JPH02151377A - Alloy foil for liquid phase diffusion joining which can be joined in oxidation atmosphere - Google Patents

Abstract

PURPOSE:To obtain the alloy foil useful for liquid phase diffusion joining and to obtain a joint part having high strength in oxidation atmosphere by incorporating specific rations of B, Si and V into Ni and specifying the thickness of the foil. CONSTITUTION:The compsn. of the alloy foil is composed, by atomic%, 0.5 to <10.0% B, 15.0 to 30.0% Si, 0.1 to 20.0% V, and the balance substantially Ni and inevitable impurities. If necessary, >=1 kinds of 0.1 to 20.0% Cr, 0.1 to 20.0% Fe and 0.1 to 20.0% Mo, and further, >=1 kinds of 0.1 to 10.0% W and 0.1 to 10.0% Co are incorporated therein. The thickness of the foil is specified to 3.0 to 120mum. This alloy foil is preferably substantially glassy. The V is incorporated as the component of an insert metal into this alloy foil, by which the Cr oxide film is converted to the low melting multiple oxide of Cr2O3- V2O5 and is thus spheroidized. The alloy foil is thereby made harmless to the liquid phase diffusion joining.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to liquid phase diffusion bonding of metal materials, and more specifically to liquid phase diffusion bonding of stainless steel, high nickel-based alloys, and heat-resistant alloy steels, or of these alloy steels. The present invention relates to a material for liquid phase diffusion bonding, which is useful for liquid phase diffusion bonding of carbon steel, is capable of bonding in an oxidizing atmosphere, and is capable of obtaining a joint with high bond strength.

[Conventional technology]

Liquid phase diffusion bonding involves bonding foil between the materials to be bonded.

(b) An alloy having a eutectic composition with a melting point lower than that of the materials to be joined is interposed in the form of metal or plating, and the joint is heated to a temperature just above the liquidus line of the insert alloy (hereinafter referred to as insert metal). This is a joining method in which the material is melted and solidified isothermally by heating, and is considered a type of solid phase joining method.

Since liquid phase diffusion bonding can be bonded with relatively low pressure, it is used for bonding where residual stress and deformation due to bonding must be avoided as much as possible, and it is also applicable to bonding high alloy steel and heat-resistant steel that are difficult to weld. This is a technology that has been used.

Materials to be bonded by liquid phase diffusion bonding often contain 1.0% or more of Cr as an alloy composition. C
The r-containing material is dense Cr oxide (often CrzO3)
Because a film is formed on the surface, it is characterized by excellent oxidation and corrosion resistance. Therefore, heating during bonding naturally results in the formation of an oxide film on the bonding surfaces, which inhibits wetting of the molten insert metal and significantly impedes the diffusion of atoms necessary for bonding.

Therefore, conventionally, JP-A-53-81458, JP-A-62
As seen in JP-A-34685 and JP-A-62-227595, the atmosphere is vacuumed during bonding.

It has to be kept inert or reducible, leading to a significant increase in bonding costs.

As a result of repeated research based on the above findings, the present inventors found that insert metal containing (1) as a component can be bonded by liquid phase diffusion even in an oxidizing atmosphere. Moreover, although (■) is an element that increases the melting point of the insert metal, it has been found that by appropriately adjusting other elements (in the present invention, St), it is possible to obtain an insert metal with extremely excellent bonding properties. .

There is almost no precedent for an alloy foil for liquid phase diffusion bonding that contains (2) and has increased 5iil. US Pat. No. 3,856,513 discloses an alloy having the composition M a Y b Z c. In the formula, M is Fe, Ni, Co, V
, Cr, and Y is P, B
, is an element selected from the group consisting of C, and Z is /V, S
j, Sn.

It is an element selected from the group consisting of Ge, In, Sb, and Be, where a is in the range of about 60 to 90 atomic%, and b
is in the range of about 10 to 30 atomic percent, and C is about 0.1 to 1
It is in the range of 5 at.%. Such materials are currently manufactured industrially by rapid cooling from the melt using well-known processing techniques and are in practical use.

However, in this case, (1) is intended to be used as a base material and to make the alloy amorphous, and is not disclosed as an alloy foil for bonding. Furthermore, since the Si content is low and the melting point of the foil is considerably higher than that of the present invention, it is extremely difficult to realize liquid phase diffusion bonding.

In addition, the B content is completely different from that of the present invention, and because it is high, coarse precipitates are formed near the joint on the Mo or Cr-containing alloy side, so that the joint strength cannot be improved by using the foil of the present invention. It is quite low compared to the other parts. JP-A-53-81458 is U.S. Patent No. 3856513
The alloy described in the specification is provided in the form of a foil,
In this case, liquid phase diffusion bonding in an oxidizing atmosphere is completely impossible since it does not contain (1) as a component.

In the present invention, the term "oxidizing atmosphere" refers to a bonding atmosphere that contains 0.1% or more of oxidizing gas by volume and has an oxidation potential of 10 to 10 atm or more, that is, a reducing gas such as H2, Even if it contains H2S, water vapor, etc., it means an atmosphere in which the oxidizing power is equivalent to the oxygen concentration, which is 0.1% or more.

In addition, the term "melting point" refers to the solidus line on the phase diagram of an alloy of two or more elements, unless otherwise specified.

[Problem to be solved by the invention]

The present invention solves the above-mentioned conventional drawbacks, namely, by rendering harmless the Cr oxide film that is formed on the surfaces of materials to be joined during liquid phase diffusion bonding in an oxidizing atmosphere and hindering diffusion bonding, and thereby liquid phase diffusion bonding can be performed even in an oxidizing atmosphere. This was done to make it possible to convert the Cr oxide film into a low melting point Crz (h-vz) by containing V as a component of the insert metal.
The object of the present invention is to provide an alloy foil for liquid phase diffusion bonding that becomes spherical by forming an Os composite oxide and becomes harmless to liquid phase diffusion bonding, thereby realizing liquid phase diffusion bonding in an oxidizing atmosphere.

[Means to solve the problem]

The present inventors have found that when carrying out liquid phase diffusion bonding in an oxidizing atmosphere, bonding is possible by using an insert metal containing 0.1 to 20.0% of ■ and increased Si. Ta.

The present invention was made based on these findings, and its gist is that B: 0.5 to 10.
Less than 0%, St: 15.0-30.0%, ■: 0, 1-
20.0%, or further contains (A) Cr: 0, 1
~20.0%, Fe: 0.1~20.0%, Mo: 0
．． 1 to 20.0% of one or more types and/or (B) W: o, t to 10.0%, Co: 0.1 to 101
0% of one or two types, the remainder has a composition consisting essentially of Ni and unavoidable impurities, and has a thickness of 3.0%.
An alloy foil for liquid phase diffusion bonding that can be bonded in an oxidizing atmosphere, characterized by a thickness of ~120 μm, or an alloy foil for liquid phase diffusion bonding, characterized by being substantially glassy. .

The present invention will be explained in detail below.

[Effect]

First, the reason for limiting the range of each component in the present invention as described above will be described below.

First, B is an element necessary as a diffusion atom to realize isothermal solidification necessary to achieve liquid phase diffusion bonding, or to make the melting point of Ni of the base material lower than that of the materials to be joined.
For each purpose, it is necessary to contain 0.5% or more, but the present inventors conducted detailed research and found that 10%
．． It has been found that if the content is 0% or more, coarse borides with a size of 5 μm or more are generated at the grain boundaries on the side of the Mo- and Cr-containing alloy near the joint, and the strength of the joint is significantly reduced.
The content was 5% to less than 10.0%. This low B content is also one of the features of the present invention.

Next, Si is an element effective in lowering the melting point of the base material Ni, but the alloy foil of the present invention is characterized by containing a large amount of It is necessary to add 15.0% or more to prevent the length from increasing. However, if it exceeds 30.0%, coarse oxides containing St may be generated in the insert metal during liquid phase diffusion bonding in an oxidizing atmosphere, which may deteriorate the strength and toughness of the joint. The component range was limited to 1560-30.0%.

(2) melts and spheroidizes the Cr oxide film on the surface of the Cr-containing alloy to improve wetting of the molten insert metal and the alloy;
It is an extremely important element that realizes liquid phase diffusion bonding in an oxidizing atmosphere by preventing the diffusion of Cr from being inhibited by the Cr oxide film. If the amount added is less than 0.1%, it is insufficient to melt the Cr oxide film, so it is ineffective, and if it is added in excess of 20.0%, the melting point of the insert metal will exceed 1300"C. 0.1 to 20.0% as liquid phase diffusion bonding becomes virtually impossible.
The range of

The above are the basic components of the present invention, but in the present invention, in addition to these, (A) Cr: 0.1 to 0.1 depending on the respective use.
20.0%, Fe: 0.1-20.0%, Mo:
0, 1 to 20.0% of one or more types and/or (B) W: 0. l~to, o%, Co:0. l~1
One or two types can be contained at 0.0%.

First, Cr, Fe, and Mo are elements that are added to reduce the difference in mechanical properties between the alloy and the insert metal when alloy steel containing these is bonded by liquid phase diffusion. The content should be determined within a range commensurate with the steel composition. In addition, if the joint part is likely to be exposed to a corrosive environment, Mo and Cr are used to improve the corrosion resistance of the old insert metal area, and if the material to be joined is heat-resistant steel, Mo and Cr are used to ensure high-temperature strength. Mo as a precipitation strengthening element
, Cr, and Fe are effective. If either element is less than 0.1%, it has no effect, and if it is added in excess of 20.0%, the melting point of the insert metal will exceed 1300°C, making liquid phase diffusion bonding virtually impossible.
．． It was made into the range of 1-20.0%.

Further, W and Co are elements added mainly for the purpose of imparting high strength to the old insert metal part when joining high-strength materials, and are precipitated as intermetallic compounds or carbides, dramatically increasing the strength. If it is less than 0.1%, it will have no effect, and if it exceeds 10.0%, coarse intermetallic compounds will form in the insert metal, which may significantly deteriorate the joint toughness. ~1
The range was 0.0%.

Each of the above-mentioned alloy components may be added individually or in combination.

The alloy foil for liquid phase diffusion bonding of the present invention can be provided as an insert metal in various shapes. For example, it is fully possible and most suitable to make an alloy having any of the components of claimed steels 1 to 4 into a foil by the liquid quenching method based on the chemical components of the present invention. Furthermore, it is also possible to provide the material in the form of a foil by vacuum melting, casting, rolling and annealing in a conventional manner.

The reason why the alloy foil has a glassy crystal structure is that the alloy foil of the present invention needs to be uniformly melted during liquid phase diffusion bonding. This is because if the composition is non-uniform and there is segregation of the alloy components contained, the melting point of the insert metal will differ depending on the position of the joint, making it impossible to obtain a homogeneous joint interface. Needless to say, if an alloy foil with a homogeneous composition can be easily obtained, the crystal structure does not need to be glassy.

In the present invention, the foil is normally manufactured by a liquid quenching method using a molten alloy, but the basic manufacturing method employed here is to spray the molten alloy onto a cooling substrate through a nozzle and rapidly cool it by thermal contact. Among the liquid quenching methods for solidification, the so-called single roll method is suitable. Of course, there are methods that use the centrifugal quenching method that uses the inner wall of the drum, methods that use an endless type belt, improved versions of these methods such as methods that include auxiliary rolls and roll surface temperature control devices, or methods that use the cooling method under reduced pressure, in a vacuum, or This also includes casting in an inert gas. Furthermore, a twin roll method in which molten metal is injected between a pair of rolls and rapidly solidified can also be applied.

The thinner the alloy foil is, the less changes in mechanical properties near the bonding area, and the shorter the time required for bonding, which is advantageous for liquid phase diffusion bonding. However, if the thickness is less than 3.0 μm, the absolute amount of It becomes insufficient to render harmless the Cr oxide film on the surface of the bonding material alloy, and 120. If it exceeds On, the time required to complete liquid phase diffusion bonding will be more than 10 hours, which is impractical, so the thickness is set to 3.0 to 120.0 pm.

The present invention relates to an alloy foil for liquid phase diffusion bonding, but since bonding is possible in the atmosphere, the alloy foil of the present invention can also be applied to bonding methods such as brazing and soldering. Yes, it is useful.

〔Example〕

As shown in Tables 1 to 6, about 100 g of the alloy having the composition according to any one of claims 1 to 4 was prepared by (1) a single roll method (Cu
(2) Melt in a vacuum melting furnace, cast, and then hot rolled in the usual way to form a sheet with a width of 2 to 215 mm, thickness of 30 mm, and Opta foil. did. Note that the foil manufactured by hot rolling was homogenized annealed at 700° C. for 10 hours to eliminate macroscopic non-uniformity of the components. The casting conditions for the quenched foil are a roll circumferential speed of 5.0 to 15
．． It is held between 0 m/s. The width and thickness of the obtained foil were measured at 5 points each to ensure that the above dimensions were obtained, and then subjected to DTA (differential thermal analysis).
The melting point was measured. The melting points are also shown in Tables 1 to 6. The components were then identified through chemical analysis. Tables 1 to 6 show the analysis results, and the unit is atomic %.

Each foil is based on Ni, and the sum of each component is 10
The difference from 0% means the total concentration of Ni and unavoidable impurities. Under the above manufacturing conditions, the crystal structure of each foil will be either an amorphous two-crystal structure or a partially mixed crystalline and amorphous structure, but which structure it takes depends on its composition. It is determined.

Claims 1 to 6 further include a total of 235 foils in Tables 1 to 6.
Liquid phase diffusion bonding was carried out using insert metals satisfying 5 and comparative insert metals (including conventional insert metals) shown in Table 7. The base material of each foil in Table 7 is Ni, and the difference between the sum of each component and 100% is Ni
and the total concentration of unavoidable impurities. The manufacturing method of the foils shown in Table 7 is also exactly the same as that of the foils of the present invention shown in Tables 1 to 6. The shape of the test piece is as shown in Figure 1 <Loom thickness x
10001111II width x 2000 mm length, low carbon steel and 62% Ni corrosion resistant alloy were prepared respectively, and an insert metal was sandwiched between them as shown in FIG. Table 8 shows the chemical components of the materials to be joined used in liquid phase diffusion bonding. The thickness of the insert metal was 3.0 to 500 pm.

The atmosphere is air, and the bonding temperature is just above the melting point of each foil ~ melting point +50
``C range, and substantially 1050℃ using a large heating furnace.
Bonding was performed at ~1300°C. No particular pressure was applied, and both were joined by their own weight. The joining time was all 1 hour, and in order to ensure the strength, corrosion resistance, and toughness of the unjoined materials, the heat treatment after joining was annealing, quenching + annealing, annealing and ten-tempering, quenching, ten-annealing, and ten-tempering, as appropriate. or in combination. During these heat treatments, interdiffusion of elements between the materials to be joined progressed and the joint became more homogeneous, but because the amount of B in the insert metal was small, almost no formation, increase, or growth of precipitates was observed. Ta. Next, the soundness of the joint was investigated using a one-sided test method based on "JIS G-0601-5R Ultrasonic Flaw Detection Test Method for Clad Steel Plate", but all tests using insert metal satisfying claims 1 to 5 The non-bonded area ratio for each piece was 0%.

Further, JISA-2 tensile test pieces 4 were cut out from the plate thickness direction in the manner shown in FIG. 3, and the relative strength at break of the bonded portion of each bonding material was investigated using an Instron type tensile tester at room temperature.

The tensile breaking strength of the joint is determined by the material of the materials to be joined.

Although it is determined by the plate thickness and usage environmental conditions, in this example, 30 kg/- is tentatively set as the minimum required strength due to practical limitations, and if the breaking strength above this value is obtained, it is sufficient. It was determined that the bonding had been achieved.

FIG. 4 shows the influence of the concentration of V in the insert metal on the fracture strength of the joint. ■The concentration is 0 in atomic percent.
If it is less than 1%, the Cr oxide film on the surface of the non-bonded alloy cannot be sufficiently rendered harmless, so the breaking strength of the joint will be low, but if it is more than 0.1%, the breaking strength of the joint will be the same as that of the base metal or even worse than the base material. As described above, (2) effectively acts to render the Cr oxide film harmless. However, if ■ exceeds 20.0%, the melting point of the insert metal increases, resulting in insufficient bonding time and a decrease in the fracture strength of the bonded portion.

, FIG. 5 is a diagram similarly showing the relationship between St and joint breaking strength. When Si is less than 15.0% and more than 30.0%, the joint breaking strength is low;
In the case of 0%, high joint breaking strength can be obtained.

FIG. 6 is a diagram showing the relationship between B and joint breaking strength.

When B is less than 0.5%, the melting point of the insert metal is high, and when it is 10.0% or more, the fracture strength of the joint decreases due to boride generated near the joint interface. 0.
When B is 5% to less than 10.0%, high joint breaking strength can be obtained.

FIG. 7 is a diagram showing the relationship between the thickness of the insert metal and the bonding time required to ensure a tensile strength of 30 kg/- or more at the bonded portion. It is clear that a foil with a thickness exceeding 1201 tm requires a bonding time of 1° or more within the composition range of the present invention, which is not practical.

Table 7 shows the chemical composition analysis results and melting points of comparative alloy foils with respect to the alloy foils of the present invention, and the joint tensile rupture strength of clad steel plates manufactured using the comparative alloy foils in exactly the same manner as in the examples. .

Foil No. 236 had a melting point of 130 due to insufficient B content.
Example where the temperature exceeded 0°C and the breaking strength was low as a result, No. 23
Foil No. 7 has a high B content, and a large number of coarse borides are formed on the side of the alloy to be joined near the joint, resulting in a significant decrease in the breaking strength of the joint. Foil No. 238.

No. 239 foil has a melting point of 13 due to lack of 5iil.
00°C or higher, and cases where the amount of Si was too large and coarse SiO An example in which the Cr oxide film formed on the alloy surface of the welded material due to insufficient detoxification was not sufficiently rendered harmless.For foil No. 241, vl was 20.
．． 242,243.
Foil No. 244 was an example in which Fe, Cr, and Mo each exceeded 20.0%, resulting in a rise in melting point and insufficient liquid phase diffusion bonding, and foils No. 245 and 246 had too much B. This is an example in which, although the Si content is low and the melting point is low, a large number of coarse borides are formed near the joint, resulting in insufficient joint strength at break.

Table 1: Invention foil Table 2: Invention foil Table 2: Present invention foil (Continued) Table 4: Present invention foil Table 3: Present invention foil Table 5: Present invention foil Table 5: Present invention foil (continued) Part 6 Table Invention M (Continued) Table 6 Invention foil steel), 3... Alloy foil for liquid phase diffusion bonding (insert metal), 4... Tensile test piece for joint fracture strength investigation,
5... Liquid-phase diffusion bonded clamped steel plate, X... Cladded steel plate width direction, y... Cladded steel plate length direction,
2... Clad steel plate thickness direction.

〔Effect of the invention〕

The present invention provides an alloy foil for liquid phase diffusion bonding that enables liquid phase diffusion bonding even in an oxidizing atmosphere and realizes liquid phase diffusion bonding with extremely high breaking strength.It will greatly contribute to the development of industry. There is something.

[Brief explanation of the drawing]

Figure 1 is an example of a schematic diagram of the materials to be joined, Figure 2 is a diagram showing the assembly procedure for liquid-phase diffusion bonded clad steel plates, and Figure 3 is a completed clad steel plate and the collection of tensile test specimens for evaluating the fracture strength of the joint. Figure 4 shows the relationship between the amount of v in the insert metal and the breaking strength of the joint, Figure 5 shows the relationship between the amount of St in the insert metal and the breaking strength of the joint, and Figure 6 shows the relationship between the amount of St in the insert metal and the breaking strength of the joint. Figure 7 shows the relationship between the amount of B in the metal and the breaking strength of the joint. Figure 7 shows how the thickness of the insert metal affects the joining time required to obtain a joint with a breaking strength of 30 kg/- or more by liquid phase diffusion bonding. It is a diagram showing the influence. 1... Material to be joined (carbon steel), 2... Material to be joined (alloy Fig. 1 m-20 (7f7-111111 Fig. 4) B (5z1 in Fig. 5 Ishi+r+methano b)

Claims (5)

[Claims] (1) Contains B: 0.5% to less than 10.0% in atomic %, Si: 15.0% to 30.0%, V: 0.1% to 20.0%, and the remainder is substantially Ni. An alloy foil for liquid phase diffusion bonding capable of being bonded in an oxidizing atmosphere, characterized in that it has a composition comprising: and unavoidable impurities, and has a thickness of 3.0 to 120 μm. (2) B: 0.5% to less than 10.0% in atomic % Si: 15.0% to 30.0% V: 0.1% to 20.0% In addition to Cr: 0.1% ~20.0% Fe: 0.1% ~ 20.0% Mo: 0.1% ~ 20.0% Contains one or more of the following, and the remainder essentially consists of Ni and unavoidable impurities. has a composition and a thickness of 3.0
An alloy foil for liquid phase diffusion bonding that can be bonded in an oxidizing atmosphere and having a thickness of ~120 μm. (3) B: 0.5% to less than 10.0% in atomic % Si: 15.0% to 30.0% V: 0.1% to 20.0% In addition to W: 0.1% ~10.0% Co: 0.1% ~ 10.0% Co: Contains one or two types of Co: 0.1% ~ 10.0%, and the remainder has a composition consisting essentially of Ni and unavoidable impurities, and has a thickness of 3.0 ~ 1
An alloy foil for liquid phase diffusion bonding that can be bonded in an oxidizing atmosphere and having a thickness of 20 μm. (4) B: 0.5% to less than 10.0% in atomic % Si: 15.0% to 30.0% V: 0.1% to 20.0% In addition to Cr: 0.1% -20.0% Fe: 0.1% - 20.0% Mo: 0.1% - 20.0% One or more of the following and W: 0.1% - 10.0% Co: 0. 1% to 10.0% of one kind or two kinds, and the remainder has a composition consisting essentially of Ni and unavoidable impurities, and has a thickness of 3.0 to 1%.
An alloy foil for liquid phase diffusion bonding that can be bonded in an oxidizing atmosphere and having a thickness of 20 μm. (5) The alloy foil for liquid phase diffusion bonding which can be bonded in an oxidizing atmosphere according to any one of claims 1 to 4, which is substantially glassy.