WO2019054483A1 - Hot-dip plated checkered plate and manufacturing method thereof - Google Patents

Abstract

This hot-dip plated checkered plate has: a base material steel plate, an Ni plated layer, and a hot-dip plated layer, and has on the plate surface a projecting part and a flat part. The film thickness of the Ni plated layer of the projecting part is 0.07 to 0.4 µm, the film thickness of the Ni plated layer of the flat part is 0.05 to 0.35 µm, and the film thickness of the Ni plated layer of the projecting part is more than 100% and 400% or less than the film thickness of the Ni plated layer of the flat part.

Description

Hot-dip galvanized steel sheet and method of manufacturing the same

The present invention relates to a hot-dip galvanized steel sheet and a method of manufacturing the same.
Priority is claimed on Japanese Patent Application No. 2017-178011, filed September 15, 2017, the content of which is incorporated herein by reference.

The striped steel plate is a steel plate having a non-slip projection (convex portion) continuous on the surface by rolling. Generally, projections of a constant width, a constant length and a constant height are provided at a constant angle and a constant pitch with respect to the rolling direction. Usually, a striped steel plate is manufactured by hot rolling. And it is used for floor boards and steps such as buses and trucks, floor boards for factories, decks of ships, temporary scaffolds for construction sites, stairs and the like.

Conventionally, striped steel plates are often used as they are hot-rolled or painted. In particular, when rust prevention is required, the cut sheet of the striped steel plate is galvanized by going through a batch-type hot dip galvanization process by a flux method. However, batch-type hot-dip galvanizing process has low productivity, and the Fe-Zn alloy layer generated in the hot-dip plating process is enlarged, so that the processability of the plating layer is impaired, and the plating cracking and peeling of the plating layer occur. It may occur and cause problems in corrosion resistance.

Continuous galvanization is more productive than batch galvanization. Continuous galvanization is generally performed by passing a steel sheet heated to a predetermined temperature in a reducing or non-oxidizing atmosphere to a hot dip galvanizing bath. Further, since at least about 0.05% of Al is contained in the molten zinc bath, it is possible to suppress the growth of the Fe—Zn alloy layer which impairs the processability of the plating film. In addition, in batch hot dip galvanization by a general flux method, when Al is contained in a Zn bath, Al decomposes a flux, so that non-plating occurs frequently and plating can not be performed well.

When applying continuous hot-dip galvanization to a striped steel plate, it is necessary to consider the subject resulting from the surface shape etc. For example, Patent Document 1 teaches a continuous hot-dip galvanizing method for strip-shaped striped steel plates, in particular, tension in a plating line and appropriate conditions for gas wiping after hot-dip plating. Currently, continuous hot-dip galvanized striped steel plates are commercialized.

In recent years, in addition to hot-dip galvanized steel sheets, hot-dip zinc-based alloy coated steel sheets such as Zn-Al, Zn-Al-Mg and Zn-Al-Mg-Si have been developed from the demand for excellent corrosion resistance over zinc plating. It is commercialized. In response to this, attempts have also been made to apply hot-dip zinc-based alloy plating to striped steel plates.

Patent Document 2 has a Ni-Al-Zn-Fe quaternary alloy layer having a thickness of 2 μm or less as a first layer on the surface of a striped steel plate, and 0.1 to 1% in weight conversion as a second layer. Disclosed is a striped steel plate excellent in workability and corrosion resistance characterized by having a hot-dip plating layer of a Zn-based alloy containing Al. As a specific plating method, Patent Document 2 performs Ni plating of 0.5 to 2.0 g / m ^{2 on} a striped steel plate, and then heats the striped steel plate, and subsequently 0.1 to 1% in weight conversion. The method of producing a striped steel plate is provided, which comprises the steps of immersing in a molten zinc bath to which Al is added for an immersion time of 1 to 30 seconds.

Patent Document 3 uses a plating bath considered to be substantially the same as Patent Document 2, but specifies the structure of a hot-dip plating film obtained by the Sendzimir method. Each of Patent Documents 2 and 3 is essentially characterized by using a molten zinc-based alloy having an Al concentration of 1% or less. In Patent Documents 2 and 3, since the Al concentration in the plating layer is 1% or less, it is difficult to obtain the barrier anticorrosion effect caused by Al, and a preferable improvement in the remarkable corrosion resistance of the plating film itself can not be expected.

Patent Document 4 is, by mass%, Al: 4.0-20.0%, Mg: 1.0-4.0%, and optionally, Ti: 0.002-0.1% and B: 0. Disclosed is a hot-dip galvanized steel sheet excellent in scratch resistance, wear resistance and corrosion resistance characterized in that it is covered with a hot-dip plating layer containing 001 to 0.045% and the balance being Zn and unavoidable impurities. Do. This plated layer has a large proportion of ternary eutectic structure of Al / Zn / ZnMg intermetallic compound, and since this ternary eutectic is hard, the Vickers hardness becomes 120 to 180 Hv, and in addition to corrosion resistance, It is considered to be excellent in scratch resistance and abrasion resistance.

As described above, conventionally, striped steel plates are often used without plating, and zinc plating is optionally performed, and application of zinc-based alloy plating has also been tried in place of zinc plating. . In addition, it has not been examined at all so far to apply Ni pre-plating to a base material steel plate and apply zinc base alloy plating having an Al concentration of more than 1.0% after Ni pre-plating.

Japanese Patent Application Laid-Open No. 7-11411 Japanese Patent Application Laid-Open No. 6-81170 Japanese Patent Application Laid-Open No. 6-248409 Japanese Patent Application Laid-Open No. 11-279732

The present inventors also initially attempted to apply zinc base alloy plating with an Al concentration of more than 1.0% to a striped steel plate for the purpose of further improving the corrosion resistance of the striped steel plate. However, as a result of examination, it has become clear that non-plating occurs frequently only by applying zinc base alloy plating having an Al concentration of more than 1.0% to the striped steel sheet. That is, as in Patent Documents 2 and 3, if the Al concentration in zinc-based alloy plating is 1.0% or less, occurrence of non-plating does not become a problem, but as in Patent Document 4, zinc-based alloy plating is It became clear that the occurrence of non-plating becomes a problem if the Al concentration of Al exceeds 1.0%.

Specifically, the present inventors initially intended to impart excellent corrosion resistance to a striped steel plate, and generally said that the corrosion resistance is generally superior to Zn plating. It was studied to apply a Zn-based alloy plating containing a slight amount of Mg to a striped steel plate. And in that process, when the Zn-Al-Mg alloy with Al concentration over 1.0% is electroplated on the striped steel sheet by Sendzimir method that is usually adopted as the hot dip plating method, non-plating occurs frequently. Found out.

The inventors of the present invention have found that the non-plating tends to occur in the process of hot-dip plating a Zn-based alloy containing Al: more than 1.0% and a certain amount of Mg onto the striped steel sheet. It is considered that the wettability between the steel plate and the molten metal is reduced as it is performed, and that a specific cause resulting from the hot rolling history of the striped steel plate is also related.

With respect to the problem of this non-plating, the present inventors tried to adopt Ni pre-plating, which is also adopted in Patent Document 2. As a result of examination, the present inventors can suppress the occurrence of non-plating to some extent by performing zinc-based alloy plating after Ni pre-plating, but a zinc-based alloy having an Al concentration of more than 1.0% with respect to a striped steel plate It has been found that in the case of plating, it is necessary to relatively increase the amount of Ni attached in Ni pre-plating. However, on the other hand, as a result of the above investigations, when the amount of deposited Ni in Ni pre-plating is increased as a result of the above examination, it is also combined that the corrosion resistance tends to be reduced in the convex portions when the hot-dip galvanized steel sheet is worn out. I found out.

That is, the present inventors have found the following regarding application of a zinc-based alloy plating with an Al concentration of more than 1.0% to a striped steel sheet in order to further improve the corrosion resistance.
(A) Non-plating occurs frequently only by applying zinc-based alloy plating having an Al concentration of more than 1.0% to a striped steel plate.
(B) In order to apply zinc base alloy plating having an Al concentration of more than 1.0% to a striped steel sheet, it is necessary to pre-plate Ni, and it is necessary to increase the amount of attached Ni more than before.
(C) However, when the deposition amount of Ni pre-plating is increased with respect to the striped steel plate, when the hot-dip galvanized striped steel plate is worn out, the corrosion resistance tends to be deteriorated at the convex portion.

The present inventors considered the above phenomenon as follows. For example, when a hot-dip galvanized steel sheet is used as a floor plate or the like, wear and wear of the hot-dip plating layer may be large at the convex portions, and the Ni plating layer may be exposed. When Ni pre-plated steel plates are plated with molten Zn or molten Zn-Al etc., some Ni will move into the plating layer or melt due to the reaction with the molten metal, but some Ni will move It remains on the surface of a steel plate as a Ni plating layer. Therefore, when the Ni adhesion amount of Ni pre-plating is large, the Ni plating layer remaining on the surface of the steel sheet after hot-dip plating becomes thick.

Usually, the natural immersion potential is higher in the order of Ni, Fe and plated layer, but the natural immersion potential of a relatively thin Ni plated layer is a hybrid potential of Ni and Fe. In hot-dip plating of a Ni-preplated Zn-based alloy, the galvanized layer of the upper Zn-based alloy is worn away, and when the Ni-plated layer is exposed, Galvanic corrosion occurs between the exposed portion and the vicinity of the exposed portion. For example, in the hot-dip galvanized steel sheet, Galvanic corrosion occurs between the Ni plating layer exposed at the convex portion and the hot-dip plating layer near the exposed portion. Even if the Ni plating layer is exposed, if the Ni plating layer is thin, the natural immersion potential of the Ni plating layer becomes a mixed potential and becomes close to the potential of Fe, and Galvanic corrosion between the Ni plating layer and the hot-dip plating layer The speed is not big. Conversely, when the Ni plating layer is thick, the natural immersion potential of the Ni plating layer is substantially close to the Ni potential even if it is the hybrid potential, so the Galvanic corrosion rate between the Ni plating layer and the hot-dip plating layer Becomes larger. As a result, the hot-dip plating layer is susceptible to corrosion and wear.

Hereinafter, in order to prevent confusion, in the present specification, unless otherwise specified, "Ni plating layer" to indicate a plating layer, "Ni plating" is used, Ni coating remaining after hot-dip plating A layer is meant, "Ni pre-plating layer", "Ni pre-plating" shall mean the Ni coating layer which exists before a hot dip plating process. Further, in the following description of the present specification, when using expressions such as “hot-dip plating of Zn-based alloy” and “hot-dip plating”, it means “hot-dip plating of Zn—Al—Mg-based alloy”.

The present invention is a striped steel plate on which a Zn-Al-Mg-based alloy containing 1.0% or more of Al has been subjected to hot-dip plating, which has almost no non-plating and a Zn-based alloy at the convex portion of the striped steel plate. It is an object of the present invention to provide a hot-dip galvanized steel sheet which exhibits excellent corrosion resistance even when hot-dip plating is worn out (corrosion or wear) and a method for producing the same. In the present invention, after satisfying the plating appearance and processability, etc., which are general characteristics required for hot-dip galvanized striped steel sheets, the hot-dip plating can achieve both the suppression of the non-plating and the corrosion resistance after wear. It aims at providing a striped steel plate and its manufacturing method.

The present inventors attempted to carry out the hot-dip plating of a Zn-Al-Mg-based alloy containing 1.0% or more of Al on a Ni pre-plated striped steel plate, the relatively large Ni adhesion from the viewpoint of preventing non-plating. Although the amount is required, it was considered that at least the amount of Ni adhesion at the convex portion needs to be suppressed to a certain value or less from the viewpoint of securing the corrosion resistance at the convex portion of the striped steel plate.

When pre-plating Ni on steel strip, electroplating is usually employed. Although it is possible to deposit Ni on a steel strip by the electroless method, it is not preferable because the productivity is inferior and, in addition, a large amount of elements other than Ni are mixed into the deposited film. When electroplating is performed on a general steel strip, usually, the anode is disposed to face the steel strip surface which is a cathode, and electrolysis is performed by minimizing the distance between the steel strip and the anode as much as possible. The power cost can be reduced while ensuring the uniformity of the current distribution.

However, when performing electroplating on a striped steel plate, the distance between the electrode and the anode is closer to the convex portion of the striped steel plate than to the flat portion of the striped steel plate, so the amount of Ni attached becomes large at the convex portion of the striped steel plate. That is, in the case of performing Ni pre-plating by electroplating a striped steel plate in a conventional electrolytic cell under conventional conditions, the amount of Ni attached on the convex portion becomes very large, and as a result, the hot-dip galvanized steel layer There is a concern that significant Galvanic corrosion will occur at the ridges when the.

The present inventors, regarding hot-dip galvanized steel sheets of Zn-Al-Mg-based alloy containing 1.0% or more of Al, have a lower limit value of the thickness of Ni pre-plating layer required for preventing non-plating and By determining the upper limit value of the thickness of the Ni plating layer to be limited in order to secure the corrosion resistance in the convex portion, and defining the thickness ratio of the Ni plating layer in the convex portion and the flat portion, I found that I could overcome the problem.

The gist of the present invention is as follows.
(1) The hot-dip galvanized striped steel sheet according to one aspect of the present invention comprises a base steel plate, a Ni-plated layer disposed on the surface of the base steel plate, and a hot-dip plated layer disposed on the surface of the Ni-plated layer. A Ni-plated layer in the convex portion having a thickness of 0.07 to 0.4 μm per side, and the Ni plated layer in the flat portion is The film thickness is 0.05 to 0.35 μm per one side, and the film thickness of the Ni plating layer in the convex portion is more than 100% and 400% or less of the film thickness of the Ni plating layer in the flat portion. The adhesion amount of the layer is 60 to 400 g / m 2 per one side, and the hot-dip plating layer has a chemical composition of Al: more than 1.0% and 26% or less, Mg: 0.05 to 10%, Si: Containing 0 to 1.0%, Sn: 0 to 3.0%, Ca: 0 to 1.0%, the balance being Zn and impurities It consists of things.
(2) In the hot-dip galvanized striped steel sheet according to (1), the thickness of the Ni plating layer in the convex portion is more than 100% and 300% or less of the thickness of the Ni plating layer in the flat portion. Good.
(3) In the hot-dip galvanized steel sheet described in the above (1) or (2), the film thickness of the Ni plating layer in the convex portion may be 0.07 to 0.3 μm per one surface.
(4) In the hot-dip galvanized striped steel sheet according to any one of the above (1) to (3), the hot-dip plated layer has a chemical composition of, by mass%, Al: 4.0 to 25.0%, Mg May contain 1.5 to 8.0%.
(5) In the hot-dip galvanized striped steel sheet according to any one of the above (1) to (4), the hot-dip plated layer has a chemical composition represented by mass: Si: 0.05 to 1.0%, Sn It may contain at least one of 0.1 to 3.0% and Ca: 0.01 to 1.0%.
(6) In the hot-dip galvanized striped steel sheet according to any one of the above (1) to (5), when viewed from the thickness direction, the coverage of the hot-dip plating layer is 99 to 99% in area% with respect to the plate surface. It may be 100%.
(7) The method of manufacturing a hot-dip galvanized striped steel sheet according to an aspect of the present invention is a method of producing the striped steel sheet according to any one of the above (1) to (6) The pre-plating process includes a rolling process for providing a convex portion and a flat surface, a pre-plating process for applying Ni pre-plating to a steel plate subjected to the rolling process, and a hot-dip plating process for hot dip plating on a steel plate subjected to the pre-plating process. In the process, the rolling surface and the anode surface of the steel plate are arranged to face each other, the distance between the projections of the rolling surface and the anode is controlled to 40 to 100 mm, and the plating adhesion amount per one side is 0.5 on average. ~ perform electrical Ni plating at 3 g / ^{m 2} and comprising condition, the hot dipping step, heating the steel sheet contains, by mass%, Al: 1.0 super 26% or less, Mg: 0.05 ~ 10%, Si: Contains 0 to 1.0%, Sn: 0 to 3.0%, Ca: 0 to 1.0% The steel plate is immersed in a hot-dip plating bath containing the remainder of Zn and impurities, and continuous hot-dip plating is performed under the condition that the plating adhesion amount per one side is 60 to 400 g / m ^{2 on} average.
(8) In the method of manufacturing a hot-dip galvanized steel sheet according to (7), the distance between the electrodes may be controlled to 45 to 100 mm in the pre-plating step.

According to the above aspect of the present invention, since the hot-dip plating layer contains Al of more than 1.0%, excellent corrosion resistance is obtained, and additionally, the film thickness of the Ni plating layer is controlled. The occurrence can be suppressed, and the corrosion when the hot-dip plating layer is worn out and the Ni plating layer is exposed can also be suppressed. As a result, it is possible to suppress floor plates, base plates, structures, and other life cycle costs as hot-dip galvanized steel sheets.

It is a schematic diagram at the time of seeing the base material steel plate of the hot-dip galvanized striped steel plate which concerns on one Embodiment of this invention from thickness direction. It is a cross-sectional schematic diagram at the time of seeing the base material steel plate of the hot-dip galvanized striped steel plate which concerns on the embodiment by the cut surface where a thickness direction and a cutting direction become parallel, Comprising: It is GG sectional drawing of FIG. It is a cross-sectional schematic diagram at the time of seeing the base material steel plate of the hot-dip galvanized striped steel plate which concerns on the embodiment by the cut surface where a thickness direction and a cutting direction become parallel, Comprising: It is FF sectional drawing of FIG. It is a cross-sectional schematic diagram at the time of seeing the hot-dip galvanized striped steel plate which concerns on the embodiment by the cut surface where a thickness direction and a cutting direction become parallel.

Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to only the configuration disclosed in the present embodiment, and various modifications can be made without departing from the spirit of the present invention. Further, the lower limit value and the upper limit value are included in the numerical limitation range described below. The numerical value shown as "super" or "less than" does not include the value in the numerical range.

The hot-dip galvanized striped steel sheet according to the present embodiment comprises a base steel plate, a Ni plating layer disposed on the surface of the base steel plate, and a Zn-based (Zn-Al-Mg-based) alloy disposed on the surface of the Ni plating layer. And a convex portion and a flat portion on the plate surface. In addition, the film thickness of the Ni plating layer in the convex portion is 0.07 to 0.4 μm per one surface, the film thickness of the Ni plating layer in the flat portion is 0.05 to 0.35 μm per one surface, and The film thickness of the Ni plating layer is more than 100% and 400% or less of the film thickness of the Ni plating layer in the flat portion. In addition, the adhesion amount of the hot-dip plating layer is 60 to 400 g / m ² per one side, and the hot-dip plating layer has a chemical composition of Al: more than 1.0% and 26% or less, Mg: 0.05 to 10%, Si: 0 to 1.0%, Sn: 0 to 3.0%, Ca: 0 to 1.0%, the balance being Zn and impurities.

In addition, a thin intermetallic compound layer may be formed on the Ni plating layer side of the hot-dip plating layer based on the reaction between a molten metal (hot-dip plating bath of Zn-based alloy) and a steel plate preplated with Ni. Varies with the composition of the Zn-based alloy hot-dip plating bath. In the present embodiment, the “hot-dip plating layer of a Zn-based alloy” is used in the meaning including the intermetallic compound layer.

First, the hot-dip galvanized steel sheet according to the present embodiment will be described in detail.

The hot-dip plating layer is a Zn-based alloy and contains, as a chemical composition, by mass, Al: more than 1.0% and not more than 26%, and Mg: 0.05 to 10%.

Al (aluminum) is important for securing the corrosion resistance of the hot-dip plating layer, and also prevents the oxidation of the molten metal and the generation of the Fe-Zn dross. Therefore, the Al concentration of the hot-dip plating layer exceeds 1.0%. On the other hand, if the Al concentration in the plating bath increases, the melting point rises, so it is necessary to raise the temperature of the molten metal. If the Al concentration exceeds 26%, it is difficult to secure the beauty of the surface properties of the plating layer It is easy to cause the deterioration of processability. Therefore, the Al concentration of the hot-dip plating layer is 26% or less. From the viewpoint of corrosion resistance, the Al concentration of the hot-dip plating layer is preferably 4.0% or more. From the viewpoint of processability, the Al concentration of the hot-dip plating layer is preferably 25.0% or less, more preferably 21.0% or less.

Mg (magnesium) forms a stable corrosion product in a corrosive environment to form a barrier layer against corrosion and makes the corrosion resistance more excellent. If the Mg concentration is less than 0.05%, this effect is poor, so the Mg concentration in the hot-dip plating layer is made 0.05% or more. On the other hand, the oxidation of the molten metal is promoted as the Mg concentration in the molten metal increases. For this reason, the Mg concentration in the hot-dip plating layer is 10% or less. Moreover, when the concentration of Mg exceeds 10%, it becomes difficult to secure the beauty of the surface property of the plating layer, including the influence of the increase in the amount of generation of oxide dross. The preferable lower limit of the Mg concentration is 0.5%, more preferably 1%, still more preferably 1.5%, and still more preferably 2.0%. The upper limit of the Mg concentration is preferably 8.5%, more preferably 8.0%, and still more preferably 6.0%.

The hot-dip plated layer of the hot-dip galvanized striped steel sheet according to the present embodiment contains Al and Mg which are the above-described basic elements as a chemical composition, and the balance is made of Zn and impurities. For example, in the hot-dip plating layer, the Zn concentration is 64 to 98.95% in mass%. The hot-dip plating layer contains 1.0% or less of Si, 3.0% or less of Sn, and 1.0% or less of Ca in mass%, as a selective element, instead of part of Zn that is the above-mentioned remaining portion. You may

Si (silicon) suppresses the growth of the interfacial alloy phase formed at the interface with the base steel plate, contributes to the improvement of the workability, suppresses the oxidation of Mg, and forms Mg and Mg ₂ Si. Contributes to the improvement of corrosion resistance. Therefore, the Si concentration of the hot-dip plating layer may be 0 to 1.0%. In order to preferably obtain the above-mentioned effect of Si, Si is contained in an amount of 0.05% or more, preferably 0.1% or more. On the other hand, the above effect is saturated even if the Si concentration exceeds 1.0%. The preferred upper limit of the Si concentration is 0.6%.

Sn (tin) forms Mg and Mg ₂ Sn and also contributes to the improvement of the corrosion resistance, particularly the edge corrosion resistance. Therefore, the Sn concentration of the hot-dip plating layer may be 0 to 3.0%. In order to preferably obtain the above effect of Sn, 0.1% or more, preferably 0.3% or more of Sn is contained. On the other hand, when the Sn concentration exceeds 3.0%, the corrosion resistance, particularly the corrosion resistance of the flat portion tends to be reduced. The preferred upper limit of the Sn concentration is 2.4%.

Ca (calcium) is effective in preventing oxidation of the plating bath surface. The molten metal of the Zn-Al-Mg-based alloy tends to be easily oxidized as compared with the case where it does not contain Mg. By including Ca, oxidation of the plating bath surface can be preferably suppressed. Therefore, the Ca concentration of the hot-dip plating layer may be 0 to 1.0%. The Ca concentration is preferably 0.01% or more, more preferably 0.1% or more. On the other hand, when the Ca concentration exceeds 1.0%, precipitation of Ca-based intermetallic compounds is increased, which may lower the corrosion resistance, particularly the corrosion resistance of the flat portion. The preferred upper limit of the Ca concentration is 0.7%.

With respect to the chemical composition of the hot-dip plating layer, the balance of the above-mentioned basic element and selective element consists of Zn and impurities. In addition, an "impurity" refers to the thing mixed from a raw material or a manufacturing environment etc. For example, in the hot-dip plated layer of the hot-dip galvanized striped steel sheet according to the present embodiment, Ni, Fe and the like dissolve from the surface of the steel plate into the plating bath to become impurities of the Zn-based alloy. For example, the hot-dip plating layer may contain Ni derived from the Ni pre-plating layer, and the Ni concentration may be 0.01 to 0.3% by mass%. In the hot-dip plating layer of the hot-dip galvanized striped steel sheet according to the present embodiment, impurities are allowed to be contained as long as the target characteristics are not impaired.

In addition, a Ni-Al based intermetallic compound layer may be formed at the interface between the hot-dip plating layer and the Ni plating layer. In this embodiment, this intermetallic compound layer is considered to be part of the hot-dip plating layer.

Moreover, in this embodiment, the average adhesion amount of the hot-dip plating layer is 60 g / m ² or more per one side. The average amount of adhesion means the average amount of adhesion including the convex portion and the flat portion of the hot-dip galvanized steel sheet. That is, it means the amount of adhesion per projected area ignoring the unevenness of the convex part of the hot-dip galvanized steel sheet. When the average adhesion amount of the hot-dip plating layer is less than 60 g / m ² , the corrosion resistance is insufficient. The upper limit of the average adhesion amount of the hot-dip plating layer is not necessarily limited, but excessive adhesion of the hot-dip plating layer makes the plating sagging remarkable and impairs the appearance, so the average adhesion amount of the hot-dip plating layer is 400 g / m ² or less per side. It is preferable to do.

Further, in the present embodiment, when the hot-dip galvanized striped steel sheet is viewed from the thickness direction, the coverage of the hot-dip plating layer is preferably 99 to 100% in area% with respect to the plate surface. If the coverage of the hot-dip plating layer is 99% or more in area%, it can be judged that the occurrence of non-plating can be preferably suppressed.

Next, the Ni plating layer of the hot-dip galvanized steel sheet according to the present embodiment will be described in detail.

In the Ni plating layer, a Ni pre-plating layer previously formed on the surface of the base steel plate in order to prevent non-plating in the hot-dip plating process remains between the base steel plate and the hot-dip plating layer even after hot dipping. It is.

The Ni-plated layer is, for example, a light-colored contrast area observed between the base steel plate and the hot-dip plating layer when the cross section of the hot-dip streaked steel plate is observed by a reflection electron image of SEM (Scanning Electron Microscope) It is the range displayed white). In the present embodiment, an intermetallic compound layer containing Ni that may be formed at the interface between the Ni plating layer and the base steel plate, and Ni that may be formed at the interface between the Ni plating layer and the hot-dip plating layer The intermetallic compound layer is not included in the Ni plating layer.

The Ni plating layer contains Ni as a chemical composition, and the balance consists of impurities. For example, the Ni concentration of the Ni plating layer is preferably 50 to 100% by mass. In addition, an "impurity" refers to the thing mixed from a raw material or a manufacturing environment etc. For example, the Ni plating layer of the hot-dip galvanized striped steel sheet according to the present embodiment contains impurities due to diffusion of Fe from the base steel sheet, and the like.

In the present embodiment, the thickness of the Ni plating layer on the convex part of the hot-dip galvanized steel sheet is 0.4 μm or less on average per one side when viewed in a cut surface in which the thickness direction and the cutting direction are parallel. is necessary. When the film thickness exceeds 0.4 μm, the hot-dip plating layer of the Zn-based alloy is worn away in the convex portions, and the corrosion resistance when the Ni plating layer is exposed is reduced. It is preferable that the film thickness of the Ni plating layer of this convex part is 0.3 micrometer or less. On the other hand, the lower limit of the film thickness of the Ni plating layer of the convex portion is set to 0.07 μm or more per one surface on average. When the film thickness is less than 0.07 μm, non-plating occurs in the convex portion. It is preferable that the film thickness of the Ni plating layer of this convex part is 0.1 micrometer or more.

Further, in the present embodiment, the thickness of the Ni plating layer in the flat portion of the hot-dip galvanized steel sheet is 0.05 μm or more per one surface on the cut surface in which the thickness direction and the cutting direction are parallel. It is necessary. If this film thickness is less than 0.05 μm, non-plating occurs on the flat portion. On the other hand, the upper limit of the film thickness of the Ni plating layer in the flat portion is 0.35 μm or less on an average per one side. If the film thickness exceeds 0.35 μm, the effect of improving the plating adhesion on the flat portion is saturated, which is not economical.

Further, in the present embodiment, the thickness of the Ni plating layer in the convex portion is 100 as compared to the thickness of the Ni plating layer in the flat portion when viewed in a cut surface in which the thickness direction and the cutting direction are parallel. It is necessary to be more than% and not more than 400%.

As described above, under the conventional plating conditions for electroplating, in the case of a striped steel plate, Ni adheres preferentially to not the flat portion but the convex portion. For example, when the distance between the projections of the striped steel plate and the anode is less than 40 mm as in the prior art, the thickness of the Ni plating layer of the projections is the thickness of the Ni plating layer of the flat portion. In contrast, it was confirmed that it might be 2000% or more.

However, as described above, the present inventors do not thicken the film thickness of the Ni plating layer of the convex part so as to enhance the corrosion resistance after the wear in the convex part, while suppressing the non-plating in the flat part It has been found that in order to achieve this, it is necessary to secure a film thickness of the Ni plating layer in the flat portion to a certain extent. That is, in this embodiment, the film thickness ratio of the Ni plating layer of the convex portion to the flat portion (film thickness of convex portion / film thickness of flat portion × 100) is smaller than that of the conventional hot-dip galvanized steel sheet.

When the film thickness ratio of the Ni plating layer of the convex portion to the flat portion (film thickness of the convex portion / film thickness of the flat portion × 100) exceeds 400%, suppression of non-plating in the flat portion and corrosion resistance after wear at the convex portion In the present embodiment, the film thickness ratio of the Ni plating layer of the convex portion to the flat portion is 400% or less. The film thickness ratio of the Ni plating layer of the convex portion to the flat portion is preferably 350% or less, more preferably 300% or less, and most preferably 250% or less.

On the other hand, making the thickness of the Ni plating layer in the convex portion smaller than the thickness of the Ni plating layer in the flat portion, or making the thickness of the Ni plating layer the same between the convex portion and the flat portion Due to its shape, electroplating is substantially difficult. Therefore, in the present embodiment, the film thickness ratio of the Ni plating layer of the convex portion to the flat portion is set to be more than 100%.

In addition, by controlling the film thickness ratio of the Ni plating layer of the convex portion to the flat portion within the above range, the effect of being able to achieve both the non-plating suppression in the flat portion and the corrosion resistance after wear at the convex portion can be obtained. In addition to the above, it is possible to increase the Ni deposition amount in the necessary area (flat portion) and reduce the Ni deposition amount in the unnecessary area (convex portion), so it is also possible to effectively use Ni, which is a limited resource.

Next, the base material steel plate of the hot-dip plated striped steel plate according to the present embodiment will be described in detail.

In the present embodiment, the base steel plate (original plate to be plated) is a striped steel plate. The striped steel sheet is usually given the shape of the convex portion by hot rolling. The steel type of the base steel plate is not particularly limited, but generally, a steel type corresponding to the general structural rolled steel defined in JIS G3101 is used. The convex shape of the striped steel sheet can be imparted, for example, by transferring the concave shape formed on the work roll to the steel sheet surface at the finishing stage of hot rolling. In the present embodiment, the stripe height (height of the convex portion) and the occupancy ratio of the stripe portion (convex portion) are not necessarily limited, but in particular, in view of slip prevention as a floor plate and usability. The stripe height is 0.5 to 3.5 mm, and the area occupancy of the stripe portion is 15 to 60%.

FIGS. 1A to 1C show the shape of a striped steel plate to be a base steel plate. FIG. 1A is a schematic view when a base steel plate of a hot-dip galvanized striped steel plate according to an embodiment of the present invention is viewed from the thickness direction. FIG. 1B is a schematic cross-sectional view of the base steel plate of the hot-dip galvanized striped steel plate according to the embodiment as viewed from a cut surface in which the thickness direction and the cutting direction are parallel. FIG. FIG. 1C is a schematic cross-sectional view of the base steel plate of the hot-dip galvanized striped steel plate according to the embodiment as viewed from a cut surface in which the thickness direction and the cutting direction are parallel. FIG. A, B, C, D, E and H in these figures are as follows, respectively. A: Alignment angle of convex portions with respect to the rolling direction. B: Length of one convex portion. C: Maximum width of one convex portion. D: Minimum width of one convex portion. E: Arrangement pitch of convex portions. H: Height of convex portion.

Next, an observation method and a measurement method will be described with respect to the hot-dip galvanized steel sheet according to the present embodiment.

The convex portion and the flat portion of the hot-dip galvanized steel sheet may be observed in the appearance and the cross section of the hot-dip galvanized steel sheet. For example, when the appearance of the hot-dip galvanized striped steel sheet is observed from the thickness direction, it can be determined that a convex portion and a flat portion exist in the hot-dip galvanized striped steel sheet if the appearance is equivalent to that of the striped steel plate shown in FIG.

More specifically, the hot-dip galvanized striped steel sheet is a cross section corresponding to the GG cross section of FIG. 1A, that is, a cutting plane in which the cutting direction is parallel to the thickness direction and the center point (center of gravity) of the convex portion It may be observed on a cut surface including the major axis of the and the convex portion to determine whether or not the convex portion and the flat portion exist. For example, with respect to the contour curve of the hot-dip galvanized steel sheet appearing in this cross section, a reference line is determined on the basis of the region corresponding to the flat portion of the hot-dip galvanized steel sheet. If the distance is 0.5 mm or more, it may be determined that the peaks on the contour curve are convex. When one or more convex portions are present per 100 mm ² when the steel plate is observed in the thickness direction, it may be determined that the steel plate is a hot-dip galvanized steel plate.

Whether or not the base steel plate, the Ni plating layer, and the hot-dip plating layer are present in the hot-dip galvanized steel sheet may be observed by a field emission scanning electron microscope (FE-SEM) or a transmission electron microscope (TEM). For example, the test piece may be cut out so that the cutting direction is parallel to the thickness direction, and the cross-sectional structure of the cut surface may be observed by FE-SEM or TEM at a magnification at which each layer is included in the observation field of view. FIG. 2 shows a schematic view of the cross-sectional structure of the hot-dip galvanized steel sheet according to the present embodiment.

For example, in order to identify each layer in the cross-sectional structure, the acceleration voltage is 15kV, the irradiation current is 10nA, the beam diameter is 10kA along the thickness direction at 20000 magnification using EDS (Energy Dispersive X-ray Spectroscopy). Linear analysis may be performed with about 100 nm less, a measurement pitch of 0.025 μm, and an aperture diameter of the objective lens of 30 μmφ, and quantitative analysis of the chemical composition of each layer may be performed with a total of 100% by mass of Ni, Fe and Zn. After moving average processing to average the data of 5 points before and after in order to remove the measurement noise to the result of this line analysis, the area where Ni concentration becomes 50 mass% or more on the scanning line is Ni plating layer It may be determined that there is. Further, the region on the surface side may be determined as the hot-dip plating layer, and the region on the inner side may be determined as the base steel plate, with the Ni plating layer identified on the scanning line as a reference. The hot-dip plating layer is a Zn-based alloy, and the base steel plate is a Fe-based alloy.

The film thickness of the Ni plating layer of the convex portion may be determined by identifying the Ni plating layer of the convex portion in a cross section corresponding to the GG cross section of FIG. 1A. For example, in the above cross section, line analysis is performed along the thickness direction so as to include the top of the highest peak on the contour curve of the hot-dip galvanized steel sheet, and the Ni plating layer is identified on the scanning line of the line analysis; A line segment of the Ni plating layer on the scanning line may be obtained, and this line segment may be adopted as the film thickness of the Ni plating layer of the convex portion.

The film thickness of the Ni plating layer in the flat portion may be measured in the same manner as described above. For example, in the cross section corresponding to the GG cross section in FIG. 1A, line analysis is performed along the thickness direction at a flat portion at a position 2 mm or more away from the end of the convex portion. The layer may be identified, a line segment of the Ni plating layer on the scanning line may be determined, and this line segment may be adopted as the film thickness of the Ni plating layer in the flat portion.

In addition, the film thickness of the Ni plating layer of a convex part and a plane part may be measured in at least three or more places, respectively, and the average value may be adopted. In addition, when the film thickness of the Ni plating layer in the convex portion and the flat portion is less than 0.3 μm, it is preferable to obtain the film thickness not by SEM but by TEM.

Moreover, based on the film thickness of the Ni plating layer of the convex part and the flat part obtained above, the film thickness ratio of the Ni plating layer of the convex part to the flat part (film thickness of convex part 凸 film thickness of flat part × 100) You can calculate

The chemical composition and the adhesion amount of the hot-dip plating layer may be measured using ICP (Inductive Coupled Plasma) emission spectroscopy. For example, a sample of 30 mm × 30 mm in size is taken from any part of a hot-dip galvanized steel sheet, and an inhibitor (eg, Asahi Chemical Industries Ibit, model number: Ibit 710-K, concentration: 300 ppm, ppm is Only the plating layer is pickled and peeled off using 10% hydrochloric acid added with mg / kg), ICP quantitative analysis is performed to determine the concentration of each element, and the chemical composition and adhesion amount of the hot-dip plating layer from the concentration of each element You just need to ask. In addition, what is necessary is to carry out said measurement with respect to the sample extract | collected from at least 3 or more places, and what is necessary is just to employ the average value.

The coverage with respect to the plate surface of the hot-dip plating layer may be determined by observing the hot-dip galvanized steel sheet from the thickness direction. For example, a sample of 100 mm × 100 mm may be taken from any part of the hot-dip galvanized steel sheet, and this sample may be observed from the thickness direction to determine the area ratio of the unplated area in the sample area. The area ratio may be determined using image analysis software (for example, WinROOF manufactured by Mitani Corporation). More specifically, the 100 mm × 100 mm sample is divided into sizes that can be measured by EDS or EPMA (Electron Probe Micro-Analyzer), and surface analysis is performed on each of the divided samples using EDS or EPMA. The Fe distribution map may be obtained, and the area ratio of the non-plating area (the area where the Fe concentration is 20 mass% or more) in the sample area may be obtained from these Fe distribution maps. The coverage of the hot-dip plating layer may be determined based on the area ratio of the non-plating area.

Next, a method of manufacturing the hot-dip galvanized steel sheet according to the present embodiment will be described in detail.

In the method of manufacturing a hot-dip galvanized striped steel sheet according to the present embodiment, a rolling step of providing a convex portion and a flat portion on a rolled surface of a steel plate, a pre-plating step of applying Ni pre-plating to a steel plate subjected to the rolling step, and pre-plating And D. a hot-dip plating process for hot-dip plating a steel plate that has undergone the process. In the pre-plating step, the rolling surface and the anode surface of the steel plate are arranged to face each other, the distance between the projections of the rolling surface and the anode is controlled to 40 to 100 mm, and the plating adhesion amount per one side is 0 on average. Electro Ni plating is performed under conditions of 5 to 3 g / m ² . Further, in the hot-dip plating process, the steel plate is heated, and Al: 1.0 to 26% or less, Mg: 0.05 to 10%, Si: 0 to 1.0%, Sn: 0 to 3% by mass. The steel sheet is immersed in a hot-dip plating bath containing 0%, Ca: 0 to 1.0%, the balance being Zn and impurities, and the plating adhesion amount per one side is 60 to 400 g / m ^{2 on} average. Conduct continuous hot-dip plating.

In the rolling process, a convex portion and a flat portion are provided on the rolling surface of the steel plate. The rolling conditions are not particularly limited, but the convex portion and the flat portion may be provided on the rolled surface of the steel sheet by transferring the concave shape formed on the working roll to the steel sheet surface at the finishing stage of hot rolling. The striped steel plate shaped by hot rolling is subjected to pretreatment such as pickling to remove scale and the like. Brush grinding or the like may be performed on the surface of the steel plate as necessary.

In the pre-plating step, the pre-treated striped steel plate is subjected to Ni pre-plating. It is desirable to use electroplating from the viewpoint of productivity and the viewpoint of suppression of mixing of an impurity element in Ni pre-plating. The electroplating is exemplified by a method using a watt bath, a sulfamic acid bath or the like.

In the case of a method using a watt bath, the preferred Ni plating bath composition is NiSO ₄ .6H ₂ O: 250 to 350 g / L, Na ₂ SO ₄ : 50 to 150 g / L, H ₃ BO ₃ : 30 to 50 g / L PH: 2 to 3.5, preferred bath temperature is 50 to 70 ° C., preferred cathodic current density is 5 to 30 A / dm ² . Specifically, for example, NiSO ₄ · 6H ₂ O: 340 g / L, Na ₂ SO ₄ : 100 g / L, H ₃ BO ₃ : 45 g / L, pH: 2.5, temperature: 60 ° C., cathodic current density: 20 A / dm ² can be mentioned.

In the present embodiment, in order to prevent the occurrence of non-plating in the hot-dip plating process, the Ni adhesion amount in Ni pre-plating is increased as compared to the conventional method. However, even if the hot-dip plating layer is worn out and the Ni plating layer is exposed at the convex portion, excessive Ni precipitation at the convex portion is avoided so that the corrosion of the steel plate is suppressed.

In an electroplating bath (electrolytic bath), usually, a steel strip is used as a cathode, and an anode is disposed to face the steel plate surface. The steel strip surface and the anode are parallel and approximated by a parallel plate electrode system. When electroplating is performed on the striped steel plate in such an electrolytic cell, the distance between the poles of the convex portion of the striped steel plate and the anode is close, so that current concentration easily occurs in the convex portion. In the present embodiment, the distance between the electrodes (the distance between the convex portion of the steel strip surface and the anode) is increased in order to suppress current concentration on the convex portion of the striped steel plate. In the conventional conditions, in order to reduce the power cost while securing the uniformity of the current distribution, the inter-electrode distance is set to less than 40 mm, but in the present embodiment, the inter-electrode distance is set to 40 to 100 mm. If the distance between the electrodes is less than 40 mm, current concentration occurs in the projections, making it difficult to control the thickness of the Ni plating layer of the projections within a predetermined range. On the other hand, if the distance between the electrodes exceeds 100 mm, an increase in power loss due to liquid resistance is caused. The lower limit of the distance between the electrodes is preferably 45 mm, and more preferably 50 mm. The upper limit of the distance between the electrodes is preferably 90 mm, and more preferably 85 mm.

For example, in a hot-dip galvanized steel sheet manufactured by setting the distance between the electrodes to less than 40 mm as in the prior art, the film thickness ratio of the Ni plating layer of the convex to the flat (film thickness of the convex ÷ film thickness of the flat × 100) may be 2000% or more. On the other hand, in the hot-dip galvanized steel sheet manufactured by setting the distance between the electrodes to 40 mm or more, the film thickness ratio of the Ni plating layer of the convex portion to the flat portion can be easily controlled to 400% or less. In addition, when the distance between the electrodes is set to 45 mm or more, the thickness ratio of the Ni plating layer of the convex portion to the flat portion can be easily controlled to 300% or less when the hot-dip galvanized steel sheet is formed.

In the pre-plating step, the average adhesion amount per side of Ni pre-plating is set to 0.5 to 3 g / m ² . If the average adhesion amount is less than 0.5 g / m ² , the film thickness of the Ni plating layer in the flat portion of the striped steel plate after hot-dip plating becomes less than 0.05 μm, and non-plating tends to occur. When the average adhesion amount exceeds 3 g / m ² , the Ni plating layer remaining in the convex portions after hot-dip plating becomes excessive, and it becomes difficult to make the thickness of the Ni plating layer in the convex portions 0.4 μm or less.

The Ni adhesion amount of Ni pre-plating may be measured based on the following procedures a to e before hot-dip plating of a Zn-based alloy.
Procedure a: Dissolve Ni pre-plated steel plate with 30% by mass nitric acid (dissolution solution A).
Procedure b: A sample is taken from the vicinity of the sample used in procedure a, and after removing the pre-plated Ni layer by grinding or the like, it is dissolved in 30% by mass nitric acid (solution B).
Procedure c: The amount of Fe and the amount of Ni dissolved in the solution B are determined by ICP, and the ratio of the amount of Fe to the amount of Ni is determined.
Procedure d: The amount of Fe dissolved in the solution A is determined by ICP, and the amount of Ni dissolved from the base steel plate is determined from the ratio calculated in the procedure c.
Step e: The amount of Ni dissolved in the solution A is determined by ICP, and the amount of Ni derived from the base steel plate calculated in step d is subtracted to calculate the amount of Ni derived from the pre-plated Ni layer. The amount of Ni derived from the Ni pre-plated layer is converted to the amount of adhesion per unit area.

In addition, although it depends on the design of the electrolytic cell, an edge overcoat due to current concentration may occur at the width direction end of the steel plate in the continuous electroplating apparatus for steel strip. Therefore, when calculating said average adhesion amount, you may exclude the width direction edge part (for example, area | region of 50 mm from both ends) of a steel strip from a measuring object.

In the hot-dip plating process, after preheating a Ni pre-plated striped steel plate (steel strip) in a non-oxidizing atmosphere, the hot-dip plating bath is continuously passed (continuously immersed in the hot-dip plating bath). The non-oxidizing atmosphere is, for example, a mixed gas of nitrogen and hydrogen. The preheating temperature is preferably in the range of [temperature of plating bath + 10 ° C.] to [temperature of plating bath + 50 ° C.]. When the preheating temperature is low, non-plating tends to occur frequently. In preheating, it is preferable to rapidly heat the steel plate so that the time for which the temperature is 350 ° C. or more is 40 seconds or less. Since the diffusion of Ni into the base steel plate can be suppressed by shortening the time during which the steel plate is 350 ° C. or more, the amount of Ni pre-plating for preventing non-plating can be sufficiently secured.

Al: more than 1.0% and 26% or less, Mg: 0.05 to 10%, if necessary Si: 0 to 1.0%, Sn: 0 to Passing (immersing in a hot-dip plating bath) a hot-dip zinc-based alloy plating bath containing 3.0%, Ca: 0 to 1.0%. The temperature of the plating bath is preferably in the range of [melting point + 20 ° C. of molten Zn-based alloy] to [melting point + 50 ° C. of molten Zn-based alloy]. The striped steel plate is dipped in a plating bath, preferably for 1 to 6 seconds, and then wiped, and optionally cooled by an air-water spray or the like.

In the hot-dip plating process, the average adhesion amount per one side of the hot-dip plating layer is set to 60 to 400 g / m ² . If the average adhesion amount is less than 60 g / m ² , the corrosion resistance may be insufficient. When the average adhesion amount is more than 400 g / m ² , excessive deposition of the hot-dip plating layer may cause significant plating sag and damage the appearance.

The chemical composition of the hot-dip plating bath and the adhesion amount of hot-dip plating may be measured using ICP emission spectroscopy in the same manner as described above. The chemical composition of the hot-dip plating bath may be ICP measurement based on a sample collected from the hot-dip plating bath, not a sample collected from the hot-dip galvanized steel sheet.

Next, the effects of one aspect of the present invention will be described in more detail by way of examples, but the conditions in the examples are one example of conditions adopted to confirm the feasibility and effects of the present invention. However, the present invention is not limited to this one condition example. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the scope of the present invention.

A 2.3 mm thick hot-rolled steel plate was used as a plating base plate.
The shape of this striped steel plate (base steel plate) was equivalent to that of FIGS. 1A to 1C. In the figure, A, B, C, D, E and H are as follows respectively.
A: Alignment angle of convex portions with respect to the rolling direction.
B: Length of one convex portion.
C: Maximum width of one convex portion.
D: Minimum width of one convex portion.
E: Arrangement pitch of convex portions.
H: Height of convex portion.
This striped steel plate is a hot-rolled Al-killed steel and has an angle A = 45 °, a width C = 5.1 mm, a length B = 25.3 mm, a height H = 1.5 mm, and a pitch E = 28.6 mm. The As described above, the striped steel plate in which the convex portions are regularly arranged is pickled, and Ni pre-plating is performed at various distances between the electrodes to change the average adhesion amount of Ni. Tables 1 and 2 show the conditions for Ni pre-plating. The electrolysis efficiency was about 80%. The obtained striped steel plate had a cross-sectional structure as shown in FIG.

Hot-dip plating of a Zn-based alloy was performed using a hot-dip plating bath of a Zn-based alloy shown in Table 2 on a Ni pre-plated steel plate. Table 2 also shows the temperature of the Zn-based alloy hot-dip plating bath. In hot-dip plating of a Zn-based alloy, the steel plate is heated to a plating bath temperature of + 30 ° C. in a non-oxidizing atmosphere (N ₂ -2% H ₂ ) at a heating rate of 10 ° C./sec. After cooling to a plating bath temperature of + 10 ° C., the steel sheet was immersed in the plating bath. The immersion time was 3 seconds, and the hot-dip deposition adhesion adjustment was adjusted by the hot-dip deposition adhesion adjustment device on the hot-dip plating apparatus outlet side.

Regarding the obtained hot-dip galvanized steel sheet, based on the observation and measurement method described above, it is confirmed that the base steel sheet, the Ni plating layer, and the hot-dip plating layer are present in the cross-sectional structure. It confirmed that it had. In addition, the film thickness of the Ni plating layer of the convex portion, the film thickness of the Ni plating layer of the flat portion, and the film thickness ratio of the Ni plating layer of the convex portion to the flat portion (film thickness of the convex portion 膜厚 film thickness of the flat portion × 100) The adhesion amount of the hot-dip plating layer, the chemical composition of the hot-dip plating layer, the coverage of the hot-dip plating layer, the Ni adhesion amount of Ni pre-plating, the chemical composition of the hot-dip plating bath, etc. were measured.

Moreover, the obtained hot-dip galvanized steel sheet was evaluated based on the following method.

Corrosion test after abrasion A steel plate pasted with 5 mm thick styrene butadiene rubber is placed on a 100 mm × 50 mm sample, a 1 kg weight is placed on it, and it is reciprocated in the horizontal direction (stroke: 30 mm, reciprocation number 1000) Times) to wear the plating. The exposed steel plate is exposed southward at a 45 ° inclination to the ground in the exposure frame, and the test is continued for one month with a 20 ml solution of 5% aqueous NaCl solution once a week in a rainy environment. did. After continuing for one month, the area rate of red rust generation near the convex portion was evaluated. The evaluation of the area rate of occurrence of red rust was performed by using WinROOF (image analysis software) manufactured by Mitani Corporation, and the area rate was calculated by measuring the area of the red rust occurrence part. The red rust generation part measured the area ratio by extracting the color of red rust by color extraction. It was judged that the corrosion resistance after abrasion was poor when the rate of occurrence of red rust was 5% or more. In the table, the ratio of red rust occurrence area: less than 5% is indicated by “Good”, and the percentage of red rust generation area: 5% or more by “Bad”.

Plating appearance A 100 mm square sample is prepared, and the plating surface is observed from the thickness direction, and the area ratio (referred to as "dross area ratio") of the area where the plating appearance is deteriorated due to dross is made by Mitani Corporation. It measured using WinROOF (image analysis software). When the dross area ratio was 20% or more, it was determined that the plating appearance was poor. In the table, the dross area ratio: less than 20% is indicated by “Good”, and the dross area ratio: 20% or more by “Bad”.

Processability After bending the sample to 90 °, attach a polyester adhesive tape made by Nitto Denko to the outside of the bending part, and after peeling off the tape, check whether the peeling material from the plating layer is attached to the tape did. When the peeling material from the plating layer adhered to the tape, it was determined that the processability was poor. In the table, the case without the release is indicated by "Good", and the case with the release is indicated by "Bad".

Table 3 shows the manufacturing results and the evaluation results of the manufactured hot-dip galvanized steel sheet. The “film thickness ratio of the Ni plating layer” shown in Table 3 means the film thickness ratio of the Ni plating layer of the convex portion to the plane portion (film thickness of the convex portion / film thickness of the plane portion × 100).

In Comparative Example 1, since the distance between the electrodes at the time of applying Ni pre-plating is not appropriate, the thickness of the Ni plating layer in the convex portion exceeds 0.4 μm, and the thickness of the Ni plating layer in the flat portion is 0.05 μm. It did not reach. As a result, a plating failure due to non-plating occurs, and sufficient corrosion resistance can not be obtained in the corrosion test after wear.
In Comparative Example 2, since the adhesion amount of Ni pre-plating was small, the film thickness of the Ni plating layer in the flat portion of the striped steel plate was insufficient. As a result, a plating failure due to non-plating occurs, and sufficient corrosion resistance can not be obtained.
In Comparative Example 3, since the adhesion amount of Ni pre-plating was large, the film thickness of the Ni plating layer in the convex portion exceeded 0.4 μm. As a result, sufficient corrosion resistance could not be obtained in the corrosion test after abrasion.
In Comparative Example 4, because the amount of Al in the hot-dip plating layer of the Zn-based alloy is small, sufficient corrosion resistance can not be obtained, and the plating appearance is also poor.
In Comparative Example 5, since the amount of Al in the hot-dip plating layer of the Zn-based alloy is large, the plating appearance is poor, the processability is not sufficient, and the hot-dip galvanized steel sheet is industrially undesirable.
In Comparative Example 6, sufficient corrosion resistance could not be obtained because the amount of Mg in the hot-dip plating layer of the Zn-based alloy is small.
In Comparative Example 7, since the amount of Mg in the hot-dip plating layer of the Zn-based alloy is large, the plating appearance is poor, and the hot-dip galvanized steel sheet is industrially undesirable.
In Comparative Example 8, since the adhesion amount of the hot-dip plating layer of the Zn-based alloy is small, sufficient corrosion resistance can not be obtained.
On the other hand, in Examples 1 to 10, the occurrence of non-plating was suppressed and corrosion resistance was sufficient even after abrasion. In addition, the plating appearance and processability were also satisfactory.

According to the above aspect of the present invention, it is possible to provide a hot-dip galvanized striped steel sheet in which the occurrence of non-plating is suppressed and the corrosion when the hot-dip plating layer is worn and the Ni plating layer is exposed is suppressed. Can. Therefore, industrial applicability is high.

1 ... convex part,
2 flat part,
3 ... Hot-dip plating layer of Zn-based alloy,
4 ... Ni plating layer,
5 ... base material steel plate

Claims (8)

1. A base plate steel plate, a Ni plating layer disposed on the surface of the base plate steel plate, and a hot-dip plating layer disposed on the surface of the Ni plating layer, and melting having a convex portion and a flat portion on the plate surface Plated striped steel plate,
   The film thickness of the Ni plating layer on the convex portion is 0.07 to 0.4 μm per one side,
   The film thickness of the Ni plating layer on the flat portion is 0.05 to 0.35 μm per one side,
   The thickness of the Ni plating layer of the convex portion is more than 100% and 400% or less of the thickness of the Ni plating layer of the flat portion,
   The adhesion amount of the hot-dip plating layer is 60 to 400 g / m ² per one side,
   Al: 1.0% or more and 26% or less, Mg: 0.05 to 10%, Si: 0 to 1.0%, Sn: 0 to 3.0% by mass as a chemical composition of the hot-dip plating layer %, Ca: 0 to 1.0%, the balance being Zn and impurities, characterized in that the hot-dip galvanized steel sheet.
2. The film thickness of the Ni plating layer of the convex portion is more than 100% and 300% or less with respect to the film thickness of the Ni plating layer of the flat portion. Hot-dip galvanized steel plate.
3. The hot-dip galvanized striped steel sheet according to claim 1 or 2, wherein the film thickness of the Ni plating layer of the convex portion is 0.07 to 0.3 μm per one surface.
4. The said hot-dip plating layer contains Al: 4.0-25.0% and Mg: 1.5-8.0% by mass% as said chemical composition, It is characterized by the above-mentioned. The hot-dip galvanized striped steel sheet according to any one of 3.
5. The hot-dip plating layer is composed of Si: 0.05 to 1.0%, Sn: 0.1 to 3.0%, Ca: 0.01 to 1.0% by mass as the chemical composition. The hot-dip galvanized steel sheet according to any one of claims 1 to 4, comprising at least one.
6. The coverage of the said hot-dipped layer is 99 to 100% by area% with respect to a plate surface, when it sees from thickness direction, It is characterized by the above-mentioned. Hot-dip galvanized steel plate.
7. A method of manufacturing a hot-dip galvanized steel sheet according to any one of claims 1 to 6,
   A rolling process for applying a convex portion and a flat portion to a rolled surface of a steel plate;
   Pre-plating step of applying Ni pre-plating to the steel plate which has passed through the rolling step;
   A hot-dip plating process of subjecting the steel plate that has undergone the pre-plating process to hot-dip plating;
   Equipped with
   In the pre-plating step, the rolling surface and the anode surface of the steel plate are disposed to face each other, the distance between the projections of the rolling surface and the anode is controlled to 40 to 100 mm, and the plating adhesion amount per one surface is average Perform electrolytic Ni plating under the conditions of 0.5 to 3 g / m ²
   In the hot-dip plating process, the steel plate is heated, and by mass%, Al: more than 1.0 and 26% or less, Mg: 0.05 to 10%, Si: 0 to 1.0%, Sn: 0 to 3.0 The steel sheet is immersed in a hot-dip plating bath containing 0%, Ca: 0 to 1.0%, the balance being Zn and impurities, and the plating coverage per side is on average 60 to 400 g / m ^{2 on an} average Do hot-dip plating,
   A method of producing a hot-dip galvanized steel sheet, characterized in that
8. 8. The method according to claim 7, wherein the distance between the electrodes is controlled to 45 to 100 mm in the pre-plating step.

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