JPH0144434B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a new method for joining metal members, and in particular,
This invention relates to a method for joining Ni-based and Co-based superalloys in a solid state. Recently, the operating temperature of gas turbines has been rising year by year in order to improve thermal efficiency. In order to address this problem, research into the development of materials and cooling structures for nozzles and blades has been active. The development of materials has already reached a plateau, and in order to cope with higher temperatures in the future, we must rely on research into cooling structures. Cooling structures are becoming more complex year by year. The blades of these gas turbines are generally manufactured using a precision casting method, so the cooling holes formed to form the cooling structure are either drilled by post-casting processing or made using a ceramic core during casting. , holes may be made by casting. However, the cooling structure is complicated,
Alternatively, if the turbine blade is made of a unidirectionally solidified casting material or a single crystal material, which requires a long solidification time, it becomes difficult to make holes by precision casting. One method of obtaining a gas turbine blade having more complicated cooling holes is to manufacture divided pieces by precision casting and then integrate the divided pieces by diffusion bonding. Among diffusion bonding methods, there are liquid phase diffusion bonding method and solid phase diffusion bonding method. Typical liquid phase bonding methods include TLP bonding (Transient Liquid Phase Bonding) and AD bonding (Activated Diffusion Bonding). The TLP bonding method uses a thin plate of nickel or cobalt alloy containing boron as an insert material, heats it below the melting point of the base material, melts the insert material, and holds it under heat. During this heating and holding, B in the insert material is diffused into the base material, and a high-strength joint is obtained by preventing excessive B from being present in the joint. The AD bonding method uses Ni alloy or Co alloy powder containing B as the insert material, and the bonding process is the same as the TLP bonding method. These joining methods use Ni alloy or Co alloy containing a large amount of B as the insert material, so B diffuses into the base material during joining, forming boride at the grain boundaries of the base material, and causing damage to the joint and its surroundings. If B segregates in the vicinity or is insufficiently diffused, a large amount of B will remain at the joint, resulting in a disadvantage of lowering the high-temperature strength of the base material and the joint. On the other hand, solid phase bonding is a method of joining base materials at high temperature, high vacuum, and under high pressure without using an insert material. However, since the base material is a heat-resistant superalloy, it is difficult to deform even under high temperatures and high stress, and no matter how precise the surface processing is, it is difficult to obtain a sound joint. be. An object of the present invention is to provide a method for diffusion bonding heat-resistant alloys with high bonding strength. The present invention involves interposing a thin metal layer between members made of a heat-resistant alloy containing at least one of Fe, Ni, and Co as a main component and containing 30% by weight or less of Cr, and below the melting point of the thin metal layer. In the method of joining the members to each other under high temperature and pressure, the thin metal layer is made of an insert alloy containing at least one of Fe, Ni and Co as a main component and 5 to 25% by weight of Al, A diffusion bonding method for heat-resistant alloy members, characterized in that the alloy foil is manufactured by pouring molten metal onto the surface of a roll rotating at high speed, or the plastically worked alloy foil is a sintered material obtained using the atomized powder of the insert alloy. It is in. Examples of insert materials include conventional melting,
A large amount of material that is difficult to make into plates or foils using the forging method.
Alloys containing Al, especially Co-Cr-Al-Y alloys, have an extremely high elongation rate near the welding temperature, and when welding, they conform to the fine irregularities of the joint surface, deform in the same way as in a liquid state, and welding progresses easily. do. Furthermore, foil manufactured by a molten metal rapid cooling method in which molten metal of this alloy is poured onto a metal surface and cooled at a rate of 10 ⁴ C/sec or more,
Alternatively, alloy powder produced by atomizing molten metal with an inert gas such as argon or helium is used as a raw material, and after hot compaction, the foil is extracted from a thin plate produced by hot processing. Therefore, a more reliable bond can be obtained. In particular, as this alloy composition, Al5~25% by weight
or alloys containing 30% or less Cr and 10% or less Y at a bonding temperature of 1000 to 1200℃ when manufacturing gas turbine nozzles and blades made of Co-based and Ni-based superalloys by diffusion bonding. They have an elongation rate of over 500%, making their joining extremely easy and highly reliable. Unless the thin metal layer has an elongation rate of 150% or more at the bonding temperature, it will not be able to deform and fill in the extremely fine irregularities on the bonding surface without any gaps, making it impossible to form a good bond. In particular, those having an elongation rate of 500% or more are preferred. More preferably, it is 1000% or more. Foils manufactured by the molten metal quenching method or the method using atomized alloy powder as raw materials have extremely fine crystal grains, so even if the surface processing accuracy of the joint surface is poor, it is possible to join in a short time and with low stress. It has high ductility and toughness, and good joint efficiency. TLP bonding and AD bonding methods use diffusion in a liquid phase, which results in the formation of harmful phases, but the method of the present invention uses diffusion bonding in a solid state, so no harmful phases are formed and the bonding strength is sufficiently high. is obtained. As a member to be joined, an alloy containing at least one of Fe, Ni, and Co as a main component and 30% or less of Cr by weight, or an alloy containing 10% or less of Mo, Al10
% or less, Ti10% or less, Nb5% or less, Ta10% or less,
A heat-resistant alloy member containing one or more of Hf5% or less and Zr5% or less is preferable.

【table】

【table】

[Table] Table 1 shows the components (% by weight) of foils obtained by various manufacturing methods. All foils were 100 μm thick and had crystal grains of several hundred microns. No.
The elongation rate for items 1 to 4 is approximately 500% at temperatures above 1/2 of the melting point.
However, No. 5 was also about 50%. The molten metal quenching method was carried out using the twin-roll method and the single-roll method.As for the surface condition, the twin-roll method had superior smoothness on both surfaces, so the foil obtained by the twin-roll method was used in the following experiments. Using. The cooling rate of these molten metals was 10 ⁵ °C/second or more. Further, as the base material, alloys used for gas turbine rotor blades and stationary blades shown in Table 2 were used. The size is the diameter
10mm and length 100mm. As a foil obtained by the molten metal quenching method and a comparison material, a foil taken by mechanical cutting from a cast material was used as an insert material, sandwiched between base materials, and hot-pressed. Hot welding is held at 1000℃ and 1225℃ for about 30 minutes,
The experiment was carried out under an Ar+ _H2 gas atmosphere. The pressure welding stress at this time was examined, and the stress that would provide a good bonding surface was determined. The results are shown in the figure. Nos. 1 to 4, which used foils obtained by the molten metal quenching method, had almost the same values, and compared to No. 5, which used foils obtained by machine cutting from cast materials, the values were smaller than those of No. 5, which used foils obtained by machine cutting from cast materials. It was confirmed that a good bonding surface was obtained and the bonding performance was excellent. Thereafter, a diffusion treatment was performed at 1100 to 1200°C for about 1 to 2 hours. Comprehensive evaluation of the 982℃ creep rupture properties of test materials sampled from the bonded parts with the joint surface in the center shows that the 982℃ creep rupture properties of the test materials sandwiched with foil manufactured by the molten metal quenching method are 90 to 90% higher than the base material properties. 100%
showed the characteristics of Example 2 Alloy powders were produced using the argon atomization method for alloys No. 1 to 4 listed in Table 1. The alloy powder is placed in a steel tube with a wall thickness of approximately 2 mm, and after vacuum sealing, the
It was rinsed and consolidated at 1000°C, and hot worked at 900-1100°C. The final cross-sectional reduction rate at this time is 1/
The coated steel was peeled with a thickness of 6 to 1/10, and a foil with a thickness of about 150 μm was obtained by mechanical cutting. The particle size at this time is maximum 2 μm, almost 0.5 to 1 μm,
It was confirmed that it is highly flexible. The elongation rate at a temperature of 1/2 or more of these melting points was about 1000% or more. After forming into a foil, hot pressure welding was carried out in the same manner as in Example 1. Although the properties were slightly inferior to those of the joining member using the foil produced by the molten metal quenching method as the insert material in Example 1, it was confirmed that the properties were approximately the same. Example 3 As insert materials, Fe and Ni-based alloys containing approximately the same amounts of Cr, Al, and Y shown in Table 1 were bonded in the same manner as in Example 1 using foils manufactured by the molten metal quenching method. As a result, No. of Example 1.
Although inferior to 1 to 4, the same bonding strength was obtained. The elongation rate at a temperature of 1/2 or more of these melting points was about 500% or more. According to the present invention, diffusion bonding can be performed extremely easily. In particular, Co-Cr-Al, which is difficult to make into foil using conventional melting and forging methods, is used as an insert material.
-Y alloy is processed by molten metal rapid cooling method or atomized powder method.
When used in foil form, the crystal grains are fine, making it highly flexible, tough, and easy to handle.
Furthermore, it has high ductility and deformability at high temperatures, so it can be easily joined. Also, since no harmful phases are formed at the joint, the high temperature strength is high. According to the present invention, it is possible to easily manufacture moving blades and stationary blades for gas turbines having complicated cooling holes, and the operating temperature of the gas turbine can be significantly increased, which has a great effect on improving efficiency. .

[Brief explanation of drawings]

The figure is a diagram showing the relationship between bonding temperature and pressurizing stress.

Claims (1)

[Claims] 1 A thin layer of metal is interposed between the joints of members made of a heat-resistant alloy containing at least one of Fe, Ni, and Co as a main component and 30% by weight or less of Cr, and a high temperature below the melting point of the thin layer of metal is provided. In the method of joining said parts together under pressure, said thin layer of metal is
Mainly containing at least one of Fe, Ni and Co,
Consists of insert alloy containing 5~25% by weight of Al,
A heat-resistant alloy foil manufactured by pouring molten metal of the insert alloy onto the surface of a roll rotating at high speed and rapidly cooling it, or a plastically worked alloy foil of a sintered material obtained using atomized powder of the insert alloy. Diffusion bonding method for alloy parts.