JPH07102361A - Surface-treated steel sheet excellent in brazability - Google Patents

Abstract

PURPOSE:To obtain a surface treated steel sheet excellent in brazability and high temp. oxidation resistance at a low cost by forming a plated film of an alloy having a specified compsn. constituted of B, Si, Cr and Ni to regulate its film thickness into a specified one. CONSTITUTION:At least on one side of a steel sheet, a plated film having 0.1 to 25mum film thickness is formed by dry plating. This plated film is constituted of, by weight, 0.2 to 30% Si and, if required, of 5 to 40% Cr, and the balance Ni with inevitable impurities. Moreover, as for the relationship between the film thickness and coating rate, the ranges surrounded by coordinates A (0.1, 100), B (0.1, 30), C (1, 10), D (12, 10), E (12, 50) and F (10, 100) shown by the figure are preferably regulated. Thus, the surface-treated steel sheet easy to interpose in brazing and suppressed in the generation of thermal strain caused by the structural change of the surface of the substrate without deteriorating joining strength can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-treated steel sheet which is required to have a brazing property, and is particularly effectively applied to a carrier substrate to which a catalyst is attached in a catalytic converter for cleaning exhaust gas of an automobile engine or the like. The present invention relates to a surface-treated steel sheet having excellent brazing property and high-temperature oxidation resistance.

[0002]

2. Description of the Related Art Generally, a metal base material for an exhaust gas purifying catalyst for automobiles is manufactured by stacking a flat heat-resistant steel sheet and a corrugated heat-resistant steel sheet on each other, winding them in a roll, and brazing them together. The obtained honeycomb molded body is covered with an outer cylinder and joined by brazing or welding.

The following methods are known as known brazing joining methods. (1) A method in which a brazing material foil is inserted between a flat plate and a corrugated plate and heat-bonded (see JP-A-3-60740).

(2) A method in which a brazing filler metal component is applied to a flat plate or a corrugated plate by a roll, and then the flat plate and the corrugated plate are wound in a roll shape, and both are bonded by heating (see Japanese Patent Laid-Open No. 3-60740). However, braze foil (or braze component to be applied)
Is expensive (see Japanese Patent Application Laid-Open No. 1-171641), and it is not necessary to interpose it all over in terms of strength. Therefore, the coating amount of the brazing filler metal component is reduced by the following method.

(3) A brazing foil is partially inserted. (JP-A-3-86329, JP-A-3-86370, JP-A-3-27881
No.). (4) The brazing material component is partially applied (Japanese Patent Laid-Open No. 3-65244).
No.). (5) Adjust the weight of the brazing material foil within a certain range with respect to the foil serving as the substrate (see Japanese Patent Laid-Open No. 3-65244).

[0006]

However, the method of inserting the brazing material foil has the following problems. (1) Brazing foil is not easily inserted and positioning is difficult. (2) Since the amount of brazing filler metal is large, the brazing filler metal diffuses into the base material as the temperature rises during brazing and changes from the ferrite structure of the base material to the austenite structure. Thermal strain occurs due to the difference in expansion.

(3) In the brazing material foil (20 to 50 μm), Ni or B is used.
The material cost is high, and the productivity when forming the foil is poor, and the cost of using the brazing filler metal foil is high. On the other hand, the method of applying the brazing material has the following problems.

(4) It is technically difficult to apply the brazing material thinly, and the application amount increases. For this reason, as in the case of using the brazing foil, the brazing material diffuses into the base material and deteriorates the performance of the base material as the temperature rises for a short time when the engine is started. (5) The material cost increases as the coating amount increases.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to facilitate interposition in brazing, not reduce the bonding strength, and make the structure of the surface layer of a base material. The object of the present invention is to provide a surface-treated steel sheet that suppresses the occurrence of thermal strain due to changes and is excellent in cost.

[0010]

According to the present invention, a brazing plating film is formed on at least one surface of a steel sheet, and the plating film has a film thickness and composition, a film thickness and coverage, and a film thickness and composition. The coverage is a specific range. That is, the film thickness is 0.1 μm or more and 25 μm or less. The composition is an alloy consisting of 0.2 wt% to 30 wt% of B and Si and the balance Ni and inevitable impurities, or 5 wt% to 40 wt% of Cr and 0 of 1 or 2 of B and Si. 0.2% to 30% by weight and the balance Ni and unavoidable impurities. The coverage is 10 to 100%, but the film thickness (μm)
And the coverage (%) are at the point A (0.1, 100) at the coordinates shown in Fig. 1.
), Point B (0.1, 30), point C (1, 10), point D (12, 1)
0), the point E (12, 50) and the point F (10, 100). The plating film is preferably a dry plating film, particularly a film formed by vacuum deposition and ion plating.

In the present invention, when heat resistance is required for the steel plate, a heat resistant steel plate is used, and it is appropriately selected according to the application to be used. For example, Fe-20 wt% Cr-5 wt% Al-REM steel plate, SUS430 stainless steel plate and the like can be used. When used as a carrier substrate for an exhaust gas purifying catalyst, a suitable steel plate has a plate thickness of 30 to 100 μm.

The thickness of these plating films is limited to the above range in consideration of adhesion and diffusion to the substrate. If the thickness of the plating film is less than 0.1 μm, the bonding force cannot be secured. If the film thickness exceeds 25 μm, the adhesion between the film and the base material deteriorates, and the film easily peels off, making it difficult to interpose during film formation and brazing, and the brazing filler metal component as the base material. Diffuses much and deteriorates the base material,
In addition, the material cost also increases. From this, in the present invention, the thickness of the plating film is set to 0.1 μm to 25 μm.
Particularly, the preferable film thickness range of the film excellent in brazing property and high temperature oxidation resistance is 1 μm or more and 12 μm or less.

The composition of the plating film is Ni- (B, Si) -based or Ni-Cr in consideration of brazing property and high temperature oxidation resistance.
-(B, Si) based alloy is used. The reason for limiting the composition range is as follows. ing.

B and Si are added to lower the melting point of the plating film. If the amount of one or two of B and Si in the plating film is less than 0.2% by weight, the effect of addition is not exhibited. If it exceeds 30% by weight, a boride is formed when B is added, and a silicide is formed when Si is added, resulting in embrittlement. A particularly suitable range for decreasing the melting point of the plating film is B
The amount of one or two of Si and Si is 3% by weight or more and 20% by weight or less.

Cr is added to improve the high temperature oxidation resistance. The reason for limiting the Cr content to 5% by weight or more and 40% by weight or less is that no improvement in high temperature oxidation resistance is observed at less than 5% by weight, and when it exceeds 40% by weight, the Ni component decreases and the melting point decreases. This is because the brazing effect cannot be recognized. A Ni range particularly suitable for improving high temperature oxidation resistance is 8% by weight to 30% by weight.

The plating film is formed by plating,
The plating method is not particularly limited, but dry plating is preferred from the standpoint of the arbitrariness in which the film elements can be freely selected. Among the dry plating methods, vacuum deposition and ion plating are preferred from the viewpoint of productivity.

The plating film of the present invention may be formed on the entire surface of the substrate (steel plate), but may be formed partially.
That is, it suffices to form it only in a portion that requires brazing. This is a coverage of 10-100%. In Figure 2,
An example is shown in which a plating film is formed on both sides and the center of a steel sheet by dividing it in the width direction. Furthermore, the film thickness (μm) and the coverage (%) are points A (0.1, 100) and B at the coordinates shown in FIG.
(0.1, 30), point C (1, 10), point D (12, 10), point E
It is within the range enclosed by (12,50) and the point F (10,100). The reason is as follows. If the film thickness is less than 0.1 μm, the bonding force cannot be secured even if the coverage is 100%. Further, when the amount of adhesion exceeds 12 μm and is excessive, even if the coverage is controlled to 10 to 50%, the brazing filler metal component is diffused in a large amount into the metal member (heat resistant steel plate) which is the base material and the base material performance is deteriorated. Let For example, Ni
When plating a base brazing filler metal component, Ni, which is an austenite forming element, diffuses into a base material such as steel or a stainless steel plate having a ferrite structure, which causes a problem of impairing the heat resistance and high temperature strength of the base material. In addition, stress corrosion cracking may occur. 10 μm even if the film thickness is 12 μm or less
If it exceeds the range, the amount of diffusion will increase in the case of full-scale plating.
Like 50%. Limited to ~ 100%. 12 μm
If the coverage is less than 10% in the film thickness range below, the bonding force cannot be secured, so the coverage was set to 10% or more. However, in the case of a thin film having a film thickness of 0.1 μm or more and 1 μm or less, the bonding force cannot be secured when the coverage is small, so that the coverage is set to 10 to 30% or more in this film thickness range as shown in FIG. Plating the brazing component in the range limited in FIG. 1 suppresses the formation of different textures and cracks in the metal member (heat resistant steel plate) that is the base material. Therefore, for example, it is possible to obtain a heat-resistant structure material which is easy to form into a honeycomb and has a good joining force. In particular, in the present invention, since the brazing layer is thin, the alloying elements can be rapidly diffused at the time of joining, and the heating temperature can be lowered and the heating time can be shortened, so that the productivity can be improved.

When the steel sheet of the present invention is brazed, as a general rule, brazing is performed at all places where the plating film (brazing film) is provided, that is, at all contact points. In this respect, known technology (Japanese Patent Laid-Open No. 2-174939,
JP-A-2-218442, JP-A-2-261550, JP-A-3-
47540), which is different from the one in which the contact ratio of contact points is limited.

The surface-treated steel sheet having excellent brazing properties of the present invention includes those having a coating formed on one side of the steel sheet and those having both sides formed. When forming on both sides, the type of coating is different. Same type (for example, Ni-B alloy film or N on both sides)
Even i-Cr-B alloy film) is different (for example, N
i-B alloy film and Ni-Cr-B alloy film).
Further, even in the case of the same kind, the composition and the film thickness can be appropriately changed.

The working temperature of the surface-treated steel sheet according to the present invention is 6
When the temperature is 00 ° C. or less, brazing property and necessary high temperature oxidation resistance can be obtained by performing Ni—B single layer plating on the heat resistant steel plate. Here, the heat-resistant steel plate may be a steel plate having heat resistance in a high temperature environment of 300 ° C. or higher. However, when used as a carrier for automobiles, the operating temperature is 600
May be exposed to high temperature environment above ℃. In this case, Ni-Cr-B single layer plating is applied to obtain N
An i-Cr alloy can be obtained, and the high temperature oxidation resistance can be further improved. In this case, the heat resistant steel plate is preferably a heat resistant stainless steel foil having a ferrite structure for the purpose of suppressing thermal expansion at high temperatures.

When a honeycomb core is formed from this steel plate, it is preferable that the thickness is 30 μm or more and 200 μm or less in view of ensuring strength of the honeycomb core, moldability and weight reduction. The shape thereof is flat or corrugated to form a honeycomb core, and the honeycomb core is formed by combining and winding the flat steel plate and the corrugated steel plate.

[0022]

Since the surface-treated steel sheet according to the present invention forms a plating film (brazing property and high temperature oxidation resistant alloy film) by plating, the thickness of this film is set to a desired thickness, particularly to the conventional one. Can be thinner than. The chemical composition can also be adjusted by applying a known plating technique, for example, multi-source vapor deposition or alloy plating, to a plating film of any composition (for example, Ni- (B, Si) -based alloy, on a desired portion of the base material, Ni—Cr— (B, Si) alloy) can be formed.

The surface-treated steel sheet of the present invention is a steel sheet precoated with a brazing filler metal component. Therefore, when this steel sheet is used, the working process can be simplified as compared with the case of manufacturing the honeycomb core by the method of molding using the brazing material foil, and a positioning error that occurs when the brazing material foil is provided may occur. Absent.

Further, according to the present invention, when the base steel sheet is partially plated, the thermal stress can be relaxed in a high temperature atmosphere when the metal carrier base material is used, as compared with the whole surface plating.
The surface-treated steel sheet of the present invention thus obtained is 400
It is useful as a metal carrier base material (honeycomb core) that needs to be joined by brazing, which is used in a high temperature environment of ℃ or higher, especially for exhaust gas purifying devices for automobiles and motorcycles.

[0025]

EXAMPLES A production example of the surface-treated steel sheet of the present invention and its constitution will be described below. FIG. 2 shows a surface-treated steel plate for manufacturing the honeycomb molded heat-resistant structure according to the present invention. The steel plate is formed in a corrugated plate shape and a flat plate shape. On one side (hatched portion) of the corrugated plate steel sheet 2 and the flat plate steel sheet 3, there are three rows of Ni-Cr series on both sides and the center along the longitudinal direction, respectively. The alloy film 6 is formed by plating. This alloy film 6 is a brazing component and can withstand a high temperature of 600 ° C. Winding these corrugated steel plate 2 and flat plate steel plate 3,
By brazing, this forms a honeycomb body in which a plurality of cells 4 are formed between the corrugated steel plate 2 and the flat steel plate 3.

FIG. 3 is a perspective view showing an example of a honeycomb heat-resistant structure 1 manufactured by using the surface-treated steel sheet according to the present invention. The corrugated steel sheet 2 and the flat sheet shape wound as shown in FIG. A honeycomb body composed of the steel plate 3 is covered with an outer cylinder 5 and brazed.

4 to 6 show steps of manufacturing a honeycomb-molded heat-resistant structure using the surface-treated steel sheet according to the present invention. In the present invention, a step of preparing a base foil (steel plate), a step of plating a brazing component on at least one surface of the base foil, a step of forming into a corrugated steel plate, a corrugated steel plate and a flat steel plate Is classified into a joining process of brazing.

Description will be given based on the single-sided plating method of method A in FIG. First, at least one surface of the steel plate is Ni-
Cr-based alloy plating is performed to form an alloy film. In the next forming step, a part of the steel sheet (foil) on which the alloy film is formed is prepared as the flat steel sheet 3 as it is. Further, a part of the flat plate-shaped steel plate is corrugated by a corrugating device to prepare a corrugated plate-shaped steel plate 2 in which a predetermined linear corrugation is continuously bent and formed. These corrugated plate-shaped steel plates and flat plate-shaped steel plates are alternately wound from a fixed center and piled up in multiple layers. In the joining step, the corrugated steel sheet 2 and the flat steel sheet 3 are joined by heating after the forming step. That is, the Ni-based component laminated in the brazing component plating step is melted by heating and joins both the corrugated steel plate and the flat steel plate. Then, the heat-resistant structure 1 is manufactured through these manufacturing steps, that is, the preparation step, the brazing component plating step, the molding step, and the joining step.

Except for the manufacturing process described above, as shown in Method B in FIG. 5, N is formed on both sides of the steel plate (foil) in the plating process.
After the i-Cr alloy plating, the flat steel plate 3 is prepared as it is, and the unplated steel plate is corrugated by a corrugating device to continuously bend and form a predetermined linear corrugation. The corrugated plate-shaped steel plate 2 and the corrugated steel plate 2 are melted by heating and joined together.

Further, as in the method C of FIG. 6, both sides of the steel sheet (foil) were plated with Ni—Cr alloy in the plating step and then corrugated by a corrugating device to continuously form irregularities by bending. The corrugated plate-shaped steel plate 2 may be joined to the unplated flat plate-shaped steel plate 3 by heating.

Next, examples of the present invention will be described. Example 1: Limitation of thin film thickness and coverage As a heat-resistant steel plate, 30 to 200 μm shown in Table 1 and Table 2
The ferritic stainless steel of was mainly used. Vacuum vapor deposition and ion plating were used as a method for plating the heat-resistant steel sheet with a Ni-Cr alloy film. As the composition of the alloy film, Ni-Cr based plating species shown in Tables 1 and 2 were used. The partial plating method is a method in which a mask is placed above the vapor deposition crucible to partially inhibit the deposition of the vapor deposition material,
Further, a method of placing vapor deposition crucibles at intervals in the coil width direction and partially vaporizing was used.

The bondability between the heat-resistant steel plate and the alloy film was examined by the method described below. First, the plated heat-resistant steel plate was cut into a size of 50 mm × 100 mm, and a stripping material of boron nitride was applied while leaving a size from one short side to an end of 5 mm. Then, in a vacuum atmosphere of 10 ⁻⁴ Torr, 11
Brazing was performed between the plated surface and the non-plated heat resistant steel plate under the condition of holding at 00 to 1200 ° C. for 10 to 30 minutes.
After that, the peel test shown in FIG. 7 was performed, and the value obtained by dividing the maximum load by the brazing area was taken as the joint strength, and the joint strength was 2 kgf /
The test piece having a size of ² mm ² or more and a break in the base material foil portion was accepted. In addition, the joined test piece is immersed in a boiling liquid specified by the JIS G 0567 stainless steel 42% magnesium chloride corrosion test method, and the cross-section is observed for the presence of corrosion cracks caused by residual stress after joining. Therefore, the corrosion cracking property was evaluated. The obtained results are shown together in Table 1 together with the film forming method.

Next, a metal carrier (honeycomb core) is manufactured by the method shown in FIG. 4 (single-sided plating) and the method shown in FIGS. 5 and 6 (double-sided plating), and the joint between the flat plate-shaped steel plate and the corrugated plate-shaped steel plate is formed. The test piece was cut out so as to include it, and the bondability was evaluated. The obtained results are shown in Tables 1 and 2.

Experiments were also carried out on Comparative Examples 1 to 3 in which the film thickness and film rate of the brazing component were out of the range of the present invention and Comparative Examples 4 and 5 using the brazing material foil, and the results are shown in the table. It is also shown in the latter part of 2.

From Tables 1 and 2 below, in the case of the comparative example in which the film thickness and the coating rate are out of the range of the present invention and the comparative example using the brazing material foil, the brazing material foil and the base material foil at the time of brazing Voids are generated due to the gaps between them, resulting in poor joint strength and poor productivity. On the other hand, in the present invention, it is clear that good joint strength and corrosion cracking resistance are obtained, and productivity and economy are excellent. Example 2: Limitation of coating film thickness and coating composition Tables 3 to 5 show examples of Ni-Cr and Ni-Cr-B single-layer plating for the surface-treated steel sheet according to the present invention. As the base material, a ferritic stainless steel plate having a thickness of 30 to 200 μm was mainly used. The vacuum deposition method and the ion plating method were used as a method of plating a plating film on this base material. The thickness and composition of the plating film are shown in Table 3 to Table 5.
As shown in.

The bondability between the plated surfaces and the bondability between the plated surface and the non-plated substrate of the prepared sample are
It evaluated by the method described below. (1) Cut out plated stainless foil or unplated stainless foil to a size of 15 mm × 15 mm.

(2) Figure 8 (a) on one heat-resistant stainless steel foil
A protrusion having a diameter of 2.0 mm and a depth of 0.1 mm is processed at the position of the apex of an equilateral triangle with a side of 9.5 mm as shown in FIG. (3) As shown in FIG. 8 (b), a stainless foil having a protrusion and a stainless foil not having a protrusion are stacked and a predetermined weight is placed on the stainless foil.

(4) Put into a vacuum furnace as it is, 10 ^-4 Tor
5 to 1 at 1100 to 1250 ° C. in a vacuum atmosphere of r
Brazing is performed under the condition of holding for 20 minutes. The surfaces to be brought into contact are the plated surfaces or the plated surfaces and the stainless foil not plated.

(5) After brazing, a hole with a diameter of about 1 mm is made in each stainless steel foil, and a wire is passed through. (6) Perform a tensile test as shown in FIG. 9 to measure the bonding strength.

The obtained results are summarized in Tables 3 to 5 together with the film forming method (Nos. 1 to 49). Also,
Experiments were also carried out on comparative examples in which the film thickness and composition of the brazing component deviate from the scope of the present invention and comparative examples using a brazing foil, and the results are shown in the latter part of Table 5 (No. 5).
0-56).

From Table 5 below, in the case of the comparative example in which the film thickness and the alloy composition are out of the range of the present invention and the comparative example using the brazing filler metal foil, the joint strength is deteriorated or the brazing filler metal content is large. The diffusion deteriorates the durability of the base material, or the adhesion between the base material and the plating film deteriorates, resulting in a decrease in productivity. On the other hand, in the present invention, it can be seen that good bonding strength, durability and adhesion are obtained, and productivity and economy are excellent.

Example 3 A steel sheet was coated with Ni-Si, Ni-Cr-Si, and Ni-Cr-.
A plating film having a composition of Si-B was formed to prepare a surface-treated steel sheet according to the present invention, and the joint strength was examined in the same manner as in the above-mentioned examples. The results are shown in Table 6 together with the thickness and composition of the plating film. In addition, for comparison, Table 7 shows the joint strength of the surface-treated steel sheet which is out of the present invention. It can be seen from Tables 6 and 7 that the bonding strength of the present invention is excellent.

[0043]

According to the present invention, the following effects are exhibited by brazing using a surface-treated steel sheet with a plating film having a limited film thickness and alloy composition or film thickness and coverage.

First, it is not necessary to perform positioning as compared with the conventional structure in which the brazing foil is arranged in the middle of the steel plate (in the case of the honeycomb body, between the flat plate-shaped steel plate and the corrugated plate-shaped steel plate). Therefore, the manufacturing process can be simplified and the manufacturing process can be simplified.

Secondly, the brazing thin film can be made thinner than the conventional method using a brazing material foil, and the change in the structure of the surface layer of the base material can be neglected. Therefore, high temperature oxidation resistance and durability are improved. Third, since the thin film of the expensive brazing component is thin, the weight is reduced and the cost is reduced.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

[Table 4]

[0050]

[Table 5]

[0051]

[Table 6]

[0052]

[Table 7]

[Brief description of drawings]

FIG. 1 is a film thickness (μ of a film of a surface-treated steel sheet according to the present invention.
The figure which shows the range of m) and a coverage (%).

FIG. 2 is a perspective view showing a coating state of an alloy coating on a surface-treated steel sheet according to the present invention.

FIG. 3 is a perspective view showing an example of a heat-resistant structure using a surface-treated steel sheet according to the present invention and a manufacturing method thereof.

FIG. 4 is a diagram showing a manufacturing process of a heat resistant structure (single-sided plating method A).

FIG. 5 is a diagram showing a manufacturing process of a heat resistant structure (double-sided plating method B).

FIG. 6 is a diagram showing a manufacturing process of a heat resistant structure (double-sided plating method C).

FIG. 7 is an explanatory diagram of a peel test.

FIG. 8 is a view showing a method of a joining test, (a) shows a shape of a test piece, and (b) shows a setting method of the test piece.

FIG. 9 is an explanatory diagram of a tensile test method.

[Explanation of symbols]

1 ... Heat resistant structure, 2 ... Corrugated steel plate, 3 ... Flat steel plate, 4
... Honeycomb body, 5 ... Outer cylinder.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Kibe 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd. (72) Yoshimasa Funakawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Steel Tube Co., Ltd. (72) Inventor Yoshihiko Yasue Marunouchi 1-2-2, Chiyoda-ku, Tokyo Japan Steel Tube Co., Ltd. (72) Inventor Yoshinori Aomura 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Japan (72) Inventor Tetsuro Toyoda 600 Tanaka-cho, Akishima-shi, Tokyo Showa Aircraft Industry Co., Ltd.

Claims (4)

[Claims] 1. A film thickness of 0.1 on at least one surface of a steel sheet.
A plating film having a thickness of μm to 25 μm is provided, and the plating film contains Cr5, an alloy consisting of 0.2% to 30% by weight of one or two kinds of B and Si, and the balance Ni and inevitable impurities.
% To 40% by weight and one or two of B and Si in an amount of 0.
A surface-treated steel sheet excellent in brazing property and high-temperature oxidation resistance, having an alloy composition selected from the group of alloys consisting of 2 wt% to 30 wt% and the balance Ni and inevitable impurities. 2. A film thickness of 0.1 on at least one surface of the steel sheet.
A coating film having a thickness of μm to 25 μm and a coverage of 10 to 100% is provided, and the film thickness (μm) and the coverage (%) are the points A (0.1, 100) and B (0.1, 30) at the coordinates shown in FIG. ), Point C
(1,10), point D (12,10), point E (12,50) and point F
A surface-treated steel sheet with excellent brazing properties and high-temperature oxidation resistance, which is within the range surrounded by (10,100). 3. A film thickness of 0.1 on at least one surface of the steel sheet.
It has a plated film with a thickness of μm to 25 μm and a coverage of 10 to 100%, and the film thickness (μm) and the coverage (%) are points A (0.1, 100) and B (0.1, 30) at the coordinates shown in FIG. , Point C (1,
10), point D (12,10), point E (12,50) and point F (10,
100), and the composition of this plating film is Cr5, an alloy consisting of 0.2 wt% to 30 wt% of one or two of B and Si, and the balance Ni and unavoidable impurities.
% To 40% by weight and one or two of B and Si in an amount of 0.
A surface-treated steel sheet excellent in brazing property and high-temperature oxidation resistance, having an alloy composition selected from the group of alloys consisting of 2 wt% to 30 wt% and the balance Ni and inevitable impurities. 4. The surface-treated steel sheet excellent in brazing property and high temperature oxidation resistance according to claim 1, wherein the plating film is a dry plating film.