JP2000129487A - Galvanized steel sheet excellent in press formability and adhesivity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a galvanized steel sheet excellent in press formability and adhesivity by forming an appropriate Fe-Ni-Zn-O film on the plating layer of a galvanized steel sheet. SOLUTION: An Fe-Ni-Zn-O film 23 contg. Fe, Ni, Zn and O and fulfilling the following conditions (1) to (5) is formed at least on one surface of the plating layer. The conditions are (1) the Ni content of the Fe-Ni-Zn-O film is controlled to 10 to 1500 mg/m2, (2) an oxide layer 24 having 4 to 100 nm thickness and consisting essentially of the oxides and/or hydroxides of Fe, Ni and Zn is formed on the surface in the Fe-Ni-Zn-O film, (3) the ratio of the Zn content (wt.%) to the sum of the Fe content (wt.%), Ni content (wt.%) and Zn content (wt.%) is controlled to >=0.3 in the oxide layer, (4) the ratio of the Fe content (wt.%) to the sum of the Fe content (wt.%), Ni content (wt.%) and Zn content (wt.%) is adjusted to >=0.04 in the outermost surface layer of the oxide layer, and (5) the O content (wt.%) of the lower layer of the Fe-Ni-Zn-O film except the oxide layer is controlled to <=10 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a galvanized steel sheet having excellent 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 galvanized steel sheet as a rust-preventive steel sheet for automobiles, it is required to have excellent press formability and adhesiveness in the vehicle body manufacturing process in addition to corrosion resistance and coating compatibility.

[0003] However, galvanized steel sheets generally have a disadvantage 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,
This is because it is larger than that of the cold rolled steel sheet. That is, since the sliding resistance is large, the zinc-plated steel sheet hardly flows into the press die in a portion where the sliding resistance between the bead and the galvanized steel sheet is extremely large, and the steel sheet is easily broken.

[0004] As a method for improving the press formability of a galvanized steel sheet, a method of applying a high-viscosity lubricating oil has been widely used. However, in this method, there are problems such as the occurrence of coating defects due to poor degreasing in the coating process due to the high viscosity of the lubricating oil, and the unstable press performance due to running out of oil during pressing. Accordingly, there is a strong demand for improving the press formability of a zinc-based plated steel sheet.

[0005] Further, in the manufacturing process of an automobile body,
Various types of adhesives are used for the purpose of preventing rust and damping the body, but in recent years it has become clear that the adhesion of galvanized steel sheets is inferior to that of cold-rolled steel sheets. Have been.

As methods for solving the above-mentioned problems, Japanese Patent Application Laid-Open Nos. 53-60332 and 2-190483 disclose electrolytic treatment, immersion treatment, coating oxidation treatment, or heat treatment on the surface of a zinc-based plated steel sheet. Discloses a technique for forming an oxide film mainly composed of ZnO to improve weldability or workability (hereinafter referred to as “prior art 1”).

Japanese Patent Application Laid-Open No. 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 a galvanized steel sheet,
A technique for forming an oxide film mainly composed of P oxide by spraying the aqueous solution to improve press formability and chemical conversion treatment (hereinafter referred to as “prior art 2”) is disclosed.

[0008] Japanese Patent Application Laid-Open No. Hei 3-91093 discloses a press-forming property and a chemical conversion by forming Ni oxide on a surface of a galvanized steel sheet by electrolytic treatment, dipping treatment, coating treatment, coating oxidation treatment, or heating treatment. A technique for improving processability (hereinafter, referred to as “prior art 3”) is disclosed.

Japanese Patent Application Laid-Open No. 58-67885 discloses a technique for improving the corrosion resistance by generating metals such as Ni and Fe on the surface of a galvanized steel sheet (hereinafter referred to as "prior art 4").
Is disclosed.

[0010]

However, the above-mentioned prior art has the following problems.

[0011] Prior art 1 is based on the various processes described above.
Since this method generates ZnO-based oxides on the surface of the plated steel sheet, the effect of reducing the sliding resistance between the press die and the plated steel sheet is small, the effect of improving the press formability is small, and the adhesion Has no improvement effect.

Prior art 2 discloses a method in which P
Because it is a method of forming an oxide film mainly composed of oxide,
There is a problem that press formability and adhesiveness are deteriorated.

Prior art 3 is a method of forming a single layer of Ni oxide on the surface of a zinc-based plated steel sheet, so that the effect of reducing the sliding resistance between the press die and the plated steel sheet is small and the press formability is reduced. Has little effect of improving the adhesiveness and has no effect of improving the adhesiveness.

Prior art 4 discloses a method for coating a surface of a galvanized steel sheet.
Since this is a method for forming a metal film of Ni, Fe, etc., the effect of improving press formability is not sufficient.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a galvanized steel sheet excellent in press formability and adhesiveness.

[0016]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to solve the above-mentioned problems, and as a result, it has been found that a proper Fe-Ni- Zn-O
It has been found that press formability and adhesiveness can be significantly improved by forming a system coating.

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 zinc having a low melting point and a mold cause an adhesion phenomenon under a high surface pressure, thereby increasing the sliding resistance. Is the cause. In order to prevent the adhesion between zinc and the mold, the present inventors have 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. Considered to be effective. As a result of studying based on this consideration, it was found that it is effective to form a proper Fe-Ni-Zn-O-based film on the surface of the zinc-based plating layer to improve the press formability. In particular, this Fe-N
By appropriately controlling the thickness of the oxide-based layer on the surface of the i-Zn-O-based coating and the Zn content, the sliding resistance between the plating layer surface and the press mold during press molding is reduced, It has been clarified that the moldability can be dramatically improved. This is considered to be because the Fe—Ni—Zn—O-based coating is hard and has a high melting point, so that it does not easily adhere to a mold during press molding.

It has been known that the galvanized steel sheet has inferior adhesiveness to that of the cold rolled steel sheet, but the cause has not been clarified. As a result of intensive studies, the present researchers found that it is effective to form a proper Fe-Ni-Zn-O-based coating on the surface of the zinc-based plating layer to improve the adhesiveness. In particular, the composition of the outermost layer of the oxide-based layer of this Fe-Ni-Zn-O-based coating is important, and an appropriate amount of
It was discovered that the presence of Fe can significantly improve the adhesion.

The present invention has been made based on the above findings. The gist of the present invention is that at least one of the plating layers contains Fe, Ni, Zn and O on the surface thereof, and
A zinc-based plated steel sheet having excellent press formability and adhesiveness, characterized by forming a Fe-Ni-Zn-O-based film satisfying (5).

(1) The Ni content of the Fe—Ni—Zn—O based film is 10 to
It is within the range of 1500 mg / m ² , and (2) Fe-Ni-Zn-O-based coatings mainly contain oxides and / or hydroxides of 4 to 100 nm thick Fe, Ni, and Zn on the surface. An oxide-based layer is formed. (3) Zn content (wt%) with respect to the sum of Fe content (wt%), Ni content (wt%), and Zn content (wt%) of the oxide-based layer Is not less than 0.3, and (4) the Fe content (wt.
%), The ratio of the Fe content (wt%) to the sum of the Ni content (wt%) and the Zn content (wt%) is 0.04 or more, and (5) the Fe-Ni-Zn-O-based coating described above. The O content in the lower layer portion excluding the oxide-based layer is 10 wt% or less.

[0021]

Next, the reason why the structure of the Fe—Ni—Zn—O based coating of the present invention is limited as described above will be described.

FIG. 1 shows a cross section of a galvanized steel sheet of the present invention. 21 is a steel plate, 22 is a zinc-based plating layer, 23 is Fe-Ni-Zn
-O-based film, 24 is an oxide-based layer.

If the Ni content is less than 10 mg, the effect of improving press formability is insufficient. If the Ni content exceeds 1500 mg / m ² , the effect of improving press formability is saturated, which is economically undesirable. Therefore, the Ni content is set to 10 to 1500 mg / m ² .

By properly controlling the thickness and the Zn content of the oxide-based layer, the effect of improving press formability is greatly increased.

When the thickness of the oxide-based layer is 4 nm or more, the effect of improving the press formability is increased. If it exceeds 100 nm, the formation of phosphate crystals is suppressed, and the chemical conversion property deteriorates.
Therefore, the thickness of the oxide-based layer is set to 4 to 100 nm.

[0027] Zn present in the oxide-based layer has the function of further improving press formability. Z with respect to the sum of the Fe content (wt%), the Ni content (wt%), and the Zn content (wt%) of the oxide-based layer
The ratio of the n content (wt%) (hereinafter, Zn / (Fe + Ni + Zn) ratio) is set to 0.
By setting it to 3 or more, the effect of improving press formability is increased. Therefore, the ratio of Zn / (Fe + Ni + Zn) of the oxide-based layer is set to ≧ 0.3.

[0027] Adhesive compatibility is determined on the outermost layer of the oxide-based layer.
Dramatic improvement is achieved by containing Fe in an appropriate amount.
Fe content (wt%) and Ni content (wt%) in the outermost layer of the oxide-based layer
The ratio of Fe content (wt%) to the sum of Zn content and Zn content (wt%) (hereinafter, Fe / (Fe + Ni + Zn) ratio) is 0.04 or more, greatly improving adhesive compatibility. Can be done. Therefore,
The ratio of Fe / (Fe + Ni + Zn) in the outermost layer of the oxide-based layer is set to 0.04 or more.

If the O content of the lower layer portion other than the oxide-based layer exceeds 10%, the formation of phosphate crystals is suppressed, and the chemical conversion property deteriorates. Therefore, the O content needs to be 10% or less.

The method for measuring the composition distribution in the thickness direction and the depth direction of the oxide-based layer formed on the surface of the Fe—Ni—Zn—O-based coating is not particularly limited. X-ray photoelectron spectroscopy (XPS) in combination with X-ray photoelectron spectroscopy (XPS), depth-resolved X-ray analysis from surface using angle-resolved XPS, Auger electron spectroscopy
S), secondary ion mass spectrometry (SIMS), and other methods that perform depth analysis from the surface.

For example, when measuring by AES combined with Ar ion sputtering, after sputtering to a predetermined depth, the composition at that depth can be obtained by correcting the relative sensitivity factor from the spectral intensity of each element to be measured. By repeating this analysis from the surface, the composition distribution in the depth direction of the plating film can be measured.

Fe / (Fe + Ni + Zn) at the outermost layer of the oxide-based layer
The ratio can be determined from the composition measured by AES after removing the contamination layer on the sample surface layer by Ar ion sputtering.

In this measurement, the content of Ni, which is a Fe—Ni—Zn—O-based coating component, decreases after reaching a maximum value at a certain depth and becomes constant. When the Ni content is deeper than the maximum value,
A depth that is 1/2 of the sum of the maximum value and the constant value is obtained, and the portion from the outermost surface of the oxide-based layer to this depth is defined as an Fe-Ni-Zn-O-based coating.

Furthermore, O due to oxides or hydroxides
After reaching a maximum value at a certain depth, decreases. The depth at which the O content is half the sum of the maximum value and the constant value at a position deeper than the maximum value is defined as the thickness of the oxide-based layer of the Fe-Ni-Zn-O-based coating. The range from the outermost layer portion of the oxide-based layer to this depth is defined as the oxide-based layer, and the Zn / (Fe + Ni + Zn) ratio of the oxide-based layer can be determined from the composition in this range.

Further, the O content is calculated from the composition of the lower layer portion of the Fe—Ni—Zn—O-based coating except for the oxide-based layer.

In the present invention, the steel sheet having a zinc-based plating used for forming a Fe-Ni-Zn-based film on the surface may be a hot-dip plating method, an electroplating method, or a vapor-phase plating method. Any steel plate having a zinc-based plating layer formed thereon can be used. The components of this zinc-based plating layer include pure Zn, Fe, Ni, Co, Mn, Cr, Al, Mo, Ti, Si, W, Sn, P
It is made of a metal such as b, Nb and Ta (however, Si is also treated as a metal) or an oxide, or a single or multiple plating layer containing one or more organic substances. Further, the plating layer may contain fine particles such as SiO ₂ and Al ₂ O ₃ . Further, as the zinc-based plated steel sheet, a multi-layer plated steel sheet and a functionally graded plated steel sheet in which the composition of the plating layer is changed can be used.

In the present invention, Fe, Ni and Zn contained in the Fe—Ni—Zn—O-based film may be any of metals, oxides and hydroxides. In addition, component elements and component elements inevitably contained in the lower zinc-based plating layer, for example,
Cr, Co, Mn, Mo, Al, Ti, Si, W, Sn, Pb, Nb or T
Elements such as a may be incorporated in the form of oxides, hydroxides, and / or simple metals. This is because even in such a case, the effect of the Fe-Ni-Zn-O-based coating described above is exerted.

The method for forming the Fe—Ni—Zn—O-based film of the present invention comprises:
There is no particular limitation, such as displacement plating, a method by immersion in an aqueous solution containing an oxidizing agent, cathodic electrolytic treatment and anodic electrolytic treatment in an aqueous solution containing an oxidizing agent, spraying of a predetermined aqueous solution, roll coating, etc., and laser CVD. , Photo CVD, vacuum deposition,
In addition, a vapor phase plating method such as a sputter deposition method can be adopted. Also, two or more of these processes can be combined.

[0038]

Next, the present invention will be described in more detail with reference to examples.

First, a zinc-plated steel sheet (hereinafter referred to as an original sheet) before forming a Fe—Ni—Zn—O-based film was prepared. The adjusted original plate consists of three types of plating with a thickness of 0.8 mm,
The following symbols are used according to the plating method, plating composition, and plating adhesion amount.

GA: alloyed hot-dip galvanized steel sheet (10 wt% F
e, balance Zn), and the adhesion amount is 60 g / m ² on both sides. GI: Hot-dip galvanized steel sheet with 90g /
a m ^2. EG: Electrogalvanized steel sheet with 40g / m ^{2 on} both sides
It is.

An Fe—Ni—Zn—O-based film was formed on the surface of the thus-prepared galvanized steel sheet by one of the following two methods.

[Formation Method A] The original plate was subjected to cathodic electrolysis in a sulfuric acid acidic aqueous solution containing pH 2 containing Fe ²⁺ , Ni ²⁺ , Zn ²⁺ and an oxidizing agent, so that the surface of the original plate was Fe-N
An i-Zn-O based film was formed. The temperature was 50 ° C. Here, the total concentration of Fe ²⁺ , Ni ^2+, and Zn ²⁺ was 1 mol / l, and the composition of the entire film and the oxide-based layer was controlled by changing the mixing ratio. Also, use sodium nitrate as the oxidizing agent,
The thickness of the oxide-based layer and the O content of the lower layer were adjusted by changing the concentration to various predetermined values. Further, the Ni content in the film was controlled by adjusting the electrolysis time.

[Forming Method B] A hydrochloric acid acidic aqueous solution containing pH 2 containing Fe ²⁺ , Ni ²⁺ , Zn ²⁺ and an oxidizing agent is sprayed on the original plate, so that Fe-Ni-Zn -O-based film was formed. The temperature was 60 ° C. Here, Fe ²⁺ , Ni ²⁺ and Zn
The total concentration of ²⁺ was 0.6 mol / l, and the composition of the entire film and the oxide-based layer was controlled by changing the mixing ratio. Also,
Hydrogen peroxide was used as an oxidizing agent, and the concentration was changed to various predetermined values to adjust the thickness of the oxide-based layer and the O content in the lower layer. Further, the Ni content in the film was controlled by adjusting the spraying time.

Specimens were sampled from the respective zinc-based plated steel sheets having a Fe-Ni-Zn-O-based film formed on the surface by the above method. In addition, the specimen was also sampled from the case where the Fe-Ni-Zn-O-based film was not formed on the surface. Next, the test specimens collected were subjected to an analysis test on the Fe-Ni-Zn-O-based coating and a property evaluation test of the press-formability, chemical conversion treatment, and adhesion of the zinc-based plated steel sheet. The analytical test method and the characteristic evaluation test method are as follows.

(1) Analytical test “Ni content in film (mg / m ² )” The Fe—Ni—Zn—O film and the lower plating layer were dissolved and peeled off with dilute hydrochloric acid, and Ni was removed by ICP.
Was quantitatively analyzed, and the Ni content in the film was calculated from the results.

"The thickness (nm) of the oxide-based layer,
Zn / (Fe + Ni + Zn) ratio (wt% / wt%), Fe / (Fe + Ni + Zn) ratio (wt% / wt%) of the outermost layer of the oxide-based layer, oxide-based layer O content (wt%) of lower layer part excepted ”First, Ar ion sputtering was performed for 30 seconds to remove the contamination layer on the surface of the specimen. Next, the content (wt%) of each element in the Fe-Ni-Zn-O-based film was measured by AES, and the Fe / (Fe + Ni + Zn) ratio was calculated. The result was obtained by comparing the Fe /
(Fe + Ni + Zn) ratio.

Subsequently, after performing Ar ion sputtering to a predetermined depth, each element in the Fe—Ni—Zn—O based film is measured by AES, and the measurement is repeated to obtain the Fe—Ni—Zn—O based film. The composition distribution of each element in the depth direction was measured.

In this measurement, the Ni content, which is a Fe—Ni—Zn—O-based film component, decreases after reaching a maximum value at a certain depth, and becomes constant. When the Ni content is deeper than the maximum value,
A depth that was 1/2 of the sum of the maximum value and the constant value was determined, and the Fe-Ni-Zn-O-based film was formed from the outermost surface of the oxide-based layer to this depth.

Furthermore, O due to oxides or hydroxides
After reaching a maximum value at a certain depth, decreases. The depth at which the O content was half of the sum of the maximum value and the constant value at a position deeper than the maximum value was defined as the thickness of the oxide-based layer of the Fe-Ni-Zn-O-based coating. The range from the outermost layer of the oxide-based layer to this depth was defined as the oxide-based layer, and the Zn / (Fe + Ni + Zn) ratio of the oxide-based layer was determined from the composition in this range.

Further, the O content was calculated from the composition of the lower layer portion of the Fe—Ni—Zn—O-based coating excluding the oxide-based layer.

Note that SiO ₂ was used as a standard sample for the sputtering rate.
And the sputtering speed was 4.5 nm / min.

(2) Property evaluation test "Friction coefficient measurement test" In order to evaluate press formability,
The friction coefficient of each specimen was measured by the following device as follows.

FIG. 2 is a schematic front view showing a friction coefficient measuring device. As shown in the figure, 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 is
It is fixed to the upper surface of the horizontally movable slide table 3. On the lower surface of the slide table 3, a vertically movable slide table support 5 having rollers 4 in contact therewith
The first load cell 7 for measuring the pressing load N of the bead 6 against the friction coefficient measurement sample 1 by being pushed up is attached to the slide table support 5. A second load cell 8 for measuring a sliding resistance force F for moving the slide table 3 in the horizontal direction while the pressing force is applied is attached to one end of the slide table 3. As a lubricating oil, Noxlast 55 manufactured by Nippon Parkerizing Co., Ltd. was used.
The test was performed by applying 0HN 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: 400kg
f, Sample pulling speed (horizontal moving speed of slide table 3): 100 cm / min.

FIG. 3 is a schematic perspective view showing the shapes and dimensions of the beads used. The bead 6 slides while being pressed against the surface of the sample 1. The shape of the bead 6 is width
The sample is 10 mm, the length of the sample in the sliding direction is 69 mm, the lower part of both ends in the sliding direction is a curved surface with a curvature of 4.5 mmR, and the lower surface of the bead against which the sample is pressed has a flat surface of 10 mm in width and 60 mm in the sliding direction.

"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 the figure, width 25mm,
A specimen 13 was prepared by laminating two specimens 10 having a length of 200 mm and bonding them together with a 0.15 mm spacer 11 therebetween so that the thickness of the adhesive 12 became 0.15 mm.
Perform baking at ° C for 10 minutes. The specimen thus prepared was bent into a T-shape as shown in FIG. 5 and subjected to a tensile test at a speed of 200 mm / min using a tensile tester. n = 3 times). The peel strength was determined by calculating an average load from a load chart of a tensile load curve at the time of peeling, and expressed in units of kgf / 25 mm. FIG.
In the equation, P indicates a tensile load. The adhesive used was a PVC-based hemming adhesive.

"Chemical conversion test" In order to evaluate the chemical conversion property, the following test was conducted. Each specimen was treated with an immersion type zinc phosphate treatment solution (PBL3080 manufactured by Nippon Parkerizing Co., Ltd.) for a base material for automotive coating under normal conditions to form a zinc phosphate film on the surface. The crystal state of the zinc phosphate film thus formed was observed by a scanning electron microscope (SEM), and divided into three stages according to the crystal state. The signs of the evaluation categories and their contents are as follows.

：: The crystals of the zinc phosphate film are dense and small. ×: The crystals of the zinc phosphate coating are coarse.

Table 1 shows the production conditions of the test specimens and the results of analysis tests and characteristic evaluation tests.

[0060]

[Table 1]

From the test results in Table 1, the following matters are clear. (1) In the case where the Fe—Ni—Zn—O based film is not formed, the press formability and adhesiveness are inferior even if the plating type is GA, EG or GI (Comparative Examples 7 and 8). , 9).

(2) When the Ni content of the Fe—Ni—Zn—O-based coating is lower than the range of the present invention, the effect of improving press formability is small (Comparative Example 1).

(3) When the thickness of the oxide-based layer of the Fe-Ni-Zn-O-based coating is smaller than the range of the present invention, the effect of improving press formability is small (Comparative Example 2).

(4) If the thickness of the oxide-based layer of the Fe—Ni—Zn—O-based coating is larger than the range of the present invention, the chemical conversion property is deteriorated (Comparative Example 3).

(5) Zn in oxide layer of Fe—Ni—Zn—O based film
When the content is lower than the range of the present invention, the effect of improving press formability is small (Comparative Example 4).

(6) When the Fe content of the outermost layer of the oxide-based layer of the Fe-Ni-Zn-O-based coating is lower than the range of the present invention, no effect of improving the adhesiveness is exhibited (Comparative Example 5).

(7) When the O content of the lower layer portion of the Fe—Ni—Zn—O-based coating other than the oxide-based layer is higher than the range of the present invention, the chemical conversion property is deteriorated (Comparative Example 6).

(8) On the other hand, the invention examples within the scope of the present invention are excellent in press moldability and adhesiveness regardless of the plating type, GA, GI or EG, and The properties are also good.

[0069]

The present invention is configured as described above.
The Fe-Ni-Zn-O-based coating formed on the surface of the zinc-based plated steel sheet is hard and has a high melting point, which reduces the sliding resistance between the plating layer surface and the press mold during press forming. And improve press formability. In addition, the presence of Fe in the outermost layer of the oxide-based layer has the effect of improving the adhesiveness. Further, since the Fe-Ni-Zn-O-based coating has a high melting point, it has an effect of improving continuous spotting property in spot weldability. As described above, according to the present invention, it is possible to provide a zinc-based plated steel sheet having excellent press formability, adhesiveness, and spot weldability, and an industrially useful effect is provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a galvanized steel sheet according to the present invention.

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

FIG. 3 is a schematic perspective view showing a bead shape and dimensions in FIG. 2;

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

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

[Explanation of symbols]

 REFERENCE SIGNS LIST 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 Rail 10 Specimen 11 Spacer 12 Adhesive 13 Specimen for adhesion test 21 Steel plate 22 Zinc Plating layer 23 Fe-Ni-Zn-O-based film 24 Oxide-based layer N Pressing load F Sliding resistance P Tensile load

Continuing from the front page (72) Inventor: Ritaka Sakurai, 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor: Masaru Sagiyama 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan In-house F-term (reference) 4K024 AA05 AA14 AA17 BA03 BB02 BC01 DB03 GA08 GA10 GA11 GA16 4K026 AA02 AA07 AA12 AA13 AA22 BA08 BA11 BA12 BB04 BB09 BB10 CA13 CA18 CA32 CA33 CA35 DA16 4K044 AA02 CA04 CB10

Claims (1)

[Claims] 1. A method according to claim 1, wherein at least one of the plating layers has Fe,
Zinc plating excellent in press formability and adhesion characterized by forming a Fe-Ni-Zn-O coating containing Ni, Zn and O and satisfying the following (1) to (5). steel sheet. (1) Yes Ni content of Fe-Ni-Zn-O-based film is in the range of 10~1500mg / m ^{2, (2)} thickness Fe-Ni-Zn-O-based surface in the film
An oxide-based layer mainly composed of oxides and / or hydroxides of Fe, Ni, Zn of 4 to 100 nm is formed. (3) Fe content (wt%) and Ni content of the oxide-based layer (4) the ratio of the Zn content (wt%) to the sum of the Zn content (wt%) and the Zn content (wt%) is 0.3 or more;
Fe content (wt%) and Ni content in the outermost layer of the oxide-based layer
The ratio of the Fe content (wt%) to the sum of (wt%) and Zn content (wt%) is 0.04 or more, and (5) excluding the oxide-based layer of the Fe-Ni-Zn-O-based coating The O content in the lower layer is 10 wt% or less.