JP4507943B2 - Brazing clad material and brazing product using the same - Google Patents

Description

  The present invention relates to a brazing clad material for brazing a brazed member such as a heat exchanger or a fuel cell member, and a brazed product using the same.

  Stainless steel-based clad materials are used as joining materials for automobile oil coolers. In this, copper having a function as a brazing material is clad on one side or both sides of a stainless steel plate as a base material.

  Further, there are brazing composite materials and brazing materials having high corrosion resistance and heat resistance. For example, a brazing composite material in which a Ni-Cr alloy layer containing 1 to 30 mass% of Cr as a Fe atom diffusion suppression layer is provided on the surface of a substrate made of a corrosion-resistant steel material and a Cu brazing layer is provided thereon (see FIG. Patent Document 1).

JP 2003-145290 A

  When the above-described stainless steel-based clad material is used as a joining material for an automobile oil cooler, there is no problem with respect to heat resistance and corrosion resistance. However, this stainless steel-based clad material is exposed to highly corrosive gases or liquids at high temperatures, such as heat exchangers for fuel cells and coolers for exhaust gas recirculation (EGR). When applied to exchanger products, there is a problem with corrosion resistance. Specifically, high temperature and highly corrosive solutions and exhaust gases are circulated in the heat exchanger for fuel cells and the EGR cooler. There was a problem that the corrosion resistance was not sufficient.

  Further, in the brazing composite material described in Patent Document 1, the Ni component and the Cr component of the Ni—Cr alloy layer disposed in the lower layer of the Cu brazing layer diffuse into the brazing material, so that the corrosion resistance of the brazing material portion. And oxidation resistance is improved. However, as a characteristic of this brazing composite material, when brazing is performed at a temperature higher than the melting point of the Cu brazing layer, the Ni component and the Cr component are diffused from the Ni-Cr alloy layer as the underlayer into the brazing material. First, the Cu brazing layer melts and flows out and accumulates (concentrates) in the brazed joint. Therefore, after the Cu brazing layer is melted, the Ni component and the Cr component are supplied from the Ni—Cr alloy layer to the brazing joint through the contact portion between the brazing joint and the Ni—Cr alloy layer. However, the contact area between the brazed joint and the Ni—Cr alloy layer is smaller than the total area of the Ni—Cr alloy layer, and the thickness of the brazed joint is thicker than the Cu braze layer. For this reason, if Ni and Cr components are supplied from the Ni-Cr alloy layer to the brazed joint, local thickness reduction of the Ni-Cr alloy layer, insufficient diffusion (supply) of the Ni and Cr components, or brazing There was a possibility that the composition (Ni component and Cr component) of the solder joint would be non-uniform. In particular, the non-uniformity of the Ni component and the Cr component in the brazed joint may cause a local decrease in strength and a decrease in corrosion resistance of the brazed joint.

  An object of the present invention created in view of the above circumstances is to provide a brazing clad material having good corrosion resistance and bonding strength of a brazed joint and a brazed product using the same.

In order to achieve the above object, the brazing clad material according to the present invention is composed of a composite material in which a brazing material layer is integrally provided on the surface of a base material, and is brazed to a brazed member. In the clad material, the brazing material layer is formed by laminating a copper layer and a nickel layer in this order from the base material side, and the composition of the entire brazing material layer is Cu-Ni-4 to 20.5 mass% Cr. is there.

  Of the layers constituting the brazing filler metal layer of the brazing clad material according to the present invention, the nickel layer has a melting point higher than that of the copper layer and is made of a Ni alloy containing a Cr component. It is preferable that it contains 4 to 20.5 mass% of Cr component.

  The copper layer is preferably made of a Cu-P alloy. The base material is preferably made of stainless steel.

On the other hand, a brazing product according to the present invention is a brazing product obtained by brazing the above-described brazing clad material and a member to be brazed, and includes the Ni component and the Cr component at the brazed joint portion. It is a brazed product characterized in that the concentration variation is less than 5% by mass.
In addition, the term “nickel layer” and “copper layer” refers to a layer made of a single metal or an alloy containing each of them as a main component, as will be described later.

  ADVANTAGE OF THE INVENTION According to this invention, the outstanding effect that the clad | crud material for brazing with the favorable corrosion resistance of a brazing junction part and joining strength can be obtained is exhibited.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of the invention will be described with reference to the accompanying drawings.

  A cross-sectional view of a brazing clad material according to a preferred embodiment of the present invention is shown in FIG.

  As shown in FIG. 1, a clad material 10 for brazing according to the present embodiment is brazed to a member to be brazed and brazed to the surface of the base 11 (only the upper surface in FIG. 1). It is composed of a composite material in which the material layer 15 is provided integrally. By appropriately rolling the composite material, a brazing clad material (final product) 10 having a desired thickness can be obtained. The surface of the base material 11 here refers to all surfaces exposed to the outside.

  The brazing filler metal layer 15 is formed by laminating and cladding the copper layer 13 and the nickel layer 14 in this order from the base material 11 side. The brazing filler metal layer 15 contains a Cr component in a ratio of 4 to 20.5 mass% as a whole. In other words, the brazing clad material 10 is adjusted so that the composition of the entire brazing material layer 15 is Cu—Ni-4 to 20.5 mass% Cr. For example, the nickel layer 14 of the brazing material layer 15 is made of a Ni—Cr alloy so that at least the nickel layer 14 of each layer constituting the brazing material layer 15 contains a Cr component. The Cr component is adjusted by adjusting the thicknesses of the layers 13 and 14, adjusting the alloy compositions of the layers 13 and 14, and the like. By including the Cr component in a ratio of 4 to 20.5% by mass in the entire brazing material layer 15, a film having high corrosion resistance is formed on the surface layer of the brazed joint after the brazing treatment. Of course, only the copper layer 13 or the copper layer 13 and the nickel layer 14 may contain a Cr component. Preferably, the nickel layer 14 is made of a Ni-4 to 20.5 mass% Cr alloy.

  Here, the content (concentration) of the Cr component is limited to 4 to 20.5% by mass. If the content of the Cr component is less than 4% by mass, the effect of containing the Cr component (improvement of corrosion resistance) is insufficient. This is because corrosion occurs in the brazed joint. On the other hand, when the content of the Cr component exceeds 20.5% by mass, the melting point of the brazing material increases and the hot-water flow property decreases.

  The constituent material of the copper layer 13 may be either Cu alone or a Cu alloy (for example, Cu—Cr alloy).

  The reason why Ni or Ni alloy, Cu or Cu alloy is selected as the constituent material of the brazing filler metal layer 15 of the brazing clad material 10 according to the present embodiment is that a plate-like material or a foil-like material is obtained relatively easily. This is because it is excellent in workability such as rolling, pressing and drawing. Moreover, it is because the brazed joint portion formed by melting and mixing the brazing filler metal layer 15 composed of these materials is excellent in corrosion resistance.

  On the other hand, it is preferable that the base material 11 is comprised with the material same as or substantially the same as the structural member (member to be brazed) which comprises the brazing product mentioned later. For example, the constituent material of the base material 11 includes stainless steel, preferably austenitic stainless steel (for example, SUS304 (JIS standard)). Here, stainless steel is preferable because it is a general-purpose product that has sufficient corrosion resistance under the same environment as the brazing material having excellent corrosion resistance, is available at a relatively low cost, and is rolled and pressed. This is because of excellent workability such as drawing.

  The brazing filler metal layer 15, preferably the copper layer 13, may contain P in a proportion of 0.02 to 10.0% by mass, preferably 0.02 to 5.0% by mass. As a result, the hot metal flow and oxidation resistance of the brazing material can be remarkably improved. Here, the reason why the P content is limited to 0.02 to 10% by mass is that if it is less than 0.02% by mass, improvement in hot water flow cannot be expected, and conversely if it exceeds 10.0% by mass, brazing is performed. This is because the strength is lowered depending on the type of brazing member to be performed.

  Moreover, you may make Al component contain in the ratio of 1-7 mass% in at least 1 layer of each layer which comprises the brazing filler metal layer 15. FIG. By containing the Al component, the corrosion resistance of the brazed joint can be further improved.

  The brazing clad material 10 having such a structure is appropriately rolled, pressed and drawn to form a semi-finished product having a desired shape, and then a brazed member (not shown) for joining with the semi-finished product. And a portion to be brazed and joined (a brazed joint) is brought into contact. Then, brazing products are obtained by performing brazing processing by heating to these combination members. Alternatively, a brazing clad material 10 may be used as a brazing member. For example, a plurality of brazing clad materials 10 according to the present embodiment are prepared, each composite material 10 is appropriately pressed to form a semi-finished product of a desired shape, and then the semi-finished products are combined. Bring the brazed joint into contact. Then, you may make it obtain a brazing product by performing the brazing process by heating to these combination members.

  In the present embodiment, the brazing clad material 10 in which the brazing material layer 15 is provided only on one surface (the upper surface in FIG. 1) of the base material 11 has been described. However, the present invention is not particularly limited thereto. For example, a brazing clad material in which the brazing material layer 15 is provided on both surfaces (upper and lower surfaces in FIG. 1) of the base material 11 may be used.

Moreover, in this Embodiment, although demonstrated using the clad material 10 for brazing which exhibited foil shape, the shape of a composite material is not specifically limited to foil shape. For example, as shown in FIG. 2, the brazing material layer 15 formed by laminating the copper layer 13 and the nickel layer 14 in this order from the substrate 21 side is provided on the surface of the rod-shaped or wire-shaped substrate 21. The clad material 20 for brazing may be provided integrally. In this case, the same material as the base material 11 is applied as the base material 21. The layers 13 and 14 are formed by a plating method, an extrusion method, a pipe making method, or the like.

  Examples of brazing products using the brazing clad material 10 according to the present embodiment include heat exchangers such as fuel cell reformer coolers that circulate highly corrosive solutions or gases, and EGR coolers. , Fuel cell members, oil coolers, radiators, secondary battery members, and the like. The brazing clad material according to the present embodiment, in particular, the rod-like or wire-like brazing clad material 20 (see FIG. 2) has a small diameter size and good handleability. In addition to the heat exchanger for the cooler for the quality device, the cooler for the EGR, the fuel cell member, etc., it can be applied to an oil cooler, a radiator, a secondary battery member, and the like.

  Next, a brazing method using the brazing clad material according to the present embodiment will be described.

  The brazing clad material 10 according to the present embodiment is appropriately rolled, pressed, and drawn to produce a semi-finished product having a desired shape. This semi-finished product (the brazing clad material 10) and the member to be brazed (not shown) are combined, and the brazed joint is brought into contact. Thereafter, these combination members are subjected to a brazing treatment by heating. Here, prior to the brazing treatment, the semi-finished product (or both the semi-finished product and the member to be brazed) is preheated at a temperature of 850 to 950 ° C., preferably 880 to 920 ° C. By this pre-heat treatment, the stress remaining in the semi-finished product processed into a desired shape can be released. In addition, this pre-heat treatment can alleviate thermal deformation at the brazing temperature (1150 to 1300 ° C.) and can improve the reliability of the brazed joint by improving the thermal uniformity of the entire brazing material. .

  Thereafter, the preheated semi-finished product and the member to be brazed are subjected to a brazing treatment at a temperature of 1150 to 1300 ° C., preferably 1170 to 1280 ° C. in a vacuum atmosphere (or almost in a vacuum atmosphere). By this brazing process, a melting reaction of the brazing material layer 15 (brazing material) occurs, and the brazing material flows out and gathers at the brazed joint. The brazing material gathered at the brazed joint is cooled and solidified to obtain a brazed product in which the semi-finished product and the member to be brazed are joined via the brazed joint.

  In the brazing clad material 10 (see FIG. 1) according to the present embodiment, the concentration of the Cr component in the entire brazing material layer 15 is adjusted to 4 to 20.5% by weight so as not to impair the hot metal flowability of the brazing material. Therefore, the hot metal flowability of the brazing material is good.

  Further, in the brazing clad material 10 according to the present embodiment, a nickel layer 14 having a melting point higher than that of the copper layer 13 is disposed on the outer layer side (upper side in FIG. 1) of the copper layer 13. For this reason, when the brazing process is performed at a temperature equal to or higher than the melting point of the copper layer 13, the copper layer 13 is melted, but the molten Cu is blocked by the unmelted nickel layer 14. There is no risk of running out. Further, since the entire surface of the copper layer 13 is closed with the nickel layer 14, the Ni component and the Cr component are supplied into the copper layer 13 from the entire surface of the unmelted nickel layer 14.

  Therefore, the Ni component and the Cr component can be sufficiently diffused into the copper layer 13 and mixed with the Cu component, and there is no possibility of insufficient diffusion (supply) of the Ni component and the Cr component. Further, there is no possibility that local thickness reduction of the nickel layer 14 and non-uniformity (variation) of the composition (Cu component, Ni component, and Cr component) in the brazed joint will occur. Since a dense protective film mainly composed of Cr oxide with high corrosion resistance is formed on the surface layer of the brazed joint, and the Ni and Cr components in the brazed joint are uniform, the brazed joint In this case, there is no possibility that local strength reduction or corrosion resistance reduction occurs, and the reliability of the brazed joint is high.

  Furthermore, since the brazing clad material 10 according to the present embodiment is constituted by a general-purpose product having excellent workability such as rolling, pressing, drawing, etc., each constituent layer of the base material 11 and the brazing material layer 15 is configured. The processing is simple and the manufacturing cost is low.

  Moreover, since the brazing clad material 10 according to the present embodiment is provided with the brazing material and the base material 11 integrally, the conventional brazing joint portion between the base material 11 and the brazed member is used. The operation | work of arrange | positioning brazing | waxing material like a powder brazing material becomes unnecessary. For this reason, when manufacturing a brazing product, it becomes excellent in productivity (workability, assembling property, handling property, etc. of the brazing clad material 10).

  The brazing clad material 10 according to the present embodiment is not only a heat exchanger product such as a fuel cell heat exchanger or an EGR cooler, but also all brazed products that require high corrosion resistance at a brazed joint. It is applicable to.

  As described above, the present invention is not limited to the above-described embodiment, and it goes without saying that various other things are assumed.

  Next, although this invention is demonstrated based on an Example, this invention is not limited to this Example.

Example 1
On the surface of the base material stainless steel strip (SUS304 strip), a Cu strip with a thickness of 1.0 mm and a Ni-20 mass% Cr strip with a thickness of 0.34 mm are laminated in order, and then clad by a rolling method. Thus, a composite material was produced. Further, rolling was repeated to produce a brazing clad material (Ni-Cr / Cu / SUS304) in which the total thickness of the two-layered brazing material layer was 40 μm. The concentration of Cr component in the entire brazing filler metal layer was 5% by mass.

  This clad material is first preheated to 900 ° C in a tube furnace in a vacuum atmosphere, and the preheated clad material is subjected to a heat treatment (brazing treatment) at 1200 ° C to melt the brazing material layer. Evaluation was performed.

(Example 2)
On the surface of the base material stainless steel strip (SUS304 strip), a Cu strip with a thickness of 1.0 mm and a Ni-30 mass% Cr strip with a thickness of 0.69 mm are laminated in order, and then clad by a rolling method. Thus, a composite material was produced. Using this composite material, a brazing clad material was produced in the same manner as in Example 1. The concentration of the Cr component in the entire brazing filler metal layer was 12% by mass. Using this clad material, the brazing characteristics were evaluated in the same manner as in Example 1.

(Example 3)
On the surface of the stainless steel strip (SUS304 strip) that is the base material, a 0.5 mm thick Cu strip and a 0.52 mm thick Ni-40 mass% Cr strip are laminated in order and clad by a rolling method. Thus, a composite material was produced. Using this composite material, a brazing clad material was produced in the same manner as in Example 1. The concentration of Cr component in the entire brazing filler metal layer was 20% by mass. Using this clad material, the brazing characteristics were evaluated in the same manner as in Example 1 except that the brazing temperature was 1250 ° C.

(Comparative Example 1)
On the surface of the stainless steel strip (SUS304 strip) that is the base material, a Cu strip with a thickness of 1.0 mm and a Ni-20 mass% Cr strip with a thickness of 0.18 mm are sequentially laminated and clad by a rolling method. Thus, a composite material was produced. Using this composite material, a brazing clad material was produced in the same manner as in Example 1. The concentration of the Cr component in the entire brazing filler metal layer was 3% by mass. Using this clad material, the brazing characteristics were evaluated in the same manner as in Example 1.

(Comparative Example 2)
On the surface of the base material stainless steel strip (SUS304 strip), in order, 0.29 mm thick Ni-40 mass% Cr strip, 0.5 mm thick Cu strip, 0.29 mm thick Ni-40 A mass% Cr strip was laminated and clad by a rolling method to produce a composite material. Using this composite material, a brazing clad material was produced in the same manner as in Example 1. The concentration of the Cr component in the entire brazing filler metal layer was 21% by mass. Using this clad material, the brazing characteristics were evaluated in the same manner as in Example 1.

(Comparative Example 3)
On the surface of the stainless steel strip (SUS304 strip) as the base material, a Ni-20 mass% Cr strip with a thickness of 0.34 mm and a Cu strip with a thickness of 1.0 mm are laminated in order, and then clad by a rolling method. Thus, a composite material was produced. Using this composite material, a brazing clad material was produced in the same manner as in Example 1. The concentration of Cr component in the entire brazing filler metal layer was 5% by mass. Using this clad material, the brazing characteristics were evaluated in the same manner as in Example 1.

(Comparative Example 4)
On the surface of the base material stainless steel strip (SUS304 strip), a Ni-30 mass% Cr strip with a thickness of 0.69 mm and a Cu strip with a thickness of 1.0 mm are laminated in order, and then clad by a rolling method. Thus, a composite material was produced. Using this composite material, a brazing clad material was produced in the same manner as in Example 1. The concentration of the Cr component in the entire brazing filler metal layer was 12% by mass. Using this clad material, the brazing characteristics were evaluated in the same manner as in Example 1.

(Conventional example 1)
A Cu strip was laminated on the surface of a stainless steel strip (SUS304 strip) as a base material and clad by a rolling method to produce a composite material. Further, rolling was repeated to produce a brazing clad material (Cu / SUS304) having a Cu layer thickness of 40 μm. The clad material was subjected to a heat treatment at 1120 ° C. in a tubular furnace to melt the brazing material layer, and the brazing characteristics were evaluated.

  Table 1 shows the laminated structure and the concentration (% by mass) of the Cr component in the entire brazing material layer for each of the samples of Examples 1 to 3, Comparative Examples 1 to 4, and Conventional Example 1. Table 1 also shows the evaluation of the brazing characteristics of each sample. The evaluation of the brazing characteristics was performed with respect to variations in brazing material composition in the brazed joint, presence or absence of occurrence of corrosion, fillet formation state (water flowability), and comprehensive evaluation thereof.

  Regarding the variation in composition, first, as shown in FIG. 3, each sample 31 of Examples 1 to 3, Comparative Examples 1 to 4, and Conventional Example 1 and the stainless steel pipe 32 were brazed and joined, and the sample 30 was Produced. As shown in FIG. 4, in the cross-sectional portion of the brazed joint 35 of each sample 30, five areas 41 were extracted, and each area 41 was subjected to EDX analysis. The EDX analysis values in each area 41 were compared, and a sample having a Ni component and Cr component concentration variation of 5% by mass or more was evaluated as “variable”.

  In the corrosion test, first, each sample after the brazing treatment was immersed in a corrosive solution containing chlorine ions, nitrate ions, and sulfate ions for 1000 hours. Thereafter, each of these samples was taken out of the solution, and the structure of the brazed joint (brazing melted portion) was observed, and the presence or absence of corrosion was evaluated to evaluate the corrosion resistance. At the same time, the solution after the corrosion test was analyzed, and a quantitative comparison of the eluate eluted from the brazing material into the solution was performed to determine the degree of corrosion.

  Hot water flow is measured by placing a stainless steel pipe made of SUS304 on the surface of the brazing filler metal layer of each sample, heating and brazing, measuring the cross-sectional area of the fillet at the brazed joint, Evaluation was performed according to the size of the area.

  As shown in Table 1, in each of the samples of Examples 1 to 3, the Ni—Cr alloy layer is disposed outside the brazing filler metal layer, and the concentration of the Cr component in the entire brazing filler metal layer is 4 to 20.5 mass. % Has been adjusted. For this reason, each sample of Examples 1-3 did not have dispersion | variation in the composition of a brazing junction. In addition, each of the samples of Examples 1 to 3 had good corrosion resistance (no occurrence of corrosion) and good hot water flow. Therefore, the overall evaluation of the brazing characteristics of the samples of Examples 1 to 3 was good. In particular, the sample of Example 3 having a high Cr component concentration of 20% by mass had very good corrosion resistance.

  On the other hand, in each sample of Comparative Examples 1 and 2, since the Ni—Cr alloy layer was disposed outside the brazing material layer, there was no variation in the composition of the brazed joint. However, the Cr component concentration in the entire brazing filler metal layer was outside the specified range (3% by mass and 21% by mass), respectively. For this reason, the sample of Comparative Example 1 in which the concentration of the Cr component is too low has not been sufficiently resistant to corrosion. Moreover, the sample of Comparative Example 2 in which the concentration of the Cr component was too high deteriorated the hot water flowability and became insufficient.

  In each sample of Comparative Examples 3 and 4, the concentration of Cr component in the entire brazing filler metal layer was within the specified range (5% by mass and 12% by mass), respectively. However, since the Ni-Cr alloy layer is arranged in the inner layer of the brazing material layer and not in the outer layer, the composition of the brazed joint varies, resulting in insufficient corrosion resistance (corrosion occurs) did).

  On the other hand, in the sample of Conventional Example 1, since the brazing material is made of a single metal (Cu), there was no variation in the composition of the brazed joint, and the hot metal flowability was good. However, since the brazing material is composed of Cu alone, the corrosion resistance is not sufficient, and the result is that it cannot be used in a highly corrosive environment.

  From the above results, a brazing clad material in which a base material and a brazing material layer having a layer structure of a Cu layer and a Ni—Cr alloy layer in order from the base material surface are integrated, and the brazing material layer of the clad material It was confirmed that excellent corrosion resistance and hot water flowability can be achieved by defining the Cr component concentration in the whole as 4 to 20.5% by mass.

1 is a cross-sectional view of a brazing clad material according to a preferred embodiment of the present invention. It is a cross-sectional view showing a modification of the brazing clad material in FIG. It is a cross-sectional view of the sample for evaluating the dispersion | variation in the brazing filler metal composition in a brazing joint part. It is a principal part enlarged view of FIG.

DESCRIPTION OF SYMBOLS 10 Brazing clad material 11 Base material 13 Copper layer 14 Nickel layer 15 Brazing material layer

Claims (4)

In a brazing clad material composed of a composite material in which a brazing material layer is integrally provided on the surface of a base material and brazed to a member to be brazed,
The brazing filler metal layer is composed of a copper layer and a nickel layer laminated in this order from the base material side. The nickel layer has a melting point higher than that of the copper layer and is composed of a Ni alloy containing a Cr component. A brazing material for brazing, wherein the composition of the entire brazing material layer is Cu-Ni-4 to 20.5 mass% Cr .   The clad material for brazing according to claim 1, wherein the copper layer is made of a Cu alloy containing 0.02 to 10.0 mass% of P.   The clad material for brazing according to claim 1 or 2, wherein the base material is made of stainless steel. A brazed product obtained by brazing the brazing clad material according to any one of claims 1 to 3 and a member to be brazed, wherein the Ni component and the Cr component vary in concentration at the brazed joint. Brazed product characterized by less than 5% by weight.

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