JPS5961583A - Joining method of heat-resistant nickel alloy - Google Patents

Abstract

PURPOSE:To form a joined part having the metallic texture and high temp. strength equivalent to those of a base material by interposing a layer of Zr or a Zr-Ni alloy in the joined part of a heat-resistant nickel alloy and pressurizing the joined part while heating the same in a specific temp. range. CONSTITUTION:A layer of Zr or a Zr-Ni layer is interposed in the joined part of a heat-resistant nickel alloy. The compsn. of Ni in the alloy may be any compsn. as far as it is <=20wt% in the case of using the Zr-Ni alloy. A pressure is applied to the base material, and the entire part of the material is heated and held in an inert atmosphere. The temp. is required to be higher than the melting point of the Zr-Ni alloy and lower than the m.p. of the heat resistant Ni alloy. The joined part is cooled to prevent oxidation upon ending of the diffusion of Zr, whereby the intended joined part is obtd.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides that the metal composition of the joint is equivalent to that of the composite fibers of the base material, which is a Ni-based thermal alloy, and therefore the strength of the joint is also equivalent to that of the base material. Regarding the joining method of Ni-based heat-resistant alloy such that
More specifically, the present invention relates to a more improved filler metal.

[Technical background of the invention and its problems]

Usually, a Ni-based heat-resistant alloy is used as a material for high-temperature gas turbine blades, which has a cooling blade structure with complicated internal cooling passages in order to increase its operating temperature.

A typical structural example is a wafer blade constructed by (a) return flow complete precision cast blade) made up of ten or more wafers joined together on a plane.

In manufacturing gas turbine blades provided with these complicated cooling passages, a diffusion bonding method is usually applied. For example, in the case of (to), as shown in the cross-sectional view in Figure 1, after building the member 1.1' into the ↓ of the shape divided into two in the span direction, the joint curved surface of the two is 2 and 2 with an insert filler metal interposed therebetween, and are integrated by diffusion bonding. In this case, since the joining curved surface is wide, it is preferable that the filler metal used is a quenched ribbon filler that is easy to handle and has a high density.

In the case of [F]), there are many joint surfaces and the dimensional accuracy of the plane is strict, so a thin filler metal is used.

Note that high-temperature isostatic compression is sometimes applied as a diffusion bonding method for curved surfaces, but this method requires a special, large-sized press, and the process is complicated because it makes full use of capsule technology and masking technology. Moreover, it is expensive, and there are problems in putting it into practical use.

The diffusion bonding method used for manufacturing (2) and 03) is usually the liquid phase diffusion bonding method (hereinafter referred to as TLP method).
has been adopted. This is because the TLP method increases the reliability of bonding. When joining Ni-based heat-resistant alloys by the TLP method, conventionally, N1-B, N1-B-8i, N
Filler metals with compositions such as i-Cr-B have been used. This filler metal is made of Ni, an element that lowers the melting point, and
, st, p, etc., and melts at a temperature several tens of degrees lower than the 6111 point of the base material (Ni metametallic alloy).

Therefore, in joining, the filler metal is interposed between the base metals, and the position corresponding to the joint of the groove is heated to a temperature above the melting point of the filler metal and below the melting point of the base metal to melt the filler metal, and After wetting the materials and brazing them, a method is applied in which the temperature is maintained for a longer period of time to diffuse B l si and the like into the base material. At this time, at the same time, the filler metal undergoes an isothermal solidification phenomenon in which it solidifies in the same manner as the base metal, forming a strong joint.

However, joining Ni-based heat-resistant alloys by the 'I' LP method using filler metals as described above has the following problems.

First, recently, strong Ni-based heat-resistant alloys for precision casting have appeared, such as IN738LC and MAR-M247.
In basic heat-resistant alloys, in order to maximize the amount of r' in the metal structure, the alloy composition range is set at the very edge based on alloy design.
Its range is extremely narrow.

Therefore, for such a base material, the above-mentioned Ni
When the '1' LP method is applied using a filler alloy, the metallographic structure of the joint 19 will be different from that of the base metal, and therefore the joint efficiency equal to that of the base metal will be lower. Yusuke becomes.

I cut it. Since the filler metal contains elements that lower the melting point such as B, Si, and P, there is a risk of damaging high-temperature strength including high-temperature side corrosion at the joint.i1. There is. especially,
This is not necessarily sufficient for bonding between members used under severe high-temperature operation conditions, such as the aforementioned wing structural members.

Historically, filler metal material A;1 has extremely poor workability.
1 is restricted. For this reason, powders have conventionally been used in the form of sheets bound with organic binders or amorphous ribbons produced by rapid cooling.

In the former case, the handling of the sheet becomes unstable, and inconvenient conditions such as contamination due to binder residue and reduction of sheath due to dimensional shrinkage during melting occur. There is a problem that it is only possible to manufacture
(G), Q3) turbine blade, iF'! It is not possible to freely set the thickness of the filler metal based on the calligraphy required for the work. However, methods have also been proposed in which these filler metals are attached to the bonding surface using plating or vapor deposition methods (
(Japanese Patent Publication No. 48-29984), in the former case, the filler metal of N1-p composition is present, and there is a problem of surface contamination peculiar to wet plating, and in the latter case, composition fluctuations and uniformity during vapor deposition may occur. An older sister point occurs.

Therefore, up to now, TL
When the P method is applied, the metal structure of the joint becomes the same as the structure of the base metal, and a filler metal that has excellent high-temperature strength, excellent workability, and a high degree of supply flexibility has not been provided.

[Purpose of the invention]

The present invention applies to N such as IN738LC and MAR-M247.
The present invention aims to provide a joining method using a filler metal that does not cause the above-mentioned problems even when the TLP method is applied to an i-base heat-resistant alloy.

[Summary of the invention]

The inventors of the present invention conducted intensive research on filler metals in order to resolve the Queen's problem, and discovered that zirconium (Zr) is an element for grain boundary strengthening in Ni-based rigid thermal alloys. In fact, in the Ni-Zr alloy, in its eutectic composition region (Ni17% by weight-Zr), Ni alone
Melting point 1453G), 7. r simple substance (melting point 1860 t:'
), its melting point is extremely low at 985C, and ■Ni-2r alloy has excellent workability in most of its tl composition range and can be processed into any shape. Based on this fact, N of each ii composition is
The effectiveness of i-zr gold alloy as a filler metal was investigated. As a result, even in the N1-zr alloy with a composition richer in Zr than in the eutectic composition region or in the simple substance of Zr, the interdiffusion rate of Zr and Ni is extremely high, so when they are used as filler metals, At the joint, the diffusion reaction between Ni contained in the Fi matrix (Ni-based heat-resistant alloy) and Zr of the filler metal progresses rapidly, and the composition of the joint becomes a Ni-Zr eutectic composition and melts. The present invention was completed based on the knowledge that the filler metal functions as a filler metal.

That is, in the method of the present invention, a layer of Zr or Zr-Ni alloy is interposed in the joint of a nickel-based thermal alloy, and the joint is heated to a temperature higher than the melting point of the Zr-Ni alloy in an inert atmosphere. The feature is that the bonding is performed by applying pressure while heating and maintaining the temperature at a temperature lower than the melting point of the Ni-based heat-resistant alloy.

In the method of the present invention, the base material to be welded is lN73
8LC and MAR-M247 are Ni-based heat-resistant alloys.

First, 7. r or 7. A layer of r-Ni alloy is interposed. The thickness of the layer is not particularly limited, but it is usually preferably 100 μm or less thick,
It may have any thickness within this range.

In addition, the layer is a layer of powder of 7, r or Zr-Ni deposited to a predetermined thickness uniformly covering f4, a predetermined thickness of Zr or Zl--Ni alloy. It can take the form of a layer formed by applying a commonly used vacuum evaporation method, sputtering method, etc. to either or both of the seedlings and the bonding surface of the base material.

When using a zr-Ni alloy, the composition of Ni in the alloy may be any composition as long as it is 20x141x or less. If it exceeds 20% by weight, the composition of the alloy will deviate from the eutectic composition region, which is not preferable. Further, even if the composition is partially non-uniform, the influence is almost nil.

The whole is then heated and maintained in an inert atmosphere by applying pressure monthly.

The pressure may be 0.01 to 5 □PA2. Further, the atmosphere may be any oxidation-preventing atmosphere such as vacuum or inert gas.

The temperature needs to be higher than the melting point of the Zr-Ni alloy and lower than the melting point of the Ni-based tempered alloy. Specifically, 990~
1300C, preferably in the range of 1100-1250C. Note that even when Zr (melting point 1840 C) is used, the above temperature range may be used because the diffusion rate of Zr and Ni is high as described above. The holding time may generally be 1 to 100 hours.

Note that during this bonding, when the bonding is completed at the bonded portion, the pressure may be removed and the integrated structure may be moved to another inert atmosphere and heated again to diffuse Zr.

After the Zr diffusion is completed in the manner described above, oxidation is prevented and the joint is cooled to obtain the joint aimed at by the present invention.

[Embodiments of the invention]

Example I MAR-M247 (Cr 8.5'llr, C
o 10%, W10%.

Ti 1%, A) 5.5%, Bo, 05%, MOo
, 65% 1Zr0.065%t'l'a 3%, C0
, 15%, Hf 1.4%, and the balance Ni (both weight %) were prepared.

Diameter: 13 mm, length: 50 mm.

After polishing the joint surfaces with No. 600 emery paper, they were cleaned with trichloride and acetone and degreased. Between the bonding surfaces of the base material, a 7.0 mm film with a thickness of 3 μn1 and a Ni composition of 17% by weight was placed. Insert r-Ni alloy foil, 2X10 'l'
It was set in a hot press that had already been vacuumed. A pressure of 1 kyfnm2 was applied from above and below between the base materials, and the joint was heated to 1200 t:' by high frequency heating. The joint dissolved immediately. Thereafter, it was held at 1200G for 5 minutes to cool the fc ridge, and the integrated round bar was heated at 1250C in an argon atmosphere.

It was held for 24 hours.

The cross section of the obtained joint was examined under an optical microscope fi (X 100)
I observed it. The results are shown in Figure 2. The joint has the same structure as the base metal, and no boundary with the base metal is observed.

Next, the obtained joined round bar was subjected to a tensile test using an Instron type testing machine. It broke at the base material. The maximum tensile strength at that time is 9 U.

T, S,) were also the same values as the base metal.

Example 2 IN738LC (Cr15.9%, Mo1.65%,
co 8.2% + W2.46%, 'rla, 4x chi, A) 3.60%, NbO, 85%.

Zr0.03%, Bo, 01%, FeO, 13%
+ Two disks were prepared, each having 1.71% of Ta, 0.09% of rC', and the remainder Nti (all weight percentages). Diameter 50mm, thickness 10yrvn.

After polishing the bonded surfaces of both with No. 180 emery paper, they were cleaned and degreased with trichlene and acetone.

Next, simple Zr was deposited on the bonding surfaces of the double-ended plates by FB evaporation. The thickness was approximately 20 μm.

After that, the joint surfaces of the two discs are brought together and the vacuum level is 2X.
Set in hot press at 10' Torr, 1k
118 by applying a pressure of g/1 rnn2 and high frequency heating.
I set it to 0C. The joint melted in less than 1 minute.

It was then held at 118 (I') for 8 minutes and then cooled.

Further, the sample was held at 1180C for 36 hours in an argon atmosphere to diffuse Zr. The structure of the joint was comparable to that of the base metal.

〔Effect of the invention〕

As is clear from the above explanation, the method of the present invention can: ■ form a joint having metal fibers equivalent to Jυ material; ■ therefore, its high-temperature strength is also equivalent to that of the base material; ■ the filler metal used is There is a large degree of freedom in thickness from thin to thick 1 depending on the base material, and the composition range is wide.■
Therefore, it has the advantage of being easily applicable to the joining of structural members having a complex shape, and its industrial value is high.

[Brief explanation of drawings]

Figure 1 is a color 1 diagram of a gas turbine cooling blade. FIG. 2 is an optical head mirror photograph of the joint according to Example 1. ■, 1'...Several members, 2...Joint curved surface.

Claims (1)

[Claims] 1. A layer of zirconium or a zirconium-nickel alloy is interposed in the joint of a nickel-based heat-resistant alloy, and the joint is heated to a temperature higher than the melting point of the zirconium-nickel alloy in an inert atmosphere. A method for joining nickel-based heat-resistant alloys, characterized by joining by applying pressure while heating and maintaining the temperature at a temperature lower than the melting point of the nickel-based heat-resistant alloys. 2. The nickel composition of the zirconium-nickel alloy is 2.
A method for joining a nickel-based heat-resistant alloy according to claim 1, which has a weight of 0 weight or less.