JPH11241187A - Enameled steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain enameled steel sheet excellent in bending adhesion, corrosion resistance in the bent part and edge face rusting resistance at a low cost by providing the surface of a steel sheet with an Al-Zn alloy plating layer whose upper layer is composed of Al, Ni and a small amt. of Zn and providing the surface of the layer with an enamel coating layer. SOLUTION: The surface of a steel sheet is provided with an Al-Zn alloy plating layer contg., by weight, about 4 to 70% Al by about 80 to 300 mg/m<2> both side coating weight. The surface of this plating layer is dipped into an aq. soln. of pH <=4 contg. Ni, and an upper layer part composed of <=1% Zn, about 4 to 70% Al and about 30 to 96% Ni is formed to a depth of about 20 Å. The surface of this plating layer is provided with an enamel coating layer. The enamel coating layer preferably contains 45 to 65% P2 O5 , 5 to 15% Sb2 O3 , 2 to 10% Al2 O3 , 0.5 to 5% B2 O3 , 7<=Na2 O+K2 O+Li2 O<15% 7<=ZnO+ BaO+CaO+SrO<=20% and 1<=TiO2 +SiO2 +ZrO2 <=10%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides an enameled steel sheet used as a marker board, a chalk board, a tunnel interior material, a building interior material, and a building exterior material. Provided is an enameled steel sheet which has excellent enamel adhesion, and has excellent bending adhesion, corrosion resistance at the bent part, and end-face rust resistance that can be easily processed and formed after enamel coating as an interior material for buildings in advance. Things.

[0002]

2. Description of the Related Art Painting and enamel coating methods are known as methods of imparting functions such as corrosion resistance, chemical resistance, weather resistance, and design to a steel sheet to improve the life of a substrate. Enamel-coated steel sheets (hereafter abbreviated as enamel steel sheets) have superior properties in terms of hardness, weather resistance, cleaning recovery properties, heat resistance, non-combustibility, etc., compared to painted steel sheets, but are disadvantageous in that they are peeled off when processed at a high price. There is. In other words, plastically processed products using enameled steel sheets are generally so-called post-coated products, which are manufactured in such a procedure that the base metal is plastically processed and then enameled, and the strip-shaped metal is continuously coated. ,afterwards,
The production cost is significantly higher than that of a so-called pre-coated product subjected to plastic working. On the other hand, coated steel sheets have a coating film that follows the processing to some extent, so if it is a lightly processed product, it can be manufactured with a pre-coat that is processed after being continuously coated with a coil coat, and the manufacturing cost is low and low price Becomes Therefore, it is applied to various uses. In other words, the enameled steel sheet is a post-coated product, and thus has a problem that the price is high. However, for example, in a hospital or the like, the contamination prevention effect due to the excellent cleaning recovery property of the enamel is preferred, and the enamel product is widely used. Accordingly, there has been a demand for an enameled steel sheet which does not peel off even if it is bent after enamel coating, particularly as an interior material of a building which emphasizes hygiene such as a hospital, for example. In this case, since the thickness of the enameled steel sheet is usually 0.3 mm or more, the surface of the enameled steel sheet is subjected to a tensile processing of 10% or more during bending. The enamel layer has a low elongation rate because it is vitreous, and cracks cannot enter the enamel layer. Therefore, as an essential condition of the enameled steel sheet that can be bent, it is necessary that even if a crack is formed in the enameled layer, the enameled layer must be firmly adhered to the base metal and that no rust is generated from the cracked portion.

[0003]

An enameled steel sheet which is bent after enamel coating is disclosed in
No. 43257 has been proposed. This is a metal plate whose surface is made of aluminum and has an enamel layer with a specified composition and thickness on the surface.However, when a severe bending process is applied as applied to painted steel sheet, the enamel layer is Even if the enamel layer does not fall off, cracks in the enamel layer penetrate into the underlying aluminum plating and crack the plating. Aluminum itself has good rust prevention properties, but it has no sacrificial corrosion protection against steel in the general atmosphere, so if cracks occur in plating, red rust (iron rust) is inevitable. There was a point. Further, in the case of the enameled steel sheet processed after enamel coating, the steel base is always exposed at the end face, but when the base plating is aluminum, there is a problem that the generation of red rust from the end face is unavoidable.

On the other hand, as an enameled steel sheet having a corrosion-resistant base material below the enameled layer, the invention of Japanese Patent Publication No. 5-71667 has been proposed. This is an enamel coating on aluminum zinc alloy plating.In the case of painted steel sheets, aluminum zinc alloy plating has been conventionally used as a coating base treatment for the same corrosion resistance purpose. By applying enamel coating to a plating layer containing, the generation of red rust from pinholes and the like of the enamel is prevented. However, zinc, which is a component constituting the aluminum zinc alloy plating layer, has poor adhesion to the enamel layer, and thus has an inherent disadvantage that the enamel layer is peeled off when bent after enamel coating. Therefore, there has been no product in the world that uses an enameled steel sheet and is excellent in post-bending. In other words, even if the method disclosed in Japanese Patent Publication No. 5-71667 was used as it was, the enamel layer peeled off after the post-bending process. Further, in this case, no consideration is given to the enamel composition as the enamel layer for processing, and the enamel composition does not have sufficient adhesion performance. In addition, as described above, no consideration was given to factors affecting the adhesion between the plating layer and the enamel coating layer other than the enamel layer composition. Here, the reason why the adhesion between zinc and the enamel layer is not good is not clear, but since zinc has a very easily oxidizable property, oxidation by inorganic oxide (enamel) is severe and the reaction layer at the interface contributing to adhesion is brittle. In other words, it is considered that the invention of Japanese Patent Publication No. Hei 5-71667 had problems in the adhesion between the plating layer and the enamel layer and the peeling resistance of the enamel layer itself during processing.

[0005]

SUMMARY OF THE INVENTION The present invention has been studied in view of the above-mentioned circumstances, and is excellent in enamel adhesion, and thus, is excellent in bending adhesion, corrosion resistance in a bent portion, and low in end surface rust resistance. It is an object of the present invention to provide an enameled steel plate that can be manufactured at a low temperature.

That is, the present invention has an aluminum zinc alloy plating layer on the surface of a steel sheet, and the upper layer of the aluminum zinc alloy plating layer is made of aluminum, nickel and
It is an object of the present invention to provide an enameled steel sheet comprising zinc in an amount of not more than 10% by weight and having an enameled coating layer on the aluminum zinc alloy plating layer. Further, it is preferable that the upper layer portion is made of aluminum and nickel formed by immersing the surface of the aluminum zinc alloy plating layer in an aqueous solution containing nickel and having a pH of 4 or less, and zinc of 1% by weight or less. Further, the enamel coating layer, P ₂ O _5: 45~65 wt%, Sb ₂ O _3: 5~
15% by weight, Al ₂ O ₃ : 2 to 10% by weight, B ₂ O ₃ :
0.5 to 5% by weight, 7% by weight ≦ Na ₂ O + K ₂ O + Li
₂ O <15% by weight, 7% by weight ≦ ZnO + BaO + CaO
+ SrO ≦ 20% by weight, 1% by weight ≦ TiO ₂ + SiO ₂
It preferably contains + ZrO ₂ ≦ 10% by weight.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The present invention has an aluminum zinc alloy plating layer on a steel sheet surface. The metal ratio in the aluminum-zinc alloy plating layer is preferably such that the aluminum content is 4 to 70% by weight, and the remainder consists of zinc and ordinary impurities and additional substances for not impairing or improving the film properties. If the aluminum content is less than 4% by weight, the excellent corrosion resistance inherent in aluminum zinc alloy plating cannot be expected. On the other hand, when the aluminum content is more than 70% by weight, the sacrificial corrosion prevention effect of the crack portion generated in the bent portion tends to be insufficient. More preferably, the aluminum content is 25 to 70.
% By weight. If the aluminum content is 25% by weight or more, the melting point of the aluminum-zinc alloy plating becomes higher, and the plating layer is less likely to be damaged by melting. Additives for aluminum zinc alloy plating include Si, La, Ce, Mg, Sn and the like. Especially Si
Is preferably added in an amount of 1 to 2% by weight from the viewpoint of plating adhesion of the processed portion. The adhesion amount of the aluminum zinc alloy plating layer is preferably 80 to 300 mg / m ^{2 on} both sides.

As described above, zinc as an underlayer of an enamel layer has poor enamel adhesion, so that when subjected to bending, enamel peeling occurs. On the other hand, aluminum has good adhesion to an enamel. Aluminum zinc alloy plating
It is generally manufactured by hot-dip plating, but is separated into an Al-rich phase and a Zn-rich phase because it separates into an Al-rich phase and a Zn-rich phase during the cooling process in the hot-dip plating process and precipitates on the steel sheet surface. . For example, Al content 25 to
In the case of plating in the range of 75% by weight, α-Al is first crystallized in a dendritic manner, and then α-Al and β-Zn are crystallized between the dendrites. In the present invention, while the Al-rich phase mainly consisting of α-Al is left, if the enamel base layer of nickel deposited and adhered to the surface of the Zn-rich phase consisting of α-Al and β-Zn, the enamel coating layer and The present inventors have found that an upper layer portion of aluminum zinc alloy plating serving as an enamel base layer having excellent adhesion can be obtained, and have reached the present invention.

The upper part of the aluminum zinc alloy plating layer as the enamel underlayer of the present invention is made of zinc, aluminum and nickel of 1% by weight or less. Here, the upper layer portion means a range up to a depth of about 20 ° in the surface layer, and the composition of each component in the upper layer portion is evaluated as an area ratio by obtaining a mapping image by an Auger electron spectroscopy, multiplying by specific gravity, and evaluating as weight%. . The content of Al on the surface is preferably 4 to 70% by weight, and the content of Ni is preferably 30 to 96% by weight. Since the metal surface usually has a thin oxide or hydroxide layer, aluminum and nickel may each contain an oxide or hydroxide. Further, as a preferable manufacturing method of such an upper layer portion, a method of immersing an aluminum zinc alloy plating layer in a nickel plating bath used as an enamel pretreatment is exemplified. In this case, phosphorus, phosphorus contained in the nickel plating bath used is used. It may contain an additive substance or an impurity for preventing or improving the adhesion of an acid or a bath anion. In particular, it is preferable that phosphoric acid be contained together with Ni in the upper layer portion of the aluminum zinc alloy plating layer because the adhesion to the phosphoric acid enamel is excellent. Although the reason is not clear, it is considered that the bond between phosphoric acids occurs. Further, in the case of the phosphoric acid-based enamel layer presented in the present application, it is excellent in chemical durability such as chemical resistance as described later, and can be fired at a low temperature of 540 ° C. or less. Without
Excellent adhesion and corrosion resistance, enamel characteristics (hardness, weather resistance,
It is possible to provide an enameled steel sheet having excellent recovery and recovery properties, heat resistance, and noncombustibility. The zinc content of the upper layer is 1% by weight or less. If more than 1% by weight of zinc is present, the adhesion between the underlying aluminum zinc alloy plating layer and the enamel coating layer will deteriorate.

In addition, as a method of forming the upper layer portion of the aluminum-zinc alloy plating layer with aluminum, nickel, and 1% by weight or less of zinc, Ni is deposited on Zn by electrolytic plating, electroless plating, displacement precipitation, or the like. The method of forming is preferred. In particular, p containing nickel ions
When the surface of the aluminum zinc alloy plating layer is immersed in an aqueous solution of H4 or less, the aluminum-rich phase does not dissolve, and nickel can be easily precipitated only on the zinc-rich phase, which is preferable. PH containing nickel ions
Examples of the aqueous solution of 4 or less include a nickel plating bath used when nickel plating a steel plate. If the pH is more than 4, the zinc-rich phase does not dissolve but a part of the aluminum-rich phase dissolves, and zinc remains on the surface, which is not preferable from the viewpoint of the adhesion between the plating layer and the enamel coating layer. Furthermore, by immersing in an aqueous solution containing nickel ions and phosphoric acid and having a pH of 4 or less, it is possible to contain Ni and phosphoric acid in the upper layer portion of the plating layer. Preferred for reasons.

The enameled steel sheet according to the present invention has an enamel coating layer on the outermost layer of the steel sheet, the upper layer of which is an aluminum-zinc alloy plating layer of 1% by weight or less of Zn and aluminum and nickel.

The composition of the enamel coating layer used in the present invention is not particularly limited. For example, although it depends on the enamel firing time, if the firing time exceeds 600 ° C. for 5 minutes, the aluminum-zinc alloy plating layer of the underlayer is completely removed. Since it is mixed in the enamel layer, the excellent rust-preventive property, sacrificial corrosion-proof property, etc. of the aluminum-zinc alloy plating are significantly reduced. Therefore, it is preferable to use a low melting point glaze of less than 600 ° C. for the enamel coating layer. Furthermore, the aluminum zinc alloy plating layer is 5
If the temperature exceeds 40 ° C., the plating starts to melt and mixes into the enamel layer. Therefore, when the enamel coating layer is formed on only one side, the enamel firing temperature is preferably set to 540 ° C. or lower. Since the enameled steel sheet of the present invention uses an aluminum-zinc alloy-plated steel sheet excellent in rust resistance and sacrificial corrosion resistance as an enamel base, an enamel coating layer is not necessarily required on the back surface. If the enamel layer is formed only on the front side, the cost can be reduced because only one side of the glaze is required. However, in this case, it is preferable to have an aluminum zinc alloy plating layer on the back surface. In this case, it is preferable to perform firing at as low a temperature as possible as an enamel firing condition in which the plating layer is not damaged. When firing at a temperature exceeding the melting point of plating, plating flows into the furnace during enamel firing, which also affects equipment, damages the plating layer on the back side as a product, and loses rust prevention and sacrificial corrosion protection, This is because red rust occurs. The aluminum zinc alloy plating layer present on the back side without the enamel coating layer does not have the specific upper layer described above, but may have the upper layer.

The low melting point glaze composition having a melting point of less than 600 ° C. is mainly composed of lead borate based on PbO, lead borosilicate based, zinc phosphate based on P ₂ O ₅ , and lead phosphate based. And soda glass mainly composed of Na ₂ O can be applied. A composition in which several to several tens of oxides are added to these basic compositions can be used.

Particularly, as the glaze composition, P ₂ O ₅ : 45-6
5 wt%, Sb ₂ O _3: 5~15 wt%, Al ₂ O _3:
2 to 10 wt%, B ₂ O ₃ : 0.5 to 5 wt%, 7 wt% ≦ Na ₂ O + K ₂ O + Li ₂ O <15 wt%, 7 wt% ≦ ZnO + BaO + CaO + SrO ≦ 20 wt%, 1
% By weight ≦ TiO ₂ + SiO ₂ + ZrO ₂ ≦ 10% by weight,
In the case of a composition containing the above range, enamel firing at 540 ° C. or lower can be performed without containing lead, which is preferable. The glaze composition is preferably in this range for the following reasons.

When P ₂ O ₅ is 45 to 65% by weight, there is an advantage that low-temperature firing at 540 ° C. or lower can be performed without impairing the chemical resistance of the enamel. P ₂ O ₅ constitutes the glass of the enamel according to the present invention, and is formed in a mesh shape.
Since P ₂ O ₅ contains simple double bond oxygen, it has low chemical durability and strong volatility as it is. Therefore, by adding the following elements, characteristics required for the enamel can be exhibited. P ₂ O ₅ is preferably in the range of 45 to 65% by weight from the viewpoint of enamel baking at a low temperature. That is, when the content is less than 45% by weight, the baking temperature of the glass increases, and baking at 540 ° C. or less cannot be performed. Conversely, if the content exceeds 65% by weight, solidification of the slip occurs during ball mill pulverization in the production of the slip. Sb ₂ O ₃ is 5
When it is 15% by weight, there is an advantage that low-temperature firing at 540 ° C. or less can be performed without impairing the chemical resistance of the enamel. Sb ₂ O ₃ is a composition that affects the chemical resistance of the enamel, and is preferably in the range of 5 to 15% by weight. In other words, when the content is less than 5% by weight, the sintering temperature of the enamel increases, and low-temperature baking at 540 ° C. or less cannot be performed,
Conversely, if it exceeds 15% by weight, the acid resistance of the enamel is not exhibited.

When Al ₂ O ₃ is 2 to 10% by weight, there is an advantage that low-temperature firing can be performed without impairing the mechanical properties of the enamel. Al ₂ O ₃ is a composition that affects the mechanical properties and chemical resistance of the enamel, and is 2 to 10% by weight.
Is preferable. That is, if the content is less than 2% by weight, the mechanical properties and chemical resistance of the enamel are not exhibited. Conversely, if the content exceeds 10% by weight, the baking temperature of the enamel becomes high, and baking at 540 ° C. or less cannot be performed. B ₂
O ₃ is a composition which affects the temperature of the enamel at low temperatures, acid resistance, and gloss, and is preferably in the range of 0.5 to 5% by weight. B
_{When the} content of ₂ O ₃ exceeds 5% by weight, the acid resistance is poor, and the content of 0.
If it is less than 5% by weight, the gloss decreases and the firing temperature increases, so that the range of 0.5 to 5% by weight is preferable. Na
₂ O, K ₂ O and Li ₂ O are used for lowering the temperature of the enamel,
The composition affects the chemical resistance, and preferably contains at least one selected from these. That is, 7
It is preferable that the range of wt% ≦ Na ₂ O + K ₂ O + Li ₂ O <15 wt% is satisfied. 7% by weight of Na ₂ O + K ₂ O + Li ₂ O
When the content is less than 15% by weight, there is an advantage that low-temperature firing at 540 ° C. or less can be performed without impairing the chemical resistance of the enamel. That is, if it is less than 7% by weight, the gloss of the enamel is reduced, and the baking temperature is increased to 540 ° C.
You will not be able to print on: Conversely, if the content is more than 15% by weight, the chemical resistance of the enamel decreases.

ZnO, BaO, CaO, and SrO are compositions that affect the chemical resistance, mechanical properties, and coefficient of thermal expansion of the enamel, and preferably contain at least one selected from these. That is, 7% by weight ≦ ZnO + BaO
+ CaO + SrO ≦ 20% by weight is preferred. Zn
When O + BaO + CaO + SrO is 7 to 20% by weight, there is an advantage that low-temperature firing at 540 ° C. or lower can be performed without impairing the chemical resistance and mechanical properties of the enamel.
That is, when the content is less than 7% by weight, the chemical resistance and mechanical properties of the enamel are not exhibited. Conversely, if it exceeds 20% by weight, the baking temperature of the enamel becomes high, so that baking at 540 ° C. or less cannot be performed. In addition, the coefficient of thermal expansion of the enamel is increased, causing a mismatch with the steel plate, and the enamel is cracked.

TiO ₂ , SiO ₂ and ZrO ₂ are compositions which affect the chemical resistance and mechanical properties of the enamel, and preferably contain at least one selected from these. That is, 1% by weight ≦ TiO ₂ + SiO ₂ + ZrO
The range of ₂ ≦ 10% by weight is preferred. TiO ₂ + SiO ₂
When + ZrO ₂ is 1 to 10% by weight, low-temperature firing at 540 ° C. or lower can be performed without impairing the chemical resistance and mechanical properties of the enamel. That is, if it is less than 1% by weight, the enamel cannot exhibit its chemical resistance and mechanical properties. Conversely, if the content exceeds 10% by weight, the baking temperature of the enamel becomes high, and baking at 540 ° C. or less cannot be performed.

The raw material of the composition constituting the low-temperature enamel glaze of the present invention may be any raw material that produces an oxide of the above-mentioned components or a mixture of these oxides by firing. For example, ammonium monohydrogen phosphate, ammonium dihydrogen phosphate, aluminum oxide, antimony oxide, (anhydrous) boric acid, sodium carbonate, sodium silicate, potassium carbonate, lithium carbonate, zinc oxide, barium carbonate, calcium carbonate, strontium carbonate , Titanium oxide, (anhydrous) silicic acid, zirconium oxide,
Zircon and the like can be mentioned. In particular, lead is toxic and poses a problem for disposal of enamel slips. In particular, when the enamel coating layer is formed by a spray method, scattering to the surroundings is large, which is a problem both in the working environment and in discarding the slip. In addition, glazes that do not use lead as described above are preferable because they cause problems such as being unable to be recycled after they become products as enameled steel plates.

Further, a frit made of these glazes mixed with an oxide as a color pigment is prepared and glazed on the underlayer (upper layer of aluminum zinc alloy plating), and then baked in a furnace. Form a layer. As a glaze method, any of a spray method, a coater method, and an electrostatic method may be used.

The thickness of the enamel coating layer of the present invention is not particularly limited. Usually, the thickness of the enamel is 50 μm or more.
However, especially when used for bending, the enamel adhesion is further improved by setting the enamel film thickness to 50 μm or less. Since the steel sheet and the enamel have different coefficients of thermal expansion, the surface of the steel sheet receives stress at the interface with the enamel during cooling immediately after the enamel firing. As the enamel thickness increases, the stress increases and the adhesion at the interface decreases. In the case of further bending, the processing rate of the enamel on the surface increases as the enamel thickness increases. For these two reasons, a film thickness of 50 μm or less is preferable for bending. However, the film thickness may be more than 50 μm particularly in such an application where there is no requirement.

The enameled steel sheet of the present invention is preferably used for applications that are processed after enamel firing. Excellent adhesion and corrosion resistance for post-bending. Also, of course, the plate may be used without being processed after firing. Further, the enameled steel sheet of the present invention may be a strip-shaped enameled steel strip.

[0023]

Next, the effects of the present invention will be specifically described based on examples.

(Example) Galvalume steel strip having an aluminum zinc alloy plating layer having a thickness of 0.35 mm and an adhesion amount of 75 g / m ² per side (Al content 55% by weight, Si content 1.6% by weight) (AZ150) and an aluminum-plated steel strip (Si content 1.6% by weight)
After performing various pretreatments shown in Table 1, the process was successively led to a glaze step, and glaze was applied by a spray method using a glaze shown in Table 2, followed by firing for 5 minutes. Table 3 shows the performance of the obtained enameled steel strip.

[0025]

[0026]

The following describes various test methods and their evaluation methods. (Coating composition of plating surface) Al, N in the upper part (within about 20 mm from the outermost surface) of the plating layer by Auger electron spectroscopy
The mapping images of i and Zn were obtained, the area ratios were determined, and the specific ratios were converted to weight%. Table 3 shows the presence or absence of lead in the glaze from the viewpoint of environmental protection. Further, as the back surface appearance, the appearance of the back surface after enamel coating was evaluated for the deterioration state due to plating flow due to heating during firing.

(Bending Adhesion) Bending was performed at a processing rate of 0.5 mmR using a bender that bent at 90 degrees.
After performing the cellophane tape peeling test after the bending, the peeling state of the enamel layer was visually observed. [Judgment] ：: Excellent No peeling ○: Good Very slight peeling (peeling area less than 1%) △: Poor Peeling area 1% or more and less than 10% ×: Poor peeling area 10% or more

(Enamel adhesion tensile test) The adhesion strength of the enamel layer was measured. Two enameled steel sheets were adhered to each other with a thermosetting epoxy adhesive so as to have an adhesion area of 3 cm ^2, and were heat-treated at 170 ° C. for 20 minutes. The strength when the two enameled steel sheets bonded together after the adhesive was cured were pulled off from the opposite ends was measured.

(Corrosion Resistance of Bent Section) The enameled steel sheet subjected to the above-described bending section was subjected to a cycle test in which spraying with pure water (35 ° C., 4 hours) → drying (60 ° C., 2 hours) → wetting (50 ° C., 2 hours) was repeated. After one month, the occurrence of red rust was observed.

(End face rust resistance) An enameled steel sheet was heated at 37 ° C.
It was stored for one month in a 95 RH% constant temperature and humidity box, and the occurrence of red rust on the end face was observed.

(Acid resistance) JIS R4301-197
8 Based on the normal temperature spot test with citric acid (10% citric acid, 15 minute spot) specified in “Enamel product quality standards”, the surface erosion degree was determined by AA, A, B specified by the same test method. , C, and D were evaluated.

(Alkali resistance) JIS R 4301-
Based on the alkali resistance test (10% sodium carbonate, 15 minute spot) specified in 1978 "Enamel Product Quality Standard", the degree of surface erosion was determined based on the following standard. ：: No discoloration, no pencil line mark visible. Δ: Discoloration or a pencil line mark is visible. X: Both discoloration and a pencil line mark are visible.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

[0037]

[Table 4]

[0038]

According to the present invention, an enameled steel sheet having both corrosion resistance and enamel adhesion at low cost, which is inexpensive with the conventional method, which is not obtainable by the conventional method, is excellent in bending adhesion for post-bending and corrosion resistance in the bent portion. Enameled steel sheet can be provided. This not only has a large industrial effect, but also contributes to improving the hygiene of interior materials. Also, using the present invention, even for products that are not post-bent, enamel adhesion,
Because of the excellent end face rust resistance, the life of the enameled steel sheet that cannot be obtained with the conventional enameled steel sheet can be obtained. This improves durability and contributes to saving of earth resources.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yasumasa Fukushima 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside the Technical Research Institute of Kawasaki Steel Corporation (72) Inventor Toshihide Suzuki 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture (72) Koji Watanabe 2-18-13 Higashi Narashino, Narashino City, Chiba Prefecture Kawasaki Iron & Steel Corp. (72) Inventor Hiroshi Nagaishi 2-18-13 Higashi Narashino, Narashino City, Chiba Prefecture (72) Fukuo Togashi, Inventor 2-18-13 Higashi Narashino, Narashino City, Chiba Pref.

Claims (3)

[Claims] An aluminum zinc alloy plating layer is provided on the surface of a steel sheet, and an upper layer portion of the aluminum zinc alloy plating layer is made of aluminum, nickel and 1% by weight or less of zinc, and an enamel coating is applied on the aluminum zinc alloy plating layer. An enameled steel sheet having a layer. 2. The method according to claim 1, wherein the upper layer portion comprises aluminum and nickel formed by immersing the surface of the aluminum zinc alloy plating layer in an aqueous solution containing nickel and having a pH of 4 or less, and zinc of 1% by weight or less. The described enameled steel sheet. 3. The enamel coating layer according to claim ₂ , wherein P ₂ O ₅ : 45.
65 wt%, Sb ₂ O _3: 5~15 wt%, Al
₂ O ₃ : 2 to 10% by weight, B ₂ O ₃ : 0.5 to 5% by weight, 7% by weight ≦ Na ₂ O + K ₂ O + Li ₂ O <15% by weight, 7% by weight ≦ ZnO + BaO + CaO + SrO ≦ 20% by weight, 1 3. The enameled steel sheet according to claim 1, comprising: wt% ≦ TiO ₂ + SiO ₂ + ZrO ₂ ≦ 10 wt%.