JP2010284722A - Alloy for joining - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide inexpensive alloy for joining with a low melting point by optimizing alloy composition of a joining material. <P>SOLUTION: The alloy for joining contains, in atom%, ≥4% and ≤18% of B, ≥0.1% and ≤10% of P, ≥4% and ≤8% of Si, ≥0.1% and ≤10% of C, and the balance Fe with inevitable impurities. In addition, the alloy for joining contains at least one of ≥0.1% and ≤20% of Cr, ≥0.1% and ≤10% of V, and ≥0.1% and ≤40% of Ni. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a bonding alloy for bonding materials such as various parts and structures.

  Liquid phase diffusion bonding is known as a method for bonding materials such as various parts and structures. In liquid phase diffusion bonding, a bonding material having a melting point lower than that of the material to be bonded is interposed between the materials to be bonded and heated at a temperature not lower than the liquidus temperature of the bonding material and not higher than the liquidus temperature of the material to be bonded. In this method, the diffusion element in the bonding material is diffused for bonding.

  The inventors have invented and disclosed a bonding alloy foil capable of realizing liquid phase diffusion bonding in an oxidizing atmosphere (see Patent Document 1). The alloy foil contains P: 1.0 to 20 atomic%, Si: 1.0 to 10 atomic%, V: 0.1 to 20 atomic%, B: 1.0 to 20 atomic%, A foil having a composition of Cr, Ni, Co, W, Nb, Ti as required, the balance of Fe and inevitable impurities, and a thickness of 3.0 to 200 μm.

  Moreover, a single roll method, a twin roll method, etc. are known as a method for manufacturing such an alloy foil. In these methods, a foil is cast by rapidly solidifying the outer peripheral surface of a metal drum rotating at high speed by ejecting molten metal / alloy from an orifice or the like. By properly selecting the alloy composition, an amorphous alloy foil similar to a liquid metal can be produced.

  The present inventors have disclosed an alloy foil for liquid phase diffusion bonding, which is an improvement over the alloy foil for liquid phase diffusion bonding disclosed in Patent Document 1 (see Patent Documents 2 and 3). These alloy foils for liquid phase diffusion bonding disclosed in Patent Documents 2 and 3 are aimed at improving the bonding strength, and the feature is that the Si content of the bonding alloy foil is reduced.

The present inventors have investigated the cause of the bonding strength deterioration, has a base point of cracking SiO ₂ results in deterioration of strength, due to the fact that that the SiO ₂ is due to Si in the bonding foil was found.

  However, although improvement in the bonding strength after bonding was realized, there was a slight problem in the manufacturability of this alloy foil. Specifically, there was a problem that the foil did not break and became a continuous foil, or even if it became continuous, it was not a flat foil, or the surface properties were poor. If the production becomes difficult, the production yield is reduced, resulting in an increase in the production cost.

JP-A-9-323175 JP 2004-001065 A JP 2004-114157 A

  This invention makes it a subject to reduce manufacturing cost by improving the manufacturability of the alloy for joining.

  In the present invention, by optimizing the alloy components of the joining alloy, the productivity of this alloy was improved, and the above-described problems were realized.

  The gist of the present invention is as follows.

(1) Atomic%
B: 4% or more and 18% or less,
P: 1% or more and 10% or less,
Si: 4% or more and 8% or less,
C: A joining alloy comprising 0.1% or more and 10% or less, the balance being Fe and inevitable impurities.

(2) Furthermore, in atomic%,
Cr: The joining alloy as described in (1) above, containing 0.1% to 20%.

(3) Furthermore, in atomic%,
V: The joining alloy according to (1) or (2) above, containing 0.1% or more and 10% or less.

(4) Furthermore, in atomic%,
Ni: 0.1% or more and 40% or less are contained, The alloy for joining in any one of said (1)-(3) characterized by the above-mentioned.

  According to the present invention, the foil breakage due to embrittlement is eliminated, and a flat foil having a good surface property can be easily obtained, so that the manufacturability of the bonding alloy is improved, and as a result, the manufacturing cost can be reduced. This can be realized and an inexpensive bonding alloy can be provided.

It is a figure which shows the joining experiment in an Example. It is a figure which shows the tensile test piece in an Example.

  The joining alloy of the present invention has improved manufacturability by optimizing the alloy components so as to enhance the forming ability as a foil. The formation of an amorphous phase is important for facilitating the formation of the foil, but the amorphous phase may not be formed on the entire foil. However, since the formation of the foil becomes difficult if the proportion of the amorphous phase formed is too small, the proportion of the amorphous phase formed is preferably 50% or more of the entire foil, more preferably 70% or more.

  It is also an important requirement that the bonding alloy has a low melting point. Although there is no particular limitation in the present invention, the lower the melting point, the better when considering the thermal effect on the base material, and the melting point of the bonding alloy is preferably 1200 ° C. or lower, more preferably 1100 ° C. or lower.

  The reasons for limiting the components will be described below.

  If B is less than 4 atomic%, amorphous formation becomes difficult, and the foil forming ability deteriorates, so that it is 4 atomic% or more, and preferably 6 atomic% or more. On the other hand, if it exceeds 18 atomic%, a boride is generated at the joint and the bonding strength is lowered, so that it is 18 atomic% or less, preferably 16 atomic% or less.

  When the content of P exceeds 10 atomic%, it becomes difficult to suppress extreme toughness deterioration in the bonding layer. P is an element effective for improving the amorphous forming ability of the alloy and lowering the melting point. However, if it is less than 1 atomic%, these effects are not recognized. Therefore, the P content is set to 1 atom% or more and 10 atom% or less. In addition, the one where there is much content of P tends to express the effect, and it is more preferable to set it as 3 atomic% or more.

Si is an element useful for stabilizing the amorphous phase, and stabilization of the amorphous phase increases the foil forming ability, so Si plays an important role in improving the productivity of the foil. In order to exhibit the effect, addition of 4 atomic% or more is necessary. On the other hand, excessive addition of more than 8 atomic% is not preferable because SiO ₂ is frequently generated in the bonding layer and the bonding strength is extremely deteriorated. Therefore, the Si content is 4 atomic% or more and 8 atomic% or less, preferably 7 atomic% or less.

  C, like Si, is an element important for amorphous forming ability, and is also an element effective for lowering the melting point. Therefore, in the present invention, the foil forming ability could be improved by increasing the C content. However, excessive addition of the C amount causes deterioration of the characteristics of the bonding layer, so the content was made 10 atomic% or less. On the other hand, if it is less than 0.1 atomic%, effects on improving the amorphous forming ability and lowering the melting point are no longer recognized. Accordingly, the C content is 0.1 atomic% or more and 10 atomic% or less, preferably 0.5 atomic% or more and 8 atomic% or less.

  Cr is added as necessary to enhance corrosion resistance and oxidation resistance. If it is less than 0.1 atomic%, the effect is insufficient, and if it exceeds 20 atomic%, the melting point becomes high, which is not preferable. Therefore, the Cr content is 0.1 atomic% or more and 20 atomic% or less, preferably 1 atomic% or more and 18 atomic% or less.

V has the effect of making the oxide film forming substance on the surface of the material to be joined a low melting point substance. For example, has the effect of the _Fe 2 _{O 3} having a low melting point composite oxides having a melting point of about _{800 ℃ V 2 O 5 -Fe 2} O 3, in a normal bonding temperature oxidation film is melted. When such an oxide melts, it spheroidizes due to the difference in surface tension, so that a gap is formed, and diffusion elements such as B and P can freely diffuse, and liquid phase diffusion bonding can be achieved even in an oxidizing atmosphere.

  If the V content is less than 0.1 atomic%, this effect is insufficient, and if it exceeds 10 atomic%, the melting point becomes high. Therefore, the V content is 0.1 atomic% or more and 10 atomic% or less, preferably 0.5 atomic% or more and 8 atomic% or less.

  Ni has an effect of lowering the melting point, and further improves the foil forming ability. If the Ni content is less than 0.1 atomic%, this effect is insufficient, and if it exceeds 40 atomic%, this effect cannot be obtained, and the raw material cost increases. Therefore, the Ni content is set to 0.1 atomic percent or more and 40 atomic percent or less. In addition, the one where content of Ni is large tends to express the effect, and 5 atomic% or more is preferable.

  The balance other than the above elements consists of Fe and inevitable impurities. As an inevitable impurity, there is no particular problem even if Mn, S, etc. are contained up to about 0.2 atomic%.

  In addition, joining in an oxidizing atmosphere is possible by adding V, but the V-added alloy of the present invention is not limited to an oxidizing atmosphere.

  The bonding alloy of the present invention can be used not only for liquid phase diffusion bonding but also for bonding methods called so-called brazing and brazing. In general, this bonding method is a method in which, after the bonding material is melted, the diffusion element in the bonding material is solidified and diffused before being diffused into the material to be bonded.

  Further, the joining alloy of the present invention can be cast into a foil by a single roll method or a twin roll method known as a rapid solidification method and used as a foil-like joining material. In addition to foil as a shape, powder or the like can be used depending on the application. Further, not only amorphous but also crystalline ones can be used depending on applications.

  The present invention will be described in detail below based on examples. About each alloy shown to Table 1, 2, foil was cast on the following conditions by the single roll method. In Tables 1 and 2, “-” means that the content is less than the detection limit. Tables 3 and 4 show the melting point and the result of the joining experiment.

Cooling roll: Material; Cu-1 mass% Cr
Diameter: 300mm
Width: 50mm
Surface speed (peripheral speed): 25 m / s
Nozzle-cooling roll gap: 250 μm
Nozzle opening shape: 0.6mm x 25mm

  Each alloy contains about 0.2 atomic% of impurities such as Mn and S. The temperature of the molten alloy at the time of casting was about 150 ° C. higher than the melting points shown in Tables 3 and 4. The melting point of each alloy was determined by a DTA apparatus and shown in Tables 3 and 4.

  As a result of casting, the productivity of the foil was evaluated from the properties of the obtained foil, and the results are shown in Tables 3 and 4. Good foils were obtained in all of the examples.

  The foil indicated by “Δ” obtained in the comparative example was not good over the entire length. The comparative example No. 35, no. 43, no. In No. 49, a continuous foil was not obtained by breaking, and subsequent joining experiments could not be performed. In Tables 3 and 4, “−” in the melting point, the bonding atmosphere, and the bonding strength means that the test has not been performed.

  Manufacturability was evaluated by observing the appearance of the foil obtained during production. If the obtained foil is a flat foil with good surface properties without breakage, the manufacturability is good, and it is determined that it is not good if breakage occurs, it is not a flat foil, or even a foil with poor surface properties. did.

  Next, a joining experiment was performed using the obtained foil. In the joining experiment, two pieces of foil having a disk shape with a diameter of 20 mm were overlapped to form a joining material, and STK490 round steel having a diameter of 20 mm (melting point of 1550 ° C. or higher) was used as the joining material.

  As shown in FIG. 1, a bonding material 2 is sandwiched between two bonded materials 1 and bonded. The bonding temperature was set to a melting point + 50 ° C. immediately above the melting point of each bonding material 2 and heated in respective atmospheres shown in Tables 3 and 4 using a heating furnace capable of controlling the atmosphere. During heating, a pressure of 2 MPa was applied in order to improve the adhesion between the material to be bonded 1 and the bonding material 2. The joining time was all 10 minutes.

  After the joining experiment, a tensile test was performed to evaluate the tensile strength of the joint joint. In the tensile test, as shown in FIG. 2, a JIS No. 2 tensile test piece 5 was cut out from the round bar 3 to which the material to be joined 1 was joined, with the joining line 4 as the center, and a tensile test was performed using a JIS No. 2 tensile tester. . In addition, the same test piece was cut out from the base material of the material to be joined before the joining experiment and the tensile test was performed in the same manner, and the joint strength is shown in Tables 3 and 4 in terms of base material ratio (joint strength / base material strength). It was.

  As shown in Tables 3 and 4, all of the examples of the present invention gave a good foil and exhibited a tensile strength exceeding 1.0 in terms of the base material ratio.

  On the other hand, as shown in Tables 3 and 4, good foils were not obtained in all the comparative examples.

  In the joining of materials such as various parts and structures having a complicated joining shape, liquid phase diffusion joining that enables a joining temperature to be lowered and wide joining at once is an industrially useful joining method. Since the bonding alloy foil of the present invention has realized cost reduction, it can greatly contribute to the cost reduction of this liquid phase diffusion bonding.

DESCRIPTION OF SYMBOLS 1 To-be-joined material 2 Joining material 3 Round steel after joining 4 Joining wire 5 Tensile test piece

Claims (4)

Atomic%
B: 4% or more and 18% or less,
P: 1% or more and 10% or less,
Si: 4% or more and 8% or less,
C: A joining alloy comprising 0.1% or more and 10% or less, the balance being Fe and inevitable impurities. Furthermore, in atomic%,
The alloy for bonding according to claim 1, containing Cr: 0.1% to 20%. Furthermore, in atomic%,
V: 0.1% or more and 10% or less are contained, The alloy for joining of Claim 1 or 2 characterized by the above-mentioned. Furthermore, in atomic%,
Ni: 0.1% or more and 40% or less are contained, The alloy for joining of any one of Claims 1-3 characterized by the above-mentioned.

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