JP3111889B2 - 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 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.

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

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. (Hereinafter referred to as "prior art 1") by forming an oxide film mainly composed of ZnO to improve weldability or workability.

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 (hereinafter, referred to as "prior art 2") for improving press formability and chemical conversion property coated with a Mn-based oxide film 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. (Hereinafter referred to as “prior art 3”).

JP-A-3-7282 discloses Fe, Ni and Co.
Japanese Patent Application Laid-Open No. 58-67785 discloses a method of substituting and precipitating one or more metals selected from the group consisting of: Discloses a technique (hereinafter, referred to as “prior art 4”) for generating a metal such as Ni and Fe to improve corrosion resistance.

Japanese Patent Publication No. 58-15554 discloses a continuous coating surface layer of Fe-Zn system comprising Zn 40% or less,
A technique for improving the cationic electrodeposition coating property by providing a surface layer containing Ni or the like (hereinafter, referred to as “prior art 5”) is disclosed.

JP-A-61-207597 discloses a technique for improving workability by forming an electric Zn-Ni alloy plating layer containing Ni: 30 wt.% Or less as an upper layer of an alloyed galvanized steel sheet. (Hereinafter referred to as “prior art 6”).

[0013]

However, the above-mentioned prior art has the following problems. Prior art 1 is a method of generating an oxide mainly composed of ZnO on the surface of a plating layer by the above-described various treatments. Therefore, the effect of reducing the sliding resistance between the press die and the plated steel sheet is small, and the press formability is low. There is a problem that the effect of the improvement is small, and that if the oxide mainly composed of ZnO is present on the plating surface, the adhesion 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 effect of improving the press formability and the chemical conversion treatment is great, but the spot weldability and the adhesiveness are improved. Has a problem that it deteriorates.

Prior Art 3 is a method of forming a single-phase Ni oxide film, so that the corrosion resistance is improved.
There is a problem that the adhesiveness is reduced. Prior art 4 is Ni
However, since the method is a method of forming only a metal such as that described above, corrosion resistance is improved, but the effect of improving press moldability is not sufficient because the metal properties of the film are strong. Furthermore, there is a problem that the wettability of the metal to the adhesive is low and sufficient adhesiveness cannot be obtained.

Prior art 5 or prior art 6 includes Fe, Zn,
Since this method involves forming only a metal such as Ni, the effect of improving the press formability is not sufficient because the metallic properties of the film are strong. Furthermore, there is a problem that the wettability of the metal to the adhesive is low and sufficient adhesiveness cannot be obtained.

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.

[0018]

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 alloy It has been found that press formability, spot weldability, adhesiveness, and chemical conversion treatment properties can be improved by forming a film. According to Japanese Patent Application No. 6-257499, it is assumed that press formability is excellent, and Appropriately applied for a patent for a zinc-based plated steel sheet having excellent spot weldability, adhesion and chemical conversion treatment properties.

The present inventors have found that the zinc-coated steel sheet described above has a problem that the adhesion of the chemical conversion coating film is slightly inferior when the amount of the Fe-Ni-O coating film is large, and the chemical conversion treatment property is further improved. As a result of intensive studies to improve the quality, press-formability, spot weldability, adhesiveness, and the like were achieved by forming an appropriate Fe-Ni-Zn-O-based film on the surface of the galvanized steel sheet. It has been found that the chemical conversion property can be 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. Fe-Ni-Zn-O in the present invention
Since the system coating is hard and has a high melting point, the formation of a Fe-Ni-Zn-O coating on the surface of a zinc-plated steel sheet allows sliding resistance between the plating layer surface and the press mold during press forming. And the galvanized steel sheet slips easily into the press die, and the press formability is improved. In addition, Ni of the Fe-Ni-Zn-O-based coating in the present invention has a property of easily adsorbing press oil components when a new surface is exposed during sliding under a high surface pressure, and is adhered by the adsorbed film. It has the effect of preventing the phenomenon.

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 plating surface 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 the 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 film is low, when exposed to a humid environment after coating, the chemical conversion 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. The present inventors have found that by forming an appropriate Fe-Ni-O-based film on the surface of the plating layer of a zinc-based plated steel sheet, it is possible to improve the chemical conversion treatment property.
No. 257499, based on the premise that press formability is excellent, a patent application was filed for a zinc-based plated steel sheet having excellent spot weldability, adhesiveness and chemical conversion treatment properties as appropriate for the intended use. In the galvanized steel sheet, during the chemical conversion treatment, Ni and Fe in the Fe-Ni-O-based film are incorporated into the phosphate crystals, forming a chemical conversion film having good adhesion, and a dense and uniform coating. Phosphate crystals are formed,
It was found that not only the hot water secondary adhesion but also the corrosion resistance were improved.

However, as a result of further studies by the present inventors, Ni was originally inferior in reactivity with the chemical conversion treatment solution,
It was found that zinc phosphate crystals were hardly generated on the metal plate. That is, the formation of phosphate crystals in the chemical conversion treatment requires that Zn be eluted into the chemical conversion treatment solution and hydrogen be generated in the solution. However, when Ni completely covers the surface of the steel sheet, elution of the metal into the chemical conversion treatment liquid is suppressed, resulting in poor reactivity. This is the reason why, when the amount of the Fe-Ni-O-based film deposited on the zinc-based plated steel sheet is increased, the adhesion is deteriorated. On the other hand, when the Fe-Ni-O-based film adhesion amount was low, excellent performance was exhibited because the Fe-Ni-O-based film was partially dissolved during the chemical conversion treatment, and the part of the original plate where Zn was exposed was exposed. It was presumed that it was formed and the reactivity of the chemical conversion treatment was improved.

Therefore, as a result of further study by the present inventors, it was found that Fe-Ni-Zn-O
By forming an appropriate coating of the system, the chemical conversion property does not deteriorate even when the coating amount is large. In addition, dense and uniform phosphate crystals are formed, and not only the hot water secondary adhesion but also the corrosion resistance It was found to improve.

As described above, a mixed film containing at least a metal of Ni, Fe and Zn and an oxide of Ni, Fe and Zn (hereinafter referred to as “Fe-Ni-Zn-O-based That the zinc-coated steel sheet is excellent in press formability, spot weldability, adhesion and chemical conversion treatment properties. That is, it is an essential condition of the present invention that the Fe-Ni-Zn-O-based 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-plated steel sheet according to claim 1 is characterized in that at least one surface of the plated layer has Fe-Ni-Zn-O
A zinc-based plated steel sheet having a system-based coating, wherein the Fe-N
i-Zn-O-based Ni content in the coating is in the range of 10-5000 / m ^2, further, Zn content of the Fe-Ni-Zn-O-based film is from 5 to 50
It is characterized in that it is in the range of 00 mg / m ² and the oxygen content in the Fe—Ni—Zn—O-based film is in the range of 1 to 50 at.

The zinc-plated steel sheet according to the second aspect is the invention according to the first aspect, further comprising a Fe-Ni-Zn-O-based coating.
It is characterized in that the ratio of the Fe content (wt.%) To the sum of the content (wt.%) And the Ni content (wt.%) Is in the range of more than 0 to 0.9. Have

The galvanized steel sheet according to the third aspect is the invention according to the first aspect, further comprising a Fe-Ni-Zn-O-based coating.
It is characterized in that the ratio of the Fe content (wt.%) To the sum of the content (wt.%) And the Ni content (wt.%) Is in the range of 0.05 to less than 1.0. Have

According to a fourth aspect of the present invention, there is provided the galvanized steel sheet further comprising the Fe-Ni-Zn-O-based coating according to the first aspect.
It is characterized in that the ratio of the Fe content (wt.%) To the sum of the content (wt.%) And the Ni content (wt.%) Is in the range of 0.05 to 0.9. Things.

The galvanized steel sheet according to claim 5, wherein a Fe-Ni-Zn-O-based film is formed on at least one surface of the plated layer, wherein the Fe-Ni- Zn-O-based Ni content in the coating is in the range of 10-5000 / m ^2, further, Zn content of the Fe-Ni-Zn-O-based film in the 5 ~5000mg / m
² , and further, Fe in the Fe-Ni-Zn-O-based coating
The ratio of the Fe content (wt.%) To the sum of the content (wt.%) And the Ni content (wt.%) Is in the range of 0.05 to 0.9, and the Fe-Ni-Zn The oxygen content in the -O coating is 1 to 20at.
%.

The zinc-plated steel sheet according to claim 6, wherein the Fe-Ni-Zn-O-based film is formed on at least one surface of the plated layer, wherein the Fe-Ni- Zn-O-based Ni content in the coating is in the range of 10~4000mg / m ^2, further, Zn content of the Fe-Ni-Zn-O-based film in the 5 ~4000mg / m
² , and further, Fe in the Fe-Ni-Zn-O-based coating
The ratio of the Fe content (wt.%) To the sum of the content (wt.%) And the Ni content (wt.%) Is in the range of 0.1 to 0.3, and the Fe-Ni-Zn The oxygen content in the -O coating is 1 to 20at.
%.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the reason why the amount of the Fe-Ni-Zn-O-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. State.

"Ni content in Fe-Ni-Zn-O-based film" As described above, the press-formability, spot weldability, adhesiveness, and chemical conversion property can be obtained by forming the Fe-Ni-Zn-O-based film. Is improved. However, the Ni content in the Fe-Ni-Zn-O-based coating is 10
If it is less than mg / m ² , the effect of improving press formability and spot weldability cannot be obtained.

On the other hand, if the amount of adhesion exceeds 5000 mg / m ² , the effect of improving press formability and spot weldability is saturated, and it is wasteful in cost to use more expensive Ni than this. . Further, although the Fe-Ni-Zn-O-based Zn in the film has the effect of improving the chemical conversion treatability, when the Ni content to coexist exceeds 5000 mg / m ^2, the generation of phosphate crystals It is suppressed and the chemical conversion property deteriorates. In order to improve the chemical conversion property, the Ni content is desirably 4000 mg / m ² or less. Therefore, Ni content of the Fe-Ni-Zn-O-based film in the range of 10-5000 / m ^2, preferably 10~4000mg / m
^It should be limited to the range of ² .

"Zn content in Fe-Ni-Zn-O based film"
By containing an appropriate amount of Zn in the Zn-O-based coating, the chemical conversion treatment property is improved. However, if the Zn content in the Fe—Ni—Zn—O-based coating is less than 5 mg / m ² , the effect of improving the chemical conversion property cannot be obtained.

On the other hand, if the adhesion amount exceeds 5000 mg / m ² , the effect of improving the chemical conversion treatment is saturated, and furthermore, the spot weldability and the adhesiveness may be deteriorated, and the press formability may be deteriorated. Absent. In order to further improve the above effects, the Zn content is desirably 4000 mg / m ² or less. Therefore, the Fe-Ni-Zn-O-based coating
Zn content in the range of 5 ~5000mg / m ^2, preferably from 5 to 40
It should be limited to the range of 00 mg / m ² .

"Oxygen content in Fe-Ni-Zn-O based film" Fe-N
By containing an appropriate amount of oxygen in the i-Zn-O coating,
Press formability is improved. However, if the oxygen content in the Fe-Ni-Zn-O-based coating is less than 1 at.%, The metallic properties of the coating are so strong that the effect of improving press formability is not exhibited. Also, the wettability with the adhesive is reduced.

On the other hand, when 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, for applications that do not require excellent chemical conversion properties, the upper limit of the oxygen content may be increased, but if it exceeds 50 at.%, Fe-Ni-
Zn-O-based coatings are mostly composed of oxides,
The presence of simple metal in the coating is slight. In this case,
Due to the low conductivity of the oxide, the electrical 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 if the chemical conversion property is not a problem, the oxygen content of the film should be 50 at.% Or less in order to ensure spot weldability.

Therefore, press formability, press formability and spot weldability, press formability and adhesion,
Alternatively, in order to improve press formability, spot weldability and adhesion, the oxygen content of the Fe-Ni-Zn-O-based coating should be in the range of 1 to 50 at.%, And In order to improve press formability, spot weldability, adhesion and chemical conversion treatment, the oxygen content of the Fe-Ni-Zn-O-based
Should be in the range of 1-20at.%.

"Ratio of Fe content to the sum of Ni content and Fe content in Fe-Ni-Zn-O-based film" Fe-Ni-Zn-O-based film contains an appropriate amount of Fe Thereby, the adhesiveness is improved. This is because the adhesiveness is better for a metal having a higher surface potential, and Fe belongs to the metal having the highest surface potential. Therefore,
The higher the Fe content, the better the adhesion. However, Fe content (wt.%) And Ni content in Fe-Ni-Zn-O-based coating
If the ratio of the Fe content (wt.%) to the sum of the Fe content (wt.%) (hereinafter referred to as “Fe / Fe + Ni in film”) is less than 0.05, the effect of improving the adhesiveness is not exhibited. In addition, when extremely excellent adhesion is required stably, it is present in the film.
In order to secure the Fe content, it is desirable that the content of Fe / Fe + Ni in the film be 0.1 or more.

However, for applications that do not require excellent adhesion, the lower limit of Fe / Fe + Ni in the coating is not required. However, when Fe / Fe + Ni in the film is 0 (zero), Fe-Ni-Zn
Since Fe is no longer present in the -O-based coating, the essential requirement of the present invention that the Fe-Ni-Zn-O-based coating is formed on the surface of the plating layer is not satisfied.

Therefore, Fe / Fe + Ni in the film should be more than 0 (zero) even when the adhesion is not a problem.
On the other hand, if the content of Fe / Fe + Ni in the coating exceeds 0.9, the Ni content in the coating decreases, and the proportion of the high-melting Zn-Ni alloy formed during welding decreases, resulting in deterioration of the electrode. And the effect of improving spot weldability is not exhibited. Also, 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, if Fe / Fe + Ni in the coating is 1.0, metal Ni
And Fe, and a mixed film containing Ni and Fe oxide,
That is, it does not satisfy the essential requirement of the present invention that the Fe-Ni-Zn-O-based film is present.

Therefore, even if spot welding is not a problem, the content of Fe / Fe + Ni in the coating should be less than 1.0. Therefore, in order to improve the press formability and spot weldability, the content of Fe / Fe + Ni in the coating should exceed 0 (zero).
9, and in order to improve press formability and adhesion, Fe / Fe + Ni in the coating should be 0.05 to 0.05.
It should be within the range of less than 1.0, and at least in order to improve the press formability, spot weldability and adhesion, Fe / Fe + Ni in the coating should be in the range of 0.05 to 0.9,
However, in order to further improve the adhesiveness and the spot weldability, it should be limited to the range of 0.1 to 0.3.

The galvanized steel sheet requires certain properties (four properties such as 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-Zn-O-based film formed on the surface, depending on what property and at what level, the Fe-Ni-Zn-O-based coating The Ni content, Zn content and their oxygen content and the proper range of Fe / Fe + Ni in the film should be determined. This proper range is based on the above,
It is as follows.

"Fe-N necessary for the property to satisfy a predetermined value.
Ni-content of the i-Zn-O-based film, Zn content and its oxygen content and Fe / Fe + Ni in the film `` Fe-Ni-Zn-O-based zinc-plated steel sheet with a film formed on the surface, (1) At least, in order to obtain excellent press formability, Ni content: 10 to 5000 mg / m ² , Zn content: 5 to 5000 mg / m ² , and oxygen content: 1 to 50 at. %, That is, the present invention described in claim 1 is hereinafter referred to as "the present invention 1", and (2) to at least provide excellent press formability and spot weldability. For Ni content: 10 to 5000 mg / m ² , Zn content: 5 to 5000 mg / m ² , oxygen content: 1 to 50 at.%, And Fe / Fe + Ni in the coating: more than 0 to 0.9 In other words, the present invention described in claim 2 is hereinafter referred to as "the present invention 2", and (3) at least excellent in press moldability and adhesiveness. Meniwa, Ni content: 10~5000mg / m ^2, Zn content: 5 ~5000mg / m ^2, the oxygen content:. 1~50at%, and, the film in Fe / Fe + Ni: less than 0.05 The present invention according to claim 3 is hereinafter referred to as "the present invention 3", and (4) at least excellent in press formability, spot weldability and adhesion. Ni content: 10 to 5000 mg / m ² , Zn content: 5 to 5000 mg / m ² , oxygen content: 1 to 50 at.%, And Fe / Fe + Ni in the coating: 0.05 to 0.9 should be satisfied, that is, the present invention described in claim 4 is hereinafter referred to as "the present invention 4", and has (5) press formability, spot weldability, adhesiveness, and chemical conversion treatment properties. to better ones, Ni content: 10~5000mg / m ^2, Zn content: 5-5000 mg / m ^2, an oxygen content:. 1 to 20 at%, and, the film in Fe / Fe + Ni ： Coating structure of 0.05-0.9 Should be satisfied, i.e., below the invention according to claim 5, referred to as "the present invention 5", and,
(6) In the above (5), in order to further improve the press formability, spot weldability, adhesion and chemical conversion treatment properties, the Ni content: 10 to 4000 mg / m ² , the Zn content: 5 40004000 mg / m ² , oxygen content: 1-20 at.%, And Fe / Fe + Ni in the film: 0.1-0.3. Hereinafter, this is referred to as "the present invention 6".

The Fe—Ni—Zn—O-based film includes Zn, Co, Mn, Mo, Al, Ti, Sn, W, Si, Pb, and Nb contained in the underlying plating film.
The above-described effects can be obtained even when an oxide, a hydroxide, or a simple metal containing a component element such as Ta and Ta is included.

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

The chemical composition of the zinc-based plating layer is not only pure zinc, but also metals such as Fe, Ni, Co, Mn, Cr, Al, Mo, Ti, Si, W, Sn, Pb, Nb and Ta, or oxides. Any material may be used as long as it is a single-layer or multiple-layer plating layer containing a predetermined amount of one, two, or more of substances, hydroxides, and organic substances. Also,
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 i-Zn-O-based film is not particularly limited by its forming method, such as displacement plating, a method by immersion in an oxidizing agent-containing aqueous solution, a cathodic or anodic electrolytic treatment in an oxidizing agent-containing aqueous solution, Spraying aqueous solution, roll coating method, etc.
Vapor phase plating methods such as laser CVD, optical CVD, vacuum deposition, and sputter deposition can be employed.

Since the above-mentioned Fe—Ni—Zn—O-based coating is formed on at least one surface of the plating layer of a zinc-based plated steel sheet,
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—Zn—O-based 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 as necessary. Alternatively, it may be formed on only one surface of the steel sheet on which the film is formed.

[0055]

Next, the present invention will be described in more detail with reference to examples. A zinc-based plated steel sheet within the scope of the present invention (hereinafter referred to as “the present invention specimen”) and a zinc-based plated steel sheet outside the scope of the present invention (hereinafter referred to as “the comparative specimen”) are prepared by the following methods. Was adjusted.

First, a zinc-based plated steel sheet (hereinafter, referred to as an “original sheet”) before forming an Fe—Ni—Zn—O-based film 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 the steel plate used for plating is 0.8 mm in each case.

GA: is a galvannealed steel sheet (10w
% Fe, balance Zn), and the adhesion amount is 60 g / m ² on both sides. GI: Hot-dip galvanized steel sheet, adhesion amount is 90 on both sides
g / m ² .

EG: Electrogalvanized steel sheet with an adhesion amount of 40 g / m ² on both sides. Zn-Fe: Electric Zn-Fe alloy plated steel sheet (15wt.% F
e), and the adhesion amount is 40 g / m ² on both sides.

Zn-Ni: An electrical Zn-Ni alloy-plated steel plate (12 wt.% Ni), and the amount of adhesion is 30 g / m ² on both sides. Zn-Cr: Electric Zn-Cr alloy plated steel plate (4 wt.% C
r), and the adhesion amount is 20 g / m ² on both sides.

Zn-Al: A hot-dip Zn-Al alloy-plated steel sheet (5 wt.% Al), and the adhesion amount is 60 g / m ² on both sides. The Fe-N
An i-Zn-O-based film was formed by any of the following three types of forming methods. [Formation Method A] A predetermined Fe-Ni-Zn-O-based film is formed on the surface of the original plate by subjecting the original plate to a cathodic electrolytic treatment in a mixed solution of iron sulfate, nickel sulfate and zinc sulfate containing an oxidizing agent. Formed. Here, the nickel sulfate concentration was kept constant at 100 g / l, the iron sulfate concentration and the zinc sulfate concentration were changed to various predetermined values, the pH was kept constant at 2.5, the bath temperature was kept constant at 50 ° C, and the excess was used as an oxidizing agent. The oxygen content of the coating was adjusted by changing the concentration to various predetermined values using a hydrogen oxide solution. "Forming method B": An aqueous solution containing nickel chloride concentration of 120 g / l and various predetermined concentrations of iron chloride and zinc chloride was sprayed on the original plate, and the Fe-Ni-Zn-O-based film was formed in a mixed atmosphere of air and ozone. By drying while adjusting the oxygen content of the sample, a predetermined Fe-Ni-Zn-O-based film was formed on the surface of the original plate. "Forming Method C" The original plate was immersed in an aqueous solution containing nickel chloride at a concentration of 120 g / l, various predetermined concentrations of iron chloride and zinc chloride, pH = 2.5-3.5, and a bath temperature of 50 ° C. By adjusting the immersion time, the Ni content and Zn content of the Fe-Ni-Zn-O-based film were changed to various predetermined values. Further, the oxygen content of the Fe—Ni—Zn—O-based film was changed to various predetermined values by adjusting the pH. In addition, in order to adjust the oxygen content, a predetermined oxidizing agent is appropriately added to the aqueous solution, and a predetermined heat treatment is performed in a predetermined oxidizing atmosphere.
An Fe-Ni-Zn-O-based film was formed.

According to the above-described forming method, a predetermined Fe—Ni—Zn—O
By forming a system coating on the surface of a given original plate,
A specimen of the present invention was obtained. For the Fe-Ni-Zn-O-based film of each specimen, the contents of Ni and Zn in the film, Fe / Fe + Ni in the film,
And the oxygen content of the film was measured as follows. "Ni and Zn contents in the film, and Fe / Fe + in the film
Regardless of the type of plating of the “Ni” original plate, the measurement was performed by the following measurement method.

Since the lower plating layer contains the constituent elements in the Fe—Ni—Zn—O-based film, the upper Fe—Ni—Zn
It is difficult to completely separate the components in the -O-based coating from the component elements in the lower plating layer. Therefore, of the elements in the Fe—Ni—Zn—O-based film, only the elements not contained in the lower plating layer were quantitatively analyzed by the ICP method. Further, Ar
After the 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-Zn-O-based coating from the surface by the XPS method. In this measurement method, the element of the Fe-Ni-Zn-O-based film not contained in the lower plating layer is not detected at a depth (x) from the surface at which the element has the maximum concentration. 1 / (1 / x) of the difference (y-x) between the depth from the surface (assumed to be y) and the depth from the surface showing the maximum concentration (x) (x)
2 from the surface (x + (y−x) / 2), that is, the depth from the surface showing the maximum concentration (x) and the depth from the surface where the element is no longer detected (y) The average depth ((x + y) / 2) from the surface was defined as the thickness of the Fe—Ni—Zn—O-based film. Then, based on the results of the ICP method and the XPS method, the amount and composition of the Fe—Ni—Zn—O-based film were calculated. Next, Fe / (Fe + Ni) in the film was calculated. "Oxygen Content of Film" The oxygen content was determined from the results of Auger electron spectroscopy (AES) analysis in the depth direction.

Tables 1 to 4 show, for each specimen (the specimen of the present invention and the comparative specimen), the type of zinc-plated steel sheet of the original sheet and the formation of the Fe-Ni-Zn-O-based film on the original sheet. The method is indicated by each sign, the Ni content of the Fe-Ni-Zn-O-based coating,
The Zn content, Fe / Fe + Ni in the film, and the oxygen content are shown.

[0064]

[Table 1]

[0065]

[Table 2]

[0066]

[Table 3]

[0067]

[Table 4]

For each of the above test pieces, the evaluation of press formability was made by the coefficient of friction between the test piece and the bead, the evaluation of spot weldability was made by the number of continuous spots in the continuous spot test, and the evaluation of the adhesiveness was made by the surface of the test piece. The peel strength after bonding each other,
The chemical conversion property was evaluated based on the state of formation of the phosphate crystals and the adhesion.

Tables 5 to 8 show the test results. In addition, each evaluation test method is as follows.

[0070]

[Table 5]

[0071]

[Table 6]

[0072]

[Table 7]

[0073]

[Table 8]

"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 FIG. 1, a sample 1 for measuring a friction coefficient collected from a specimen 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, there is provided a vertically movable slide table support 5 having a roller 4 in contact with the slide table 3. By pushing up the slide table support 5, a load N on the sample 1 for friction coefficient measurement by the bead 6 is measured. Is mounted on the slide table support 5. With the pressing force applied, a second load cell 8 for measuring a sliding resistance force 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. 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 coefficient of friction μ between the specimen and the bead is
Formula: Calculated by μ = F / N. However, pressing load N: 400
kgf, sample withdrawal speed (horizontal movement speed of slide table 3): 100 cm / min.

FIG. 2 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 underside shape is width 1
It has a plane of 0 mm and a length of 60 mm in the sliding direction, and at the front and rear ends of this plane, a quarter portion of a cylindrical surface having 4.5 mmR is formed in contact with as shown in FIG. "Continuous spot test" To evaluate spot weldability,
A continuous hitting test was performed on each specimen.

[0077] Two identical specimens are stacked, and the same
Resistance welding (spot welding) in which current was concentrated by sandwiching between a pair of electrode tips and energizing under pressure was continuously performed under the following conditions. -Electrode tip: Dome type with a tip diameter of 6 mm-Pressure: 250 kgf-Welding time: 0.2 sec-Welding current: 11.0 kA-Welding speed: 1 point / sec. As the evaluation of the continuous hitting property, the diameter of the melt-solidified metal part (hereinafter, referred to as nugget) generated at the joint part of the two welded base materials (specimens) during spot welding was 4 × t1 / 2.
(T: the thickness of one sheet) was used. The number of hit points is hereinafter referred to as electrode life. "Adhesion test" The following test specimens for adhesion test were prepared from each test specimen.

FIG. 3 is a schematic perspective view for explaining the assembling process. As shown in the figure, width 25 mm, length 2
Two test pieces 10 of 00 mm are placed between them by 0.15 mm
The thickness of the adhesive 12 is 0.1
5 mm to form an adhesive test specimen 13 at 150 ° C. × 10 min. Baking. The specimen thus prepared was bent into a T-shape as shown in FIG.
/ Min. , And the average peel strength (n = 3 times) when the test piece was peeled was measured. 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.
P indicates a tensile load. The adhesive used was a PVC-based hemming adhesive. "Chemical conversion treatment test" In order to evaluate the chemical conversion treatment, the following test was performed.

Each specimen was treated with a immersion type zinc phosphate treatment solution (PBL30 manufactured by Nippon Parkerizing Co., Ltd.)
80), a treatment was carried out under ordinary conditions to form a zinc phosphate film on the surface. The crystal state of the zinc phosphate film thus formed was observed with a scanning electron microscope (SEM). It was divided into three stages according to its 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. Δ: The crystals of the zinc phosphate film are slightly coarse and large. ×: The crystals of the zinc phosphate film are coarse or not formed. The specimen for "adhesion test of chemical conversion coating" was treated with the above-mentioned immersion type zinc phosphate treating agent for the undercoat of an automobile coating, and further treated for 20 minutes.
After performing ED coating at a coating pressure of μm, a chemical conversion coating adhesion test was performed. FIG. 5 schematically shows a method for evaluating the adhesion between the chemical conversion coating and the zinc-based plating layer itself. 100x
The thickness of the adhesive 16 is 0.15 mm through a spacer 15 of 0.15 mm between the specimens 14 having a size of 25 mm,
A test body was prepared so that the adhesion area was 25 × 10 mm, and baked at 170 ° C. for 30 minutes. The adhesive used was an epoxy structural adhesive. The specimen 14 is a variety of steel sheets having a thickness of 0.8 mm. However, depending on the material, the strength of the specimen is small and the base material may be broken during a tensile test. Steel plate reinforcing plate 1
The sample was designated as 7 and used as an adhesion test specimen 18 of the chemical conversion coating. The test piece was pulled at a speed of 200 mm / min using a tensile tester, the average peel strength at the time of peeling was measured, and the peeled surface was observed with a scanning electron microscope (SEM).

The peeling occurs at a position where the strength is weakest.
When GA [symbol A] is used, peeling occurs at the interface between the GA film and the steel sheet, and the peel strength is the interface adhesion strength between the GA film and the steel sheet. GI [code B], EG [code C], Zn
-Fe [code D], Zn-Ni [code E], Zn-Cr
[Code F] and Zn-Al [Code G]
Cohesive failure occurs inside the adhesive, and the peel strength becomes the strength of the adhesive itself.

The adhesion between the chemical conversion coating and the zinc-based plating layer itself was evaluated as follows.
When the peel strength was lower than that of the untreated material, it was evaluated as x.
From the test results of the test specimens of the present invention in Tables 5 to 8, the following matters are clear. The invention corresponding to each of claims 1 to 6 is hereinafter referred to as “present invention 1”, “present invention 2”, “present invention 3”,..., “Present invention 6”. (1) The present invention 1 has at least a low coefficient of friction and is therefore excellent in press formability. (2) The present invention 2 has at least a small coefficient of friction and a large number of continuous hit points, and therefore has excellent press formability and spot weldability. (3) The present invention 3 has at least a small coefficient of friction and a high peel strength after bonding, and therefore has excellent press moldability and adhesiveness. (4) The present invention 4 has at least a low coefficient of friction, a large number of continuous hit points, and a high peel strength after bonding, and therefore has excellent press formability, spot weldability, and adhesiveness. (5) The present invention 5 has a low coefficient of friction, a large number of continuous hit points, a high peel strength after bonding, and a dense and small crystal of a chemical conversion coating film. Excellent adhesion and chemical conversion properties. (6) The present invention 6 has a small coefficient of friction, a large number of continuous impact points, a high peel strength after bonding, and a dense and small crystal of the chemical conversion coating film. Excellent adhesion and chemical conversion treatment,
In particular, it is excellent in press formability, spot weldability and adhesiveness.

The relationship between the present inventions 1 to 6 and the characteristic values of press formability, spot weldability, adhesiveness and chemical conversion treatment are as described above. Even so, it was confirmed that the following effects were exerted on the above-mentioned respective characteristic values depending on the properties of the Fe-Ni-Zn-O-based coating.

“Effect of Ni Content on Press Formability and Spot Weldability” If the Ni content of the Fe—Ni—Zn—O-based coating is within the range of the present invention, the Ni content increases and It turns out that press formability and spot weldability become favorable.

"Effect of Zn Content on Press Formability, Spot Weldability and Adhesion" If the Zn content of the Fe-Ni-Zn-O-based film is within the range of the present invention, the Zn content is It can be seen that the press formability becomes better with the increase. However, spot weldability and adhesiveness tend to decrease as the amount of adhesion increases.

[Fe Effect on Adhesion and Spot Weldability]
Influence of / Fe + Ni '' It can be seen that if Fe / Fe + Ni of the Fe-Ni-Zn-O-based coating is within the range of the present invention, Fe / Fe + Ni increases and the adhesiveness becomes good. . However, the spot weldability tends to decrease as Fe / Fe + Ni increases.

From the test results of the comparative specimens in Tables 5 to 8,
The following is clear: (1) In the case where the Fe-Ni-Zn-O-based film was not formed (hereinafter referred to as "Comparative Example [1])", the type of the plated steel sheet was GA, GI, Zn-Fe, Zn-. Ni, Zn
Regardless of whether it is represented by -Cr or Zn-Al, it is inferior in press formability, spot weldability, adhesiveness and chemical conversion treatment. (2) Among the elements constituting the Fe—Ni—Zn—O-based film, those that do not contain Ni (hereinafter, referred to as “Comparative Example [2]”) are:
Poor spot weldability, adhesiveness and chemical conversion treatment. (3) Among the elements constituting the Fe—Ni—Zn—O-based film, those that do not contain Zn (hereinafter referred to as “Comparative Example [3]”) are:
Slightly inferior in chemical conversion treatment. (4) Among the elements constituting the Fe—Ni—Zn—O-based film, those that do not contain Fe (hereinafter, referred to as “Comparative Example [4]”) are:
Poor adhesion. (5) If the Ni content of the Fe-Ni-Zn-O-based coating is too small outside the range of the present invention (hereinafter, referred to as “Comparative Example [5])”,
Poor press formability and spot weldability. (6) Those in which the Ni content of the Fe—Ni—Zn—O-based coating is excessively outside the range of the present invention (hereinafter, referred to as “Comparative Example [6]”):
Poor chemical conversion property. (7) If the Zn content of the Fe—Ni—Zn—O-based coating is too small outside the range of the present invention (hereinafter referred to as “Comparative Example [7]”),
Poor chemical conversion property. (8) If the Zn content of the Fe—Ni—Zn—O-based coating is too large outside the range of the present invention (hereinafter referred to as “Comparative Example [8]”),
Poor press formability, spot weldability and adhesion. (9) When the oxygen content of the Fe—Ni—Zn—O-based coating is too small outside the range of the present invention (hereinafter referred to as “Comparative Example

[9]. " )
Are inferior in adhesiveness. (10) If the oxygen content of the Fe—Ni—Zn—O-based film is excessively outside the range of the present invention (hereinafter referred to as “Comparative Example [10]”), the spot weldability and the chemical conversion property are poor. Inferior. (11) The Fe—Zn upper layer plating, which was tested as a comparative sample, was inferior in weldability (see “Comparative Example [11]”). (12) The Zn—Ni upper layer plating, which was tested as a comparative sample, was inferior in adhesiveness and chemical conversion treatment (see “Comparative Example [12]”).

[0087]

According to the present invention, the Fe-Ni-Zn film formed on the surface of the plating layer of the zinc-based plated steel sheet is constructed as described above.
-O-based coatings are harder and have a higher melting point than zinc or zinc alloy plating layers, which reduces the sliding resistance between the plating layer surface and the press mold during press forming of zinc-based plated steel sheets. In addition, the galvanized steel sheet can easily slide into the press die. In addition, the presence of Fe-Ni-Zn-O-based coatings, especially Ni
Is contained in a predetermined amount, thereby ensuring the formation of a high melting point Zn—Ni alloy at the time of welding, thereby suppressing the wear of the electrode and consequently improving the continuous spotting property in spot welding. Further, the chemical conversion treatment film, Ni and Fe in the Fe-Ni-Zn-O system film
Is taken into the phosphate crystals, so that the adhesiveness is excellent, and the formation of dense and uniform phosphate crystals also results in excellent secondary contact with warm water. In the case of chemical conversion treatment, Fe
Since the Zn in the -Ni-Zn-O-based film is eluted, the elution of the metal into the chemical conversion treatment liquid is not suppressed, so that Fe-Ni-Zn-O
Even if the coating amount of the system coating increases, the reactivity of the chemical conversion treatment does not deteriorate, and therefore, the adhesion does not deteriorate. Thus Fe
-Since the amount of Ni-Zn-O-based film deposited can be increased, the effect of improving the dust resistance during spot welding can also be obtained.

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 in FIG.

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

FIG. 4 is a schematic perspective view illustrating a load of a tensile load when a peel strength is measured in an adhesion test.

FIG. 5 is a schematic perspective view illustrating a method for evaluating the adhesion between the chemical conversion coating and the zinc-based plating layer itself.

[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 Adhesive specimen 14 Specimen 15 Spacer 16 Adhesive 17 Reinforcement plate 18 Adhesion test piece N Press load F Sliding resistance P Tensile load

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takayuki Urakawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside Nippon Kokan Co., Ltd. (72) Inventor Junichi Inagaki 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan (72) Inventor Masaaki Yamashita Nippon Kokan Co., Ltd. 1-2-1, Marunouchi, Chiyoda-ku, Tokyo (72) Inventor Ryuji Nagayama 1-1-2 Marunouchi, Chinoda-ku, Tokyo Nippon Kokan ( 72) Inventor Shigeru Inoue 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (56) References JP-A-10-259467 (JP, A) JP-A 10-25596 (JP, A) Kaihei 10-25597 (JP, A) 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
Fe-Ni-Zn-O-based coating formed zinc-coated steel sheet, the Ni content in the Fe-Ni-Zn-O-based coating is 10 ~ 5000mg / m
Is in the ² range, further, Zn content of the Fe-Ni-Zn-O-based film is in the range of 5 ~5000mg / m ^2, and said Fe-N
A zinc-based plated steel sheet, wherein the oxygen content in the i-Zn-O-based coating is in the range of 1 to 50 at.%. 2. The invention according to claim 1, further comprising the Fe-N
The ratio of the Fe content (wt.%) to the sum of the Fe content (wt.%) and the Ni content (wt.%) in the i-Zn-O-based film is in the range of more than 0 to 0.9. A galvanized steel sheet characterized by the following: 3. The method according to claim 1, further comprising adding the Fe-N
The ratio of the Fe content (wt.%) to the sum of the Fe content (wt.%) and the Ni content (wt.%) in the i-Zn-O-based coating is in the range of 0.05 to less than 1.0. A galvanized steel sheet characterized by the following: 4. The invention according to claim 1, further comprising the Fe-N
The ratio of the Fe content (wt.%) to the sum of the Fe content (wt.%) and the Ni content (wt.%) in the i-Zn-O-based film is in the range of 0.05 to 0.9. A galvanized steel sheet characterized by the following. 5. The method according to claim 1, wherein at least one surface of the plating layer has
Fe-Ni-Zn-O-based coating formed zinc-coated steel sheet, the Ni content in the Fe-Ni-Zn-O-based coating is 10 ~ 5000mg / m
² , and Zn in the Fe-Ni-Zn-O-based coating.
The content is in the range of 5 ~5000mg / m ^2, further wherein Fe
The ratio of the Fe content (wt.%) To the sum of the Fe content (wt.%) And the Ni content (wt.%) In the -Ni-Zn-O-based coating is 0.05 to 0.9.
And the oxygen content in the Fe-Ni-Zn-O-based coating is in the range of 1 to 20 at.%. 6. At least one surface of the plating layer,
Fe-Ni-Zn-O-based coating formed zinc-coated steel sheet, wherein the Ni content in the Fe-Ni-Zn-O-based coating is 10 ~ 4000mg / m
² , and Zn in the Fe-Ni-Zn-O-based coating.
The content is in the range of 5 ~4000mg / m ^2, further wherein Fe
The ratio of the Fe content (wt.%) To the sum of the Fe content (wt.%) And the Ni content (wt.%) In the -Ni-Zn-O-based coating is 0.1 to 0.3.
Wherein the oxygen content in the Fe-Ni-Zn-O-based coating is in the range of 1 to 20 at.%.