JP2005297047A - Brazing composite material and brazing product using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brazing composite material and a brazing product using the same, in which there is no possibility that a brittle intermetallic compound layer is generated during annealing treatment and the brazing material is hardly corroded. It is.
A brazing composite material 10 according to the present invention is brazed to a member to be brazed, and a brazing layer 15 includes a Ti or Ti alloy layer 13, a Ni or Ni alloy layer 12, and a Fe. Or, it is composed of a laminate of at least three layers of the Fe alloy layer 14, and between the Ti or Ti alloy layer 13 and the Fe or Fe alloy layer 14, Ti and Fe react to produce a brittle intermetallic compound. The Ni or Ni alloy layer 12b is disposed as a reaction preventing layer that suppresses this.
[Selection] Figure 1

Description

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

  Stainless steel-based clad materials are used as joining materials for automobile oil coolers. In this case, a Cu material 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, as a brazing material for members made of stainless steel, Ni-base or Co-base alloy, various Ni brazing materials having excellent corrosion resistance at the brazed joint are defined by JIS standards. Furthermore, as a Ni brazing material used for joining heat exchangers, a powder obtained by adding 4 to 22 wt% of a metal powder selected from Ni, Cr, or Ni—Cr alloy to a powdered Ni brazing material Ni brazing filler metal has been proposed (see, for example, Patent Document 1).

  In addition, there is a self-brazing composite material having a brazing layer made of Ni and Ti on the surface of stainless steel as a base material (see, for example, Patent Document 2). As shown in FIG. 6, this self-brazing composite material has a Ni or Ni alloy layer 12, a Ti or Ti alloy layer 13, and a Ni or Ni alloy layer 12 in this order from the substrate 11 side on the surface of the substrate 11. A laminated brazing layer 65 is integrally provided.

JP 2000-107883 A Japanese Patent Laid-Open No. 7-299592

  The brazing layer 65 (brazing material) of the self-brazing composite material 60 described in Patent Document 2 described above is composed of Ti or a Ti alloy at a ratio of 60 to 70 mass% and Ni or a Ni alloy at a ratio of 40 to 30 mass%. Yes. Therefore, when the brazing material is a material containing an Fe component such as stainless steel, when the brazing material is melted at a brazing treatment temperature, for example, 1150 ° C., the Fe component of the brazing material is contained in the brazing material. The material to be brazed may be eroded. The concentration of the Fe component in the brazed joint after the brazing treatment varies in the range of about 20 to 40 mass% depending on the Ni / Ti ratio in the brazing material.

  Here, the degree of erosion of the brazing material increases as the amount of brazing material increases. For this reason, depending on the degree of erosion, the structural strength of the brazing material is significantly impaired, or the brazing material is thinned. As a result, there has been a problem that the strength of the brazed joint is lowered.

  In order to prevent the brazing material from eroding, as a constituent material of the brazing layer, there is a brazing composite material using a Ni or Ni alloy layer, a Ti or Ti alloy layer and an Fe or Fe alloy layer. By using the Fe or Fe alloy layer, when the brazing material is melted, the Fe component of the Fe or Fe alloy layer is dissolved in the brazing material, so that the elution of the Fe component of the brazing material into the brazing material is suppressed. Is done. As a result, erosion of the brazing material is suppressed.

  By the way, when brazing a brazing composite material 60 described in Patent Document 2 or a brazing composite material using an Fe or Fe alloy layer as a constituent material of a brazing layer, the brazing treatment is performed. Prior to annealing, the brazing composite material is subjected to press molding. The annealing treatment is performed to ensure elongation during press molding.

  However, during this annealing treatment, the Ti component of the Ti or Ti alloy layer constituting the brazing layer reacts with the Fe component of the Fe or Fe alloy layer, and the Ti or Ti alloy layer and the Fe or Fe alloy layer are reacted. A brittle intermetallic layer is produced at the interface. As a result, at the time of press molding, the brazing composite material may be broken or damaged, or the brazing layer may be peeled off from the base material, which may cause problems in the brazing assembly process. It was.

  The purpose of the present invention created in view of the above circumstances is that there is no possibility of forming a brittle intermetallic compound layer during annealing, and there is almost no risk of the brazing material being eroded. It is to provide a composite material and a brazing product using the same.

To achieve the above object, the brazing composite material according to the present invention is composed of a composite material in which a brazing layer is integrally provided on the surface of a base material, and is brazed to a brazed member. In composite materials,
The brazing layer is composed of a laminate of at least three layers, and between the first metal layer and the second metal layer, both metals react to prevent formation of a brittle intermetallic compound. The reaction preventing layer is provided. The layer thickness of the reaction preventing layer is preferably 6 μm or more.

Further, the brazing composite material according to the present invention is composed of a composite material in which a brazing layer is integrally provided on the surface of a base material, and in the brazing composite material to be brazed with a member to be brazed,
The brazing layer is composed of a laminate of at least three layers of Ti or Ti alloy layer, Ni or Ni alloy layer, Fe or Fe alloy layer, and between the Ti or Ti alloy layer and the Fe or Fe alloy layer. In addition, a Ni or Ni alloy layer is disposed as a reaction preventing layer that suppresses the formation of brittle intermetallic compounds by reaction of Ti and Fe.

  Here, the thickness of the Ni or Ni alloy layer is preferably 6 μm or more.

  The ratio of [Ni] weight to [Ni + Ti] weight of the brazing layer is preferably 0.55 to 0.70. Moreover, it is preferable that the ratio of Fe which occupies for the whole brazing layer is 10-30 mass%.

  The base material is preferably composed of an alloy containing Fe as a main component. Further, the alloy containing Fe as a main component is preferably stainless steel.

  On the other hand, the brazing product according to the present invention is obtained by brazing and joining the above-mentioned brazing composite material and a member to be brazed.

  According to the present invention, it is possible to obtain a brazing composite material having good press formability and capable of suppressing the erosion of a brazing material and a base material.

  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 composite material according to a preferred embodiment of the present invention is shown in FIG.

  As shown in FIG. 1, a brazing composite material 10 according to the present embodiment is brazed to a member to be brazed and brazed to the surface of the base material 11 (only the upper surface in FIG. 1). The adhesive layer 15 is provided integrally. By appropriately rolling the brazing composite material 10, a brazing composite material (final product) 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 layer 15 includes at least 3 of a Ti or Ti alloy layer (hereinafter referred to as a Ti layer), a Ni or Ni alloy layer (hereinafter referred to as a Ni layer), and a Fe or Fe alloy layer (hereinafter referred to as a Fe layer). It is composed of a laminate of layers. More specifically, the brazing layer 15 is arranged between the base material 11 and the Fe layer 14 and between the base material 11 and the Fe layer 14 when the Fe layer 14 and the Ti layer 13 are arranged and laminated in this order from the base material 11 side. Ni layers (reaction prevention layers) 12a and 12b, which are reaction prevention layers, are interposed between the layer 13 and the Ni layer 12c on the Ti layer 13, and are laminated and clad.

  The base material 11 is comprised with the material same or substantially the same as the structural member (brazed member) which comprises the brazing product mentioned later. For example, the constituent material of the substrate 11 is preferably an Fe-based alloy containing Fe as a main component, more preferably stainless steel, and particularly preferably austenitic stainless steel.

  Of the Ni layers 12a to 12c in the brazing layer 15, the layer thickness of the Ni layer 12b (hereinafter referred to as the second Ni layer 12b) interposed between the Fe layer 14 and the Ti layer 13 is adjusted to 6 μm or more. . Here, if the layer thickness of the second Ni layer 12b is less than 6 μm, the layer thickness of the Ni layer is too thin to prevent the reaction between Fe and Ti during the annealing process, and between the Fe layer 14 and the Ti layer 13. This is because a Ti—Fe-based intermetallic compound layer is formed. As a result, cracks (breaks) occur in the brazing composite material 10 during press molding described later.

  The grounds for defining the thickness of the second Ni layer 12b as 6 μm or more are as follows. When an annealing treatment is performed on the laminate of Ti layer / Ni layer / Fe layer under a certain heat treatment condition (for example, 900 to 942 ° C. × several minutes), the layer thickness is about 4 μm at the interface between the Ti layer and the Ni layer. A Ni—Ti reaction layer having a thickness of about 2 μm is formed at the interface between the Ni layer and the Fe layer. For this reason, if the layer thickness of the 2nd Ni layer 12b is more than the total value of the layer thickness of each reaction layer (6 micrometers or more), it is thought that the direct reaction of Fe and Ti can be prevented.

  The method for forming the Ni layers 12a to 12c in the brazing layer 15 is not particularly limited. For example, simply layering the Ni layer 12a, the Fe layer 14, the Ni layer 12b, the Ti layer 13, and the Ni layer 12c in this order, or stacking the Fe layer 14 and the Ti layer 13 with Ni plating films on both sides, A brazing layer 15 may be formed.

  The reason why the annealing heat treatment conditions are set to, for example, 900 to 942 ° C. (excluding 942 ° C.) is as follows. 942 ° C. is the melting start temperature of the Ni—Ti interface. For this reason, when the annealing temperature is 942 ° C. or higher, the Ni—Ti-based alloy starts to melt, and the shape of the brazing material cannot be maintained. As a result, the surface state of the brazing material is deteriorated, and a brittle intermetallic compound layer is exposed, or the brazing layer 15 is peeled off during press molding described later. Moreover, when the annealing temperature is less than 900 ° C., the base material 11 cannot be sufficiently softened, and the brazing composite material 10 is cracked (broken) during press molding described later. The temperature of the annealing treatment and the heating time are appropriately adjusted according to the layer structure of the brazing layer 15, the composition of each layer, and the layer thickness.

  The ratio (Ni / Ni + Ti) of the [Ni] weight and the [Ni + Ti] weight of the brazing layer 15 is adjusted to 0.55 to 0.70. These adjustments are made by adjusting the thicknesses of the layers 12 and 13 and adjusting the alloy compositions of the layers 12 and 13. Here, when Ni / Ni + Ti is less than 0.55 or exceeds 0.70, the melting point of the entire brazing material increases, so that the brazing treatment temperature becomes high (for example, 1200 ° C. or more). As a result, the strength of the brazing material and the base material 11 itself decreases, which is not preferable.

  The ratio of Fe in the entire brazing layer 15 is adjusted to 10 to 30 mass%, preferably 15 to 25 mass%. In other words, the brazing composite material 10 is adjusted so that the composition of the entire brazing layer 15 is Ni-Ti-10 to 30 mass% Fe. These adjustments are made by adjusting the thicknesses of the layers 12, 13, and 14, adjusting the alloy compositions of the layers 12, 13, and 14. Here, when the ratio of Fe is less than 10 mass%, it is not possible to sufficiently suppress the elution of the Fe component from the brazing material and the base material 11. Moreover, since the melting | fusing point of the whole brazing material will raise when the ratio of Fe exceeds 30 mass%, brazing processing temperature will become higher temperature and, as a result, the intensity | strength of the brazing material and the base material 11 will fall. .

  The brazing composite material 10 thus obtained is appropriately subjected to annealing treatment and press molding (pressing) to form a semi-finished product of a desired shape, and then a brazed member for joining with the semi-finished product. (Not shown) are combined, and a portion for performing brazing joining (brazing joining portion) is brought into contact. Then, brazing products are obtained by carrying out the brazing process by heating to these combination members by making a brazing junction into a main. Alternatively, the brazing composite material 10 may be used as a member to be brazed. For example, preparing a plurality of brazing composite materials 10 according to the present embodiment, appropriately pressing each composite material 10 to form a semi-finished product of a desired shape, and then combining those semi-finished products, 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.

  Brazing products include heat exchangers exposed to high-temperature, highly corrosive gases or liquids such as EGR coolers, fuel cell reformer coolers, fuel cell members, oil coolers, radiators, secondary battery members, etc. Can be mentioned.

  In the present embodiment, a brazing composite having a brazing layer 15 having a five-layer structure in which a Ni layer 12a, an Fe layer 14, a Ni layer 12b, a Ti layer 13, and a Ni layer 12c are laminated in this order from the substrate side. The material 10 was described. However, the structure of the brazing layer is not particularly limited to this, and any brazing layer having a layer structure in which an Ni layer as a reaction preventing layer is interposed between the Fe layer 14 and the Ti layer 13 may be used. . For example, a brazing layer having a three-layer structure in which the Fe layer 14, Ni layer 12b, and Ti layer 13 are laminated in this order from the substrate side, and the Ni layer 12a, Fe layer 14, Ni layer 12b, and Ti layer from the substrate side A brazing layer having a four-layer structure laminated in the order of 13 or a brazing layer having a six-layer structure or more may be used.

  Moreover, in this Embodiment, although the brazing composite material 10 which provided the brazing layer 15 only in the single side | surface (FIG. 1 upper surface) of the base material 11 was demonstrated, it does not specifically limit to this. . For example, a brazing composite material in which the brazing layer 15 is provided on both surfaces (upper and lower surfaces in FIG. 1) of the base material 11 may be used.

  Furthermore, in this Embodiment, although demonstrated using the composite material 10 for brazing which exhibited foil shape, the shape of a composite material is not specifically limited to foil shape. For example, the brazing layer 15 formed by laminating the Ni layer 12, the Fe layer 14, the Ni layer 12, the Ti layer 13, and the Ni layer 12 in this order from the substrate side is integrally formed on the surface of the rod-shaped or wire-shaped substrate. It is also possible to provide a composite material for brazing. In this case, the layers 12, 13, and 14 are formed by a plating method, an extrusion method, a pipe making method, or the like.

  Next, the operation of the present embodiment will be described.

  When the annealing treatment is applied to the brazing composite material 10 according to the present embodiment, the base material 11 is softened. Further, the Ti component of the Ti layer 13 in the brazing layer 15 and the Ni components of the Ni layers 12b and 12c are gradually dissolved and diffused to each other. Further, by this annealing treatment, the Fe component of the Fe layer 14 in the brazing layer 15 and the Ni component of the Ni layers 12a and 12b are gradually melted and diffused to each other. As a result, a Ni—Ti reaction layer is generated at the interface between the Ti layer 13 and the Ni layers 12b and 12c, and a Ni—Fe reaction layer is generated at the interface between the Fe layer 14 and the Ni layers 12a and 12b.

  Here, in the brazing composite material 10 according to the present embodiment, the thickness of the second Ni layer 12b is adjusted to a thickness (6 μm or more) sufficient to prevent direct contact between the Ti component and the Fe component. ing. For this reason, generation of a layer of Ti—Fe intermetallic compound at the interface between the Fe layer 14 and the Ti layer 13 is suppressed.

  The brazing composite material 10 after the annealing treatment is pressed to produce a semi-finished product. At this time, the base material 11 in the brazing composite material 10 is sufficiently softened by the annealing treatment. Further, almost no Ti—Fe-based intermetallic compound layer is formed at the interface between the Fe layer 14 and the Ti layer 13 of the brazing layer 15. Therefore, cracks do not occur during press working, and a semi-finished product with a desired shape can be obtained with a good yield.

This semi-finished product and a 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, so that a brazing reaction of the brazing layer 15 (brazing material) occurs at the brazed joint. The brazing is performed at a temperature of 1130 to 1150 ° C. in a vacuum atmosphere of 1 × 10 ⁻² Pa or less, for example.

  By this brazing treatment, first, the diffusion reaction between the Ti layer 13 and the Ni layers 12b and 12c in the brazing material further proceeds and is alloyed. Here, Ni, Ti having a melting point exceeding 1400 ° C. alone is alloyed by adjusting the ratio of [Ni] weight to [Ni + Ti] weight (Ni / Ni + Ti) to 0.55 to 0.70. The melting point decreases in a part of the material (the upper part in FIG. 1), and the brazing material begins to melt at a temperature of about 1100 to 1200 ° C.

  Thereafter, the Fe layer 14 is melted, and the Ti component, Ni component, and Fe component are mixed, and the brazing material flows. Since the Fe layer 14 is melted in the brazing material before the brazing material flows, the Fe concentration of the entire molten brazing material is 10 to 30 mass%, which is the same as the Fe concentration of the entire brazing layer 15. Here, even when the brazing material and the Fe component of the base material 11 are dissolved in the brazing material during the brazing process, the melting occurs until the Fe concentration reaches saturation, and the Fe that can be melted. There is a limit to the amount. Therefore, the penetration of the Fe component of the brazing material and the base material 11 into the brazing material is suppressed, and the occurrence of erosion of the brazing material and the base material 11 can be greatly reduced. Moreover, since the Fe density | concentration in a brazing material is adjusted to 10-30 mass% so that the hot water flow property of a brazing material may not be inhibited, the hot water flow property of a brazing material also becomes favorable. As a result, after brazing, the strength of the brazed joint between the material to be brazed and the substrate 11 does not decrease, and the reliability of the brazed joint is good.

  Thus, by brazing and joining the brazing composite material 10 and the member to be brazed (stainless steel plate) according to the present embodiment, a brazed product with less erosion at the brazed joint is industrially produced. It can be manufactured stably. This brazing product has high reliability because there is almost no decrease in the strength of the brazing material and the base material 11 before and after brazing, and the brazing material and the base material 11 are hardly eroded.

  Moreover, the base material 11 and the member to be brazed can be obtained by using the brazing material and the base material 11 provided integrally as in the brazing composite material 10 (see FIG. 1) according to the present embodiment. The operation | work which arrange | positions a brazing material to a brazing joint part with becomes unnecessary. For this reason, a brazed product can be obtained with good brazing productivity.

  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 these Examples.

(Example 1)
A Ni plate having a plate thickness of 0.6 mm, a Ti plate having a plate thickness of 2.3 mm, a Ni plate having a plate thickness of 0.8 mm, a Fe plate having a plate thickness of 0.5 mm, and a Ni plate having a plate thickness of 0.8 mm are sequentially stacked. A layered laminate was formed. This laminate was hot-rolled to obtain a clad plate having a thickness of 1.4 mm. This clad plate was cold-rolled to produce a clad plate having a thickness of 0.25 mm.

  This clad plate was superposed on a 2.25 mm thick stainless steel plate (SUS304 plate material) as a base material and clad by a rolling method to produce a composite material. This composite material is repeatedly subjected to cold rolling treatment, and the thickness of the layer is 50 μm. The composite material for brazing (sheet thickness) has a five-layer structure (Ni / Ti / Ni / Fe / Ni / (SUS)). Was 0.5 mm). The thickness of the second Ni layer (the Ni layer between the Fe layer and the Ti layer) is 8 μm, and the Fe concentration in the entire brazing layer is 11 mass%.

(Example 2)
A Ni plate having a thickness of 0.4 mm, an Fe plate having a thickness of 0.9 mm, a Ni plate having a thickness of 0.7 mm, a Ti plate having a thickness of 2.3 mm, and a Ni plate having a thickness of 0.7 mm are sequentially stacked. A layered laminate was formed. Thereafter, in the same manner as in Example 1, a brazing composite material (plate thickness is 0.5 mm) having a layer thickness of 50 μm and a brazing layer having a five-layer structure (Ni / Fe / Ni / Ti / Ni / (SUS)). mm). The thickness of the second Ni layer is 7 μm, and the Fe concentration in the entire brazing layer is 20 mass%.

(Example 3)
The thickness of the Ni plate is 0.8 mm, the Ti plate is 3.4 mm, the Ni plate is 0.9 mm, the Fe plate is 1.5 mm, and the Ni plate is 0.9 mm. A layered laminate was formed. Thereafter, in the same manner as in Example 1, a brazing composite material having a layer thickness of 75 μm and a brazing layer having a five-layer structure (Ni / Ti / Ni / Fe / Ni / (SUS)) (plate thickness of 0.5 mm). The thickness of the second Ni layer is 9 μm, and the Fe concentration in the entire brazing layer is 24 mass%.

(Comparative Example 1)
A Ni plate having a thickness of 0.6 mm, a Ti plate having a thickness of 1.9 mm, a Ni plate having a thickness of 0.4 mm, a Fe plate having a thickness of 1.3 mm, and a Ni plate having a thickness of 0.8 mm are sequentially stacked. A layered laminate was formed. Thereafter, in the same manner as in Example 1, a brazing composite material having a thickness of 50 μm and a brazing layer having a five-layer structure (Ni / Ti / Ni / Fe / Ni / (SUS)) (plate thickness of 0.5 mm). The thickness of the second Ni layer is 4 μm, and the Fe concentration in the entire brazing layer is 30 mass%.

(Comparative Example 2)
5 mm by sequentially stacking a Ni plate having a thickness of 0.7 mm, a Fe plate having a thickness of 0.9 mm, a Ni plate having a thickness of 0.4 mm, a Ti plate having a thickness of 2.3 mm, and a Ni plate having a thickness of 0.7 mm. A layered laminate was formed. Thereafter, in the same manner as in Example 1, a brazing composite material having a layer thickness of 50 μm and a brazing layer having a five-layer structure (Ni / Fe / Ni / Ti / Ni / (SUS)) (plate thickness of 0.5 mm). The thickness of the second Ni layer is 4 μm, and the Fe concentration in the entire brazing layer is 20 mass%.

(Comparative Example 3)
A Ni plate having a thickness of 1.2 mm, a Fe plate having a thickness of 1.1 mm, a Ni plate having a thickness of 1.2 mm, a Ti plate having a thickness of 3.7 mm, and a Ni plate having a thickness of 0.3 mm are sequentially stacked. A layered laminate was formed. Thereafter, in the same manner as in Example 1, a brazing composite material having a layer thickness of 75 μm and a brazing layer having a five-layer structure (Ni / Fe / Ni / Ti / Ni / (SUS)) (plate thickness of 0.5 mm). The thickness of the second Ni layer is 12 μm, the thickness of the third Ni layer (Ni layer between the Ti layer and the stainless steel layer) is 3 μm, and the Fe concentration in the entire brazing layer is 20 mass%.

(Conventional example 1)
A Ni plate having a thickness of 2.4 mm and a Ti plate having a thickness of 2.6 mm were overlapped to form a laminate having a two-layer structure. Thereafter, in the same manner as in Example 1, a composite material for brazing (plate thickness: 0.5 mm) having a layer thickness of 50 μm and having a two-layer structure (Ni / Ti / (SUS)) brazing layer was produced.

  For each of the composite materials for brazing of Examples 1 to 3, Comparative Examples 1 to 3, and Conventional Example 1, their laminated structure, the thickness of the entire brazing layer (μm), the thickness of the second Ni layer (μm) Table 1 shows the Fe concentration (mass%) in the entire brazing layer. Table 1 also shows the results of the remaining ratio (%) of the base material after the brazing treatment and the press formability of each composite material for brazing.

  Here, each brazing composite material is subjected to an annealing treatment before the brazing treatment. About each composite material for brazing of Examples 1-3 and the prior art example 1, the annealing process of 930 * 4min was performed in the continuous annealing furnace. About the composite material for brazing of Comparative Examples 1-3, when the annealing process of the same conditions as each brazing composite material of Examples 1-3 and the prior art example 1 is performed, reaction of Fe and Ti will advance excessively. Therefore, the surface shape is deteriorated such that a fragile layer is exposed on the surface or the surface is wavy. Therefore, the brazing composite materials of Comparative Examples 1 to 3 were subjected to annealing treatment under conditions where the surface shape did not deteriorate, specifically, under a treatment condition of 900 × 4 min in a continuous annealing furnace.

  Each brazing composite material after the annealing treatment is subjected to press molding. Specifically, a sample (20 mm × 25 mm) 21 shown in FIGS. 2A and 2B was cut out from each brazing composite material after the annealing treatment. Thereafter, the vertical bisector of the long side of each sample 21 was creased, and each sample 21 was bent by 90 ° to prepare a sample 31. At this time, it was bent so that the brazing layer was positioned inside the bend.

After that, each sample 31 was placed in a heat treatment furnace with the valleys positioned vertically downward, and each sample 31 was brazed. The brazing treatment is performed under a vacuum atmosphere of 1 × 10 ⁻² Pa or less,
Temperature rise from room temperature to 900 ° C at 10 ° C / min (Step A),
900 ℃ x 30min isothermal hold (Step B),
Increase the temperature from 900 ℃ to 1150 ℃ at 10 ℃ / min (Step C),
1150 ℃ × 15min isothermal hold (Step D),
Rapid cooling (step E),
The heat cycle pattern was used.

Thereafter, as shown in FIG. 4A, each sample 41 after the heat treatment was cut along a perpendicular bisector with a short side. The cross section of each sample 41 was observed, and the degree of erosion of the substrate was evaluated. The degree of erosion was performed using the residual rate (%) of the substrate. The residual rate (%) of the base material is expressed as _follows : t _a is the base material thickness of the sample 21 before the heat treatment, and t _b is the base material thickness of the portion where the base material is thinnest by the molten and solidified brazing material 42. It is expressed by (t _b / t _a ) × 100.

  Further, a 100 mm × 100 mm sample was cut out from each brazing composite material after the annealing treatment. Then, in order to form the convex part 51 which showed the cross-sectional shape shown in FIG. 5, each sample was press-molded and the press-formability was evaluated. The bending radius (R radius) of each bending part in the convex part 51 was 1 mm.

  As shown in Table 1, in each of the brazing composite materials of Examples 1 to 3, the Fe concentration in the entire brazing layer is 11 mass%, 20 mass%, and 24 mass%, and within a specified range (10 to 30 mass%). It was adjusted. For this reason, at the time of brazing treatment, it is greatly suppressed that the Fe component of the base material (or brazing material) is eluted into the brazing material. As a result, each of the brazing composite materials of Examples 1 to 3 is The residual ratio of the base material was 83%, 85%, 87%, and all were 80% or more. Also, the hot metal flowability of the brazing material was good.

  In each of the brazing composite materials of Examples 1 to 3, the thickness of the second Ni layer was 8 μm, 7 μm, and 9 μm, and was adjusted to a specified range (6 μm or more). For this reason, an Fe—Ti-based brittle intermetallic compound is not generated at the interface between the Fe layer and the Ti layer, and as a result, each of the brazing composite materials of Examples 1 to 3 has the convex portion shown in FIG. Even when press forming to form 51 was performed, no cracks were observed and the press formability was good.

  On the other hand, in the brazing composite materials of Comparative Examples 1 and 2, the positions of the Fe layer and the Ti layer are reversed, but the Fe concentration in the entire brazing layer is 30 mass% and 20 mass%. Yes, it was adjusted to the specified range (10-30 mass%). In the brazing composite material of Comparative Example 3, the Fe concentration in the entire brazing layer was 20 mass%, which was adjusted to the specified range (10 to 30 mass%). For this reason, the brazing composite materials of Comparative Examples 1 to 3 each had a base material residual ratio of 90%, 88%, and 85%, which were 80% or more. Also, the hot metal flowability of the brazing material was good.

  However, in each of the brazing composite materials of Comparative Examples 1 and 2, the thickness of the second Ni layer was 4 μm, which was less than the specified range (6 μm or more). For this reason, when the same annealing treatment as in Examples 1 to 3 is performed, a Fe-Ti-based brittle intermetallic compound is generated at the interface between the Fe layer and the Ti layer. Therefore, in order to prevent this, annealing treatment (900 ° C. × 4 min) at a temperature lower than that of Examples 1 to 3 was performed. In the brazing composite material of Comparative Example 3, the layer thickness of the second Ni layer was 12 μm, and was adjusted to a specified range (6 μm or more). For this reason, an Fe—Ti-based brittle intermetallic compound is not generated at the interface between the Fe layer and the Ti layer. However, the thickness of the third Ni layer, which is another reaction preventing layer, is as very thin as 3 μm. For this reason, when the annealing process similar to Examples 1-3 is performed, the Fe-Ti type brittle intermetallic compound will produce | generate at the interface of Ti layer and a stainless steel layer. Therefore, in order to prevent this, annealing treatment (900 ° C. × 4 min) at a temperature lower than that of Examples 1 to 3 was performed.

  As a result, in each brazing composite material of Comparative Examples 1 to 3, the base material was not sufficiently softened, and the elongation of each brazing composite material was lowered. Accordingly, each of the brazing composite materials of Comparative Examples 1 to 3 was cracked when subjected to press forming to form the convex portions 51 shown in FIG. 5, and the press formability was poor.

  On the other hand, the brazing composite material of Conventional Example 1 has good press formability and hot metal flowability of the brazing material, but the brazing material is a Ni-Ti-based binary alloy. A large amount of the Fe component of the material was eluted into the brazing material, and the residual ratio of the base material was as low as 49%.

  As described above, each of the brazing composite materials of Examples 1 to 3 which is a brazing composite material according to a preferred embodiment of the present invention has a high residual rate of the base material, and has good press formability. It can be seen that the brazing material has good hot-water flow and is a brazing composite material with excellent brazing joint reliability.

  The composite material according to a preferred embodiment of the present invention is not limited to a heat exchanger that is exposed to a highly corrosive gas or liquid at a high temperature such as an EGR cooler. For example, the present invention can be applied to various uses such as a fuel cell reformer cooler and a fuel cell member. In particular, a rod-like or wire-like composite material has a small diameter size and good handleability. Therefore, in addition to heat exchangers such as EGR coolers and fuel cell reformer coolers, fuel cell members, etc. In addition, it can also be applied to oil coolers, radiators, secondary battery members, and the like.

1 is a cross-sectional view of a brazing composite material according to a preferred embodiment of the present invention. It is sectional drawing before the bending process of the composite material for brazing in FIG. FIG.2 (b) is an enlarged view of the principal part 2b of Fig.2 (a). It is sectional drawing after the bending process of the composite material for brazing in FIG. It is sectional drawing which shows the state which heat-processed to the composite material for brazing after a bending process. FIG. 4B is an enlarged view of the main part 4b of FIG. It is a partial expanded sectional view after press molding of the brazing composite material in [Example]. It is sectional drawing of the conventional composite material for brazing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Composite material for brazing 11 Base material 12a-12c Ni or Ni alloy layer 13 Ti or Ti alloy layer 14 Fe or Fe alloy layer 15 Brazing layer

Claims (9)

In a composite material for brazing composed of a composite material in which a brazing layer is integrally provided on the surface of a base material and brazed to a member to be brazed,
The brazing layer is composed of a laminate of at least three layers, and between the first metal layer and the second metal layer, both metals react to generate a brittle intermetallic compound. A brazing composite material comprising a reaction preventing layer.   The brazing composite material according to claim 1, wherein the reaction preventing layer has a thickness of 6 μm or more. In a composite material for brazing composed of a composite material in which a brazing layer is integrally provided on the surface of a base material and brazed to a member to be brazed,
The brazing layer is composed of a laminate of at least three layers of Ti or Ti alloy layer, Ni or Ni alloy layer, Fe or Fe alloy layer, and between the Ti or Ti alloy layer and the Fe or Fe alloy layer. And a brazing composite material in which a Ni or Ni alloy layer is disposed as a reaction preventing layer that suppresses the formation of brittle intermetallic compounds by reaction of Ti and Fe.   The brazing composite material according to claim 3, wherein the thickness of the Ni or Ni alloy layer is 6 μm or more.   The brazing composite material according to claim 3 or 4, wherein a ratio of the [Ni] weight and the [Ni + Ti] weight of the brazing layer is 0.55 to 0.70.   The brazing composite material according to any one of claims 3 to 5, wherein a ratio of Fe in the entire brazing layer is 10 to 30 mass%.   The brazing composite material according to any one of claims 1 to 6, wherein the base material is made of an alloy containing Fe as a main component.   The brazing composite material according to claim 7, wherein the alloy containing Fe as a main component is stainless steel. A brazed product comprising the brazing composite material according to any one of claims 1 to 8 and a member to be brazed.

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