JPH069747B2 - Alloy foil for liquid phase diffusion bonding of Cr-containing materials that can be bonded in an oxidizing atmosphere - Google Patents

Description

The present invention relates to liquid phase diffusion bonding of metallic materials, and more specifically, liquid phase diffusion bonding of stainless steel, high nickel base alloy, and heat resistant alloy steel, or these alloy steels. The present invention relates to a liquid-phase diffusion bonding material, which is useful for liquid-phase diffusion bonding of carbon steel, can be bonded in an oxidizing atmosphere, and can obtain a bonded part having high bonding strength.

[Conventional technology]

Liquid phase diffusion bonding is a method of joining foils, powders,
Alternatively, by pressing through an alloy having a eutectic composition having a lower melting point than the materials to be joined in the form of plating or the like, and heating the joint to a temperature just above the liquidus of the inserted alloy (hereinafter referred to as insert metal). It is a joining method that melts and isothermally solidifies by means of, and is considered as a kind of solid-state joining method.

Since liquid phase diffusion welding can be performed with a comparatively low pressure, it is used for welding where residual stress and deformation due to welding must be avoided as much as possible, and at the same time applied to welding of high alloy steel and heat resistant steel that are difficult to weld. It is a technology that has been used.

The materials to be joined by liquid phase diffusion joining often contain 1.0% or more of Cr as an alloy composition. Cr-containing materials are characterized by excellent oxidation resistance and corrosion resistance because they form a dense Cr oxide (often Cr ₂ O ₃ ) film on the surface. Therefore, even when heating at the time of joining, an oxide film is naturally formed on the joining surface, the wetting of the melted insert metal is hindered, and the diffusion of atoms necessary for the joining is significantly hindered.

Therefore, in the prior art, as shown in JP-A-53-81458, JP-A-62-34685, and JP-A-62-227595, the atmosphere at the time of bonding is vacuum, inert, or It had to be kept reducible, which led to a significant increase in bonding cost.

As a result of repeated studies based on the above findings, the present inventors have found that insert metal containing V as a component can be liquid phase diffusion bonded even in an oxidizing atmosphere. Moreover, although V is an element that raises the melting point of the insert metal, it was found that an insert metal having extremely excellent bondability can be obtained by appropriately adjusting other elements (in the present invention, exclusively Si). .

There is almost no precedent for an alloy foil for liquid phase diffusion bonding containing V and increasing the amount of Si. MaY in US Pat. No. 3,856,513
There is a disclosure of an alloy having a composition of bZc. In the formula, M is a metal selected from the group consisting of Fe, Ni, Co, V and Cr, Y is an element selected from the group consisting of P, B and C, and Z is Al, Si, Sn, Ge, It is an element selected from the group consisting of In, Sb and Be, and a is in the range of about 60 to 90 atom%, and b
Is in the range of about 10 to 30 atomic%, and c is about 0.1 to 15
It is in the atomic% range. Such materials are industrially manufactured and put into practical use by rapid cooling from the melt using currently known processing techniques.

However, in this case, V is intended for use as a base material and for amorphizing the alloy, and is not disclosed as an alloy foil for joining. Moreover, 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 also completely different from that of the present invention, and since it is high, coarse precipitates are formed on the Mo or Cr-containing alloy side in the vicinity of the joint, so that the joint strength obtained using the foil of the present invention is high. It is quite low compared to the section.
Japanese Unexamined Patent Publication No. 53-81458 provides an alloy described in U.S. Pat. No. 3,865,513 in the form of a foil, but in this case, since it does not contain V as a component, it is exposed in an oxidizing atmosphere. Liquid phase diffusion bonding is completely impossible.

In the present invention, the term “oxidizing atmosphere” means that the bonding atmosphere contains 0.1% or more by volume of oxidizing gas and has an oxidizing potential of 10 ⁻³ atm or more, that is, a reducing gas such as H ₂ gas. , H ₂ S, steam, etc., means an atmosphere in which the oxidizing power is equivalent to the oxidizing concentration and is 0.1% or more.

The term "melting point" means a solidus line on a phase diagram of a binary or more alloy, unless otherwise specified.

[Problems to be Solved by the Invention]

The present invention has the above-mentioned conventional drawbacks, that is, the Cr oxide film which is generated on the surface of the material to be joined in the liquid phase diffusion bonding of the Cr-containing material in the oxidizing atmosphere and makes the Cr oxide film which hinders the diffusion bonding harmless, is liquid even in the oxidizing atmosphere. It was made to enable phase diffusion bonding, and by containing V as a component of the insert metal, the Cr oxide film has a low melting point of Cr ₂ O ₃ -V ₂
To provide an alloy foil for liquid phase diffusion bonding that realizes liquid phase diffusion bonding of a Cr-containing material in an oxidizing atmosphere by making it spherical by using O ₅ composite oxide and making it harmless to liquid phase diffusion bonding. Has an aim.

[Means for Solving the Problems]

The present inventors have found that when performing liquid-phase diffusion bonding in an oxidizing atmosphere, using an insert metal containing 0.1 to 20.0% of V and increasing Si, the bonding is possible. It was

The present invention has been made on the basis of these findings, and the gist of the invention is B: 0.5 to 10.0% in atomic%.
Less than, Si: 15.0 to 30.0%, V: 0.1 to 20.
0% or further (A) Cr: 0.1 to 20.0
%, Fe: 0.1 to 20.0%, Mo: 0.1 to 20.0%
1 or 2 or more and / or (B) W: 0.1
~ 10.0%, Co: 0.1-10.0%, or 2
A liquid phase of a Cr-containing material that can be bonded in an oxidizing atmosphere, characterized in that it contains a seed, and the balance is substantially Ni and inevitable impurities, and has a thickness of 3.0 to 120 μm. An alloy foil for diffusion bonding, or in addition, an alloy foil for liquid phase diffusion bonding of a Cr-containing material, which is substantially glassy.

The present invention will be described in detail below.

[Action]

First, the reason why each component range is limited as described above in the present invention will be described below.

First, B is an element necessary as a diffusion atom for achieving isothermal solidification necessary for achieving liquid-phase diffusion bonding or for lowering the melting point of Ni of the base material lower than that of the material to be bonded. It is necessary to contain 0.5% or more for this purpose.
It has been found that if the content of O is 0% or more, coarse phosphide of 5 μm or more is generated at the grain boundary of the Mo- and Cr-containing alloy side near the joint, and the joint strength is significantly reduced.
It was set to less than 0.0%. The low B content is also one of the features of the present invention.

Next, the Si base material is an element effective for lowering the melting point of Ni, but the alloy foil of the present invention is characterized by containing a large amount of V, which causes the melting point to be relatively high and the bonding time to be long. It is necessary to add 15.0% or more to prevent the lengthening. However, if added in excess of 30.0%, coarse oxides containing Si may be generated in the insert metal during liquid phase diffusion bonding in an oxidizing atmosphere, which may deteriorate the joint strength and toughness. The component range was limited to 15.0 to 30.0%.

V melts and spheroidizes the Cr oxide film on the surface of the Cr-containing alloy, improves the wettability of the molten insert metal and the alloy, and prevents the diffusion of B from being hindered by the Cr oxide film in the oxidizing atmosphere. It is a very important element that realizes liquid phase diffusion bonding. If the addition amount is less than 0.1%, it is not effective because it is insufficient to melt the Cr oxide film. If the addition amount is more than 20.0%, the melting point of the insert metal exceeds 1300 ° C. Since phase diffusion bonding becomes practically impossible, the range is set to 0.1 to 20.0%.

The above are the basic components of the present invention, but in the present invention, in addition to these, (A) Cr: 0.1 to 2 depending on each application.
0.0%, Fe: 0.1-20.0%, Mo: 0.1-2
0.0% of one or more and / or (B)
W: 0.1 to 10.0%, Co: 0.1 to 10.0% 1
One or two species can be contained.

First, Cr, Fe, and Mo are elements that are added to reduce the difference in mechanical properties between the alloy and insert metal when liquid-phase diffusion bonding of alloy steels containing them is performed. The content should be determined within the range commensurate with the steel composition. In addition, if there is a possibility that the joint part is exposed to a corrosive environment, Mo is used to improve the corrosion resistance of the old insert metal area.
And Cr are effective for securing high temperature strength when the material to be joined is heat resistant steel, and Mo, Cr, and Fe are effective as precipitation strengthening elements, respectively. If the content of each element is less than 0.1%, there is no effect. If added in excess of 20.0%, the melting point of the insert metal exceeds 1300 ° C, and liquid phase diffusion bonding is virtually impossible. The range was up to 20.0%.

W and Co are elements that are added mainly for the purpose of imparting high strength to the old insert metal portion when joining high-strength materials, and are precipitated as intermetallic compounds or carbides to dramatically increase the strength. If less than 0.1%, there is no effect, and if more than 10.0% is added, a coarse intermetallic compound is generated in the insert metal, which may significantly deteriorate the toughness of the joint. ~ 1
The range was 0.0%.

The above alloy components may be added individually or in combination.

The alloy foil for liquid phase diffusion bonding of the Cr-containing material of the present invention can be provided in various shapes as insert metal. For example, it is possible and most suitable from the chemical composition of the present invention to form a foil from an alloy having the composition of any one of claims 1 to 4 by a liquid quenching method. Further, it is also possible to perform vacuum melting, casting, rolling and annealing in a usual method, and then providing in the form of foil.

The crystal structure of the alloy foil is glassy because the alloy foil of the present invention needs to be melted uniformly during liquid phase diffusion bonding. If the composition of the alloy is non-uniform and segregation of contained alloy components occurs, the melting point of the insert metal will differ depending on the position of the joint, and a uniform joint interface cannot be obtained. Needless to say, the crystal structure does not need to be glassy when an alloy foil having a homogeneous composition can be easily obtained.

In the present invention, a foil is usually manufactured by a liquid quenching method using a molten alloy, but the basic suitable manufacturing method adopted here is to jet a molten alloy onto a cooling substrate through a nozzle and quench it by thermal contact. Among the liquid quenching methods for solidifying, the so-called single roll method is suitable. Of course, centrifugal quenching method using the inner wall of the drum or a method of using an endless type belt, these improved types such as auxiliary rolls, a method of attaching a roll surface temperature control device, or under reduced pressure or in vacuum or Casting in inert gas is also included. Also, a twin roll method in which a molten metal is injected between a pair of rolls and rapidly solidified can be applied. The thinner the alloy foil, the less change in mechanical properties in the vicinity of the joint, and the shorter the time required for joining, which is advantageous for liquid phase diffusion joining.
If it is less than 3.0 μm, the absolute amount of V becomes insufficient to render the Cr oxide film on the surface of the alloy to be joined harmless.
If the thickness exceeds 0 μm, the time required to complete the liquid phase diffusion bonding becomes 10 hours or more, which is not practical, so the thickness was set to 3.0 to 120.0 μm.

The present invention relates to an alloy foil for liquid phase diffusion bonding of Cr-containing materials, but since the alloy foil can be bonded in the atmosphere, the alloy foil of the present invention can be applied to a bonding method such as brazing and soldering. Is also possible and 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 is (1) quenched by a single roll method (300 mm diameter made of Cu alloy), or (2). The foil was melted in a vacuum melting furnace, cast, and then hot-rolled by an ordinary method to obtain a foil having a width of 2 to 215 mm and a thickness of 30.0 μm. In addition,
The foil produced by hot rolling was homogenized and annealed at 700 ° C. for 10 hours to eliminate macroscopic nonuniformity of components. The conditions for casting the quenched foil are that the roll peripheral speed is maintained between 5.0 and 15.0 m / s. The foil obtained has a width of 5 and a thickness of 5
After performing point measurement and confirming that the above dimensions were obtained, the melting point was measured by DTA (differential thermal analyzer). The melting points are also given in Tables 1 to 6 at the same time. The components were then identified by chemical analysis. Tables 1 to 6 are the analysis results,
The unit is atomic%. Each foil has Ni as a base material, and the difference between the sum of each component and 100% means the total concentration of Ni and inevitable impurities. The crystal structure of each foil is either amorphous, crystalline, or partially mixed with crystalline and amorphous under the above manufacturing conditions. Which structure is adopted depends on its composition. It is determined.

Subsequently, Table 1 to Table 6 includes a total of 235 foils.
Liquid phase diffusion bonding was carried out using insert metals satisfying 5 and comparative insert metals including Table 7 (including conventional insert metals). The base material of each foil in Table 7 is Ni, and the difference between the sum of each component and 100% means the total concentration of Ni and inevitable impurities. The method for producing the foil shown in Table 7 is exactly the same as the case of the foil of the present invention shown in Tables 1 to 6. The shape of the test piece is 100 mm thick x 1000 as shown in Fig. 1.
mm width x 2000 mm length, low carbon steel and 62% Ni corrosion resistant alloy were prepared respectively, and insert metal was sandwiched between them as shown in FIG. Table 8 shows the chemical components of the materials to be bonded used in liquid phase diffusion bonding. Insert metal thickness is 3.0-
It was set to 500 μm. The atmosphere was the atmosphere, and the joining temperature was in the range of just above the melting point of each foil to the melting point + 50 ° C, and the joining was carried out at substantially 1050-1300 ° C using a large heating furnace. No pressure was applied, and both were joined by their own weight. All joining time is 1
Annealing the heat treatment after joining to secure the strength, corrosion resistance and toughness of the non-joined material, quenching + annealing,
Annealing + tempering, quenching + annealing + tempering,
Were appropriately applied alone or in combination. During these heat treatments, mutual diffusion of elements between the materials to be joined progressed and homogenization of the joined portion proceeded, but since the amount of B in the insert metal was small, the formation, increase and growth of precipitates were hardly seen. It was Next, the soundness of the joint was investigated by the test piece method based on JIS G-0601- "Ultrasonic flaw detection test method for clad steel plate". All tests using insert metal satisfying claims 1 to 5 The non-bonded area ratio for one piece was 0%.

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

The tensile rupture strength of the joint is determined by the material, plate thickness,
In the present embodiment, 30 kg / mm ² is provisionally set as the minimum required strength due to practical restrictions, and sufficient bonding is obtained when a breaking strength of more than this value is obtained. It was decided that it was realized.

FIG. 4 shows the influence of the concentration of V in the insert metal on the joint breaking strength. When the V concentration is atomic%, it is 0.
When the content is less than 1%, the Cr oxide film on the surface of the non-bonding material alloy cannot be made sufficiently harmless, so that the fracture strength at the joint is low,
When the content is 0.1% or more, the fracture strength of the joint is equal to or higher than that of the base material, and V acts effectively to render the Cr oxide film harmless. However, when V exceeds 20.0%, the melting point of the insert metal rises, so that the joining time becomes insufficient and the joint breaking strength decreases.

Similarly, FIG. 5 is a diagram showing the relationship between Si and the fracture strength of the joint. If Si is less than 15.0% or more than 30.0%, the joint breaking strength is low, and if Si is 15.0 to 30.0%, high joint breaking strength is obtained.

FIG. 6 is a diagram showing the relationship between B and the 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 rupture strength of the joint decreases due to the phosphide formed near the joint interface. 0.
In the case of B of 5% to less than 10.0%, a high joint breaking strength is obtained.

FIG. 7 is a diagram showing the relationship between the thickness of the insert metal and the joining time required to secure a tensile strength of the joint portion of 30 kg / mm ² or more. It is clear that a foil having a thickness of more than 120 μm requires a bonding time of 10 hours or more within the range of the components of the present invention, which is not practical.

Table 7 shows the chemical composition analysis result and melting point of the comparative alloy foil with respect to the alloy foil of the present invention, and the joint tensile rupture strength of the clad steel sheet produced by the comparative alloy foil in exactly the same manner as in the examples. .

No. 236 foil has a melting point of 1300 ° C due to lack of B content.
, The resulting rupture strength was low, the No. 237 foil had a high B content, and a large amount of coarse phosphide was formed on the jointed alloy side in the vicinity of the joint, resulting in a marked decrease in joint rupture strength, The No. 238 foil and No. 239 foil each have an insufficient amount of Si and a melting point of 1300 ° C or higher, and an excessive amount of Si causes the formation of coarse SiO ₂ oxide in the insert metal. The number of 240 foils is V
An example in which the Cr oxide film formed on the surface of the alloy to be joined was not sufficiently detoxified due to insufficient amount, the V content of the 241 foil was 2
Since it exceeds 0.0%, the melting point becomes extremely high, and liquid phase diffusion bonding is not sufficiently performed.
Fe, Cr, and Mo are each 20.
An example in which the liquid phase diffusion bonding was not performed sufficiently because the melting point increased because it exceeded 0%. In the 245 and 246 foils, although the B content was excessive, the Si content was low and the melting point was low, but the vicinity of the bonding portion This is an example in which a large number of coarse borides were generated and the joint rupture strength was insufficient.

(Effects of the invention) The present invention is capable of liquid phase diffusion bonding even in an oxidizing atmosphere, and provides an alloy foil for liquid phase diffusion bonding that realizes liquid phase diffusion bonding of a Cr-containing material having extremely high breaking strength, There are extremely large things that contribute to the development of industry.

[Brief description of drawings]

FIG. 1 is an example of a schematic diagram of materials to be joined, FIG. 2 is a diagram showing an assembling procedure of a liquid phase diffusion bonding clad steel plate, and FIG. 3 is a completed clad steel plate and a tensile test piece for joint fracture strength evaluation. FIG. 4 is a diagram showing the relationship between the V content in the insert metal and the fracture strength at the joint, and FIG. 5 is a diagram showing the relationship between the Si content in the insert metal and the fracture strength at the joint.
FIG. 6 is a diagram showing the relationship between the amount of B in the insert metal and the fracture strength of the joint, and FIG. 7 shows that the thickness of the insert metal is obtained by liquid phase diffusion joining to obtain a joint having a fracture strength of 30 kg / mm ² or more. It is a figure showing the influence which it has on the joining time required for. 1 ... Material to be bonded (carbon steel), 2 ... Material to be bonded (alloy steel), 3
... Liquid phase diffusion bonding alloy foil (insert metal), 4 ... Tensile test piece for joint fracture strength investigation, 5 ... Liquid phase diffusion bonding clad steel plate, x ... Clad steel plate width direction, y ... Clad steel plate length direction, z: clad steel plate thickness direction.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Yuichi Sato Inventor Yuichi Sato 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Inside Nippon Steel & Co., Ltd. Technical Research Laboratories (56) References JP 62-34685 (JP, A) ) JP-A-59-116350 (JP, A) JP-A-62-227595 (JP, A) JP-B-55-19976 (JP, B2)

Claims (5)

[Claims] 1. At atomic%, B: 0.5% to less than 10.0% Si: 15.0% to 30.0% V: 0.1% to 20.0%, the balance being substantially An alloy foil for liquid phase diffusion bonding of Cr-containing materials, which has a composition of Ni and inevitable impurities and has a thickness of 3.0 to 120 μm, which can be bonded in an oxidizing atmosphere. 2. In atomic%, B: 0.5% to less than 10.0% Si: 15.0% to 30.0% V: 0.1% to 20.0%, and further Cr: 0. 1% to 20.0% Fe: 0.1% to 20.0% Mo: 0.1% to 20.0% One or more kinds are contained, and the balance is substantially Ni and unavoidable. It has a composition of impurities and a thickness of 3.0.
An alloy foil for liquid phase diffusion bonding of a Cr-containing material, which can be bonded in an oxidizing atmosphere, having a thickness of up to 120 μm. 3. In atomic%, B: 0.5% to less than 10.0% Si: 15.0% to 30.0% V: 0.1% to 20.0%, and further, W: 0 1% to 10.0% Co: 0.1% to 10.0% of 1 type or 2 types or more, and the balance has a composition substantially composed of Ni and inevitable impurities, and has a thickness of 3.0
An alloy foil for liquid phase diffusion bonding of a Cr-containing material, which can be bonded in an oxidizing atmosphere, having a thickness of up to 120 μm. 4. In atomic%, B: 0.5% to less than 10.0%, Si: 15.0% to 30.0%, V: 0.1% to 20.0%, and Cr: 0. 1% to 20.0% Fe: 0.1% to 20.0% Mo: 0.1% to 20.0%, one or more kinds, and W: 0.1% to 10.0% Co : 0.1% to 10.0% of 1 type or 2 types, and the balance has a composition substantially composed of Ni and inevitable impurities, and has a thickness of 3.0 to 12
An alloy foil for liquid phase diffusion bonding of a Cr-containing material, which can be bonded in an oxidizing atmosphere, having a thickness of 0 μm. 5. An alloy foil for liquid phase diffusion bonding of a Cr-containing material which can be bonded in an oxidizing atmosphere according to claim 1, which is substantially glassy.