JP2001323357A - HIGHLY CORROSION RESISTANT Al PLATED STEEL SHEET EXCELLENT IN APPEARANCE - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an Al plated steel sheet having improved corrosion resis tance of the end faces which has been the weak point of the conventional alumi num plated steel sheet, and also having a beautiful appearance. SOLUTION: In this highly corrosion resistant Al based plated steel sheet, the surface is provided with a coating layer having a composition containing, by weight, 1 to 15% Mg, 2 to 15% Si, 1 to 15% Sn, 1 to 10% Zn and 0.02 to 5% Ca, and the balance Al with inevitable impurities, and further, the size of intermetallic compounds such as Mg2Si formed in the plating layer is <10 μm by the major axis. The product according to this invention is such that the corrosion resistance of the plating layer and the corrosion resistance at the end faces are remarkably improved compared to the conventional case, and, as the product in which prolonged service life and maintenance free when used are secured, its contribution to operation is remarkable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly corrosion-resistant Al-based plating excellent in appearance used for metal building materials such as roof walls, exhaust system members of automobiles, gasoline tank materials, household appliances such as toasters and stoves. Related to steel plate.

[0002]

2. Description of the Related Art Al-based plated steel sheets are used for automobile parts, building materials, home electric parts and the like because of their high corrosion resistance, heat resistance, and beautiful appearance. In order to respond to the recent demand for improvement of corrosion resistance of automobile exhaust system members, a number of steel plates having a high corrosion resistance have been developed by applying a Cr-containing steel plate or a stainless steel to an aluminum plating to provide a high corrosion resistance (see Japanese Patent Application Laid-Open No. Sho 61).
231152, JP-A-3-277761, etc.). When Cr-containing steel or stainless steel is used as the base plate, the corrosion resistance naturally increases, but the production cost increases and the workability tends to deteriorate. Therefore, various studies have been made to add a corrosion resistance improving element to the plating bath.
JP-A-2-88754 and JP-A-7-20091 disclose the addition of Cr and Mn.
However, in these methods, the generation of red rust has not been completely suppressed in severely bent portions or end faces.

On the other hand, recently, Pb of an automobile fuel tank has been
Freedom is being studied, and the use of aluminum-plated steel sheets for this purpose is being promoted. The problem at this time is a high balance between corrosion resistance, workability, and weldability. In general, in a surface-treated steel sheet, as the amount of plating increases, the corrosion resistance naturally increases, but the workability and weldability tend to decrease. The weldability in this case means continuous workability. A
Since l easily reacts with Cu of the electrode material, when the amount of adhesion increases, the amount of reaction with the electrode increases, and the life of the electrode decreases.
Also in press working, an increase in the amount of adhesion tends to cause damage, peeling, and the like of the plating layer.

[0004] In order to make these characteristics compatible,
Again, many inventions have been made. (JP-A-10-46
358, etc.), it is difficult to say that corrosion resistance, weldability, and workability can be completely compatible. Aluminum plating is particularly excellent in corrosion resistance especially in a dry-wet environment, but tends to be easily dissolved in a constantly wet environment. In particular, the plating may sacrificially protect the steel sheet and dissolve preferentially at the side wall portion where processing is severe or at the flange end surface portion where coating is difficult, and red rust may be generated in a short period of time.

[0005] Conventional surface-treated steel sheets for building materials include:
Although Zn-plated steel sheets have been mainly used, recently, from the demand for further improvement of corrosion resistance and design, Al-Zn
There is a tendency to increase the amount of use of a system-plated steel sheet or an Al-Si system-plated steel sheet. In the Al-Zn-based alloy-plated steel sheet, as the addition amount of Al increases, the corrosion resistance is excellent, but the sacrificial anticorrosion action tends to be weakened. . Furthermore, in the case of aluminum-plated steel sheets with excellent corrosion resistance of the plating layer, there is almost no sacrificial anticorrosion effect of the base iron under normal atmospheric environment, and red rust occurs on the end face in a few days, so repair painting after construction is necessary. , The work becomes complicated. Alternatively, if the repair coating is insufficient, there is a problem that red rust is generated from the end face and the appearance is impaired.

In order to cope with this problem of the aluminum-plated steel sheet, the present inventors have disclosed a technique for suppressing the generation of red rust from a processed portion in Japanese Patent Application Laid-Open No. Hei 6-330274. However, although this can suppress the generation of red rust from the processed portion, there is a disadvantage that the generation of red rust from the end face cannot be suppressed. For the same purpose, Japanese Patent Application Laid-Open No. 11-27
JP-A-9734 and JP-A-11-279735 disclose an Al-Si-Mg-based or Al-Si-Mg-Zn-based plating technique. In this system, Be and Sr are added to secure the surface appearance. Although it is an indispensable technique, Be is toxic and has environmental problems, and Sr has a drawback that the effect of suppressing the generation of wrinkles is insufficient.

[0007]

Accordingly, in the present invention, Mg, Si, S which contributes to the corrosion resistance is added to the aluminum plating layer.
By adding n, Zn, and Ca, the corrosion resistance of the plating layer and the end face is remarkably improved, and excellent surface appearance, good workability, and post-work corrosion resistance are ensured. An object of the present invention is to provide a highly corrosion-resistant Al-based plated steel sheet having an excellent appearance.

[0008]

Means for Solving the Problems The present inventors have studied in detail the effects of the elements added to the plating bath on the corrosion resistance of the Al-based plating layer and the corrosion resistance of the processed portion and the end face.
By adding i, Sn, Mg, Zn, and Ca in appropriate amounts, it was found that the surface appearance was excellent, the corrosion resistance of the plated surface was secured, and the generation of red rust on the processed portion and the end face could be suppressed. Completed the invention.

Hereinafter, the present invention will be described in detail. JP 5
In JP-A-6-127762, the present applicants have already
A method for producing an aluminized steel sheet containing i and Mg is disclosed. The present inventors have studied in more detail the plating structure when Si, Mg, Zn and Ca are added, the corrosion resistance at that time, and have obtained the following findings. That is, S
By adding i, Sn, Mg, Zn, and Ca in a complex manner, Mg and Zn are dissolved in an air environment, a wet environment, or a salt damage environment, and a dense Mg-based or Mg-Zn-based material is exposed on the exposed surface of the base iron or the plating surface. In addition to forming a coating to prevent corrosion, the sacrificial anticorrosive action of Zn is added, and the effect of dissolving Ca raises the pH value of the Fe surface of the cut surface and suppresses the generation of red rust. As a result, it has been found that the corrosion resistance of the processed portion and the end face is remarkably improved, and the corrosion resistance of the plating layer surface is also excellent. Also, Mg ₂ Si, Mg ₂ Sn,
By generating the MgZn ₂ intermetallic compound, the corrosion resistance can be further improved.

This intermetallic compound is in a lump and is preferentially dissolved when exposed to a corrosive environment, so that the supply of Mg is excellent. However, if the size exceeds a certain size, caution is required because the intermetallic compound is hard, so that workability is reduced and corrosion from the processed portion may be accelerated.
Controlling the cooling rate is effective for crystallizing Mg ₂ Si, Mg ₂ Sn, and MgZn ₂ in a desired size and in a desired amount. For example, rapid cooling after plating is preferable. According to the present invention, Si, Sn, Mg, Zn,
By adding Ca and appropriately controlling the amount of addition thereof, it becomes possible to obtain an Al-based plated steel sheet with dramatically improved corrosion resistance. The required post-treatment film and lubricating film can be simplified, and the effect of improving weldability or workability also increases.

The gist of the present invention is as follows. (1) On the surface of the steel sheet, in mass%, Mg: 1 to 15%, S
i: 2 to 15%, Zn: 1 to 10%, Ca: 0.02 to
5%, the balance having a layer composed of Al and unavoidable impurities, and a Mg ₂ Si phase, MgZ present in the plating layer.
A highly corrosion-resistant Al-based plated steel sheet having an excellent appearance, wherein the size of an intermetallic compound such as an n ₂ phase is less than 10 μm in a major axis.

(2) On the surface of the steel sheet, Mg: 1
-15%, Si: 2-15%, Zn: 1-10%, C
a: a plating layer made of Al containing 0.02 to 5%, Sn: 1 to 15%, and the balance containing unavoidable impurities and incidental components, and the size of the intermetallic compound present in the plating layer A high-corrosion-resistant Al-based plated steel sheet having a long diameter of less than 10 μm.

(3) 5 μm thickness at the interface between the plating phase and the steel sheet
m or less Al-Fe-Si alloy layer or Al-Fe
High corrosion resistance Al having excellent appearance according to the above (1) or (2), comprising a -Si-Mg alloy layer.
System plated steel sheet. (4) The highly corrosion-resistant Al-based plated steel sheet having excellent appearance as described in (1) to (3) above, wherein the surface of the plating layer has a post-treatment film.

(5) The above-mentioned (1) to (1), wherein a lubricating film of a film removing type or a non-film removing type is provided on the post-treatment film.
(4) A highly corrosion-resistant Al-based plated steel sheet having excellent appearance according to (4). (6) The adhesion amount of the Al-based plating layer is 20 to 20 per side.
(1) to (5), wherein the content is 0 g / m ^2.
A highly corrosion-resistant Al-based plated steel sheet having an excellent appearance described in 1).

Next, the reasons for limitation of the present invention will be described. First, the reasons for limiting the Al-based coating layer (hereinafter abbreviated as plating layer) will be described. Plating layer: Si: 2 to 15%, Mg: 1
-15%, Zn: 1-10%, Ca: 0.02-5%, and optionally Sn: 1-15%,
The balance consists of Al and inevitable impurities. M
By adding g, Zn, Si, and Sn in combination, an intermetallic compound such as Mg ₂ Si, Mg ₂ Sn, and MgZn ₂ is generated in the plating layer, and the corrosion resistance can be greatly improved.
Therefore, it is desirable to add Si, Mg, Zn, and Sn in a complex manner.

As described above, when these intermetallic compounds are dissolved in the use environment, Mg or Mg-Zn
A protective film is formed to protect the plating layer itself and the exposed part of the base iron. The greater the amount, the more the effect of improving corrosion resistance. However, if this size is too large, it will adversely affect the workability and consequently reduce the corrosion resistance of the processed part,
The state in the plating layer may be a dispersed state or a lump, but the major axis is less than 10 μm when the size is observed from a cross section. The smaller the size, the better the workability. As for the size of the intermetallic compound, the structure is observed by polishing the cross section at an inclination of 5 degrees.

[0017] Although Si is added for the purpose of normal alloy layer growth suppression in Al-based plated steel sheet, the present invention Mg ₂
Used for crystallization of Si phase. If the amount of Si is too small, the crystallization effect is lost and the effect of improving the corrosion resistance is not exhibited. On the other hand, if the amount is too large, coarse Si primary crystals are formed, impairing the corrosion resistance and workability. Therefore, the amount of Si added is limited to 2 to 15%.

When Mg is added in an amount of 1% or more, the effect of improving the corrosion resistance is exhibited. Mg is an element that is very easily oxidized. However, in the case of hot-dip plating, even if such an amount is added to the aluminum plating bath, generation of dross does not particularly increase. However, as the amount of Mg added increases, the viscosity of the bath gradually increases, and the operability deteriorates, and the effect on the corrosion resistance tends to be saturated. %.

When Zn is added in an amount of 1% or more, the effect of improving corrosion resistance is exhibited. However, when it exceeds 10%, the amount of white rust generated by Zn is increased, and Mg ₂ Si, M
An intermetallic compound such as gZn ₃ tends to grow greatly, and there is a concern that the workability may decrease. Therefore, the amount of Zn added is set to 1 to 10%. When Ca is added in an amount of 0.02% or more, it is particularly effective in suppressing the appearance of wrinkles in the hot-dip plating method, and also has an effect on the corrosion resistance. Since the workability of the layer is reduced, the upper limit is set to 5%. These elements can form compounds with Si and Al in the plating layer, but their forms are not particularly limited.

Since Sn does not have the effect of suppressing the growth of the alloy layer unlike Si, it cannot be a substitute for Si. However, similar to Si, Sn forms Mg and an intermetallic compound Mg ₂ Sn to improve corrosion resistance. Therefore, it may be contained in the plating layer together with Si. In particular, when controlling the amount of Si to suppress the coarse Si crystal, it is effective to secure an intermetallic compound necessary for corrosion resistance. Sn content is 1
The lower limit is limited in consideration of the effect on corrosion resistance and the upper limit in consideration of adverse effects on operability such as bath temperature and viscosity.

The plating layer may contain Fe as an unavoidable impurity in addition to these elements.
% Or less, and the effect on the plating structure is relatively small. Further, it is also possible to add trace elements such as Cr, Mn and Ti to the plating layer. In the present invention, the method for producing the Al-based plated steel sheet is not particularly limited, and a hot-dip plating method, an electroplating method from a non-aqueous solvent, a vapor deposition method, a clad method, and the like can be applied.

At present, the most industrially widespread
It is an l-plated steel sheet. At this time, an alloy layer composed of an intermetallic compound is generated at the interface between the plating layer and the ground iron. When an Al-Si-Mg-Zn-based plated steel sheet is manufactured by the melting method, an alloy layer is naturally formed, but the composition of the alloy layer at this time is Al-
It is a Si-Fe system. However, when the amount of Mg increases, Al-
The formation of Fe-Si-Mg intermetallic compounds is also observed. The thickness of the alloy layer is desirably 5 μm or less.
This is because the alloy layer is hard and brittle, and if the alloy layer is thick, the workability of the steel sheet is greatly impaired. By adding Mg to the plating bath, an effect of reducing the thickness of the alloy layer can be obtained, and an alloy layer of 2 μm or less can be obtained.

Next, the steel composition of the base material will be described. There is no particular limitation on the steel composition, and any steel type has an effect of improving corrosion resistance. As steel types, in addition to IF steel, Al-k steel, Cr-containing steel, stainless steel, and high tensile steel to which Ti, Nb, B, etc. are added, Ti-added steel for heat resistance, and free-N addition for alloying suppression effect It is also possible to use steel or the like. Al-k or stainless steel for construction materials, Ti-IF or Ti-added steel for exhaust systems, Al-k or free-N-added steel for home appliances, fuel tanks It is preferable to use a B-added IF steel.

In the present invention, the post-treatment of plating is not particularly limited, but a chemical conversion treatment such as chromate or phosphate treatment can be performed, and post-treatment containing a resin may be used. As the chemical conversion treatment, phosphoric acid, silica, or the like can be contained, and an Mg-based compound may be added. As the resin type, for example, all treatments including general-purpose resins such as acrylic, polyethylene, polyester, melamine, epoxy, urethane, and fluorine resins are possible. Recently, various post-treatments that do not use Cr are being developed.
It is of course possible to apply these.

Depending on the application, the surface layer of this treatment may be further coated with an organic resin. As the organic resin, there is a non-film removal type resin film or a film removal type resin film such as a clear treatment utilizing the appearance of aluminum, a color treatment containing a pigment, or a treatment for improving weldability. General-purpose treatments such as acrylic resin, polyethylene resin, polyester resin, melamine resin, epoxy resin, urethane resin, and fluorine resin are all possible. The film thickness is not particularly limited, and a normal process of about 0.5 to 20 μm can be performed. In addition to this, post-plating post-treatments such as zero spangle treatment, annealing, and temper rolling may be applied, but these are not particularly limited and can be applied.

Finally, the reason for limiting the amount of plating will be described. In the present invention, the total coating amount of the Al-based coating layer and the intermetallic compound layer (hereinafter, referred to as the plating adhesion amount) is set to 20 per one side.
It is desirable to set it to 200 g / m ² . In building materials, the life of the plating layer and the generation of red rust from the processed end face tend to be suppressed by increasing the amount of adhesion. The present invention realizes increased corrosion resistance, end face, and processed portion corrosion resistance, and exhibits sufficient performance even with a lower basis weight than the conventional one, but the effect of improving the corrosion resistance is naturally obtained as the amount of adhesion increases. If the amount is less than 20 g / m ^{2 on} one side, there is a little concern in terms of long-term durability, and if the amount is too large, there is a concern that workability may be impaired. Therefore, the preferable amount of adhesion is ²⁰ to 200 g / m ² per side.

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

(Example 1) Steel having the components shown in Table 1 was melted by a normal converter-vacuum degassing process to obtain a steel slab, which was then subjected to hot rolling and cold rolling under normal conditions. Thus, a cold-rolled steel sheet (sheet thickness 0.8 mm) was obtained. Using this as a material, a hot-dip Al-based plated steel sheet was obtained. For the hot-dip Al plating, a non-oxidizing furnace-reducing furnace type line was used, and annealing was also performed in this line. The annealing temperature was 800 to 850 ° C. The composition of the plating bath is mainly Al-Si-Mg-Zn-Ca-based,
The l-Si-Sn-Mg-Zn-Ca system was also studied.

The composition was variously changed, and the temperature of the intruding plate and the cooling rate after plating were controlled so that the alloy layer was manufactured with a small thickness. The bath temperature was set to the melting point + 60 ° C. After plating, the amount of plating was adjusted by a gas wiping method. The plating appearance was good with no plating or the like. In addition, as a post-treatment, the silane coupling agent-based non-chromate film is
It was treated at 100 mg / m ² per side in terms of O ₂ and temper rolled at 0.5%. The performance of the hot-dip Al-coated steel sheet manufactured in this manner was evaluated by the following method.

[0029]

[Table 1]

[0030] (1) plating layer composition, the alloy layer thickness analysis methods plated layer composition: 3% NaOH + 1% AlCl 3 · 6H
Only the plating layer was peeled off by constant current electrolytic peeling in ₂ O. Since Mg is insoluble in an alkaline solution, after electrolytic stripping, it was further treated with 20% nitric acid and mixed with an electrolytic stripping solution to obtain a plating layer composition analysis solution. The analysis of each element was performed by ICP. When analyzing after chromate treatment,
It is necessary to reduce the influence of Cr in the chromate by lightly polishing the surface. Plating layer structure: 5 degree inclined polishing of the plating layer section,
Observation of plating structure by optical microscope (200 to 500 times)
Was done. The maximum major axis of the intermetallic compound present in the plating layer in a plating 1 mm width visual field was measured at any five locations. Alloy layer thickness: The alloy layer thickness was measured from a 400-fold cross-sectional micrograph.

(2) Appearance The occurrence of wrinkles was evaluated visually. [Evaluation criteria] ○: No wrinkles occurred ×: Wrinkles occurred

(3) Evaluation of Corrosion Resistance Salt Corrosion Resistance JIS Z 23 for a sample having a size of 70 × 150 mm
The salt spray test according to No. 71 was performed for 30 days, and the corrosion products were peeled off and the corrosion weight loss was measured. The indication of the corrosion weight loss is a value for one side of the plating. [Evaluation Criteria] ◎: corrosion weight loss 5 g / m ² or less ○: less than corrosion loss 10g / m ² △: Corrosion weight loss 10~25g / m ² ×: corrosion weight loss 25 g / m ² greater

Corrosion resistance after processing After performing bending work equivalent to 3t (t: plate thickness) with a roll former, a salt spray test in accordance with JIS Z 2371 was performed for 30 days, and the corrosion state near the processed portion was observed. . [Evaluation Criteria] ：: No red rust generated ○: Red rust generation rate 5% or less △: Red rust generation rate 5 to 30% ×: Red rust generation rate exceeds 30%

Outdoor Exposure Test An outdoor exposure test was performed on a sample having a size of 50 × 200 mm at 30 ° on the south side. Red rust occurrence rate from the end face after 3 months,
The surface discoloration was observed. [Evaluation Criteria] ○: Red rust occurrence rate from the end face is less than 30% Δ: Red rust occurrence rate from the end face is 30 to 80% ×: Red rust occurrence rate from the end face is more than 80%

(4) Workability Using a hydraulic molding tester, cup molding was performed using a cylindrical punch having a diameter of 50 mm at a drawing ratio of 2.25. The test was performed by applying oil, and the wrinkle pressure was 500 kg. The evaluation of workability was based on the following index. [Evaluation criteria] ○: No abnormality △: Cracking of plating ×: Peeling of plating

[0036]

[Table 2]

[0037]

[Table 3]

As shown in Tables 2 and 3, Comparative Example No. As in 12, when Mg is not contained, the corrosion resistance tends to be poor in a severe environment. In addition, in Comparative Example No. When Ca is not contained as in 12, 13, and 15, wrinkles tend to occur and the appearance tends to be impaired.
Red rust is easily generated from the end face. Further, the comparative example N
o. When the amount of Si is small as in 13, the alloy layer grows and the workability is poor. In addition, in Comparative Example No. Like 14,
When Zn is not contained, red rust is generated from the end face, Ca is added in a large amount, and workability is reduced. No. of Comparative Example. In No. 15, even if the amount of Zn is too large, the coating film swells due to the dissolution of Zn, and the corrosion resistance tends to decrease.

Also in the present invention examples, As shown in Fig. 4, even if there is too much Mg, the corrosion resistance tends to decrease.
g is preferably about 4 to 9% from the viewpoint of corrosion resistance. In addition, the present invention example No. Even with a large amount of Si as in No. 7, corrosion resistance and workability tend to decrease. Invention Example No. 16-18
Is particularly the case where Sn is contained in the plating layer composition. In addition, in Comparative Example No. In the case where the size of the intermetallic compound is 10 μm or more in the major axis as in 14, the workability and the post-process corrosion resistance are reduced. When the amounts of Mg, Si, Zn, and Ca are in appropriate ranges, extremely excellent corrosion resistance and workability are exhibited.

Example 2 The composition of the plating bath and the operating conditions were fixed, and the influence of the original plate was investigated. The plating bath composition is Al-10% Si-7% Mg-5% Zn-1.5% Fe
Assuming -0.2% Ca, the coating weight is 80 g / m on both sides
^{2. The} post-treatment was a silane coupling agent-based non-chromate treatment, and the adhered amount was 100 mg / m ^{2 in} terms of SiO ₂ . Evaluation items and methods are the same as those in the first embodiment. At this time, the composition of the plating layer was substantially 9.8% Si, M
g: 6.6%, Zn: 4.5%, Fe: 0.5%, C
a: 0.15%, alloy layer thickness: 2.0 to 2.8 μm were obtained. The maximum major axis of the intermetallic compound in the plating layer was 8 μm. Table 4 shows the steel types used, and Table 5 summarizes the evaluation results at that time. Regardless of the type of steel used,
Excellent characteristics were obtained.

[0041]

[Table 4]

[0042]

[Table 5]

[0043]

According to the present invention, there is provided a hot-dip aluminized steel sheet which is significantly more excellent in corrosion resistance of a plating layer and corrosion resistance of an end face than conventional ones. The application of aluminum-plated steel sheet has been started from conventional automobile exhaust system members, heat appliances, roof walls, etc., and recently it has also started to be applied to automobile fuel tanks. It is expected to be maintenance-free and has a great industrial contribution. Patent applicant Nippon Steel Corporation Attorney Patent attorney
Jin Shiina

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Jun Maki 1-1, Niwahata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Prefecture Nippon Steel Corporation Yawata Works (72) Inventor Teruaki Izaki Tobata-ku, Kitakyushu-shi, Fukuoka 1-1 Nippon Steel Corporation Yawata Works (72) Inventor Shunji Sakamoto 1-1 Tobata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka F-term (reference) in Nippon Steel Corporation Yawata Works 4K027 AA05 AA22 AB05 AB15 AB48 AC52 AC62 AC82 AC87 AE02 AE23 4K044 AA02 AB02 BA10 BA15 BA21 BB04 BC09 CA11 CA16

Claims (6)

[Claims] 1. The steel sheet contains, by mass%, Mg: 1 to 15%, Si: 2 to 15%, Zn: 1 to 10%, and Ca: 0.02 to 5%, with the balance being Al. And a plating layer comprising unavoidable impurities, and a Mg ₂ Si phase, Mg present in the plating layer.
A highly corrosion-resistant Al-based plated steel sheet having an excellent appearance, wherein a size of an intermetallic compound such as a Zn ₂ phase is less than 10 μm in a major axis. 2. On the surface of the steel sheet, by mass%, Mg: 1 to 15%, Si: 2 to 15%, Zn: 1 to 10%, Ca: 0.02 to 5%, Sn: 1 to 15% Having a plating layer made of Al containing unavoidable impurities and incidental components, wherein the size of the intermetallic compound present in the plating layer is less than 10 μm in major axis. High corrosion resistance Al-based plated steel sheet. 3. An Al—Fe—Si alloy layer or an Al—Fe—S layer having a thickness of 5 μm or less at an interface between a plating phase and a steel sheet.
The highly corrosion-resistant Al-based plated steel sheet according to claim 1 or 2, further comprising an i-Mg-based alloy layer. 4. The highly corrosion-resistant Al-based plated steel sheet according to claim 1, further comprising a post-treatment film on the surface of the plating layer. 5. The highly corrosion-resistant Al-based plated steel sheet having an excellent appearance according to claim 1, further comprising a delamination type or non-delamination type lubricating film on the post-treatment film. 6. The adhesion amount of the Al-based plating layer is 2 per one side.
The amount is from 0 to 200 g / m ² .
5. A highly corrosion-resistant Al-based plated steel sheet having an excellent appearance according to 5.