere of air and ozone to form Ni-
The thickness of the oxide-based layer in the surface layer of the O-based coating was adjusted.

With respect to each of the zinc-plated steel sheets thus obtained, the thickness of the oxide-based layer in the surface layer portion of the Ni-O-based coating and its adhesion amount were measured. Table 1 and Table 2
For the zinc-based plated steel sheets within the scope of the present invention (hereinafter referred to as "the present invention sample") No. 1 to 46, and in Table 3, zinc-based plated steel sheets outside the scope of the present invention (hereinafter referred to as " The measurement results are shown for Nos. 1 to 14).

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

The thickness of the oxide-based layer in the surface layer portion of the Ni-O-based coating and the amount of deposition were measured by the following method. [Measurement Method of Thickness of Oxide-based Layer in Surface Layer of Ni-O-based Coating] It was measured by a combination of Ar ion sputtering and XPS. After Ar ion sputtering to a predetermined depth on the surface of the specimen, the measurement of each element in the Ni-O coating by XPS is repeated from the surface to obtain Ni-O.
The composition distribution of each element in the depth direction in the system coating was measured. In particular, for Ni, the state of Ni oxide containing Ni hydroxide and metallic Ni is distinguished from the difference in the binding energy of the XPS spectrum of Ni2p electrons, and the composition distribution of Ni in the depth direction is measured. did. Here, the composition of the Ni oxide was obtained by correcting the relative sensitivity factor. However,
The relative sensitivity factor between the Ni oxide containing the Ni hydroxide and the metallic Ni was assumed to be the same.

In this measuring method, after the hydroxide or Ni as an oxide reaches the maximum concentration at a certain depth,
It decreases and becomes constant. Ni as hydroxide or oxide
However, at a position deeper than the maximum concentration, the depth which is 1/2 of the sum of the maximum concentration and the constant concentration is the thickness of the oxide-based layer in the surface layer portion of the Ni—O-based coating. Ta ₂ O ₅ was used as a standard sample for the sputtering rate. The sputter rate is 6n
It was m / min.

Further, due to the above oxide-based layer existing on the outermost layer, the metal N existing below the oxide-based layer.
The thickness of the oxide-based layer was also confirmed from the dependence of the absorption amount of photoelectrons generated from i on the energy of incident X-rays.

Each of the above-mentioned specimens was subjected to an evaluation test of press formability and adhesiveness, spot weldability and chemical conversion treatability, and the test results are also shown in Tables 1 to 3.

The press formability was evaluated by the coefficient of friction between the test piece and the bead of the press, and the adhesive property was evaluated by the peel strength. The spot weldability and chemical conversion treatability were also evaluated in terms of the number of continuous spots and the state of formation of zinc phosphate coating crystals. Each evaluation test method is as follows.

[Friction Coefficient Measurement Test] In order to evaluate press formability, the friction coefficient of each specimen was measured by the following apparatus. FIG. 2 is a schematic front view showing the friction coefficient measuring device. As shown in the figure, a sample 1 for measuring a friction coefficient taken from a sample is fixed to a sample table 2, and the sample table 2 is fixed to an upper surface of a horizontally movable slide table 3. On the lower surface of the slide table 3, the roller that is in contact with it is
A slide table supporting base 5 having a la 4 is provided, which is movable up and down, and by pushing it up, a first roll for measuring a pressing load N on a sample 1 for measuring a friction coefficient by a bead 6 is provided. -The dosels 7 are attached to 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. As a lubricating oil, Knox Thrust 5 manufactured by Nippon Parkerizing Co., Ltd.
The test was conducted by applying 50 HN to the surface of Sample 1.

The friction coefficient μ between the specimen and the bead is
Formula: Calculated by μ = F / N. However, pressing load N: 400
kgf, sample withdrawing speed (horizontal moving speed of slide table 3): 100 cm / min.

FIG. 3 is a schematic perspective view showing the shape and dimensions of the beads used. The lower surface of the bead 6 slides while being pressed against the surface of the sample 1. The underside shape is width 1
0 mm, a flat surface having a length of 3 mm in the sliding direction, and each of the front and rear surfaces having a width of 10 mm having a diameter of 4.5 mmR.
The / 4 cylindrical surface is in contact as shown in FIG.

[Adhesiveness Test] The following adhesiveness test specimens were prepared from the respective specimens. FIG. 4 is a schematic perspective view illustrating the assembly process. As shown in FIG.
Two test pieces 10 having a length of m and a length of 200 mm are provided with an adhesive 12 through a spacer 11 having a diameter of 0.15 mm.
A test body 13 is prepared by laminating and adhering so as to have a thickness of 0.15 mm and baking at 150 ° C. × 10 min. The test body thus prepared was bent into a T-shape as shown in FIG. 5, and a tensile test was conducted at a speed of 200 mm / min using a tensile tester to obtain an average peel strength ( (n = 3 times) was measured. The peel strength was determined by calculating the average load from the load chart of the tensile load curve at the time of peeling, and expressed in units of kgf / 25 mm. In FIG. 5, P indicates a tensile load. The adhesive used was a PVC-based hemming adhesive. Peel strength is 12 kgf / 2
Those having a thickness of 5 mm or more have good adhesiveness.

[Continuous Dotting Property Test] In order to evaluate the spot weldability, a continuous Dotting property test was performed on each test piece. Resistance welding (spot welding), in which two specimens of the same No. were stacked, sandwiched by a pair of electrode tips from both sides, and current was concentrated by applying pressure, was continuously performed under the following welding conditions. .・ Electrode tip: dome type with 6 mm tip diameter ・ Pressure force: 250 kgf ・ Welding time: 12 cycles ・ Welding current: 11.0 KA ・ Welding speed: 1 point / sec As an evaluation of continuous spotting property, during spot welding The diameter of the melted and solidified metal part (shape: go-stone shape, hereinafter referred to as a nugget) generated at the joint of the two welded base materials (specimen) is 4 × t ^1/2 (t: The number of spots welded continuously until it became less than the plate thickness) was used. The electrode life is the above number of dots, and ◎ 5 when the electrode life is 5000 points or more.
If less than 3,000 and 3000 points or more, then ○, less than 3,000 1
When the score was 500 points or more, it was shown as Δ, and when it was below 1500 points, it was shown as x.

[Chemical conversion treatability] In order to evaluate the chemical conversion treatability, the following tests were conducted. Each sample was treated with an immersion type zinc phosphate treatment liquid for automobile coating (PBL3080 manufactured by Nippon Parkerizing Co., Ltd.) under normal conditions to form a zinc phosphate film on its surface. The crystal state of the zinc phosphate film thus formed was observed with a scanning electron microscope (SEM). As a result, the case where the zinc phosphate film was normally formed was represented by ◯, and the case where the zinc phosphate film was not formed or the crystal had a scale was represented by x.

The following items can be understood from the test results of Tables 1 to 3. The comparative specimens outside the scope of the present invention are as follows. In the case where the Ni-O based film is not formed, the plating species are as follows: GA, GI, EG, Zn-Fe, Zn
In any of -Ni, Zn-Cr, and Zn-Al, the press formability and the adhesiveness are inferior (see comparative specimen Nos. 1 to 7). Even if the oxide-based layer in the surface layer portion of the Ni—O-based coating is formed, if the thickness thereof is smaller than the range of the present invention, the press moldability and the adhesiveness are also poor (comparative specimens). No. 9 and 12). When the thickness of the oxide-based layer in the surface layer portion of the Ni—O-based coating exceeds the range of the present invention, the effect of improving press formability cannot be obtained (Comparative Specimen No. 8, 10). , 11,
13 and 14). However, although the improvement of the adhesiveness is recognized, this is because the thickness of the zinc-based plating layer is Z because the oxide-based layer is thick.
This is probably because the effect of n-oxide is masked.

On the other hand, for the test specimen of the present invention within the scope of the present invention, the zinc-based plating species is the symbol: GA,
GI, EG, ZnFe, ZnNi, ZnCr or Zn
Any of Al is excellent in press moldability and adhesiveness (see Sample Nos. 1 to 46 of the present invention).
Among these, those having an amount of Ni—O-based coating adhered within the range of 10 to 1500 mg / m ^{2 in} terms of the total amount of metal are excellent in spot weldability and chemical conversion treatability. In addition,
When the thickness of the oxide-based layer in the surface layer portion of the Ni—O-based coating is the lower limit of the range of the present invention, the coating amount of the coating is less than 10 mg / m ^{2 in} terms of the total amount of metal, the spot is Weldability is not ensured, but it is excellent in press formability, adhesiveness, and chemical conversion treatment (see Sample No. 21 of the present invention). Even if the thickness of the oxide-based layer in the surface layer portion of the Ni—O-based coating is within the range of the present invention, if the coating deposition amount exceeds 1500 mg / m ² in terms of the total amount of metal. Although it is inferior in chemical conversion treatability, it is excellent in press formability and adhesiveness as well as spot weldability.
1 and 44).

[0050]

The present invention is configured as described above.
Ni-formed on the surface of the plating layer of zinc-based plated steel sheet
O-based coating is harder than zinc or zinc alloy plating layer,
In addition, since it has a high melting point, the sliding resistance between the surface of the plating layer and the press die during press forming of the zinc-based plated steel sheet decreases, and the zinc-based plated steel sheet easily slips into the press die. Further, the Ni—O-based coating improves the peel strength of the adhesive plate. Thus, it is possible to provide a zinc-based plated steel sheet having excellent press formability and adhesiveness,
An industrially useful effect is provided.

[Brief description of the drawings]

FIG. 1 is a view showing a structure of a cross section of a zinc-based plated steel sheet of the present invention in a direction perpendicular to a surface.

FIG. 2 is a schematic front view showing a friction coefficient measuring device.

FIG. 3 is a schematic perspective view showing the shape and dimensions of the bead in FIG.

FIG. 4 is a schematic perspective view illustrating an assembling process of an adhesiveness test specimen.

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

[Explanation of symbols]

 1 sample 2 sample stage 3 slide table 4 roller 5 slide table support 6 bead 7 first load cell 8 second load cell 9 rail 10 sample 11 spacer 12 adhesive 13 Adhesion Test Specimen 21 Steel Plate 22 Zinc-Based Plating Layer 23 Ni-O-Based Film 24 Oxide-Based Layer P Tensile Load F Sliding Resistance

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Inagaki 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Masaaki Yamashita 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Date Main Steel Pipe Co., Ltd.

Claims (1)

[Claims] 1. The method according to claim 1, wherein at least one surface of the plating layer has
A zinc-based plated steel sheet on which a Ni-O based coating containing Ni oxide, Ni hydroxide and metallic Ni is formed, wherein the surface layer portion of the Ni-O based coating is Ni oxide and Ni. Zinc-based plating excellent in press formability and adhesiveness, characterized in that the oxide-based layer is composed of a hydroxide, and the thickness of the oxide-based layer is within a range of 0.5 to 5 nm. steel sheet.