JP3111887B2 - Galvanized steel sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a galvanized steel sheet, and more particularly to at least excellent press formability among press formability, spot weldability, adhesiveness and chemical conversion treatment. The present invention relates to a galvanized steel sheet having excellent spot weldability, adhesiveness, and chemical conversion treatment properties depending on the application.

[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-proof steel sheet for automobiles, in addition to corrosion resistance and paint compatibility, the performance required in the vehicle body manufacturing process includes press formability, spot weldability, adhesiveness and chemical conversion. It is important that the processability is excellent.

[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 instability of press performance due to lack of oil during press molding. Accordingly, there is a strong demand for improving the press formability of a zinc-based plated steel sheet.

[0005] On the other hand, zinc-based plated steel sheets are susceptible to abrasion of the copper electrodes due to the reaction of molten copper and molten zinc during spot welding to easily form a brittle alloy layer. However, there is a problem that the continuous hitting property is inferior to that of

Further, in the manufacturing process of an automobile body,
Various types of adhesives are used for the purpose of rust prevention and vibration damping of car bodies, but in recent years it has become clear that the adhesion of galvanized steel sheets is inferior to that of cold rolled steel sheets. Was.

As a method 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. 3-249182 discloses that a surface of a zinc-based plated steel sheet is made of Mn oxide, phosphoric acid and other oxides.
A technique for coating a Mn-based oxide film to improve press formability and chemical conversion treatment (hereinafter referred to as prior art 2) is disclosed.

Japanese Patent Application Laid-Open No. Hei 3-91093 discloses press formability and chemical conversion treatment by forming Ni oxide on the surface of a galvanized steel sheet by electrolytic treatment, dipping treatment, coating treatment, coating oxidation treatment or heat treatment. It discloses a technology (hereinafter referred to as Prior Art 3) that improves the performance.

JP-A-3-7282 discloses Fe, Ni and Co.
Japanese Patent Application Laid-Open No. 58-67885 discloses a method of substituting and precipitating one or more kinds of metals selected from the group consisting of, for example, electroplating and chemical plating on the surface of a galvanized steel sheet. Discloses a technique (hereinafter referred to as prior art 4) for generating metals such as Ni and Fe to improve corrosion resistance.

[0011]

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

The prior art 1 is based on the various processes described above.
Because it is a method of generating an oxide mainly composed of ZnO on the plating layer surface, 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 ZnO-based When the oxide is present on the plating surface, there is a problem that the adhesiveness is deteriorated.

Prior art 2 is a method of forming a Mn oxide and a P oxide on the surface of a galvanized steel sheet, so that the press formability and the chemical conversion property are greatly improved, but the spot weldability and the adhesive property are improved. Is deteriorated.

Prior art 3 is a method of forming a single-phase Ni oxide film, so that although corrosion resistance is improved, there is a problem that adhesion is reduced.

The prior art 4 is a method of forming only a metal such as Ni, so that the corrosion resistance is improved, but the effect of the press formability is not sufficiently improved due to the strong metallic properties of the film. Furthermore, there is a problem that the wettability of the metal to the adhesive is low and sufficient adhesiveness cannot be obtained.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, to provide a basic condition that the sliding resistance with a press die is small, and to provide a chemical component having a high melting point and good adhesiveness. By forming a film having a composition on the surface of the plating layer of a zinc-based plated steel sheet, it is premised that it is excellent in press formability, and depending on the application, it is excellent in spot weldability, adhesion and chemical conversion treatment It is to provide a galvanized steel sheet.

[0017]

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 an appropriate Fe-Ni-O-based coating We found that forming a film can improve press formability, spot weldability, adhesion, and chemical conversion treatment properties.According to Japanese Patent Application No. 6-257499, based on the premise that press formability is excellent, Appropriately applied for a zinc-based plated steel sheet having excellent spot weldability, adhesion and chemical conversion treatment properties.

The present inventors have conducted intensive studies in order to further improve the press formability of the above-mentioned galvanized steel sheet. As a result, the surface of the plating layer of the galvanized steel sheet was coated with Fe-Ni-P-
It has been found that by forming an appropriate O-based film, press formability, spot weldability, adhesiveness and chemical conversion treatment can be further improved.

That is, the conventional galvanized steel sheet is inferior to the cold-rolled steel sheet in press formability. This is because the sliding resistance between the zinc-plated steel sheet and the press die is large. The reason for this is that, under high surface pressure, the low melting point zinc and the mold cause an adhesion phenomenon. In order to prevent this, it is effective to form a film having a higher melting point than the zinc or zinc alloy plating layer on the surface of the plating layer of the zinc-based plated steel sheet.

Since the Fe—Ni—PO coating in the present invention is hard and has a high melting point, the surface of the zinc-based plated steel sheet
-By forming a Ni-PO coating, the sliding resistance between the plating layer surface and the press mold during press forming decreases, and the zinc-based plated steel sheet slides easily into the press mold, improving press formability. I do. In the present invention,
Ni of the Fe-Ni-PO coating has a property of easily adsorbing the components of the press oil when the new surface is exposed during sliding under a high surface pressure, and the adsorbed film has an effect of preventing the adhesion phenomenon. Further, P of the Fe—Ni—PO coating in the present invention has an effect of reacting with the components of the press oil to form a metallic soap, thereby greatly reducing the sliding resistance.

The conventional galvanized steel sheet is inferior to the cold-rolled steel sheet in continuous hitting property in spot welding. The reason for this is that the molten zinc at the time of welding diffuses into the copper of the electrode to form a fragile alloy layer, which causes an increase in the electrode tip diameter due to peeling of the alloy layer. Therefore, as a method for improving the continuous hitting property of zinc-based plated steel sheet,
It is effective to form a high melting point film on the surface of the plating layer to suppress the reaction between the plating metal and the copper electrode. The present inventors have studied various types of coatings in order to improve the spot weldability of galvanized steel sheets, and have found that Ni or Ni oxide coatings are particularly effective. Although the reason for this is not clear, the very high melting point Ni oxide suppresses the diffusion of zinc into the copper electrode and reduces wear of the copper electrode, or Ni reacts with Zn to form a high melting point Zn-Ni alloy. Is formed and the reaction between zinc and the copper electrode is suppressed.

It has been known that the adhesiveness of the conventional galvanized steel sheet is inferior to that of the cold-rolled steel sheet, but the cause has not been clarified. Then, the present inventors investigated the cause and found that the adhesiveness is governed by the composition of the oxide film on the surface of the steel sheet.
In other words, in the case of a cold-rolled steel sheet, the oxide film on the steel sheet surface is Fe
While mainly composed of oxides, galvanized steel sheets mainly
Mainly Zn oxide. The adhesiveness differs depending on the composition of the oxide film, and the Zn oxide was inferior in adhesiveness to the Fe oxide. Therefore, by forming an Fe oxide film on the surface of a galvanized steel sheet as in the present invention, it is possible to improve the adhesiveness.

The conversion treatment property of the conventional galvanized steel sheet is as follows:
Inferior to cold-rolled steel sheet due to high Zn concentration on the steel sheet surface, resulting in coarse and uneven phosphate crystals formed and different quality of phosphate crystals I do. When the Zn concentration on the surface of the steel sheet is high, the phosphate crystals are mainly composed of whipite, and the secondary adhesion of hot water after coating is poor. This is because, since the Fe concentration in the phosphate crystals is low, when exposed to a humid environment after coating, the chemical conversion treatment film condenses and loses adhesion to the steel sheet.

In order to suppress the condensed water of the chemical conversion treatment film,
It is effective to include metals such as Fe and Ni in the phosphate crystals. By forming the Fe-Ni-PO-based coating of the present invention, Ni and Fe in the coating are incorporated into the phosphate crystals during the chemical conversion treatment, and the chemical conversion coating having good adhesion is obtained. It was found that uniform phosphate crystals were formed, and not only the secondary adhesion of hot water but also the corrosion resistance were improved.

As described above, at least Ni and Fe metals, and Ni and Fe
In addition, due to the proper formation of a mixture film containing an oxide or hydroxide of P (hereinafter referred to as Fe-Ni-PO-based film), the zinc-based plated steel sheet has a press formability,
It was found that spot weldability, adhesion, and chemical conversion properties were excellent. That is, the above-mentioned Fe-Ni-PO
It is an essential condition of the present invention that the system film is formed on the surface of the plating layer.

The present invention has been made based on the above-mentioned findings, and the zinc-based plated steel sheet of the present invention has an Fe—Ni—PO-based film formed on at least one surface of a plated layer. A galvanized steel sheet, wherein the Fe-Ni-PO
Ni content in the system coating is in the range of 10~1500mg / m ^2, further, P the content of the Fe-Ni-PO-based film is 5～1000M
g / m ² , and the oxygen content in the Fe—Ni—PO-based coating is in the range of 1 to 50 at% (hereinafter referred to as the first invention). It is.

The galvanized steel sheet according to the present invention is a galvanized steel sheet having a Fe—Ni—PO coating formed on at least one surface of the plating layer, wherein the Fe—Ni—PO coating is the Ni-content is in the range of 10~1500mg / m ^2, further, P the content of the Fe-Ni-PO-based film in the, 5 to 1000 mg / m ²
And further, the Fe content relative to the sum of the Fe content (wt%) and the Ni content (wt%) in the Fe-Ni-PO-based coating.
(wt%) is in the range of more than 0 to 0.9 and the F
The one characterized by the fact that the oxygen content in the e-Ni-PO coating is in the range of 1 to 50 at% (hereinafter referred to as the second invention).
It is.

The galvanized steel sheet according to the present invention is a galvanized steel sheet having a Fe—Ni—PO coating formed on at least one surface of a plating layer, wherein the Fe—Ni—PO coating is the Ni-content is in the range of 10~1500mg / m ^2, further, P the content of the Fe-Ni-PO-based film in the, 5 to 1000 mg / m ²
And further, the Fe content relative to the sum of the Fe content (wt%) and the Ni content (wt%) in the Fe-Ni-PO-based coating.
(wt%) is in the range of 0.05 to less than 1.0, and
The oxygen content in the Fe-Ni-PO-based coating is in the range of 1 to 50 at% (hereinafter, referred to as a third invention).

The galvanized steel sheet according to the present invention is a galvanized steel sheet having a Fe—Ni—PO coating formed on at least one surface of a plating layer, wherein the Fe—Ni—PO coating is the Ni-content is in the range of 10~1500mg / m ^2, further, P the content of the Fe-Ni-PO-based film in the, 5 to 1000 mg / m ²
And further, the Fe content relative to the sum of the Fe content (wt%) and the Ni content (wt%) in the Fe-Ni-PO-based coating.
(wt%) is in the range of 0.05 to 0.9, and
It is characterized in that the oxygen content in the Fe-Ni-PO-based film is in the range of 1 to 50 at% (hereinafter, referred to as a fourth invention).

The zinc-plated steel sheet of the present invention is a zinc-plated steel sheet having a Fe—Ni—PO coating formed on at least one surface of a plating layer, wherein the Fe—Ni—PO coating is the Ni-content is in the range of 10~1500mg / m ^2, further, P the content of the Fe-Ni-PO-based film in the, 5 to 1000 mg / m ²
And further, the Fe content relative to the sum of the Fe content (wt%) and the Ni content (wt%) in the Fe-Ni-PO-based coating.
(wt%) is in the range of 0.05 to 0.9, and
The invention is characterized in that the oxygen content in the Fe-Ni-PO-based coating is in the range of 1 to 20 at% (hereinafter, referred to as a fifth invention).

The zinc-plated steel sheet of the present invention is a zinc-plated steel sheet having a Fe—Ni—PO coating formed on at least one surface of a plating layer, wherein the Fe—Ni—PO coating is the Ni-content is in the range of 10~1200mg / m ^2, further, P the content of the Fe-Ni-PO-based film in the, 5~800mg / m ²
And further, the Fe content relative to the sum of the Fe content (wt%) and the Ni content (wt%) in the Fe-Ni-PO-based coating.
(wt%) is in the range of 0.1 to 0.3, and the F
It is characterized in that the oxygen content in the e-Ni-PO-based film is in the range of 1 to 20 at% (hereinafter, referred to as a sixth invention).

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the reason why the amount of the Fe-Ni-PO-based film formed on the surface of the plating layer of the galvanized steel sheet of the present invention and the composition thereof are limited as described above will be described.

<Ni content in Fe-Ni-PO-based film> As described above, press-formability, spot weldability, adhesion, and chemical conversion treatment are improved by forming the Fe-Ni-PO-based film. . However, the Ni content in the Fe-Ni-PO coating is 10m.
If it is less than g / m ² , the effects of improving press formability, spot weldability and chemical conversion property cannot be obtained.

On the other hand, if the amount of adhesion exceeds 1500 mg / m ² , the effect of improving the press formability and spot weldability is saturated, and furthermore, the formation of phosphate crystals is suppressed, and the chemical conversion treatment is deteriorated. . In order to improve the chemical conversion property, the Ni content is desirably 1200 mg / m ² or less.
Therefore, Ni content of the Fe-Ni-PO-based film in the 10~1500mg / m ²
, Desirably within the range of 10 to 1200 mg / m ² .

<P content in Fe-Ni-PO coating> Fe-Ni-P-
By containing an appropriate amount of P in the O-based film, press formability is improved. However, P in Fe-Ni-PO coating
If the content is less than 5 mg / m ² , the effect of improving press formability cannot be obtained.

On the other hand, if the amount exceeds 1000 mg / m ² , the effect of improving press formability is saturated, and furthermore, spot weldability and adhesion may be deteriorated, and chemical conversion treatment may be deteriorated. Not preferred. In order to improve the various effects, the P content is desirably 800 mg / m ² or less. Therefore, the P content in the Fe-Ni-PO coating is 5
In the range of 1000 mg / m ^2, preferably it should be limited to the range of the 5~800mg / m ^2.

<Oxygen Content in Fe-Ni-PO Coating> Fe-Ni
-Press formability is improved by containing an appropriate amount of oxygen in the PO-based film. However, when the oxygen content in the Fe-Ni-PO-based coating is less than 1 at%, the metallic properties of the coating become so strong that the effect of improving press formability is not exhibited.
Also, the wettability with the adhesive is reduced.

On the other hand, if the oxygen content exceeds 20 at%, the amount of the oxide becomes too large, so that the formation of phosphate crystals is suppressed and the chemical conversion property deteriorates. However, the upper limit of the oxygen content is high for applications that do not require excellent chemical conversion property. However, the oxygen content is 50at
%, The Fe-Ni-PO-based film becomes almost composed of oxides, and the presence of a simple metal in the film becomes small. In this case, since the conductivity of the oxide is low, the electric resistance during welding increases significantly, and the temperature of the electrode tip during welding increases. For this reason, the electrode is easily worn and the number of continuous hit points is reduced. Therefore, even when the chemical conversion property is not a problem, the oxygen content of the film should be reduced from the viewpoint of spot weldability.
Should be less than 50at%.

Therefore, in order to improve the press formability, or the press formability and the spot weldability, or the press formability and the adhesiveness, or the press formability, the spot weldability and the adhesiveness, Fe- The oxygen content of the Ni-PO coating should be in the range of 1 to 50 at%,
In order to improve press formability, spot weldability, adhesiveness, and chemical conversion treatment, the oxygen content of the Fe-Ni-PO-based coating should be in the range of 1 to 20 at%.

<Ratio of the Fe content to the sum of the Ni content and the Fe content in the Fe-Ni-PO-based film> The proper amount of Fe contained in the Fe-Ni-PO-based film provides the adhesive property. Is improved. Adhesion is better for metals with a higher surface potential, Fe
Belongs to the metal having the highest surface potential. Therefore, the more Fe is contained, the more the adhesion is improved. However, Fe
The ratio of the Fe content (wt%) to the sum of the Fe content (wt%) and the Ni content (wt%) in the -Ni-PO-based coating (hereinafter, Fe /
(Fe + Ni) is less than 0.05, the effect of improving the adhesiveness is not exhibited. Further, when extremely excellent adhesiveness is required stably, it is desirable that the content of Fe / Fe + Ni in the coating is 0.1 or more in order to secure the content of Fe present in the coating.

However, for applications that do not require excellent adhesion, the lower limit of Fe / Fe + Ni in the film is not required. However, when Fe / Fe + Ni in the film is 0 (zero), Fe-Ni-P-
Fe is no longer present in the O-based film, and does not satisfy the essential requirement of the present invention that the Fe-Ni-PO-based film is present. Therefore,
Fe / Fe + Ni in film even when adhesion is not a problem
Should be greater than 0 (zero).

On the other hand, when Fe / Fe + Ni in the coating exceeds 0.9,
Since the Ni content in the coating is reduced, the ratio of the high melting point Zn—Ni alloy formed during welding is reduced, so that the electrode is severely deteriorated and the effect of improving spot weldability is not exhibited. Further, when extremely excellent spot weldability is required stably, it is desirable that the content of Fe / Fe + Ni in the coating be 0.3 or less in order to secure the Ni content in the coating.

However, for applications that do not require excellent spot weldability, the upper limit of Fe / Fe + Ni in the coating is not required. However, when the ratio of Fe / Fe + Ni in the film is 1.0, Ni is no longer present in the film, and does not satisfy the essential requirement of the present invention that the Fe-Ni-PO system film exists. Therefore, even if spot welding is not a problem, Fe / Fe + Ni
Should be less than 1.0.

Therefore, in order to improve the press formability and the spot weldability, Fe / Fe + Ni in the film is reduced to 0 (zero).
It should be within the range of 0.9, and in order to improve press formability and adhesion, Fe / Fe + Ni
Should be in the range of 0.05 to less than 1, press formability,
In order to improve the spot weldability and adhesiveness, Fe / Fe + Ni in the coating should be in the range of 0.05 to 0.9, preferably 0.1 to 0.9.
Should be in the range of 0.3.

The galvanized steel sheet requires certain properties (four properties of press formability, spot weldability, adhesiveness and chemical conversion treatment) to be provided depending on the application. Therefore, among the properties of the zinc-based plated steel sheet having the above-described Fe-Ni-PO-based film formed on the surface thereof, depending on which property is at what level, the Ni content of the Fe-Ni-PO-based film, The P content and its oxygen content and the proper range of Fe / Fe + Ni in the film should be determined. The appropriate range is as follows from the above.

<Fe—N necessary for the characteristics to satisfy a predetermined value
Ni content and P content of iPO-based coatings and their oxygen content, and zinc / galvanized steel sheets with Fe / Fe + Ni> Fe-Ni-PO coatings formed on the surface of the coatings, (1) Press formability excellent in order to make the, Ni content in: 10~1500mg / m ^2, P content: 5~1000mg / m ^2, an oxygen content: 1~50at%, (2) press-formability and spot welding to excellent in sex, Ni content: 10~1500mg / m ^2, P content: 5~1000mg / m ^2, an oxygen content: 1~50at%, the film in Fe / Fe + Ni: 0 to 0.9, (3) In order to obtain excellent press formability and adhesiveness, Ni content: 10 to 1500 mg / m ² , P content: 5 to 1000 mg / m ² , oxygen content: 1 to 50at%, Fe / Fe + Ni in the film: 0.05 to less than 1.0, (4) Ni content: 10 to 1500mg / m in order to obtain excellent press formability, spot weldability and adhesion ^2, P content: 5~1000mg / m ^2, an oxygen content: 1~50at% Fe / Fe + Ni in the film: 0.05 to 0.9, (5) Ni content: 10 to 1500 mg / m ² in order to obtain excellent press formability, spot weldability, adhesion and chemical conversion treatment , P content: 5~1000mg / m ^2, an oxygen content: 1 to 20 at%, the film in Fe / Fe + Ni: 0.05~0.9, should meet. (6) In the above (5), in order to further improve press formability, spot weldability, adhesiveness and chemical conversion treatment properties, Ni content: 10 to 1200 mg / m ² , P content: 5 to 800 mg / m ² , oxygen content: 1 to 20 at%, Fe / Fe + Ni in the coating: 0.1 to 0.3.

The Fe—Ni—PO-based film includes Zn, Co, Mn, Mo, Al, Ti, Sn, W, and Zn contained in the underlying plating film.
Oxides incorporating component elements such as Si, Pb, Nb and Ta,
The above-described effects are exhibited even when a hydroxide or a simple metal is contained.

The zinc-based plated steel sheet used in the present invention means that a zinc-based plated layer is formed on a steel sheet as a base material by one or more methods such as a hot-dip plating method, an electroplating method and a vapor phase plating method. Steel sheet.

The chemical composition of the zinc-based plating layer is, in addition to pure zinc, Fe, Ni, Co, Mn, Cr, Al, Mo, Ti, Si, W, S
Metals or oxides such as n, Pb, Nb, and Ta, hydroxides, or organic substances, among others, may be any single or multiple plating layers containing a predetermined amount of one or more of them. . Further, the plating layer may contain fine particles such as SiO ₂ and Al ₂ O ₃ . In addition, as a zinc-based plated steel sheet, a multi-layer plated steel sheet composed of a plurality of layers having the same component elements and different compositions from each other in a plating layer, or a composition element in the thickness direction of the plating layer in which the constituent elements of the plating layer are the same It is also possible to use a functionally graded plated steel sheet in which is continuously changed.

Further, in the present invention, Fe—N
The iPO-based coating is not particularly limited by its forming method, such as displacement plating, immersion in an oxidizing agent-containing aqueous solution, cathodic or anodic electrolytic treatment in an oxidizing agent-containing aqueous solution, and spraying of a predetermined aqueous solution. , Roll coating method, etc.
Vapor phase plating methods such as laser CVD, light CVD, vacuum deposition and sputter deposition can be employed.

Since the above-mentioned Fe—Ni—PO-based coating is formed on at least one surface of the plated layer of the zinc-based plated steel sheet, it can be used in any process of the vehicle body manufacturing process.
Depending on the type of the steel plate used for the vehicle body, one having the film formed on one surface or both surfaces can be appropriately selected.

When the Fe—Ni—PO coating is formed only on one side of the steel sheet, the zinc-based plating layer may be formed on both sides of the steel sheet, if necessary. It may be formed on only one surface of the steel sheet on which the film is formed.

[0053]

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

A galvanized steel sheet within the scope of the present invention (hereinafter, referred to as a specimen of the present invention) and a zinc-coated steel sheet outside the scope of the present invention (hereinafter, referred to as a comparative specimen) were prepared by the following methods. It was adjusted.

First, a zinc-plated steel sheet (hereinafter, referred to as an original sheet) before forming an Fe—Ni—PO coating was prepared. The adjusted original plate was composed of the following seven plating types, and symbols were given according to the plating method, plating composition, and plating adhesion amount. The thickness of each of the steel plates used for plating was 0.8 mm.

GA: alloyed hot-dip galvanized steel sheet (10% Fe, balance Zn), 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, adhesion amount 40g / on both sides
a m ^2. Zn-Fe: Electric Zn-Fe alloy-plated steel sheet (15% Fe), the adhesion amount is 40 g / m ² on both sides. Zn-Ni: Electric Zn-Ni alloy-plated steel sheet (12% Ni), the adhesion amount is 30 g / m ² on both sides. Zn-Cr: Electric Zn-Cr alloy-plated steel sheet (4% Cr), the adhesion amount is 20 g / m ² on both sides. Zn-Al: Hot-dip Zn-Al alloy-plated steel sheet (5% Al), the adhesion amount is 60 g / m ² on both sides.

An Fe—Ni—PO-based film was formed on the surface of the plating layer of the original plate thus prepared by any one of the following three types of forming methods.

[Formation Method A] Iron sulfate containing an oxidizing agent,
In a solution containing nickel sulfate and phosphoric acid, the original plate is subjected to cathodic electrolysis, so that the surface of the original plate has a predetermined Fe-N
An iPO-based film was formed. Here, the nickel sulfate concentration was kept constant at 100 g / l, the iron sulfate concentration was changed to various predetermined values, the phosphoric acid concentration was changed to various predetermined values, and the pH was changed.
Was constant at 2.5, the bath temperature was constant at 50 ° C., hydrogen peroxide solution was used as an oxidizing agent, and the oxygen content of the film was adjusted by changing the concentration to various predetermined values.

[Formation Method B] Aqueous solutions containing nickel chloride at a concentration of 120 g / l and various predetermined concentrations of iron chloride and phosphoric acid were sprayed on the master plate, and Fe-Ni- was mixed in a mixed atmosphere of air and ozone.
By drying while adjusting the oxygen content of the PO-based film, a predetermined Fe-Ni-PO-based film was formed on the surface of the original plate.

[Formation Method C] Nickel chloride concentration of 120 g / l, containing various predetermined concentrations of iron chloride and phosphoric acid, pH = 2.5 to
3.5. The original plate was immersed in an aqueous solution having a bath temperature of 50 ° C. By adjusting the immersion time, the Ni content and the P content of the Fe-Ni-PO-based film were changed to various predetermined values. Further, the oxygen content of the Fe—Ni—PO-based film was changed to various predetermined values by adjusting the pH. Also, to adjust the oxygen content,
A predetermined oxidizing agent was appropriately added to the aqueous solution, and a predetermined Fe-Ni-PO-based film was formed on the surface of the original plate by a method such as heat treatment in a predetermined oxidizing atmosphere.

According to the above-described forming method, a predetermined Fe-Ni-PO
By forming a system coating on the surface of a given original plate,
A specimen of the present invention was obtained.

Regarding the Fe—Ni—PO coating of each specimen, the contents of Ni and P in the coating, Fe / Fe + Ni in the coating, and
The oxygen content of the film was measured as follows.

<Contents of Ni and P in Film and Fe / Fe + Ni in Film> For specimens whose plating type is GI, EG, Zn-Cr or Zn-Al, Fe-Ni-PO The system-based film and the surface layer of the underlying plating film (zinc-based plating, the same applies hereinafter) are dissolved and peeled with dilute hydrochloric acid, and the ICP method is used to analyze the quantification of Fe, Ni, and P. , Ni and P contents were measured. Next, Fe / Fe + Ni in the film was calculated. When the plating type was GI, EG, Zn-Cr, or Zn-Al, the coating was dissolved and peeled off with dilute hydrochloric acid together with the lower plating surface layer, and Fe, Ni and metal were quantitatively analyzed by ICP and measured.

When the plating type is GA, Zn-Fe, or Zn-Ni, since the lower plating layer contains the component elements in the Fe-Ni-PO-based coating, the upper Fe-Ni- It is difficult to completely separate the component elements in the PO-based film from the component elements in the underlying plating layer. Therefore, Fe-Ni-P-
Of the elements in the O-based film, only the elements not contained in the lower plating layer were quantitatively analyzed. Furthermore, after Ar ion sputtering, the composition distribution of each component element in the depth direction of the plating layer was measured by repeating the measurement of each component element in the Fe-Ni-PO-based film from the surface by the XPS method. In this measurement method, it is not included in the lower plating layer
The depth from the surface at which the element of the Fe-Ni-PO-based coating shows the maximum concentration (x), the depth from the surface at which the element is no longer detectable (y), and the depth from the surface at the maximum concentration (X + (y−x) / 2) from the surface obtained by adding の of the difference (y−x) from the depth (x) of the surface, ie, the depth (x) from the surface showing the maximum concentration. ) And the depth from the surface at which the element is no longer detectable (y) ((x
+ Y) / 2) was defined as the thickness of the Fe-Ni-O-based film. Then, based on the results of the ICP method and the XPS method, the amount and composition of the Fe-Ni-PO coating were determined. Next, Fe / F in the film
e + Ni was calculated.

<Oxygen Content of Film> The oxygen content is
It was obtained from the results of Auger electron spectroscopy (AES) analysis in the depth direction.

Tables 1 to 3 show that each specimen No. 1-74
(Specimen of the present invention and comparative specimen), the type of zinc-plated steel sheet of the original sheet, and Fe-Ni-PO
The method of forming a system-based film is indicated by a symbol, and the Ni content, the P content, the Fe / Fe + Ni, and the oxygen content in the film of the Fe-Ni-PO-based film are shown.

[0067]

[Table 1]

[0068]

[Table 2]

[0069]

[Table 3]

For each of the specimens in Tables 1 to 3, press formability was evaluated by the coefficient of friction between the specimen and the bead, and spot weldability was evaluated by the number of continuous points in the continuous point test. Was evaluated by the peel strength after the surfaces of the test pieces were bonded to each other, and the chemical conversion property was evaluated by the state of formation of phosphate crystals. Each evaluation test method is as described below, and the results are shown in the above tables.

<Friction Coefficient Measurement Test> In order to evaluate press formability, the friction coefficient of each specimen was measured by the following apparatus.

FIG. 1 is a schematic front view showing a friction coefficient measuring device. As shown in the figure, a sample 1 for measuring the coefficient of friction collected from a test sample is fixed to a sample stage 2, and the sample stage 2 is
It is fixed to the upper surface of a 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.
A first load cell 7 for measuring a 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 lubricating oil, Noxlast 55 manufactured by Nippon Parkerizing Co., Ltd.
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 as μ = F / N. However, pressing load N: 400kgf, sample pulling speed (horizontal moving speed of slide table 3):
It was 100 cm / min.

FIG. 2 is a schematic perspective view showing the shape and dimensions of a bead used. The lower surface of the bead 6 slides while being pressed against the surface of the sample 1.

The bead 6 is 69 mm long and 10 mm wide in the sliding direction.
The bottom surface at both ends in the sliding direction is formed as a curved surface of 4.5 mmR as shown in FIG.
A flat part having a width of 10 mm is a sliding surface in contact with the sample 1.

<Continuous spotting test> In order to evaluate the spot weldability, a continuous spotting test was performed for each specimen. The same No. The two specimens were stacked, sandwiched between a pair of electrode tips from both sides, and resistance welding (spot welding) in which current was concentrated by applying pressure was continuously performed under the following welding conditions.

・ Electrode tip: DR type (dome type with a tip diameter of 6 mm) ・ Pressing force: 250 kgf ・ Welding time: 0.2 sec ・ Welding current: 11.0KA ・ Welding speed: 1 point / sec During spot welding, the diameter of the molten and solidified metal part (shape: goishi, hereinafter referred to as nugget) generated at the joint of two welded base materials (specimens) was 4
× The number of continuous dots welded until the thickness became less than t ^1/2 (t: thickness of one sheet (mm)) 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. 3 is a schematic perspective view illustrating the assembling process. As shown in the figure, two specimens 10 each having a width of 25 mm and a length of 200 mm are overlapped with a spacer 11 having a diameter of 0.15 mm therebetween so that the thickness of the adhesive 12 becomes 0.15 mm. Create bonded specimen 13 and apply
Perform baking for 10 minutes. The specimen thus prepared was bent into a T-shape as shown in FIG. 4 and subjected to a tensile test at a speed of 200 mm / min using a tensile tester, and the average peel strength when the specimen was peeled off ( 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. In FIG. 4, P indicates a tensile load. The adhesive used was a PVC-based hemming adhesive.

<Chemical conversion test> In order to evaluate the chemical conversion, the following test was carried out.

Each specimen was treated with an immersion-type zinc phosphate treating solution (PBL3080, manufactured by Nippon Parkerizing Co., Ltd.) for use as a base material for automotive coating under normal conditions to form a zinc phosphate film on the surface. The crystal state of the thus formed zinc phosphate film was observed by a scanning electron microscope (SEM). It was classified into three stages according to its crystal state. The signs of the evaluation categories and their contents are as follows.

A: The crystals of the zinc phosphate film are dense and small. Δ: The crystals of the zinc phosphate film are slightly coarse and large. ×: The crystals of the zinc phosphate film are slightly coarse. From the test results of the test specimens of the present invention in Tables 1 to 3, the following matters are clear.

(1) When the Ni content in the Fe—Ni—PO coating is 10
In the range of ~1500mg / m ^2, further, P the content of the Fe-Ni-PO-based film is in the range of 5 to 1000 mg / m ^2, and the Fe-Ni-PO-based film in Those having an oxygen content within the range of 1 to 50 at% (specimens of the present invention Nos. 4 to 7, 9 to 11,
14-19, 21-26, 28-39, 43-49, 5
3, 54, 57, 58, 61, 62, 65, 66, 6
9, 70, 73, 74), that is, all the zinc-based plated steel sheets within the scope of the first invention have a small coefficient of friction and are therefore excellent in press formability.

(2) When the Ni content in the Fe—Ni—PO coating is 10
In the range of ~1500mg / m ^2, further P content of the Fe-Ni-PO-based film in is in the range of 5 to 1000 mg / m ^2, further,
Fe content (wt%) and Ni content (wt%) in the Fe-Ni-PO coating
%) And the ratio of the Fe content (wt%) to the sum of more than 0 to 0.
9 and the oxygen content in the Fe-Ni-PO-based coating is in the range of 1 to 50 at% (specimens Nos. 4 to 7, 9 to 11 and 14 of the present invention). ~ 19, 21-26, 2
9-38, 43-49, 53, 54, 57, 58, 6
1, 62, 65, 66, 69, 70, 73, 74), that is, all of the galvanized steel sheets within the scope of the second invention have a low coefficient of friction and a large number of continuous impact points, Excellent in formability and spot weldability.

(3) When the Ni content in the Fe—Ni—PO coating is 10
In the range of ~1500mg / m ^2, further P content of the Fe-Ni-PO-based film in is in the range of 5 to 1000 mg / m ^2, further,
Fe content (wt%) and Ni content (wt%) in the Fe-Ni-PO coating
%) And the ratio of the Fe content (wt%) to the sum of
Those having an oxygen content in the range of less than 1.0 and the Fe-Ni-PO-based film in a range of 1 to 50 at% (the present invention specimens Nos. 4 to 7, 9 to 11, 14-19, 21-2
6, 31-39, 43-49, 53, 54, 57, 5
8, 61, 62, 65, 66, 69, 70, 73, 7
4) That is, all of the zinc-based plated steel sheets within the scope of the third invention have a low coefficient of friction, a high peel strength after bonding, and are therefore excellent in press formability and adhesiveness.

(4) A zinc-coated steel sheet having a Fe—Ni—PO coating formed on at least one surface of the plating layer, wherein the Ni content in the Fe—Ni—PO coating is 10%. ~ 1500mg /
in the range of m ^2, and more, P content of the Fe-Ni-PO-based film in is in the range of 5 to 1000 mg / m ^2, and more, the Fe-Ni-
The ratio of the Fe content (wt%) to the sum of the Fe content (wt%) and the Ni content (wt%) in the PO-based coating is in the range of 0.05 to 0.9, and the Fe- The oxygen content in the Ni-PO-based film is in the range of 1 to 50 at% (the specimen No.
4-7, 9-11, 14-19, 21-26, 31-3
8, 43 to 49, 53, 54, 57, 58, 61, 6
2, 65, 66, 69, 70, 73, 74), that is, all the zinc-coated steel sheets within the scope of the fourth invention have a low coefficient of friction, a large number of continuous hit points, and a peel strength after bonding. Strong and therefore excellent in press formability, spot weldability and adhesion.

(5) When the Ni content in the Fe—Ni—PO coating is 10
In the range of ~1500mg / m ^2, further P content of the Fe-Ni-PO-based film in is in the range of 5 to 1000 mg / m ^2, further,
Fe content (wt%) and Ni content (wt%) in the Fe-Ni-PO coating
%) And the ratio of the Fe content (wt%) to the sum of
0.9, and the oxygen content in the Fe-Ni-PO-based coating is in the range of 1 to 20 at% (Specimens Nos. 4 to 7, 9 to 11, and 14 of the present invention). ~ 19, 21-26,
31-38, 43-46, 53, 54, 57, 58, 6
1, 62, 65, 66, 69, 70, 73, 74), that is, all the zinc-coated steel sheets within the scope of the fifth invention have a low coefficient of friction, a large number of continuous hit points, and a peel strength after bonding. And the crystals of the chemical conversion treatment film are dense and small, and are therefore excellent in press formability, spot weldability, adhesion and chemical conversion treatment properties.

(6) When the Ni content in the Fe—Ni—PO coating is 10
In the range of ~1200mg / m ^2, further in the range P content of the Fe-Ni-PO-based film in is 5~800mg / m ^2, further wherein the Fe-Ni-PO-based film in Fe content (wt%) and Ni content (wt%)
And the ratio of the Fe content (wt%) to the sum of 0.1 to 0.3
And the oxygen content in the Fe-Ni-PO-based film is in the range of 1 to 20 at% (Specimens Nos. 4 to 7, 9 to 11, 14 to 14 of the present invention). 18, 21-24, 3
1-38, 43-46, 53, 54, 57, 58, 6
1, 62, 65, 66, 69, 70, 73, 74), that is, all the zinc-coated steel sheets within the scope of the sixth invention have a low coefficient of friction, a large number of continuous impact points, and a peel strength after bonding. And the crystal of the chemical conversion coating film is dense and small, and is therefore excellent in press formability, spot weldability, adhesion and chemical conversion treatment, and particularly excellent in press moldability and adhesion.

<Effect of Ni Content on Press Formability and Spot Weldability> If the Ni content of the Fe—Ni—PO coating is within the range of the present invention, the Ni content increases and the press forming is performed. It can be seen that the weldability and spot weldability are improved.

<Effect of P Content on Press Formability, Spot Weldability, and Adhesion> If the P content of the Fe—Ni—PO coating is within the range of the present invention, the P content increases. It is also found that the press formability is improved. However, spot weldability and adhesiveness tend to deteriorate as the amount of adhesion increases.

<Effects of Fe /
Influence of Fe + Ni> It can be seen that if Fe / Fe + Ni of the Fe-Ni-PO-based film is within the range of the present invention, Fe / Fe + Ni increases and the adhesiveness becomes good. However, spot weldability tends to deteriorate with an increase in Fe / Fe + Ni.

From the test results of the comparative specimens in Tables 1 to 3, the following matters are clear. (1) No Fe-Ni-PO-based film was formed (Comparative Sample Nos. 1, 51, 55, 59, 63, 67, 7)
1) indicates the type of galvanized steel sheet: GA, GI, Zn-Fe
, Zn-Ni, Zn-Cr, or Zn-Al, compared to the same plated steel sheet type with Fe-Ni-PO coating, Poor weldability, spot weldability, adhesion, and chemical conversion treatment.

(2) Among the elements constituting the Fe—Ni—PO coating, those containing neither Ni nor Fe (comparative specimen N
o. Samples Nos. 2 and 3) are inferior in spot weldability, adhesiveness and chemical conversion treatment, and those containing no Ni (Comparative Sample No. 40) are inferior in spot weldability.

(3) Among the elements constituting the Fe—Ni—PO coating, those not containing P (Comparative Sample No. 12,
52, 56, 60, 64, 68 and 72) are slightly inferior in press formability.

(4) Ni content or P of Fe—Ni—PO coating
When the content is too small outside the range of the present invention (comparative specimens Nos. 8 and 13), the press formability is slightly inferior.

(5) Ni content or P of Fe—Ni—PO coating
Those whose content is excessive outside the range of the present invention (Comparative Samples Nos. 20 and 27) are inferior in chemical conversion treatment properties.

(6) The oxygen content of the Fe—Ni—PO coating is
Out of the scope of the present invention, a sample with too little (comparative sample No. 4
1, 42) are inferior in adhesiveness.

(7) The oxygen content of the Fe—Ni—PO coating is
Excessive ones outside the scope of the present invention (Comparative specimen No. 5
0) is inferior in spot weldability and chemical conversion treatment.

[0098]

The present invention is configured as described above.
Fe-Ni- formed on the surface of galvanized steel sheet
Because the P-0 coating is harder and has a higher melting point than the zinc or zinc alloy plating layer, the sliding resistance between the plating layer surface and the press die during press forming of zinc-based plated steel sheet is reduced. This makes it easier for the zinc-based plated steel sheet to slide into the press die. In addition, the presence of Fe-Ni-P-0 coatings, especially Ni
Is contained in a predetermined amount, so that a high melting point Zn—Ni alloy is formed at the time of welding, thereby suppressing wear of the electrode, and as a result, improving the continuous spotting property in spot welding. Furthermore,
Since a predetermined amount of Fe having a high surface potential and effective for improving the adhesiveness is contained, the peel strength of the adhesive plate is improved. In addition, the chemical conversion coating is excellent in adhesion, because Ni and Fe in the Fe-Ni-P-0-based coating are incorporated into the phosphate crystals, and the formation of dense and uniform phosphate crystals. Excellent secondary adhesion to hot water.

Therefore, according to the present invention, a zinc-coated steel sheet having excellent press formability, a zinc-coated steel sheet having excellent press formability and spot weldability, and a zinc-coated steel sheet having excellent press formability and adhesiveness , And can provide any of the zinc-based plated steel sheets excellent in press formability, spot weldability, adhesiveness and chemical conversion treatment properties,
An extremely useful effect is brought about industrially.

[Brief description of the drawings]

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

FIG. 2 is a schematic perspective view showing the shape and dimensions of a bead used for measuring a coefficient of friction.

FIG. 3 is a schematic perspective view illustrating a process of assembling a test specimen for an adhesion test.

FIG. 4 is a schematic perspective view illustrating a load of a tensile load at the time of measuring peel strength in an adhesion test.

[Description of Signs] 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 P Tensile load N Sliding resistance

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masaaki Yamashita 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Yuji Yamazaki 1-1-2, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan (56) References International Publication 96/10103 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 2/00-2/40 C23C 22/00-22/86 C23C 28/00-30/00 C25D 3/00-7/12

Claims (6)

(57) [Claims] 1. The method according to claim 1, wherein at least one surface of the plating layer has
A zinc-plated steel sheet forming the Fe-Ni-PO-based film, Ni content of the Fe-Ni-PO-based film in is in the range of 10~1500mg / m ^2, further wherein Fe- The P content of the Ni-PO coating is 5 to 1000 mg / m ²
And the oxygen content in the Fe-Ni-PO-based film is 1 to 50 at.
% Galvanized steel sheet characterized by being in the range of%. 2. The method according to claim 2, wherein at least one surface of the plating layer has
A zinc-plated steel sheet forming the Fe-Ni-PO-based film, Ni content of the Fe-Ni-PO-based film in is in the range of 10~1500mg / m ^2, further wherein Fe- The P content in the Ni-PO coating is 5 to 1000 mg /
in the range of m ^2, and more, the ratio of the Fe content to the sum of Fe content of the Fe-Ni-PO-based film in a (wt%) Ni content and (wt%) (wt%) is , 0
A zinc-based plated steel sheet wherein the oxygen content in the Fe-Ni-PO-based coating is in the range of super-0.9 and the oxygen content in the Fe-Ni-PO-based coating is in the range of 1-50 at%. 3. The method according to claim 1, wherein at least one surface of the plating layer has
A zinc-plated steel sheet forming the Fe-Ni-PO-based film, Ni content of the Fe-Ni-PO-based film in is in the range of 10~1500mg / m ^2, further wherein Fe- The P content in the Ni-PO coating is 5 to 1000 mg /
in the range of m ^2, and more, the ratio of the Fe content to the sum of Fe content of the Fe-Ni-PO-based film in a (wt%) Ni content and (wt%) (wt%) is , 0.
A zinc-based plated steel sheet, which is in the range of 05 to less than 1.0 and the oxygen content in the Fe-Ni-PO-based film is in the range of 1 to 50 at%. 4. The method according to claim 1, wherein at least one surface of the plating layer has
A zinc-plated steel sheet forming the Fe-Ni-PO-based film, Ni content of the Fe-Ni-PO-based film in is in the range of 10~1500mg / m ^2, further wherein Fe- The P content in the Ni-PO coating is 5 to 1000 mg /
in the range of m ^2, and more, the ratio of the Fe content to the sum of Fe content of the Fe-Ni-PO-based film in a (wt%) Ni content and (wt%) (wt%) is , 0.
A zinc-based plated steel sheet, which is in the range of 05 to 0.9 and the oxygen content in the Fe-Ni-PO-based coating is in the range of 1 to 50 at%. 5. The method according to claim 1, wherein at least one surface of the plating layer has
A zinc-plated steel sheet forming the Fe-Ni-PO-based film, Ni content of the Fe-Ni-PO-based film in is in the range of 10~1500mg / m ^2, further wherein Fe- The P content in the Ni-PO coating is 5 to 1000 mg /
in the range of m ^2, and more, the ratio of the Fe content to the sum of Fe content of the Fe-Ni-PO-based film in a (wt%) Ni content and (wt%) (wt%) is , 0.
A zinc-based plated steel sheet which is in the range of 05 to 0.9 and the oxygen content in the Fe-Ni-PO-based film is in the range of 1 to 20 at%. 6. At least one surface of the plating layer,
A zinc-plated steel sheet forming the Fe-Ni-PO-based film, Ni content of the Fe-Ni-PO-based film in is in the range of 10~1200mg / m ^2, further wherein Fe- The P content in the Ni-PO coating is 5 to 800 mg / m
² , and the ratio of the Fe content (wt%) to the sum of the Fe content (wt%) and the Ni content (wt%) in the Fe-Ni-PO-based coating is: 0.
The oxygen content in the range of 1 to 0.3, and the Fe-Ni-PO-based film is 1 to 20 at.
% Galvanized steel sheet characterized by being in the range of%.