JP7241586B2 - Surface-treated base material for brazing and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a surface-treated base material for brazing and a method for producing the same.

Conventionally, as a heat exchanger that requires corrosion resistance, stainless steel plates with an uneven structure formed by press molding or the like are laminated by brazing. is known.

As a brazing stainless steel plate for manufacturing such a plate heat exchanger, for example, Patent Document 1 discloses that a chromium-based brazing material layer and a nickel-based brazing material layer are formed in this order on stainless steel. A brazing surface treated substrate is disclosed.

JP-A-2002-28775

However, in the stainless steel plate for brazing described in Patent Document 1, when a brazing material layer is formed before forming, it is difficult to form it into a desired shape by press working or the like in order to manufacture a plate-type heat exchanger or the like. As a result, it was found that the nickel-based brazing material layer peeled off due to the stress during molding. If the brazing filler metal layer peels off, the stainless steel plate that is the base material will be exposed to the surface and the corrosion resistance will decrease. A problem arises. Furthermore, when the delamination spreads from a partial delamination, or when the entire delamination occurs due to severe processing, there arises a problem that brazing cannot be performed in the first place.

The present invention has been made in view of such circumstances, and provides a surface-treated substrate for brazing that is excellent in corrosion resistance and brazing jointability and that can prevent peeling of the brazing material layer after molding. It is to provide a manufacturing method.

The present inventors have found that the above object can be achieved by forming a Cr layer and a specific Ni—P layer in this order on a substrate, and have completed the present invention.

That is, according to the present invention, it comprises a base material, a Cr layer formed on the base material, and a Ni—P layer formed on the Cr layer, and the Ni—P layer contains CuKα. Among the peaks having peak tops in the range of 43 to 45° with a diffraction angle 2θ detected by X-ray diffraction measurement using a radiation source, for the peak P _A having the highest peak top intensity, the half width of the peak P _A is 2° or less.

In the surface-treated base material for brazing of the present invention, the Ni— _P layer has a diffraction _angle of The ratio (I _B /I _A ) of the peak top intensity I _B in the peak P _B having the highest peak top intensity among the peaks having the peak top in the range of 50 to 54 ° 2θ is less than 0.2 is preferred.
In the surface-treated base material for brazing of the present invention, the Ni— _P layer has a diffraction _angle of The ratio (I _C /I _A ) of the peak top intensity I _C of the peak PC having the highest peak top intensity among the peaks having the peak top _in the range of 96 to 100° 2θ is 0.2 or more. is preferred.
In the surface treated substrate for brazing of the present invention, it is preferable that the content of P in the Ni—P layer is 5 to 20 wt %.
In the surface treated substrate for brazing of the present invention, the substrate is preferably stainless steel.

Furthermore, according to the present invention, there is provided a molded article formed using any one of the surface-treated substrates for brazing described above.
It is preferable that the molded body has an uneven structure.
Further, according to the present invention, there is provided a press-formed article formed using any one of the surface-treated substrates for brazing described above.
It is preferable that the press-molded body has an uneven structure.

Further, according to the present invention, a step of forming a Cr plating layer on at least one surface of a base material, a step of forming a Ni—P plating layer on the Cr plating layer, the Cr plating layer and the A method for producing a surface-treated base material for brazing is provided, comprising the step of heat-treating a base material on which a Ni—P plating layer is formed at a temperature of 400 to 800°C.

Furthermore, according to the present invention, there is provided a method for producing a molded article, which comprises the step of forming the surface-treated base material for brazing obtained by the above-described production method by press working so that at least a part thereof has an uneven structure. be.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a surface-treated substrate for brazing that is excellent in corrosion resistance and brazing bondability, and that can prevent peeling of the brazing material layer after molding, and a method for producing the same.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing one embodiment of a plate heat exchanger provided with heat transfer plates formed using the surface-treated base material for brazing according to the present invention; FIG. 2 is a cross-sectional view of a heat transfer plate provided in the plate heat exchanger shown in FIG. 1; FIG. 4 is a cross-sectional view showing another example of the plate heat exchanger according to the present embodiment; 1 is a cross-sectional view of a surface-treated substrate for brazing according to one embodiment of the present invention; FIG. 4 is a photograph showing the results of evaluation of processing adhesion of brazing material layers of surface-treated substrates of Examples 1 to 3, 5, and 6. FIG. 4 is a photograph showing the results of evaluation of processing adhesion of a brazing material layer on the surface-treated substrates of Comparative Examples 1 to 3. FIG. 4 is a graph showing the results of X-ray diffraction measurement of the surface-treated substrate of Example 1. FIG. 10 is a graph showing the results of X-ray diffraction measurement of the surface-treated substrate of Example 5. FIG. 4 is a graph showing the results of X-ray diffraction measurement of the surface-treated substrate of Comparative Example 1. FIG.

An embodiment of the present invention will be described below with reference to the drawings. The surface-treated substrate for brazing according to the present invention can be brazed by heat treatment, and can be formed by laminating parts by brazing or by joining with other members by brazing. It can be used for parts that can be formed, and in particular for parts that require corrosion resistance. For example, the surface treated substrate for brazing according to the present invention can be used to form the heat transfer plate 23 that constitutes the plate heat exchanger 2, as shown in FIGS. In the following, the present invention will be described with reference to an embodiment in which the surface-treated substrate for brazing according to the present invention is used as the heat transfer plate 23 of the plate heat exchanger 2 .

FIG. 1 is a perspective view showing an embodiment of a plate heat exchanger 2 having heat transfer plates 23 formed using the surface-treated base material for brazing according to the present invention.

The plate-type heat exchanger 2 shown in FIG. 1 includes heat transfer plates 23 shown in FIG. 2, and after passing through a fluid flow path 24 formed between a plurality of heat transfer plates 23, flows out of the plate heat exchanger 2 from the fluid outlet 22 along the direction of the arrow shown in FIG. It is structured so that

The heat transfer plate 23 constituting the plate heat exchanger 2 can be obtained by molding the brazing surface-treated substrate according to the present invention into a desired shape by a molding method such as pressing. It can have a corrugated shape like the heat transfer plate 23 shown in FIG. In the present embodiment, a plurality of such heat transfer plates 23 are prepared, and heat treatment is performed in a state in which they are superimposed via an intervening member 25 as shown in FIG. 25, the outermost layer of the heat transfer plate 23 is melted and brazed, thereby joining the heat transfer plate 23 and the intervening member 25, and A fluid flow path 24 can be formed in the gap with 25 . Further, in the present embodiment, as shown in FIG. 3, a heat transfer plate 23 molded into a desired shape is brazed to an outer layer member 26 that constitutes the outer layer of the plate heat exchanger. Fluid passages 24a may be formed between the heat transfer plate 23 and the outer layer member 26 to manufacture a plate heat exchanger. Hereinafter, with reference to FIG. 4, the configuration of the surface-treated substrate for brazing (hereinafter also referred to as surface-treated substrate 1) according to the present invention will be described.

FIG. 4 is a cross-sectional view of the surface-treated substrate 1 used for manufacturing the heat transfer plate 23 shown in FIGS. 2 and 3. FIG. As shown in FIG. 4, the surface-treated substrate 1 of the present embodiment comprises a substrate 11, a Cr layer 12 and a Ni—P layer 13 formed in this order.

In the surface-treated substrate 1 of the present embodiment, the Ni—P layer 13 has a peak top in the range of 43 to 45° for the diffraction angle 2θ detected by X-ray diffraction measurement using CuKα as a radiation source. _Among them, the peak _PA having the highest peak top intensity has a half width of 2° or less. As a result, in the surface-treated base material 1 of the present embodiment, the adhesion between the Cr layer 12 and the Ni—P layer 13 is improved, and the brazing material layer (Ni—P layer 13) is effectively peeled off after molding. When used in a plate heat exchanger or the like, it is possible to prevent deterioration in corrosion resistance due to exposure of the base material 11 of the surface-treated base material 1 due to peeling of the brazing material layer. In addition, it is possible to prevent deterioration of the brazing bondability due to peeling of the brazing material layer.

<Base material 11>
The substrate 11 of the present embodiment is not particularly limited, but carbon steel called ordinary steel and alloy steel typified by stainless steel are preferable from the viewpoint of being excellent in formability, especially when more corrosion resistance is required. It is preferable to use a stainless steel plate from the viewpoint that the corrosion resistance of the substrate is more excellent. Examples of stainless steel sheets include martensitic, ferritic, and austenitic stainless steel sheets. Among them, austenitic stainless steel sheets are preferable, and SUS304 and SUS316 are particularly preferable. However, since the plating layer itself is also excellent in corrosion resistance, the obtained surface-treated substrate 1 can have sufficient corrosion resistance even if carbon steel is used as the substrate.

When a stainless steel plate is used as the base material 11, a hot-rolled stainless steel plate is pickled to remove surface scale (oxide film), then cold-rolled, then electrolytically washed, then annealed and tempered. A rolled product, or a product obtained by performing temper rolling without annealing after cold rolling, electrolytic cleaning, or the like can be used.

Although the thickness of the base material 11 is not particularly limited, it is preferably 0.1 to 1.0 mm, more It is preferably 0.1 to 0.5 mm, more preferably 0.1 to 0.3 mm.

In the present embodiment, it is preferable to use a plate-like substrate as the substrate 11 . By using a plate-like base material 11, the Cr layer 12 and the Ni—P layer 13 can be formed more uniformly on the base material 11. FIG. Moreover, according to the surface-treated substrate 1 of the present embodiment, by forming the specific Ni—P layer 13 as described above, the brazing material layer (Ni—P layer 13) can be effectively peeled off after molding. The plate-shaped surface-treated substrate 1 formed by forming the Cr layer 12 and the Ni—P layer 13 on the substrate 11 is preferably formed into a desired shape by press working or the like. It is something that can be done.

Conventionally, a concave-convex structure such as a fluid flow path is formed in advance on a base material by press working or the like, and a Cr plating layer and a Ni—P plating layer are applied to the base material on which the concave-convex structure is formed. There is known a method of manufacturing a stainless steel plate for brazing by sequentially forming a stainless steel sheet for brazing. Since the concave-convex structure is formed, when forming the Cr plating layer and the Ni—P plating layer by plating, continuous productivity is improved compared to plating a flat substrate. Moreover, there is a problem that a uniform plating layer cannot be formed depending on the shape of the molded base material.

In contrast, according to the present embodiment, even when a flat substrate 11 is used, the uniform Cr layer 12 and the Ni—P layer 13 are formed on the substrate 11 to provide a flat surface treatment. After obtaining the base material 1, when the surface-treated base material 1 is formed into the shape of the heat transfer plate 23 as shown in FIGS. Since the peeling of the P layer 13) can be prevented, the productivity is excellent. It is possible to prevent the brazing material layer (Ni—P layer 13) from peeling off after processing.

<Cr layer 12>
The Cr layer 12 is a layer formed as a lower layer of the Ni—P layer 13, which will be described later. In this embodiment, the presence of the Cr layer 12 as the lower layer of the Ni—P layer 13 makes it possible to improve the corrosion resistance of the surface-treated substrate 1 .

In this embodiment, the Cr layer 12 can be formed by electroplating the base material 11 with Cr. At this time, as the plating bath, a known TFS (tin-free steel) plating bath, a sargent bath for Cr plating, or the like can be used. The concentration is preferably 1-3 g/L. Electroplating conditions are not particularly limited, but for example, the bath temperature is preferably 45 to 60° C., more preferably 50 to 60° C., and the current density is preferably 20 to 60 A/dm ² , more preferably. is 50-60 A/dm ² .

Although the thickness _t1 of the Cr layer 12 is not particularly limited, it is preferably 0.5-5 μm, more preferably 1-3 μm. By setting the thickness _t1 of the Cr layer 12 within the above range, the corrosion resistance of the resulting surface-treated substrate 1 can be further improved. In this embodiment, the Cr layer 12 may be a Cr layer containing Ni or P diffused from the Ni—P plating by heat treatment after Cr plating in a part of the layer or the entire layer. However, it is preferable that the outermost surface of the Ni—P layer 13 as the surface treatment substrate does not contain Cr. Such a configuration can be confirmed using a known technique such as elemental analysis in the thickness direction by GDS.

<Ni—P layer 13>
The Ni—P layer 13 acts as a brazing material so that the surface-treated substrate 1 can be brazed and joined to other members (other surface-treated substrates 1 and members made of other materials). It is something to do. The content of P in the Ni—P layer 13 is not particularly limited, but from the viewpoint of lowering the brazing temperature, the content of P is preferably 5 wt% or more, more preferably 7 wt% or more. Preferably, it is 9 wt% or more. Although the upper limit of the P content is not particularly limited, it is preferably 20 wt% or less, more preferably 15 wt% or less, and still more preferably 13 wt% from the viewpoint of difficulty in forming the Ni—P layer 13 by plating and plating efficiency. % or less. The plating efficiency is a value (actual deposition amount/theoretical deposition amount×100) expressed as a percentage of the theoretical deposition amount of the metal plated when the cathode electrolysis efficiency is 100%. The Ni—P layer is a layer made of Ni (nickel) and P (phosphorus), but elements other than Ni and P may be contained to the extent of impurities. The total proportion of elements other than Ni and P is preferably less than 1 wt%, more preferably less than 0.5 wt%.

In the surface-treated substrate 1 of the present embodiment, the Ni—P layer 13 has a peak top in the range of 43 to 45° for the diffraction angle 2θ detected by X-ray diffraction measurement using CuKα as a radiation source. Among them, the peak _PA having the highest peak top intensity has a half width of 2° or less, preferably 1° or less, and more preferably 0.5 _° or less. If the half-value width of the peak _PA exceeds 2°, the resulting surface-treated substrate has reduced adhesion between the Cr layer and the Ni—P layer, and the surface-treated substrate is molded. In some cases, the brazing material layer (Ni—P layer) may peel off.

The above-mentioned peak P _A in the range of the diffraction angle 2θ of 43 to 45° is a peak derived from Ni—P and corresponds to the diffraction peak of the (111) plane of Ni (the peak appearing at the position of 2θ = 44°). It is considered that The present inventors have found that by controlling the half-value width of this peak P _A to 2° or less (that is, the peak P _A is controlled to a sharp peak with a half-value width of 2° or less, the Ni—P layer By making the crystallinity of the Ni—P constituting the Ni—P layer 13 relatively high, the internal stress in the Ni—P layer 13 can be relaxed, and the strain on the surface of the Ni—P layer 13 can be reduced. Based on this knowledge, by reducing the strain on the surface of the Ni—P layer 13, the adhesion between the Cr layer 12 and the Ni—P layer 13 is improved, and the resulting surface treatment It has been found that peeling of the Ni—P layer 13 can be effectively prevented when the substrate 1 is molded. In particular, by controlling the half-value width of the peak P _A to 2° or less, the surface-treated substrate 1 is subjected to molding by a method such as pressing, and the plating layers (Cr layer 12 and Ni—P layer 13) are formed. It is possible to effectively prevent peeling of the brazing material layer (Ni—P layer 13) even when a molded body having an uneven structure having protrusions and/or recesses with a height of at least the thickness of . becomes. Therefore, according to the surface-treated substrate 1 of the present embodiment, when the surface-treated substrate 1 is applied to a plate-type heat exchanger or the like, the substrate 11 of the surface-treated substrate 1 is exposed by peeling off the brazing material layer. It is possible to prevent deterioration of corrosion resistance due to delamination, and also prevent deterioration of brazing jointability due to peeling of the brazing material layer.

In the present embodiment, as a method for forming the Ni—P layer 13 described above, the Cr layer 12 formed on the base material 11 is electroplated with Ni—P plating. A method of forming a layer (Ni plating layer containing P) and heat-treating the formed Ni—P plating layer can be used. In this case, the plating bath for forming the Ni—P plating layer is not particularly limited. mentioned. The plating conditions for forming the Ni—P plating layer are not particularly limited, but the bath temperature is preferably 40 to 70° C., more preferably 50 to 60° C., and the pH of the plating bath is preferably 1. 5 to 2.5, more preferably 1.8 to 2.2, and a current density of 1 to 20 A/dm ² , more preferably 5 to 15 A/dm ² . In the present embodiment, by performing heat treatment after forming the Cr electrolytic plated layer and the Ni—P electrolytic plated layer, industrial productivity is achieved, and a constant width (width 10 to 150 cm) and It is possible to obtain a continuous metal strip of the surface-treated substrate having a length of 10 to 40,000 m or more, and the surface-treated substrate obtained from such a continuous metal strip is suitable for brazing and molding.

The heat treatment conditions for heat treatment of the Ni—P plating layer are not particularly limited, but from the viewpoint of controlling the half width of the peak _PA in the Ni—P layer 13 within the above range, the heat treatment temperature is preferable. is 400 to 800°C, more preferably 600 to 800°C, still more preferably 700 to 800°C. Further, the heat treatment time (total heat treatment time required for temperature rise and soaking) when performing the heat treatment is preferably 30 to 240 seconds, more preferably 60 to 180 seconds, and still more preferably 100 to 140 seconds. Among such heat treatment times, the soaking time after the temperature reaches the target value is desirably 30 seconds or more.

Furthermore, in the present embodiment, the Ni— _P layer 13 has a diffraction angle _2θ of 50 to Among the peaks having peak tops in the range of 54 °, the peak top intensity I _B ratio ( _IB / I _A ) of the peak P _B having the highest peak top intensity is preferably less than 0.2, more preferably It is 0.1 or less, more preferably 0.05 or less. By setting the peak intensity ratio (I _B /I _A ) within the above range, the adhesion of the Ni—P layer 13 is further improved when the surface-treated substrate 1 is molded. The peak P _B in the range of the diffraction angle 2θ of 50 to 54° described above is a peak derived from Ni—P, and a peak derived from the (200) plane of the Ni-based alloy (2θ = 51.85 ° peak appearing at the position).

The method for making the peak intensity ratio (I _B /I _A ) within the above range is not particularly limited, but a method of setting the heat treatment temperature condition to 600 ° C. or higher when heat treating the Ni—P plating layer. is mentioned.

Furthermore, in the present embodiment, the Ni— _P layer 13 has a diffraction angle _2θ of 96 to The ratio of the peak top intensity I _C of the peak P _C having the highest peak top intensity among the peaks having the peak top in the range of 100 ° (I _C /I _A ) is preferably 0.2 or more, more preferably It is 0.26 or more, more preferably 0.28 or more. By setting the peak intensity ratio (I _C /I _A ) within the above range, the adhesion of the Ni—P layer 13 is further improved when the surface-treated substrate 1 is molded. In particular, in the present embodiment, by controlling the above-described peak intensity ratio (I _B /I _A ) within the above range and also controlling the peak intensity ratio (I _C /I _A ) within the above range, Adhesion of the Ni—P layer 13 can be further improved when the surface-treated substrate 1 is molded. The peak P _C in the range of the diffraction angle 2θ of 96 to 100° described above is a peak derived from Ni—P, and a peak derived from the (222) plane of the Ni-based alloy (at the position of 2θ = 98° appearing peak).

The method for controlling the above-mentioned peak intensity ratio (I _B /I _A ) within the above range and setting the peak intensity ratio (I _C /I _A ) within the above range is not particularly limited, but Ni—P A method of setting the heat treatment temperature to 700° C. or higher in the case where the plating layer is heat treated may be used.

The thickness t ₂ of the Ni—P layer 13 is not particularly limited, but preferably 3 to 20 μm. In particular, the lower limit of the thickness t ₂ of the Ni—P layer 13 is preferably 5 μm or more, more preferably 6 μm or more, and even more preferably 8 μm, from the viewpoint of further improving the brazing bondability of the resulting surface-treated substrate 1. That's it. The upper limit of the thickness t ₂ of the Ni—P layer 13 further improves the uniformity in the width direction of the formed Ni—P layer 13, and makes brazing more effective when brazing the resulting surface-treated substrate 1. From the viewpoint of preventing this from occurring and further improving the productivity of the surface-treated substrate 1, the thickness is preferably 15 μm or less, more preferably 14 μm or less. By setting the thickness t ₂ of the Ni—P layer 13 within the above range, the brazing bondability of the resulting surface-treated substrate 1 can be further improved. Further, when processing the surface-treated substrate 1 obtained after forming the Ni—P layer 13, depending on the degree of processing with respect to the surface-treated substrate 1, if the thickness t ₂ of the Ni—P layer 13 is too thick, Ni—P There is a risk of cracking or peeling of the layer 13, especially unevenness having protrusions and/or recesses with a height greater than the thickness of the plating layer (Cr layer 12 and Ni—P layer 13) due to press molding etc. In the case of a molded body having a structure formed thereon, the molded body having an uneven structure having a bent portion at an angle of 90 degrees (for example, an angle of 87 to 90 degrees) with respect to the plane portion of the surface treatment substrate 1. or when forming a molded body with an uneven structure having a bent portion with an angle of 80 degrees or more with respect to the flat portion of the surface-treated substrate 1, or when a molded body is formed with an uneven structure having a curved surface with a bending radius R of 10 mm or less When the degree of processing is severe, such as in the case of forming a compact having a continuous concave-convex structure in which the bent portions and curved surfaces are continuous, the thickness t ₂ of the Ni—P layer 13 is preferably 15 μm or less.

In the present embodiment, the ratio of the thickness t ₁ of the Cr layer 12 to the thickness t ₂ of the Ni—P layer 13 (thickness t ₁ of the Cr layer 12/thickness t 2 of the Ni—P layer ₁₃ ) is preferably is 0.05 to 0.5, more preferably 0.1 to 0.4, still more preferably 0.2 to 0.3. By setting the ratio of the thicknesses of the Cr layer 12 and the Ni—P layer 13 to the above range, the surface treated substrate 1 obtained has corrosion resistance, brazing bondability, and adhesion of the Ni—P layer 13 after molding. can be more highly balanced.

The surface-treated substrate 1 of this embodiment is constructed as described above.

<Method for producing surface-treated substrate 1>
Next, a method for manufacturing the surface-treated substrate 1 of this embodiment will be described.

First, the base material 11 is prepared. Although the shape of the substrate 11 is not particularly limited, it is preferable to use a flat substrate. Then, the substrate 11 is plated with Cr by electroplating to form a Cr plated layer. Although the conditions for Cr plating are not particularly limited, the conditions described above are preferable.

Subsequently, the Cr-plated layer formed on the substrate 11 is electroplated with Ni--P to form a Ni--P plated layer. In addition, from the viewpoint that the adhesion between the Cr plating layer and the Ni—P plating layer can be further improved, the Cr plating layer is preliminarily formed with a Ni strike film by a known method, and the Cr plating layer It is preferable to form a Ni--P plating layer thereon via a Ni strike coating.

Then, the substrate 11 on which the Cr plating layer and the Ni—P plating layer are formed is subjected to heat treatment under specific conditions, so that the Cr layer 12 and the Ni— A surface-treated substrate 1 is obtained in which the P layer 13 is formed in this order. In the present embodiment, the Ni—P plated layer is crystallized by heat treatment under specific conditions, and the half width of the peak P _A in the above-described diffraction angle 2θ range of 43 to 45° is the above. By controlling the range, the adhesion between the Cr layer 12 and the Ni—P layer 13 is improved, and the Cr layer 12 and the Ni—P layer 13 thermally diffuse to each other by heat treatment. Adhesion between the Cr layer 12 and the Ni—P layer 13 is further improved.

As for the heat treatment conditions, the heat treatment temperature may be 400 to 800.degree. C., preferably 600 to 800.degree. C., more preferably 700 to 800.degree. If the heat treatment temperature is too low, the relaxation of the internal stress of the Ni--P plating layer becomes insufficient, and the effect of improving the adhesion between the formed Cr layer 12 and the Ni--P layer 13 becomes insufficient. On the other hand, if the heat treatment temperature is too high and the melting point of the Ni—P plating layer 13 is exceeded, the Ni—P plating layer 13 melts and flows out, resulting in the thickness of the Ni—P plating layer 13 and the thickness of the plating film. There is a possibility that the problem that uniformity of the composition is lost may occur. Moreover, even in the heat treatment near the melting point, the plating film of the Ni—P plating layer 13 may partially flow, resulting in a loss of uniformity. The melting point of the Ni—P plating layer 13 is greatly affected by the content of P. In particular, when the content of P in the Ni—P plating layer 13 is 5 to 20 wt %, the above-described problems are prevented. , the heat treatment temperature is preferably 800° C. or less.

In addition, the heat treatment time (total heat treatment time required for temperature rise and soaking) when performing the heat treatment is preferably 30 to 240 seconds from the viewpoint that the Ni—P plating layer can be crystallized more favorably. , more preferably 60 to 180 seconds, and still more preferably 100 to 140 seconds. Among such heat treatment times, the soaking time after the temperature reaches the target value is preferably 30 seconds or more. The heat treatment atmosphere for the heat treatment is preferably a non-oxidizing atmosphere or a reducing protective gas atmosphere. The method of heat treatment is not particularly limited, and either continuous annealing or box annealing may be used. When performing heat treatment by box annealing, for example, heat treatment may be performed at 400° C. for about 1 hour.

The surface-treated substrate 1 of this embodiment is manufactured as described above.

Since the surface-treated substrate 1 of the present embodiment is formed by forming the Cr layer 12 and the above-described specific Ni—P layer 13 in this order on the substrate 11, for example, FIG. , 3, after molding the surface-treated substrate 1 into a desired shape by press working or the like to form a compact, other members (other surface-treated substrate 1 or members made of other materials) are formed. When the outermost layer (Ni—P layer 13) is melted by heat treatment while in contact with the surface treatment substrate 1, the Ni—P layer 13 acts as a brazing material to braze the contact portion between the surface treatment substrate 1 and other members. can be spliced. According to the surface-treated substrate 1 of the present embodiment, the Cr layer 12 is formed, so that it has excellent corrosion resistance. Even when the treated substrate 1 is formed into a molded body by press working or the like, the Ni—P layer 13 can be prevented from being peeled off. It is possible to prevent deterioration of corrosion resistance due to exposure of the base material 11, and also prevent deterioration of brazing jointability due to peeling of the Ni—P layer 13. Therefore, the surface-treated substrate 1 of the present embodiment can be suitably used as a material for plate heat exchangers, etc., which require good brazing bondability and corrosion resistance after molding.

Conventionally, as a method of manufacturing a plate-type heat exchanger or the like, a concave-convex structure such as a fluid flow path is formed by subjecting a base material to press working or the like in advance, and Ni is formed on the base material. A method is also known in which a paste such as a brazing material is applied, and the base material to which the paste is applied is brought into contact with another member to join by brazing. When manufacturing such as, there are many points to be brazed and it is necessary to go through a complicated process in which paste must be applied to each point, so productivity is inferior and cost is disadvantageous. I had a problem.

In place of such a paste, there is also known a surface-treated substrate in which a Ni—P plating layer is formed as a brazing material layer on the substrate in advance. There is a problem in that the properties in a high-temperature environment and the corrosion resistance are insufficient when the material is used as a material for a plate-type heat exchanger only by forming the material.

On the other hand, in order to improve the corrosion resistance of surface-treated substrates, there is also known a technique of forming a Ni-based brazing layer containing Cr as a brazing layer. No alloy plating has been put into practical use, and even if there is, it is a plating process at the laboratory level and has not been put into practical use. That is, in Ni--Cr alloy plating using a trivalent chromium compound, chromium (III) cations self-ionize in a proton-accepting solvent to produce solvated hydrogen ions, which significantly lowers the pH of the solution. Therefore, during electrolysis, the generation of hydrogen gas is dominant due to the electrolysis of water, and the deposition of the Ni--Cr alloy itself is difficult. In some cases, organic solvents such as DMF (dimethylformamide) are used to maintain the pH of the plating bath and to control the generation of hydrogen gas. Considering the surface, it is very difficult to put it into practical use. There is also a report of an attempt to produce an amorphous Ni-Cr-P alloy film by electrodeposition, but the plating deposition efficiency is extremely low and the plating conditions are almost non-stirring, so continuous production is difficult. is difficult.

In addition, a stainless steel plate for brazing is manufactured by forming a Cr plating layer and a Ni—P plating layer in this order on a substrate on which an uneven structure such as a fluid flow path is formed in advance by press working or the like. However, in such a manufacturing method, since the substrate on which the Cr plating layer and the Ni—P plating layer are to be formed has a concave-convex structure in advance, the Cr plating is performed by plating. When forming the plated layer and the Ni—P plated layer, there is a problem that the productivity is inferior to that of plating a plate-shaped base material. also had the problem that a uniform plating layer could not be formed. On the other hand, a substrate having a flat shape is prepared, and a Cr plating layer and a Ni—P plating layer are formed on such a flat substrate, and then the Cr plating layer and the Ni—P plating are performed. A method of forming an uneven structure such as a fluid flow path by press working or the like on a base material on which a layer is formed is also conceivable. However, an inert oxide film is usually formed on the surface of the Cr plating layer, and the adhesion of the Ni—P plating layer formed on such a Cr plating layer tends to be low. When the substrate on which the plating layer and the Ni—P plating layer are formed is subjected to press working or the like, there is a problem that the Ni—P plating layer is easily peeled off due to the stress caused by the press working or the like.

Alternatively, as a stainless steel plate for brazing, there is also known one in which a Ni—P plating layer is first formed on a base material, and a Cr plating layer is formed on this Ni—P plating layer. However, in such a stainless steel plate for brazing, since a Cr plating layer is formed on the outermost surface, even if brazing is performed by bringing this Cr plating layer into contact with another member, the outermost surface is Ni- There is a problem that it is difficult to perform brazing joints compared to the case of the P layer. That is, the Cr plating layer has low wettability and is inferior in brazing jointability. If a high Cr plating layer is formed on the outermost surface, in order to melt and braze the Cr plating layer, it is necessary to apply a very high temperature or extend the heating time to convert the Cr plating layer to Ni—P. It was difficult to join by brazing because it had to be melted by mutual thermal diffusion with the plating layer. In particular, if the heating time during brazing is prolonged, the productivity of the surface-treated base material will decrease due to the brazing process taking a long time. Thermal diffusion occurs, which causes a phenomenon in which the thickness of the base material is reduced, and the strength of the obtained surface-treated base material is lowered.

In contrast, according to the surface-treated substrate 1 of the present embodiment, the Cr layer 12 and the above-described specific Ni—P layer 13 are formed in this order on the substrate 11, thereby forming a flat plate as the substrate 11. In the case of using a material having a shape, the Cr layer 12 and the Ni—P layer 13 can be uniformly formed, and the productivity can be improved. After molding to form a compact (for example, after press working to produce a press-molded product), the Ni—P layer 13 can be prevented from peeling off, and the braze bondability and corrosion resistance can be improved. can also be excellent. Therefore, the surface-treated substrate 1 of the present embodiment can be suitably used as a material for a plate heat exchanger that requires good brazing bondability and corrosion resistance after molding. In particular, the surface-treated substrate 1 of the present embodiment has an uneven structure of a fluid flow path formed by press work or the like, such as an EGR system (exhaust gas circulation system) used in a gasoline engine vehicle or a diesel engine vehicle. In addition, it is used in a highly corrosive and high-temperature exhaust gas atmosphere, and in a severe corrosive environment where NO _X and sulfur components in the cooled exhaust gas will aggregate and adhere together with moisture. It can be suitably used as a material for plate heat exchangers. Although the uneven structure is not particularly limited, for example, a structure having protrusions and/or recesses having a height equal to or greater than the thickness of the plating layer (Cr layer 12 and Ni—P layer 13) in the surface-treated substrate 1. An uneven structure having a bent portion at an angle of 90 degrees (for example, an angle of 87 to 90 degrees) with respect to the plane portion of the surface treatment substrate 1, and an angle of 80 degrees or more with respect to the plane portion of the surface treatment substrate 1 a concave-convex structure having a bent portion, a concave-convex structure having a curved surface with a bending radius R of 10 mm or less, or a continuous concave-convex structure in which the bent portion and the curved surface are continuous.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.
The definition of each characteristic and the evaluation method are as follows.

<Half width of peak P _A , I _B /I _A , and I _C /I _A >
The surface of the surface-treated substrate is measured using an X-ray diffractometer (manufactured by Rigaku, model number: RINT-2500) using CuKα as a radiation source, and based on the measurement results obtained, the diffraction angle 2θ is 43 to Among the peaks having peak tops in the range of 45°, the half width of the peak _PA having the highest peak top intensity was measured. Further, based on the obtained measurement results, the peak _P with the highest peak top intensity among the peaks having the peak top in the range of 50 to 54 ° at the diffraction angle 2θ with respect to the peak top intensity I _A of the peak P A A ratio ( _IB / _IA ) of the peak top intensity _IB in _B was determined. Similarly, with respect to the peak top intensity I _A of the peak P _A , the peak top intensity I C of _the peak P _C having the highest peak top intensity among the peaks having the peak top in the range of the diffraction angle 2θ of 96 to 100° The ratio of (I _C /I _A ) was also determined.

<Adhesion of Brazing Material Layer>
For the surface-treated substrate, the adhesion of the layer (Ni—P layer, Ni—P plating layer, Cr layer, Cr plating layer, or Ni plating layer) formed on the substrate is measured according to the pulling described in JIS H 8504. It was evaluated by conducting an adhesive tape peeling test based on the peeling test method. Specifically, after each layer was formed or after heat treatment, an adhesive tape (trade name “CELLOTAPE” manufactured by Nichiban Co., Ltd.) was attached to the surface of the surface-treated substrate, and after holding it with a finger, the adhesive tape was removed vigorously. , the adherence of plating on the adhesive surface of the adhesive tape was observed. The adhesion of the brazing filler metal layer was judged to be good if the layer formed on the substrate did not adhere to the adhesive surface of the adhesive tape.

<Working Adhesion of Brazing Material Layer>
The surface-treated base material was stretched to a height of 7 mm using an Erichsen tester (manufactured by Coating Tester Co., Ltd.) based on the Erichsen test method described in JIS H 8504, and the adhesive tape was attached to the stretched area. After that, the adhesive tape is peeled off, and the area of the layer (Ni-P layer, Ni-P plating layer, Cr layer, Cr plating layer, or Ni plating layer) attached to the peeled adhesive tape is visually observed, and the following criteria are observed. evaluated with If the processing adhesion of the brazing material layer is A or B in the following criteria, it is judged that it can be used well as a material for plate heat exchangers, etc., which require brazing bondability after molding processing. Passed.
A: Peeling of the layer was not confirmed.
B: Part of the layer adhered to the adhesive tape.
C: Most of the layer adhered to the adhesive tape.
D: The layer was peeled off before sticking the adhesive tape, just by performing the overhanging process.

<Brazability>
With respect to the surface-treated base material, a test piece for brazing joint was prepared, brazing heat treatment was performed in a heat treatment furnace in a non-oxidizing atmosphere, and brazing joint was performed. Observation of the cross section of the test piece after brazing joint, when the length of the brazed joint is set to 100, the ratio of the length actually brazed is calculated as the brazing joint ratio, and the following criteria are used. was used to evaluate the brazeability.
A: The brazing joint rate was 90% or more.
B: The brazing joint rate was less than 90%.

<Brazing strength>
For the surface-treated substrate, prepare a brazed T-peel test piece according to JIS K 6854, measure the T-peel strength by performing a tensile test with a tensile tester, and measure the T-peel strength. The brazing strength was evaluated. The brazing strength is based on the T-peel strength of the single-layer Ni—P plating layer, and it is judged to be good if it is equal to or greater than that. In the evaluation of the brazing strength, it was possible to prepare a T-peel test piece even under the condition that the plating film at the brazing portion was not damaged and the adhesion of the brazing material layer was poor.

<Corrosion resistance>
First, the weight of the surface-treated substrate was measured. Next, "the surface-treated substrate is immersed in an etchant at 80°C containing sulfuric acid, hydrochloric acid, nitric acid and organic acids (formic acid, acetic acid) for 4 hours, then removed from the etchant and dried at 80°C for 20 hours. After 10 cycles, the weight of the surface-treated substrate was measured to determine the amount of decrease in the weight of the surface-treated substrate. Based on the weight reduction of the surface-treated substrate of Reference Example 1, which will be described later, the ratio of the weight reduction of the surface-treated substrate of each example and each comparative example was calculated. Corrosion resistance was evaluated according to the following criteria based on the weight reduction rate of the surface-treated substrate. If the corrosion resistance is evaluated as A or B with the same corrosion resistance as that of Reference Example 1 according to the following criteria, it is judged that the surface-treated substrate can be used satisfactorily as a material for plate heat exchangers, etc., and it passes. and As the corrosive liquid, an aqueous solution of a mixed acid containing 3000 ppm by weight of sulfuric acid as a main component and containing hydrochloric acid, nitric acid and an organic acid was used.
A: The weight reduction ratio of the surface-treated substrate was 110% by weight or less.
B: The weight reduction ratio of the surface-treated substrate was more than 110% by weight and 200% by weight or less.
C: The weight reduction ratio of the surface-treated substrate was more than 200% by weight.

<<Example 1>>
First, a SUS304 stainless steel plate (thickness: 0.2 mm) having the chemical composition shown below was prepared as a base material.
C: 0.08% by weight, Si: 1.0% by weight, Mn: 2.0% by weight, P: 0.04% by weight, S: 0.03% by weight, Ni: 8 to 10.5% by weight, Cr: 18 to 20% by weight, balance: Fe and unavoidable impurities

Then, the prepared substrate was subjected to alkaline electrolytic degreasing and pickling by immersion in sulfuric acid, and then Cr plating was performed by electroplating under the following conditions to form a 1 μm-thick Cr plating layer on the substrate.
<Cr plating>
Bath composition: Chromic anhydride 250g/L, Sulfuric acid 2.5g/L
Bath temperature: 60°C
Current density: 60A/ ^dm2

Next, the substrate on which the Cr plating layer is formed is subjected to strike Ni plating using Wood's bath, and then plating is performed using the Ni—P plating bath shown below to obtain, on the Cr plating layer, A Ni—P plating layer with a thickness of 10 μm was formed. The thicknesses of the formed Cr plating layer and Ni—P plating layer are shown in Tables 1 and 2. In Tables 1 and 2 and Table 3, which will be described later, the thickness of each layer formed on the substrate is described as the thickness of the first layer and the thickness of the second layer in order from the side closer to the substrate. In addition, the amount of Ni and the amount of P were measured using an X-ray fluorescence analyzer (X-ray fluorescence analyzer ZSX100e from Rigaku Corporation). The amount of plating was calculated using a fluorescent X-ray device, and the content of P was found to be about 10 wt%. Cr has a specific gravity of 7.2, Ni has a specific gravity of 8.9, and Ni-P has a specific gravity of 8.0 at a P content of 10 wt%. In addition, the amount of plating and the thickness of plating were calculated in the same manner in any of the examples and comparative examples.
<Ni-P plating bath>
Nickel salt: Nickel sulfate 200g/L, Nickel chloride 10g/L
Phosphorus component: phosphorous acid 40g/L, sodium phosphite 110g/L
pH buffer (boric acid): 30g/L
Complexing agent (trisodium citrate): 10g/L
pH: 2.0
Bath temperature: 60°C
Current density: 10A/ ^dm2

Subsequently, the base material on which the Cr plating layer and the Ni—P plating layer are formed is heat-treated in an electric furnace at a temperature of 400° C. for a soaking time of 1 minute in a non-oxidizing atmosphere to form a Cr layer. and a surface-treated substrate having a Ni—P layer formed thereon. The resulting surface-treated base material was tested for the half-value width of peak P _A , I _B /I _A , I _C /I _A , adhesion of brazing material layer, processing adhesion of brazing material layer, and brazing according to the above methods. and brazing strength were evaluated. Tables 1 and 2 show the results. Also, for Example 1, FIG. 5A shows a photograph of the surface of the surface-treated base material after the processing adhesion of the brazing material layer (left view in FIG. 5A), and a photograph of the surface-treated base material. Photographs of the adhesive tape peeled off from the material (photographs showing the state of peeling of each layer) (right view of FIG. 5(A)) are shown. Further, for Example 1, the results of measurement by an X-ray diffraction device are shown in FIGS. 7(A) and 7(B). Here, FIG. 7B is a graph enlarging the range of 2θ=40 to 50° in FIG. 7A.

<<Examples 2 to 7>>
A surface-treated substrate was produced in the same manner as in Example 1, except that the thickness of the Cr plating layer and the heat treatment conditions after forming the Ni—P plating layer were changed to those shown in Table 1, and the above method was performed. The half width of the peak P _A , I _B /I _A , I _C /I _A , adhesion of the brazing layer, processing adhesion of the brazing layer, brazability, brazing strength, and corrosion resistance were evaluated according to gone. The results are shown in Tables 1-3. Among Examples 2 to 7, only Examples 2, 3, 5 and 7 were evaluated for brazeability and braze strength. Further, evaluation of corrosion resistance was performed only for Examples 5 and 7 out of Examples 2-7. For Examples 2, 3, 5, and 6, a photograph of the surface of the surface-treated substrate after the processing adhesion of the brazing material layer was performed, and a photograph of the adhesive tape peeled off from the surface-treated substrate (detachment of each layer). 5(B), 5(C), 5(D) and 5(E), respectively. Further, for Example 5, the results of measurement by an X-ray diffractometer are shown in FIG.

<<Comparative example 1>>
A surface-treated substrate was prepared in the same manner as in Example 1 except that the heat treatment after forming the Ni—P plating layer was not performed, and the half width of the peak P _A , I _B /I _A , I _C /I _A , the adhesion of the brazing material layer, and the processing adhesion of the brazing material layer were evaluated. Table 1 shows the results. Further, for Comparative Example 1, FIG. 6A shows a photograph of the surface of the surface-treated base material after the processing adhesion of the brazing material layer (left view in FIG. 6A), and a photograph of the surface-treated base material. Photographs of the adhesive tape peeled off from the material (photographs showing the state of peeling of each layer) (right view in FIG. 6A) are shown. Furthermore, for Comparative Example 1, the measurement results by an X-ray diffraction device are shown in FIG.

<<Comparative Examples 2 and 3>>
A surface-treated substrate was produced in the same manner as in Example 1, except that the conditions of the heat treatment after forming the Ni—P plating layer were changed to those shown in Table 1, and the evaluation was performed in the same manner. Tables 1 and 2 show the results. In addition, for Comparative Examples 2 and 3, a photograph of the surface of the surface-treated substrate after processing adhesion of the brazing material layer and a photograph of the adhesive tape peeled off from the surface-treated substrate (the state of peeling of each layer was 6(B) and 6(C), respectively.

<<Comparative Example 4>>
A surface-treated substrate in the same manner as in Example 1, except that a Ni—P plating layer was formed directly on the substrate without forming a Cr plating layer, and heat treatment was not performed after the formation of the Ni—P plating layer. were prepared, and the adhesion of the brazing material layer, the working adhesion of the brazing material layer, the brazing properties, the brazing strength, and the corrosion resistance were evaluated according to the above methods. The results are shown in Tables 1-3.

<<Comparative Example 5>>
A base material similar to that used in Example 1 was prepared, and the base material was subjected to alkaline electrolytic degreasing and pickling by immersion in sulfuric acid, and then Ni plating was performed under the following conditions to form a Ni plating layer with a thickness of 1 μm. formed.
<Ni plating>
Bath composition: nickel sulfate 250 g/L, nickel chloride 40 g/L, boric acid 30 g/L
pH: 4.2
Bath temperature: 60°C
Current density: 20A/ ^dm2

Next, the base material on which the Ni plating layer is formed is subjected to plating using the Ni—P plating bath shown below to form a Ni—P plating layer having a thickness of 10 μm on the Ni plating layer. to obtain a surface-treated substrate having a Ni plating layer and a Ni—P plating layer formed thereon. The resulting surface-treated base material was evaluated for brazing layer adhesion, brazing layer adhesion, brazing properties, brazing strength, and corrosion resistance according to the methods described above. The results are shown in Tables 1-3.
<Ni-P plating bath>
Nickel salt: Nickel sulfate 200g/L, Nickel chloride 10g/L
Phosphorus component: phosphorous acid 40g/L, sodium phosphite 110g/L
pH buffer (boric acid): 30g/L
Complexing agent (trisodium citrate): 10g/L
pH: 2.0
Bath temperature: 60°C
Current density: 10A/ ^dm2

<<Comparative Examples 6 and 7>>
A surface-treated substrate was prepared in the same manner as in Example 1 except that the thickness of the Ni plating layer was changed to that shown in Table 1, and the adhesion of the brazing layer and the processing of the brazing layer were evaluated according to the above method. Adhesion, brazeability, braze strength, and corrosion resistance were evaluated. The results are shown in Tables 1-3.

<<Comparative Example 8>>
A substrate similar to that used in Example 1 is prepared, and the substrate is subjected to alkaline electrolytic degreasing and pickling by immersion in sulfuric acid, and then plating is performed using the Ni—P plating bath shown below. Thus, a Ni—P plating layer with a thickness of 10 μm was formed.
<Ni-P plating bath>
Nickel salt: Nickel sulfate 200g/L, Nickel chloride 10g/L
Phosphorus component: phosphorous acid 40g/L, sodium phosphite 110g/L
pH buffer (boric acid): 30g/L
Complexing agent (trisodium citrate): 10g/L
pH: 2.0
Bath temperature: 60°C
Current density: 10A/ ^dm2

Subsequently, the substrate on which the Ni—P plating layer is formed is subjected to Cr plating by electroplating, and a Cr plating layer having a thickness of 1.2 μm is formed on the Ni—P plating layer. - A surface-treated base material having a P plating layer and a Cr plating layer formed thereon was obtained. The resulting surface-treated base material was evaluated for adhesion of the brazing filler metal layer, processing adhesion of the brazing filler metal layer, brazing property, and brazing strength according to the methods described above. Tables 1 and 2 show the results.

<<Comparative Example 9>>
The same base material as that used in Example 1 was directly evaluated for corrosion resistance according to the above method. Table 3 shows the results.

<<Reference example 1>>
A base material similar to that used in Example 1 was prepared, and a brazing paste containing Ni, Cr, P and Si (trade name "NICROBRAZ No. 31", manufactured by Wall Cormoloy Co., Ltd.) was applied on the base material. was applied to a thickness of 10 μm to obtain a surface-treated substrate. The obtained surface-treated substrate was evaluated for brazeability, braze strength, and corrosion resistance according to the methods described above. Tables 2 and 3 show the results.

<<Reference example 2>>
A base material similar to that used in Example 1 was prepared, and a brazing paste containing Ni and P (trade name "NICROBRAZ No. 10", manufactured by Wall Colmoloy Co., Ltd.) was applied on the base material to a thickness of A surface-treated substrate was obtained by coating so as to have a thickness of 10 μm. The obtained surface-treated substrate was evaluated for brazeability, braze strength, and corrosion resistance according to the methods described above. Tables 2 and 3 show the results.

As shown in Table 1, the surface-treated substrate provided with a Cr layer and a Ni—P layer having a peak _PA half width of 2° or less on the substrate has a brazing material layer (Ni—P layer ) was confirmed to be excellent in adhesion and processing adhesion (Examples 1 to 7).
Further, as shown in Table 2, it was confirmed that the surface-treated substrates of Examples 1, 2, 3, 5 and 7 were excellent in brazeability and brazing strength.
Furthermore, as shown in Table 3, it was confirmed that the surface-treated substrates of Examples 5 and 7 were also excellent in corrosion resistance.

On the other hand, as shown in Table 1, after forming the Ni—P plating layer, the surface-treated base material that was not heat-treated, or that was heat-treated but was heat-treated at too low a temperature, had a brazing material layer (Ni -P plating layer or Ni-P layer) was inferior in working adhesion (Comparative Examples 1 to 3).
In addition, as shown in Table 2, the surface-treated substrate in which a Ni—P layer and a Cr layer are formed in this order on the substrate was inferior in brazeability and brazing strength ( Comparative Example 8).
Furthermore, as shown in Table 3, a surface-treated substrate in which a Ni—P plating layer is formed directly on the substrate, and a Ni plating layer and a Ni—P plating layer are formed in this order on the substrate. A surface-treated base material obtained by applying a brazing filler metal paste containing Ni and P onto a base material, and the base material itself were inferior in corrosion resistance (Comparative Examples 4 to 7). , 9, Reference Example 2).
It should be noted that the surface-treated base material obtained by coating the base material with a brazing paste containing Ni, Cr, P, and Si was excellent in brazeability, brazing strength, and corrosion resistance. Since such a surface-treated base material is manufactured through a complicated process of applying paste to each brazing point, it is inferior in productivity and disadvantageous in terms of cost (Reference Example 1). .

DESCRIPTION OF SYMBOLS 1... Surface treatment base material 11... Base material 12... Cr layer 13... Ni-P layer 2... Plate type heat exchanger 21... Fluid inlet 22... Fluid outlet 23... Heat transfer plate 24, 24a... Fluid flow path 25... Interposition Member 26... Outer layer member

Claims (11)

a substrate;
a Cr layer formed on the substrate;
and a Ni—P layer formed on the Cr layer,
The Ni-P layer has the highest peak top _intensity among the peaks having peak tops in the range of 43 to 45 ° at the diffraction angle 2θ detected by X-ray diffraction measurement using CuKα as a radiation source. A surface-treated substrate for brazing, wherein the half width of the peak _PA is 2° or less. When X-ray diffraction measurement using CuKα as a radiation source is performed, the Ni—P layer has a diffraction angle 2θ with respect to the peak top intensity _IA of the peak _PA in the range of 50 to 54°. The surface treatment group for brazing according to claim 1, wherein the ratio of the peak top intensity _IB ( _IB / _IA ) of the peak _PB having the highest peak top intensity among the peaks having the highest peak top intensity is less than 0.2 material. When X-ray diffraction measurement using CuKα as a radiation source is performed, the Ni—P layer has a diffraction angle 2θ with respect to the peak top intensity I _A of the peak P _A in the range of 96 to 100°. The surface treatment group for brazing according to claim 2, wherein the ratio of the peak top intensity IC of the peak P _C having the highest peak top intensity among the peaks having the peak top intensity _IC (I _C /I _A ) is 0.2 or more material. The surface-treated substrate for brazing according to any one of claims 1 to 3, wherein the content of P in said Ni-P layer is 5 to 20 wt%. The surface-treated substrate for brazing according to any one of claims 1 to 4, wherein the substrate is stainless steel. A molded article formed using the surface-treated substrate for brazing according to any one of claims 1 to 5. The molded article according to claim 6, which has an uneven structure. A press-formed body formed using the surface-treated substrate for brazing according to any one of claims 1 to 5. The press-formed body according to claim 8, which has an uneven structure. forming a Cr plating layer by electroplating on at least one surface of the substrate;
forming a Ni—P plating layer on the Cr plating layer by electroplating;
A method for producing a surface-treated base material for brazing, comprising: heat-treating the base material on which the Cr plating layer and the Ni—P plating layer are formed at a temperature of 400 to 800°C. 11. A method for manufacturing a molded body, comprising the step of molding the surface-treated base material for brazing obtained by the manufacturing method according to claim 10 by press working so that at least a part thereof has an uneven structure.

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