KR102346426B1 - Hot-dip galvanized striped steel sheet and manufacturing method thereof - Google Patents

Abstract

This hot-dip plated striped steel sheet has a base steel sheet, a Ni plating layer, and a hot-dip plated layer, and has a convex portion and a flat portion on the plate surface. The film thickness of the Ni plating layer of the convex portion is 0.07 to 0.4 μm, the film thickness of the Ni plating layer of the flat portion is 0.05 to 0.35 μm, and the film thickness of the Ni plating layer of the convex portion is 100 with respect to the film thickness of the Ni plating layer of the flat portion % and 400% or less.

Description

Hot-dip galvanized striped steel sheet and manufacturing method thereof

The present invention relates to a hot-dip plated striped steel sheet and a method for manufacturing the same.

This application claims priority based on Japanese Patent Application No. 2017-178011 for which it applied to Japan on September 15, 2017, and uses the content here.

A striped steel plate is a steel plate with which the continuous anti-skid projection (convex part) was attached to the surface by rolling. In general, the convex portions 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 the floor plate or step of a bus, a track, etc., the pallet of a factory, the deck of a ship, a temporary scaffolding or stairs of a construction site, etc.

Conventionally, striped steel sheets are often used as hot rolled or coated. In particular, when rust prevention was required, the strip steel sheet was galvanized by passing through a batch type hot-dip galvanizing process using a flux method. However, in the batch-type hot-dip galvanizing process, productivity is low and the Fe-Zn alloy layer generated in the hot-dip plating process is enlarged. Sometimes there were problems.

Compared with batch type hot-dip galvanizing, continuous hot-dip galvanizing has high productivity. Continuous hot-dip galvanizing is generally performed by passing a steel sheet heated to a predetermined temperature in a reducing or non-oxidizing atmosphere through a hot-dip galvanizing bath. In addition, since the molten zinc bath contains at least about 0.05% of Al, it is possible to suppress the growth of the Fe-Zn alloy layer which impairs the workability of the plating film. Incidentally, in the batch type hot-dip galvanizing by the general flux method, when Al is contained in the Zn bath, Al decomposes the flux, so non-plating occurs frequently and plating cannot be performed well.

When continuous hot-dip galvanizing is applied to a striped steel sheet, it is necessary to consider the problems resulting from its surface shape and the like. For example, Patent Document 1 discloses a continuous hot-dip galvanizing method of a strip-shaped striped steel sheet, particularly the tension in the plating line, and appropriate conditions for gas wiping after hot-dip plating. At present, continuous hot-dip galvanized striped steel sheets are commercially available.

In recent years, in addition to hot-dip galvanized steel sheet, in response to the demand for superior corrosion resistance than zinc plating, hot-dip zinc-based alloy-coated steel sheets such as Zn-Al, Zn-Al-Mg, Zn-Al-Mg-Si have been developed and commercialized. have. An attempt to apply hot-dip zinc-based alloy plating to striped steel sheets is also seen as a form corresponding to this.

Patent Document 2 has a quaternary alloy layer of Ni-Al-Zn-Fe having a thickness of 2 μm or less as a first layer on the surface of a striped steel sheet, and contains 0.1 to 1% Al in terms of weight as a second layer Disclosed is a striped steel sheet having excellent workability and corrosion resistance, characterized in that it has a Zn-based alloy hot-dip plated layer. As a specific plating method, Patent Document 2 discloses a hot-dip zinc bath in which 0.5 to 2.0 g/m 2 of Ni plating is applied to a striped steel sheet, then the striped steel sheet is heated, and then 0.1 to 1% Al in terms of weight is added. It tells a method of manufacturing a striped steel sheet consisting of a step of immersing in a immersion time of 1 to 30 seconds.

Although patent document 3 uses the plating bath considered to be substantially the same as patent document 2, the structure of the hot-dip plating film obtained by the Sendzimir method is prescribed|regulated. In both Patent Documents 2 and 3, the essential feature is that Al concentration uses a molten zinc-based alloy of 1% or less. In addition, in Patent Documents 2 and 3, since the Al concentration in the plating layer is 1% or less, the barrier-corrosion effect due to Al is difficult to be obtained, and a desirable improvement in the remarkable corrosion resistance of the plating film itself cannot be expected.

Patent Document 4 contains Al: 4.0 to 20.0%, Mg: 1.0 to 4.0%, and optionally Ti: 0.002 to 0.1% and B: 0.001 to 0.045% by mass%, the balance being Zn and unavoidable impurities Disclosed is a hot-dip Zn-based striped steel sheet excellent in abrasion resistance, abrasion resistance and corrosion resistance, characterized in that it is coated with a hot-dip plating layer having a composition comprising: In this plating layer, the abundance ratio of the ternary eutectic structure of the Al/Zn/ZnMg-based intermetallic compound is large, and since this ternary eutectic is hard, the Vickers hardness is 120 to 180 Hv, and in addition to the corrosion resistance, it is excellent in abrasion resistance and abrasion resistance. becomes

As described above, conventionally, striped steel sheet is often used without plating, zinc plating is performed as necessary, and further, application of zinc-based alloy plating instead of zinc plating has been attempted. Incidentally, performing Ni-free plating on a base steel sheet and performing zinc-based alloy plating having an Al concentration of more than 1.0% after Ni-free plating has not been studied at all until now.

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

The present inventors also initially tried to perform zinc-base alloy plating whose Al concentration is more than 1.0 % on a striped steel plate for the purpose of further improving the corrosion resistance of a striped steel plate. However, as a result of examination, it was revealed that, simply by applying zinc-based alloy plating having an Al concentration of more than 1.0% to the striped steel sheet, non-plating occurred frequently. That is, for example, as in Patent Documents 2 and 3, when the Al concentration of zinc-based alloy plating is 1.0% or less, generation of non-plating does not become a problem, but, for example, as in Patent Document 4, zinc-based alloy plating It turned out that generation|occurrence|production of non-plating becomes a subject when Al concentration exceeds 1.0 %.

Specifically, the present inventors initially intended to impart excellent corrosion resistance to striped steel sheet, and a Zn-based alloy containing more than 1.0% Al and a small amount of Mg, which is generally said to have superior corrosion resistance than Zn plating. Applying plating to striped steel sheet was considered. And in the process, it was found that, when hot-dip plating of a Zn-Al-Mg-based alloy having an Al concentration of more than 1.0% on a striped steel sheet is performed by the Sendzimir method usually employed as a hot-dip plating method, non-plating occurs frequently.

The present inventors found that non-plating tends to occur in the process of hot-dip plating a Zn-based alloy containing Al: more than 1.0% and a small amount of Mg on a striped steel sheet. As the Al concentration in the molten Zn increases, the steel sheet and The deterioration of the wettability of the molten metal is related, and it is considered that the characteristic cause resulting from the hot rolling history of the striped steel sheet is also related.

Regarding this non-plating problem, the present inventors tried to employ|adopt Ni-free plating which is also employ|adopted also in patent document 2. As a result of the study, the present inventors have found that by performing zinc-based alloy plating after Ni-free plating, the occurrence of non-plating can be suppressed to some extent, but when zinc-based alloy plating having an Al concentration of more than 1.0% is applied to striped steel sheet found that it was necessary to make the Ni adhesion amount in Ni-free plating relatively large. On the other hand, on the other hand, the present inventors also found that, as a result of the above examination, when the amount of Ni adhesion in Ni-free plating is increased, corrosion resistance tends to decrease in the convex portion when the hot-dip plated striped steel sheet is worn.

That is, the present inventors discovered the following points regarding application of zinc-based alloy plating having an Al concentration of more than 1.0% to a striped steel sheet in order to further improve corrosion resistance.

(a) With respect to the striped steel sheet, simply by performing zinc-based alloy plating having an Al concentration of more than 1.0%, non-plating occurs frequently.

(b) In order to perform zinc-based alloy plating having an Al concentration of more than 1.0% on a striped steel sheet, Ni-free plating is required, and it is also necessary to increase the Ni adhesion amount compared to the prior art.

(c) However, when the Ni adhesion amount of the Ni-free plating is increased with respect to the striped steel sheet, the corrosion resistance tends to decrease in the convex portion when the hot-dip plated striped steel sheet is worn.

The present inventors considered the said phenomenon as follows. For example, when a hot-dip plated striped steel sheet is used for a bottom plate etc., the abrasion and wear of a hot-dip plated layer are large in the convex part, and Ni plating layer may be exposed. Incidentally, when a Ni-free plated steel sheet is plated with molten Zn or molten Zn-Al, a part of Ni moves into the plating layer or in the molten metal due to the reaction with the molten metal, but a part of Ni is the Ni plating layer on the surface of the steel sheet remains in Therefore, when the Ni adhesion amount of the Ni-free 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 dislocation becomes a ratio from the ear to Ni in the order of Ni, Fe, and the plating layer, but the natural immersion dislocation of a relatively thin Ni plating layer becomes a hybrid dislocation of Ni and Fe. In hot-dip plating of a Zn-based alloy with Ni-free plating, the hot-dip plated layer of the Zn-based alloy of the upper layer is worn, and when the Ni plating layer is exposed, galvanic corrosion occurs between the exposed portion and the vicinity of the exposed portion. For example, in a hot-dip plated striped steel sheet, Galvanic corrosion generate|occur|produces between the Ni plating layer exposed by the convex part, and the hot-dip plated layer in the vicinity of an exposed part. Even when the Ni plating layer is exposed, when the Ni plating layer is thin, the natural immersion potential of the Ni plating layer becomes a hybrid potential and approaches that of Fe, and the galvanic corrosion rate between the Ni plating layer and the hot-dip plating layer is not large. Conversely, when the Ni plating layer is thick, the natural immersion potential of the Ni plating layer is substantially close to the potential of Ni even if it is a hybrid dislocation, so the galvanic corrosion rate between the Ni plating layer and the hot-dip plating layer is increased. As a result, the hot-dip plated layer is likely to be corroded and worn.

Hereinafter, in order to prevent confusion, in this specification, unless otherwise specified, when "Ni plating layer" and "Ni plating" are used to indicate the plating layer, it means the Ni coating layer remaining after hot-dip plating, and "Ni Pre-plating layer" and "Ni pre-plating" shall mean the Ni coating layer which exists before a hot-dip plating process. In addition, in the following description of this specification, when expressions such as "hot-dip plating of a Zn-based alloy" or "hot-dip plating" are used, it means "hot-dip plating of a Zn-Al-Mg-based alloy".

The present invention is a striped steel sheet subjected to hot-dip plating of a Zn-Al-Mg-based alloy containing more than 1.0% Al, and there is almost no non-plating, and the hot-dip plating of a Zn-based alloy in the convex portions of the striped steel sheet is worn out. An object of the present invention is to provide a hot-dip plated striped steel sheet exhibiting excellent corrosion resistance even when (corroded or worn) and a method for manufacturing the same. Incidentally, in the present invention, a hot-dip plated striped steel sheet that satisfies the general characteristics required for a hot-dip plated striped steel sheet, such as plating appearance and workability, and is capable of both suppression of non-plating and corrosion resistance after wear and tear, and its manufacture The purpose is to provide a method.

The present inventors have found that when hot-dip plating of a Zn-Al-Mg-based alloy containing more than 1.0% Al on a striped steel sheet plated with Ni-free is attempted, a relatively large Ni deposition amount is required from the viewpoint of preventing non-plating, From the viewpoint of securing the corrosion resistance in the convex portions of the striped steel sheet, it was thought that it was necessary to at least suppress the Ni adhesion amount in the convex portions to a certain value or less.

When performing Ni-free plating on a steel strip, electroplating is employ|adopted normally. Although it is possible to precipitate Ni on a steel strip by an electroless method, it is not preferable because productivity is low and elements other than Ni are mixed in a large amount in the precipitation film. When electroplating a general steel strip, the anode is disposed in a shape opposite to the steel strip surface, which is usually the cathode, and the distance between the steel strip and the anode is made as small as possible for electrolysis to ensure uniformity of current distribution and power keep costs down

However, when electroplating the striped steel sheet, the convex portion of the striped steel sheet has a greater distance between the electrodes and the anode than the flat portion of the striped steel sheet. That is, when Ni-free plating is performed by electroplating the striped steel sheet in a conventional electrolytic bath and under conventional conditions, the amount of Ni adhered to the convex portion becomes very large, and as a result, when the hot-dip plated layer of the hot-dip plated striped steel sheet is worn out, the convex portion It is concerned that significant galvanic corrosion occurs in

The present inventors, regarding the hot-dip plated striped steel sheet of a Zn-Al-Mg-based alloy containing more than 1.0% Al, to ensure the lower limit of the thickness of the Ni-free plating layer required for preventing non-plating and corrosion resistance in the convex portion By confirming the upper limit of the thickness of the Ni plating layer which should be limited for this purpose, and also prescribing the thickness ratio of the Ni plating layer in a convex part and a flat part, it discovered that the said subject could be overcome.

The gist of the present invention is as follows.

(1) A hot-dip plated striped steel sheet according to one embodiment of the present invention has a base steel sheet, a Ni plated layer disposed on the surface of the base steel sheet, and a hot-dip plated layer disposed on the surface of the Ni plated layer, and has a convex portion and a flat portion on the plate surface It is a hot-dip plated striped steel sheet having, wherein the film thickness of the Ni plating layer of the convex portion is 0.07 to 0.4 μm per side, the film thickness of the Ni plating layer in the flat portion is 0.05 to 0.35 μm per side, the film thickness of the Ni plating layer in the convex portion is, With respect to the film thickness of the Ni plating layer, more than 100% and 400% or less, the adhesion amount of the hot-dip plated layer is 60 to 400 g/m 2 per side, and the hot-dip layer is, as a chemical composition, in 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%, Ca: 0 to 1.0%, the balance being Zn and impurities.

(2) In the hot-dip plated striped steel sheet according to (1) above, the film thickness of the Ni plating layer of the convex portion may be more than 100% and 300% or less with respect to the film thickness of the Ni plating layer of the flat portion.

(3) In the hot-dip plated striped steel sheet according to (1) or (2), the thickness of the Ni plating layer of the convex portion may be 0.07 to 0.3 µm per side.

(4) In the hot-dip plated striped steel sheet according to any one of (1) to (3) above, even if the hot-dip layer contains Al: 4.0 to 25.0% and Mg: 1.5 to 8.0% by mass% as a chemical composition do.

(5) In the hot-dip plated striped steel sheet according to any one of (1) to (4) above, the hot-dip plated layer has, as a chemical composition, mass%, Si: 0.05 to 1.0%, Sn: 0.1 to 3.0%, Ca: At least one of 0.01 to 1.0% may be included.

(6) In the hot-dip plated striped steel sheet according to any one of (1) to (5), when viewed from the thickness direction, the coverage of the hot-dip plated layer may be 99 to 100% in area% with respect to the sheet surface.

(7) The method for manufacturing a hot-dip plated striped steel sheet according to one embodiment of the present invention is the method for manufacturing the striped steel sheet according to any one of (1) to (6), wherein the convex portion and the flat portion are formed on the rolled surface of the steel sheet. A rolling process to be provided, a pre-plating process of performing Ni-free plating on the steel sheet that has been subjected to the rolling process, and a hot-dip plating process of hot-dip plating on the steel sheet that has undergone the pre-plating process, in the pre-plating process, rolling of the steel sheet Electronic Ni plating is performed under the condition that the surface and the anode face are arranged oppositely, the distance between the convex part of the rolling face and the anode is controlled to be 40 to 100 mm, and the plating adhesion amount per side is 0.5 to 3 g/m on average, In the hot-dip plating process, the steel sheet is heated and, in 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%, Ca: 0 to 1.0% The steel sheet is immersed in a hot-dip plating bath, the balance being Zn and impurities, and continuous hot-dip plating is performed under conditions such that the average amount of plating per side is 60 to 400 g/m 2 .

(8) In the manufacturing method of the hot-dip plated striped steel plate as described in said (7), you may control the distance between electrodes to 45-100 mm in a pre-plating process.

According to the above aspect of the present invention, since the hot-dip plated layer contains more than 1.0% Al, excellent corrosion resistance is obtained, and the film thickness of the Ni plated layer is controlled, so that the occurrence of non-plating can be suppressed, and further, the hot-dip plated layer Corrosion when this wears out and the Ni plating layer is exposed can also be suppressed. As a result, as a hot-dip plated striped steel sheet, it becomes possible to suppress the life cycle cost of the floor plate, pallet, structure, and other.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram at the time of seeing from the thickness direction the base steel plate of the hot-dip plated striped steel plate which concerns on one Embodiment of this invention.
1B is a schematic cross-sectional view of the base steel sheet of the hot-dip stripe steel sheet according to the embodiment when viewed from a cross-section in which the thickness direction and the cutting direction are parallel to each other, and is a GG cross-sectional view of FIG. 1A .
FIG. 1C is a schematic cross-sectional view of the base steel sheet of the hot-dip plated striped steel sheet according to the embodiment when viewed from a cross-section in which the thickness direction and the cutting direction are parallel, and is a FF cross-sectional view of FIG. 1A .
Fig. 2 is a schematic cross-sectional view of the hot-dip plated striped steel sheet according to the embodiment when viewed from a cross section in which the thickness direction and the cutting direction are parallel.

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of this invention is described in detail. However, the present invention is not limited only to the configuration disclosed in the present embodiment, and various modifications can be made without departing from the spirit of the present invention. In addition, in the following numerical limitation range, a lower limit and an upper limit are included in the range. The numerical value indicated by "more than" or "less than" is not included in the numerical range.

The hot-dip plated striped steel sheet according to the present embodiment has a base steel sheet, a Ni plating layer disposed on the surface of the base steel sheet, and a Zn-based (Zn-Al-Mg system) alloy hot-dip layer disposed on the surface of the Ni plating layer, It has a convex part and a flat part on a board surface. In addition, the film thickness of the Ni plating layer of the convex portion is 0.07 to 0.4 µm per side, the film thickness of the Ni plating layer in the flat portion is 0.05 to 0.35 µm per single surface, and the film thickness of the Ni plating layer in the convex portion is the film thickness of the Ni plating layer in the flat portion With respect to thickness, it is more than 100% and 400% or less. In addition, the adhesion amount of the hot-dip plated layer is 60 to 400 g/m 2 per side, and the hot-dip layer is, as a chemical composition, 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%, Ca: 0 to 1.0%, the balance being Zn and impurities.

Incidentally, on the Ni plating layer side of the hot-dip plating layer, a thin intermetallic compound layer may be formed based on a reaction between a molten metal (a Zn-based alloy hot-dip plating bath) and a Ni-free plated steel sheet, the composition of which is a Zn-based alloy hot-dip alloy. It changes depending on the composition of the plating bath. In this embodiment, "the hot-dip plated layer of a Zn-based alloy" is used in the meaning including this intermetallic compound layer.

First, the hot-dip plated layer of the hot-dip plated striped steel sheet according to the present embodiment will be described in detail.

The hot-dip plated layer is a Zn-based alloy, and contains, as a chemical composition, Al: more than 1.0% and 26% or less, and Mg: 0.05 to 10% by mass%.

Al (aluminum) is important in securing the corrosion resistance of the hot-dip plated layer, and also prevents oxidation of the molten metal and suppresses the generation of Fe-Zn-based dross. Therefore, the Al concentration of the hot-dip plated layer is made more than 1.0%. On the other hand, if the Al concentration in the plating bath increases, the melting point rises, so it is necessary to increase the temperature of the molten metal. If the Al concentration exceeds 26%, it becomes difficult to ensure the aesthetics of the surface properties of the plating layer, and workability. It is also easy to cause a decrease in Therefore, the Al concentration of the hot-dip plated layer is set to 26% or less. From the viewpoint of corrosion resistance, the Al concentration of the hot-dip plated layer is preferably 4.0% or more. From a viewpoint of workability, 25.0 % or less is preferable and, as for the Al density|concentration of a hot-dip layer, 21.0 % or less is more preferable.

Mg (magnesium) forms a stable corrosion product in a corrosive environment, forms a barrier layer against corrosion, and makes corrosion resistance more excellent. If the Mg concentration is less than 0.05%, this effect is insufficient, so the Mg concentration in the hot-dip plated layer is made 0.05% or more. On the other hand, as the concentration of Mg in the molten metal increases, the oxidation of the molten metal is accelerated. For this reason, the Mg density|concentration in a hot-dip plating layer shall be 10 % or less. Moreover, when the concentration of Mg exceeds 10%, it becomes difficult to ensure the aesthetics of the surface properties of the plating layer, including the influence of an increase in the amount of oxide-based dross generated. The preferable lower limit of the Mg concentration is 0.5%, more preferably 1%, still more preferably 1.5%, still more preferably 2.0%. A preferable upper limit of the Mg concentration is 8.5%, more preferably 8.0%, still more preferably 6.0%.

The hot-dip layer of the hot-dip plated striped steel sheet according to the present embodiment contains, as a chemical composition, Al and Mg, which are the above-described basic elements, and the balance consists of Zn and impurities. For example, in a hot-dip plated layer, Zn concentration becomes 64 to 98.95% by mass %. The hot-dip plated layer may contain 1.0% or less of Si, 3.0% or less of Sn, and 1.0% or less of Ca as a mass % as a selection element instead of a part of Zn which is the said remainder.

Si (silicon) suppresses the growth of the interfacial alloy phase formed at the interface with the base steel sheet, contributes to improvement of workability, suppresses oxidation of Mg, and improves corrosion resistance by forming _{Mg and Mg 2 Si} also contribute to Therefore, it is good also considering the Si density|concentration of a hot-dipping layer as 0 to 1.0 %. When it is desired to obtain the above effect of Si preferably, Si is contained in an amount of 0.05% or more, preferably 0.1% or more. On the other hand, even if the Si concentration exceeds 1.0%, the above effect is saturated. A preferable upper limit of the Si concentration is 0.6%.

Sn (tin) forms Mg and Mg ₂ Sn, and also contributes to the improvement of corrosion resistance, particularly end surface corrosion resistance. Therefore, it is good also considering the Sn concentration of a hot-dip plated layer as 0 to 3.0 %. When it is desired to obtain the above effect of Sn preferably, Sn is contained in 0.1% or more, preferably 0.3% or more. On the other hand, when the Sn concentration exceeds 3.0%, it is easy to cause a decrease in corrosion resistance, particularly a decrease in corrosion resistance in a flat portion. A preferable 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 compared to the case in which Mg is not included. By containing Ca, oxidation of the plating bath surface can be preferably suppressed. Therefore, it is good also considering the Ca concentration of a hot-dip plating layer as 0 to 1.0%. Ca concentration becomes like this. Preferably it is 0.01 % or more, More preferably, it is 0.1 % or more. On the other hand, when Ca concentration exceeds 1.0 %, the precipitation of Ca-type intermetallic compound increases, and corrosion resistance may be reduced, especially corrosion resistance of a flat part may be reduced. A preferable upper limit of the Ca concentration is 0.7%.

Regarding the chemical composition of the hot-dip plated layer, the balance of the above-described basic elements and optional elements consists of Zn and impurities. Incidentally, "impurity" refers to mixing from a raw material or a manufacturing environment. For example, in the hot-dip layer of the hot-dip plated striped steel sheet according to the present embodiment, Ni, Fe, or the like is dissolved in the plating bath from the surface of the steel sheet to become an impurity of a Zn-based alloy. For example, a hot-dip plating layer may contain Ni originating in a Ni-free plating layer, and Ni concentration may be 0.01 to 0.3 % by mass %. In the hot-dip layer of the hot-dip plated striped steel sheet according to the present embodiment, if it is within a range that does not impair the intended properties, it is allowed to contain impurities.

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

In addition, in this embodiment, the average adhesion amount of a hot-dip plated layer is 60 g/m<2> or more per single side|surface. The average adhesion amount means the average adhesion amount including the convex portion and the flat portion of the hot-dip plated striped steel sheet. That is, it means the adhesion amount per projected area ignoring the protrusion of the convex part of the hot-dip plated striped steel sheet. Corrosion resistance becomes insufficient that the average adhesion amount of a hot-dip plated layer is less than 60 g/m<2>. The upper limit of the average adhesion amount of the hot-dip plated layer is not necessarily limited, but since excessive adhesion of the hot-dip plated layer causes significant plating sagging and impairs the appearance, it is preferable that the average adhesion amount of the hot-dip plated layer be 400 g/m 2 or less per side.

Moreover, in this embodiment, when the hot-dip plated striped steel sheet is seen from the thickness direction, it is preferable that the coverage of a hot-dip plated layer is 99 to 100% in area% with respect to a board|plate surface. It can be judged that generation|occurrence|production of non-plating can be suppressed suitably that the coverage of a hot-dip plated layer is 99 % or more in area%.

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

The Ni plating layer is one in which the Ni-free plating layer previously formed on the surface of the base steel sheet in order to prevent non-plating in the hot-dip plating process remains between the base steel sheet and the hot-dip plating layer even after hot-dip plating.

In the Ni plating layer, for example, when the cross section of the hot-dip plated striped steel sheet is observed with a reflected electron image of a scanning electron microscope (SEM), the contrast observed between the base steel sheet and the hot-dip plated layer is a pale color region (displayed in white). range). In the present embodiment, the intermetallic compound layer containing Ni that may be formed at the interface between the Ni plating layer and the base steel sheet, and the intermetallic compound layer containing Ni that may be formed at the interface between the Ni plating layer and the hot-dip plating layer is, It is not included in the plating layer.

Ni plating layer contains Ni as a chemical composition, and remainder consists of an impurity. For example, the Ni concentration of the Ni plating layer is preferably 50 to 100% by mass. Incidentally, "impurity" refers to mixing from a raw material or a manufacturing environment. For example, the Ni plating layer of the hot-dip plated striped steel sheet according to the present embodiment contains impurities due to diffusion of Fe from the base steel sheet.

In the present embodiment, when viewed from a cut plane in which the thickness direction and the cutting direction are parallel, it is necessary that the film thickness of the Ni plating layer of the convex portion of the hot-dip plated striped steel sheet is 0.4 µm or less on average per side. When this film thickness exceeds 0.4 micrometer, the corrosion resistance when the hot-dip plated layer of a Zn-based alloy is worn out in a convex part and Ni plating layer is exposed will fall. 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 minimum of the film thickness of the Ni plating layer of a convex part is made into an average of 0.07 micrometers per single side|surface. When this film thickness becomes less than 0.07 micrometer, non-plating generate|occur|produces in a convex part. It is preferable that the film thickness of the Ni plating layer of this convex part is 0.1 micrometer or more.

In addition, in this embodiment, when viewed from a cut plane in which the thickness direction and the cutting direction are parallel, it is necessary that the film thickness of the Ni plated layer of the flat portion of the hot-dip plated striped steel sheet is 0.05 µm or more on average per side. When this film thickness is less than 0.05 micrometer, non-plating in a flat part generate|occur|produces. On the other hand, the upper limit of the film thickness of the Ni plating layer of the flat part is made into an average of 0.35 micrometers or less per single side|surface. When this film thickness exceeds 0.35 micrometer, the effect of the improvement of plating adhesion in a flat part is saturated, and it is not economical.

In addition, in this embodiment, when viewed from the cut surface in which the thickness direction and the cutting direction are parallel, the film thickness of the Ni plating layer of the convex portion needs to be more than 100% and 400% or less with respect to the film thickness of the Ni plating layer of the flat portion.

As described above, under the plating conditions of the conventional electroplating, in the case of a striped steel sheet, Ni is preferentially attached to the convex portion rather than the flat portion. For example, the present inventors found that, as in the prior art, when the distance between the convex portion and the anode of the striped steel sheet is less than 40 mm, the film thickness of the Ni plating layer in the convex portion is 2000% or more with respect to the film thickness of the Ni plating layer in the flat portion It was confirmed that this is the case.

However, as described above, the present inventors did not increase the film thickness of the Ni plating layer of the convex part so much in order to increase the corrosion resistance after wear and tear on the convex part, on the other hand, in order to suppress non-plating on the flat part, the flat part It was discovered that it was necessary to ensure the film thickness of the Ni plating layer to some extent. That is, in this embodiment, the film thickness ratio of the Ni plating layer of the convex part to the flat part (the film thickness of the convex part / the film thickness of the flat part x 100) is made smaller than the conventional hot-dip plated striped steel sheet.

When the film thickness ratio of the Ni plating layer of the convex portion to the flat portion (the film thickness of the convex portion / the film thickness of the flat portion x 100) is more than 400%, suppression of non-plating in the flat portion and corrosion resistance after wear and tear in the convex portion are preferably compatible Since it becomes difficult to do it, in this embodiment, the film thickness ratio of the Ni plating layer of the convex part with respect to a flat part is made into 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 film thickness of the Ni plating layer of the convex portion smaller than the film thickness of the Ni plating layer of the flat portion and making the film thickness of the Ni plating layer the same in the convex portion and the flat portion is substantially due to the shape of the striped steel sheet in electroplating. difficult with Therefore, in this embodiment, the film thickness ratio of the Ni plating layer of the convex part with respect to a flat part is made into more than 100 %.

Incidentally, 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 suppressing non-plating on the flat portion and the corrosion resistance after wear on the convex portion can be achieved is obtained, and the required area ( Since it becomes possible to reduce the Ni adhesion amount on the unnecessary region (convex portion) by increasing the Ni adhesion amount on the flat portion), effective utilization of Ni, which is a finite resource, becomes possible.

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

In the present embodiment, the base steel sheet (the original plate to be plated) is a striped steel sheet. Striped steel sheet is usually given the shape of a convex part by hot rolling. Although the steel type of a base material steel plate is not specifically limited, Usually, the steel grade corresponding to the general structural rolled steel prescribed|regulated to 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 operation roll to the steel sheet surface in the finishing step of hot rolling. Although the occupancy of the stripe height (height of the convex portion) or the stripe portion (convex portion) is not necessarily limited in the present embodiment, the stripe height is 0.5 to 3.5 mm in particular in consideration of the slip resistance and usability as a sole plate. , the area occupancy of the stripe portion is set to 15 to 60%.

1A to 1C, the shape of the striped steel sheet used as the base steel sheet is shown. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram at the time of seeing from the thickness direction the base steel plate of the hot-dip plated striped steel plate which concerns on one Embodiment of this invention. Fig. 1B is a schematic cross-sectional view of the base steel sheet of the hot-dip plated striped steel sheet according to the embodiment when viewed from a cross section in which the thickness direction and the cutting direction are parallel, and is a cross-sectional view taken along the line G-G of Fig. 1A. Fig. 1C is a schematic cross-sectional view of the base steel sheet of the hot-dip plated striped steel sheet according to the embodiment when viewed from a cross-section in which the thickness direction and the cutting direction are parallel, and is a cross-sectional view taken along the line F-F of Fig. 1A. In these figures, A, B, C, D, E, and H are as follows, respectively. A: The angle of arrangement of the convex portions with respect to the rolling direction. B: The length of one convex part. C: The maximum width for one convex portion. D: The minimum width for one convex part. E: The arrangement pitch of the convex portions. H: The height of the convex portion.

Next, an observation method and a measuring method are demonstrated about the hot-dip plated striped steel plate which concerns on this embodiment.

What is necessary is just to observe the external appearance and cross section of the hot-dip plated striped steel plate for the convex part and flat part of a hot-dip plated striped steel plate. For example, when the external appearance of the hot-dip plated striped steel sheet is observed in the thickness direction, if it has an appearance equivalent to that of the striped steel sheet shown in FIG.

More specifically, the hot-dip plated striped steel sheet is a cross-section corresponding to the GG cross-section in FIG. What is necessary is to judge whether a convex part and a planar part exist by observing it. For example, with respect to the contour curve of the hot-dip plated striped steel sheet shown in this section, a reference line is determined on the basis of an area corresponding to the flat portion of the hot-dip plated striped steel sheet, and between this reference line and the vertex of the highest mountain on the contour curve Find the distance of , and if this distance is 0.5 mm or more, it can be determined that the mountain on the contour curve is a convex part. What is necessary is just to judge this steel plate as a hot-dip plated striped steel plate, when this convex part exists in 1 or more per 100 mm<2> when a steel plate is observed from the thickness direction.

Whether the base steel sheet, the Ni plating layer, and the hot-dip plating layer exist in the hot-dip plated striped steel sheet may be observed with a Field Emission Scanning Electron Microscope (FE-SEM) or a Transmission Electron Microscope (TEM). For example, a test piece is cut out so that a cutting direction may be parallel to a thickness direction, and what is necessary is just to observe the cross-sectional structure of this cut surface with FE-SEM or TEM at the magnification which each layer enters in an observation field of view. A schematic diagram of the cross-sectional structure of the hot-dip plated striped steel sheet according to the present embodiment is shown in FIG. 2 .

For example, to identify each layer in the cross-sectional structure, using EDS (Energy Dispersive X-ray Spectroscopy), the accelerating voltage is 15 kV along the thickness direction at a magnification of 20000 times, the irradiation current is 10 kV, and the beam diameter is Line analysis is performed with a measurement pitch of less than about 100 nm, a measurement pitch of 0.025 μm, and an objective lens diaphragm diameter of 30 μmφ, and quantitative analysis of the chemical composition of each layer is performed as a total of 100 mass% of Ni, Fe, and Zn. After performing a moving average process of averaging the data of 5 points before and after the result of this line analysis in order to remove measurement noise, it is sufficient to judge the area|region where Ni concentration becomes 50 mass % or more on a scanning line as a Ni plating layer. Further, on the basis of the Ni plating layer identified on the scanning line, the surface side region may be determined as the hot-dip plated layer, and the inner region may be determined as the base steel sheet. The hot-dip plated layer is a Zn-based alloy, and the base steel sheet is an Fe-based alloy.

What is necessary is just to identify the Ni plating layer of a convex part in the cross section corresponding to the G-G cross section of FIG. 1A, and to measure the film thickness of the Ni plating layer of a convex part. For example, in the cross section, line analysis is performed along the thickness direction to include the peak of the highest mountain on the contour curve of the hot-dip plated striped steel sheet, the Ni plating layer is identified on the scanning line of the line analysis, and the Ni plating layer on the scanning line is What is necessary is just to calculate|require a line segment and employ|adopt this line segment as the film thickness of the Ni plating layer of a convex part.

What is necessary is just to measure the film thickness of the Ni plating layer of a flat part similarly to the above. For example, in a cross section corresponding to the GG cross section in Fig. 1A, a line analysis is performed along the thickness direction at a flat portion at a position spaced 2 mm or more from the end of the convex portion, the Ni plating layer is identified on the scanning line of the line analysis, and the scanning line What is necessary is just to find the line segment of the Ni plating layer on the image, and to employ|adopt this line segment as the film thickness of the Ni plating layer of a flat part.

In addition, the film thickness of the Ni plating layer of a convex part and a flat part may be measured in at least three or more, respectively, and what is necessary is just to employ|adopt the average value. In addition, when the film thickness of the Ni plating layer of a convex part and a flat part is less than 0.3 micrometer, it is preferable to calculate|require the film thickness by TEM instead of SEM.

In addition, based on the film thicknesses of the Ni plating layer of the convex portion and the flat portion obtained above, 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 x 100) may be calculated.

What is necessary is just to measure the chemical composition and adhesion amount of a hot-dip plated layer using ICP (Inductive Coupled Plasma: Inductively Coupled Plasma) emission spectroscopy. For example, a sample having a size of 30 mm x 30 mm is taken from an arbitrary location on the hot-dip galvanized striped steel sheet, and an inhibitor (eg, Asahi Chemical Co., Ltd. EBIT, model number: EBIT 710) is taken from this sample. -K, concentration: 300 ppm, where ppm is mg/kg), pickling and peeling only the plating layer using 10% hydrochloric acid, performing ICP quantitative analysis to determine the concentration of each element, and determining the concentration of each element from the concentration of each element. What is necessary is to find the composition and adhesion amount. In other words, the above-mentioned measurement may be performed on samples collected from at least three or more locations, and the average value thereof may be employed.

The coverage of the hot-dip layer with respect to the plate surface may be obtained by observing the hot-dip plated striped steel sheet in the thickness direction. For example, what is necessary is just to take a sample of 100 mm x 100 mm from arbitrary locations of a hot-dip plated striped steel plate, observe this sample from the thickness direction, and just to calculate|require the area ratio of the non-plating area|region in a sample area. What is necessary is just to calculate|require an area ratio using image analysis software (For example, WinROOF by Shoji Mitani). More specifically, the 100 mm × 100 mm sample is divided into sizes that can be measured with EDS or EPMA (Electron Probe Micro-Analyzer), and for each divided sample, surface analysis is performed using EDS or EPMA. What is necessary is just to calculate|require a Fe distribution map, and to calculate|require the area ratio of the non-plating area|region (region in which Fe concentration becomes 20 mass % or more) in a sample area from these Fe distribution maps. What is necessary is just to calculate|require the coverage of a hot-dip plated layer based on the area ratio of this non-plating area|region.

Next, the manufacturing method of the hot-dip plated striped steel plate which concerns on this embodiment is demonstrated in detail.

A method for manufacturing a hot-dip plated striped steel sheet according to the present embodiment includes a rolling step of providing a convex portion and a flat portion to the rolled surface of the steel sheet, a pre-plating step of performing Ni-free plating on the steel sheet that has undergone the rolling step, and a pre-plating step and a hot-dip plating process of performing hot-dip plating on the roughened steel sheet. In the pre-plating process, the rolled surface and the anode surface of the steel sheet are arranged to face each other, the distance between the convex portion of the rolled surface and the anode is controlled to be 40 to 100 mm, and the plating adhesion per side is on average 0.5 to 3 g/m2 Electronic Ni plating is performed under the conditions. Further, in the hot-dip plating step, the steel sheet is heated and, in 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%, Ca: 0 to 1.0 %, the steel sheet is immersed in a hot-dip plating bath whose balance consists of Zn and impurities, and continuous hot-dip plating is performed under conditions such that the average amount of plating per side is 60 to 400 g/m 2 .

In a rolling process, a convex part and a flat part are provided to the rolling surface of a steel plate. The rolling conditions are not particularly limited, but in the final step of hot rolling, the concave shape formed on the operation roll may be transferred to the steel sheet surface to provide convex portions and flat portions to the steel sheet rolling surface. The striped steel sheet shaped by hot rolling is subjected to pretreatment such as pickling to remove scale and the like. You may perform brush grinding etc. on the steel plate surface as needed.

In the pre-plating step, Ni-free plating is performed on the pretreated striped steel sheet. As for Ni-free plating, it is preferable to use electroplating from a viewpoint of productivity or a viewpoint of suppressing mixing of an impurity element. As for the electroplating, the method using a Watts bath, a sulfamic acid bath, etc. is illustrated.

If the method using a Watts bath, a 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, a preferred bath temperature is 50 to 70° C., and a preferred cathode 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., cathode current density: 20 A For example, /dm2.

In this embodiment, in order to prevent the occurrence of non-plating in the hot-dip plating process, the amount of Ni adhesion in the Ni-free plating is increased compared with the conventional method. However, excessive Ni precipitation in a convex part is avoided so that corrosion of a steel plate may be suppressed even if the hot-dip plated layer is worn out and the Ni plated layer is exposed in the convex part.

In an electroplating bath (electrolytic bath), normally, a steel strip is made into a negative electrode, and the anode is arrange|positioned in the form which opposes the steel plate surface. The steel face and the anode are parallel and approximated in a parallel plate electrode system. When the striped steel sheet is electroplated in such an electrolytic cell, since the distance between the poles of the anode and the convex portion of the striped steel sheet is close, current concentration tends to occur in the convex portion. In the present embodiment, in order to suppress the concentration of current to the convex portions of the striped steel sheet, the inter-pole distance (the distance between the convex portion of the steel facing surface and the anode) is increased. Under the conventional conditions, in order to suppress electric power cost while ensuring uniformity of current distribution, the distance between poles was set to less than 40 mm, but in this embodiment, the distance between poles is set to 40-100 mm. When the distance between the electrodes is less than 40 mm, current concentration occurs in the convex portion, and it becomes difficult to control the thickness of the Ni plating layer in the convex portion within a predetermined range. On the other hand, when the interpole distance exceeds 100 mm, an increase in power loss based on liquid resistance is caused. It is preferable that it is 45 mm, and, as for the lower limit of the distance between poles, it is more preferable that it is 50 mm. It is preferable that it is 90 mm, and, as for the upper limit of the distance between poles, it is more preferable that it is 85 mm.

For example, in a hot-dip plated striped steel sheet manufactured by setting the interpole distance to less than 40 mm as in the prior art, the film thickness ratio of the Ni plating layer of the convex portion to the flat portion (the film thickness of the convex portion ÷ the film thickness of the flat portion × 100) is, It may be 2000% or more. On the other hand, in the hot-dip plated striped steel sheet manufactured by setting the interpole distance to 40 mm or more, it is easy to control the film thickness ratio of the Ni plating layer of the convex part with respect to a flat part to 400 % or less. Moreover, when the distance between electrodes is set to 45 mm or more, when it is set as a hot-dip plated striped steel plate, it is easy to control the film thickness ratio of the Ni plating layer of the convex part with respect to a flat part to 300 % or less.

In a pre-plating process, the average adhesion amount per single side|surface of Ni-free plating shall be 0.5-3 g/m<2>. When the average adhesion amount is less than 0.5 g/m 2 , the film thickness of the Ni plating layer of the flat portion of the striped steel sheet after hot-dip plating is 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 on the convex portion after hot-dip plating becomes excessive, and it becomes difficult to set the thickness of the Ni plated layer on the convex portion to 0.4 µm or less.

What is necessary is just to measure the Ni adhesion amount in Ni-free plating based on the following procedures a to e before hot-dip plating of a Zn-based alloy.

Procedure a: The steel sheet which carried out Ni-free plating is melt|dissolved with 30 mass % nitric acid (solution A).

Procedure b: A sample is taken in the vicinity of the sample used in procedure a, and after removing a Ni-free plating layer by grinding etc., it melt|dissolves with 30 mass % nitric acid (solution B).

Procedure c: The amount of Fe and the amount of Ni dissolved in the solution B are obtained by ICP, and the ratio of the amount of Fe and the amount of Ni is obtained.

Procedure d: The amount of Fe dissolved in the solution A is obtained by ICP, and the amount of Ni dissolved from the base steel sheet is obtained from the ratio calculated in the procedure c.

Procedure e: The amount of Ni dissolved in the solution A is calculated by ICP, the amount of Ni derived from the base steel sheet calculated in the procedure d is subtracted, and the amount of Ni derived from the Ni-free plating layer is calculated. The amount of Ni derived from the Ni-free plating layer is converted into an adhesion amount per unit area.

Incidentally, although it depends on the design of the electrolytic cell, in the continuous electroplating equipment of a steel strip, edge overcoat by electric current concentration may be generated in the edge part of the width direction of a steel plate. Therefore, when calculating the said average adhesion amount, you may exclude the width direction edge part (for example, the area|region 50 mm from both ends) of a steel strip from a measurement object.

In a hot-dip plating process, after preheating the stripe steel plate (steel strip) plated with Ni in a non-oxidizing atmosphere, it is continuously passed through a hot-dip plating bath (it is continuously immersed in a 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]. If the preheating temperature is low, non-plating tends to occur frequently. In preheating, it is preferable to rapidly heat a steel plate so that the time of 350 degreeC or more may be 40 sec or less. Since the diffusion of Ni to the base steel sheet can be suppressed by shortening the time period of 350° C. or more for the steel sheet, it is possible to sufficiently secure the amount of Ni-free plating for preventing non-plating.

The striped steel sheet preheated in a non-oxidizing atmosphere has Al: more than 1.0% and 26% or less, Mg: 0.05 to 10%, if necessary, Si: 0 to 1.0%, Sn: 0 to 3.0%, Ca: 0 to 1.0% A plating bath of a hot-dip zinc-based alloy containing The temperature of the plating bath is preferably in the range of [melting point of molten Zn-based alloy +20°C] to [melting point of molten Zn-based alloy +50°C]. The striped steel sheet is preferably immersed in a plating bath for 1 to 6 sec, then wiped, and cooled by brackish spray or the like as necessary.

In a hot-dip plating process, the average adhesion amount per single side|surface of a hot-dip plating layer shall be 60-400 g/m<2>. Corrosion resistance may become insufficient that an average adhesion amount is less than 60 g/m<2>. When the average adhesion amount is more than 400 g/m 2 , plating sagging becomes remarkable due to excessive adhesion of the hot-dip plated layer, and the appearance may be impaired.

What is necessary is just to measure the chemical composition of a hot-dip-plating bath, and the adhesion amount of hot-dip plating using ICP emission spectroscopy similarly to the above. Incidentally, the chemical composition of the hot-dip plating bath may be measured by ICP based on the sample collected from the hot-dip plating bath instead of the sample collected from the hot-dip striped steel sheet.

Example 1

Next, the effects of one embodiment of the present invention will be described in more detail in detail with reference to the examples, but the conditions in the examples are examples of conditions employed in order to confirm the practicability and effects of the present invention, and the present invention is , is not limited to this one condition example. Various conditions can be employ|adopted for this invention, as long as the objective of this invention is achieved without deviating from the summary of this invention.

As the plating original plate, a hot-rolled striped steel plate having a thickness of 2.3 mm was used.

The shape of this striped steel sheet (base steel sheet) was equivalent to that of Figs. 1A to 1C. In the figure, A, B, C, D, E, and H are as follows, respectively.

A: Arrangement angle of the convex portions with respect to the rolling direction

B: the length of one convex part

C: Maximum width for one convex portion

D: Minimum width for one convex portion

E: arrangement pitch of convex portions

H: the height of the convex portion

This striped steel sheet was hot rolled Al killed steel, and had an angle A=45°, a width C=5.1mm, a length B=25.3mm, a height H=1.5mm, and the pitch E=28.6mm. The striped steel sheet in which the convex portions were regularly arranged in this way was pickled and Ni-free plating was performed at various interpole distances to change the average deposition amount of Ni. Tables 1 and 2 show the conditions for Ni-free plating. The electrolysis efficiency was about 80%. The obtained striped steel sheet has a cross-sectional structure as shown in FIG.

With respect to the Ni-free plated steel sheet, Zn-based alloy hot-dip plating was performed using the Zn-based alloy hot-dip plating bath shown in Table 2. Table 2 shows the temperature of the Zn-based alloy hot-dip plating bath. In performing hot-dip plating of a Zn-based alloy, the steel sheet _{is heated in a non-oxidizing atmosphere (N 2} -2%H ₂ ) at a temperature increase rate of 10° C./sec to a plating bath temperature of Zn-based alloy +30° C. in the atmosphere After cooling to a plating bath temperature of +10°C, the steel sheet was immersed in the plating bath. The immersion time was 3 sec, and the hot-dip plating adhesion amount was adjusted with the hot-dip plating adhesion amount adjusting device on the exit side of the hot-dip plating apparatus.

With respect to the obtained hot-dip plated striped steel sheet, based on the above-described observation and measurement method, it was confirmed that the base steel sheet, the Ni plated layer, and the hot-dip plated layer were present in the cross-sectional structure, and it was confirmed that the plate surface had a convex portion and a flat portion. 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, the film thickness ratio of the Ni plating layer of the convex portion to the flat portion (the film thickness of the convex portion / the film thickness of the flat portion × 100), the deposition amount of the hot-dip plated layer, the hot-dip plated layer The chemical composition of , the coverage of the hot-dip plated layer, the Ni adhesion amount of Ni-free plating, the chemical composition of the hot-dip plating bath, and the like were measured.

In addition, the obtained hot-dip plated striped steel sheet was evaluated based on the following method.

<Corrosion test after wear>

A steel plate with a thickness of 5 mm attached to a styrene-butadiene rubber is placed on a sample of 100 mm × 50 mm, a 1 kg weight is placed on it, and reciprocating vibration (stroke: 30 mm, number of reciprocations 1000 times) is applied in the transverse direction. The plating was worn out. A test in which the worn steel sheet was exposed to the south at an inclination of 45° with respect to the ground on the exposure mount and sprayed with 20 ml of 5% NaCl aqueous solution at a frequency of once/week in a rain environment was continued for 1 month. After continuing for one month, the area rate of occurrence of red rust in the vicinity of the convex portion was evaluated. Evaluation of the red-rust generation|occurrence|production area rate measured the area of a red-rust generation|occurrence|production part, and calculated the area rate using WinROOF (image analysis software) made from Shoji Mitani. The area ratio of the red-rust generating part was measured by extracting the red-green color by color extraction. When the red rust occurrence area ratio was 5% or more, it was determined that the corrosion resistance after abrasion was poor. In a table|surface, less than 5 % of red rust generation|occurrence|production area rate: "Good", and red rust generation|occurrence|production area rate: 5% or more are shown as "Bad".

<Plating appearance>

A rectangular sample having a side of 100 mm was prepared, the plating surface was observed from the thickness direction, and the area ratio (referred to as "dross area ratio") of the region in which the plating appearance was deteriorated due to dross was measured by Shoji Mitani. Measurements were made 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, "Good" for dross area ratio: less than 20%, and "Bad" for dross area ratio: 20% or more.

<Processability>

After V-bending the sample at 90°, a polyester adhesive tape made by Nitto Denko was affixed to the outside of the bending portion, and after peeling the tape, it was checked whether or not the peeled material from the plating layer had adhered to the tape. When the peeling material from the plating layer adhered to the tape, it was judged that workability was poor. In a table|surface, the case where there is no peeling material is shown as "Good", and the case where there is a peeling material is shown as "Bad".

In Table 3, the manufacturing result and evaluation result of the manufactured hot-dip plated striped steel sheet are shown. Incidentally, 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 flat portion (the film thickness of the convex portion / the film thickness of the flat portion x 100).

In Comparative Example 1, since the distance between the electrodes during Ni-free plating was not appropriate, the film thickness of the Ni plating layer in the convex portion was over 0.4 µm, and the film thickness of the Ni plating layer in the flat portion was less than 0.05 µm. As a result, plating failure occurred due to non-plating, and sufficient corrosion resistance was not obtained in the corrosion test after abrasion.

In Comparative Example 2, since the amount of Ni-free plating was small, the film thickness of the Ni plating layer of the flat portion of the striped steel sheet was insufficient. As a result, plating defects due to non-plating occurred, and sufficient corrosion resistance was not obtained.

In Comparative Example 3, since the adhesion amount of Ni-free plating was large, the film thickness of the Ni plating layer of the convex part exceeded 0.4 micrometer. As a result, sufficient corrosion resistance was not obtained in the corrosion test after abrasion.

In Comparative Example 4, since the amount of Al in the hot-dip plated layer of the Zn-based alloy was small, sufficient corrosion resistance was not obtained, and the plating appearance was also poor.

In Comparative Example 5, since the amount of Al in the hot-dip plated layer of the Zn-based alloy was large, the plating appearance was poor, the workability was not sufficient, and the hot-dip plated striped steel sheet was industrially undesirable.

In Comparative Example 6, since the amount of Mg in the hot-dip plated layer of the Zn-based alloy was small, sufficient corrosion resistance was not obtained.

In Comparative Example 7, since the amount of Mg in the hot-dip plated layer of the Zn-based alloy was large, the plating appearance was poor, and an industrially undesirable hot-dip plated striped steel sheet was obtained.

In Comparative Example 8, since the amount of deposition of the hot-dip plated layer of the Zn-based alloy was small, sufficient corrosion resistance was not obtained.

On the other hand, in Examples 1-10, generation|occurrence|production of non-plating was suppressed and also had sufficient corrosion resistance even after abrasion. In addition, plating appearance and workability were also satisfied.

According to the above aspect of the present invention, it is possible to provide a hot-dip plated striped steel sheet in which the occurrence of non-plating is suppressed and corrosion when the hot-dip plated layer is worn and the Ni plated layer is exposed is also suppressed, and a method for manufacturing the same. Therefore, the industrial application possibility is high.

1: convex
2: flat part
3: Hot-dip plated layer of Zn-based alloy
4: Ni plating layer
5: Base steel plate

Claims (8)

It is a hot-dip plated striped steel sheet having a base steel sheet, a Ni plating layer disposed on the surface of the base steel sheet, and a hot-dip plating layer disposed on the surface of the Ni plating layer, and having a convex portion and a flat portion on the plate surface,
A film thickness of the Ni plating layer of the convex portion is 0.07 to 0.4 μm per side,
A film thickness of the Ni plating layer of the flat portion is 0.05 to 0.35 μm per side,
The film thickness of the Ni plating layer of the convex portion is more than 100% and 400% or less with respect to the film thickness of the Ni plating layer of the flat portion,
The adhesion amount of the hot-dip plated layer is 60 to 400 g/m 2 per side,
The hot-dip plated layer contains, as a chemical composition, in 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%, Ca: 0 to 1.0% Hot-dip plated striped steel sheet, characterized in that the remainder consists of Zn and impurities. The hot-dip plated striped steel sheet according to claim 1, wherein 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. The hot-dip plated striped steel sheet according to claim 1, wherein the thickness of the Ni plating layer of the convex portion is 0.07 to 0.3 µm per side. The hot-dip plated striped steel sheet according to claim 1, wherein the hot-dip plated layer contains, in mass%, Al: 4.0 to 25.0% and Mg: 1.5 to 8.0% as the chemical composition. 5. The method according to claim 4, wherein the hot-dip plated layer contains at least one of, in mass%, Si: 0.05 to 1.0%, Sn: 0.1 to 3.0%, and Ca: 0.01 to 1.0%, as the chemical composition. Hot-dip galvanized striped steel sheet. The hot-dip plated striped steel sheet according to any one of claims 1 to 5, wherein the coverage of the hot-dip plated layer is 99 to 100% in area% with respect to the plate surface when viewed in the thickness direction. A method for producing the hot-dip plated striped steel sheet according to claim 1,
A rolling process of giving a convex portion and a flat portion to the rolled surface of the steel sheet;
A pre-plating process of performing Ni-free plating on the steel sheet that has undergone the rolling process;
Hot-dip plating process of performing hot-dip plating on the steel sheet that has undergone the pre-plating process
to provide
In the pre-plating process, the rolled surface and the anode surface of the steel sheet are disposed to face each other, the distance between the convex part of the rolled surface and the anode is controlled to be 40 to 100 mm, and the plating adhesion amount per side is 0.5 to 3 g/m 2 on average Electronic Ni plating is performed under the condition that
In the hot-dip plating step, the steel sheet is heated and, in 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%, Ca: 0 to 1.0% The steel sheet is immersed in a hot-dip plating bath containing Zn and impurities, the remainder being Zn and impurities, and continuous hot-dip plating is performed under the condition that the plating adhesion amount per side is on average 60 to 400 g/m2.
Method for producing a hot-dip plated striped steel sheet, characterized in that. The method for manufacturing a hot-dip plated striped steel sheet according to claim 7, wherein in the pre-plating step, the distance between the electrodes is controlled to be 45 to 100 mm.

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