JPH05279705A - Production of powder super alloy material - Google Patents

Abstract

PURPOSE:To provide the process for economical production of the power super alloy material which annihilates the residual powder particles having a solidified structure at the time of powder production even if the alloy is subjected to a soln. heat-treatment at the temp. at which the coarse crystal grains are not formed. CONSTITUTION:The powder particles are previously subjected to plastic working in order to prevent the powder particles having a solidified structure formed the time of powder production from remaining in the sintered body in the process for production of the powder super alloy material by subjecting the atomized powder of a super alloy to a hot isotropic pressurization and subjecting the sintered body obtd. in such a manner to the soln. heat-treatment at the temp. at which the coarse crystal grains are not formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a powder superalloy material comprising a sintered body of superalloy (superheat-resistant alloy) powder.

[0002]

2. Description of the Related Art Turbine disks for gas turbines and jet engines are formed of a superalloy because they are susceptible to thermal fatigue at high temperatures. Superalloys are often subjected to mechanical finishing using a powder superalloy material having a shape similar to that of a product in terms of machinability and homogeneity.

The powdered superalloy material is usually classified into 150 mesh or less (particle size of 100 μm or less) by classifying atomized powder of superalloy.
This powder is encapsulated in a disk capsule, subjected to hot isostatic pressing (HIP) treatment, and the obtained sintered body is subjected to solution treatment and aging treatment. In addition, there is a case where the sintered body after the HIP treatment is subjected to superplastic forging.

[0004]

The superalloy powder produced by the atomizing method has a solidification structure formed in the powder particles. With regard to the fine particles of less than 50 μm in the powder, most of the microstructure disappears because the crystallized substances and the protrusions form a solid solution in the matrix during HIP treatment or solution treatment.
Particles larger than m are hard to disappear. If powder particles (residual powder particles) having a solidification structure during powder production remain in the sintered body, it is difficult to obtain uniform mechanical properties such as large variation in low cycle fatigue properties (LCF properties), and reliability is improved. descend.

In order to eliminate the residual powder particles in the sintered body, it is sufficient to subject the sintered body after the HIP treatment to a high temperature solution treatment, but coarsening of crystal grains occurs and mechanical properties deteriorate. . Therefore, the presence of residual powder particles is unavoidable, and the solution treatment is actually performed at a low temperature at which the crystal grains are not coarsened. Incidentally, AF115 superalloy powder with 150 mesh under is 1000atm, 1130 ℃ ×
FIGS. 3 and 4 show metallographic micrographs (magnification 400 times) of the solution treated with 1170 ° C. × 3 Hr and the solution treated with 1170 ° C. × 3 Hr after HIP treatment of 3 Hr.
Note that both samples were subjected to an aging treatment at 760 ° C. × 16 Hr after the solution treatment, but the protrusions produced by the aging treatment are minute and cannot be distinguished at the same magnification. In FIG. 3, the presence of residual powder particles is recognized although the crystal grains are fine. On the other hand, in FIG. 4, although the residual powder particles have disappeared, it can be seen that the crystal grains are remarkably coarsened.

In order to eliminate the residual powder particles without coarsening the crystal grains, the superalloy powder or the sintered body after HIP treatment is extruded, and the extruded material is subjected to superplastic forging. Although solution treatment may be carried out at low temperature, extrusion requires a 30,000 to 50,000 ton class press, which is not available in Japan, and superplastic forging equipped with an expensive die made of special heat resistant material. Equipment is also required, and lacks versatility and economy.

The present invention has been made in view of the above problems, and provides an economical manufacturing method of a powder superalloy material in which residual powder particles disappear even when solution treatment is performed at a temperature at which crystal grains do not coarsen. With the goal.

[0008]

In the method for producing a powder superalloy material of the present invention, atomization powder of a superalloy is hot isostatically pressed so that the obtained sintered body does not have coarse crystal grains. In the method for producing a powder superalloy material which is subjected to solution treatment at a temperature, the powder particles are plastically processed in advance in order to prevent the powder particles having a solidified structure at the time of powder production from remaining in the sintered body.

[0009]

In order to eliminate the solidification structure of the powder particles, it is necessary to solidify the crystallized substances and extruded substances in the matrix to recrystallize them. For that purpose, it is necessary to apply energy for atom transfer to the powder particles. In the present invention, HI
Not only P and heat energy due to heating during solution treatment, but also energy required for atom movement is supplied by strain energy previously applied to powder particles by plastic working, so heating during solution treatment is performed. The solidified structure can be eliminated even if the temperature is kept at a temperature at which the crystal does not coarsen.

[0010]

Examples Super alloys that can be used in the present invention include AF115, MA6000, IN100, Rene95, and MA.
Various Ni-based and Co-based superalloys such as RL76 can be exemplified. These superalloys are easily powdered by the atomizing method. The superalloy atomized powder is sintered and integrated by the HIP process, but in the present invention, the powder particles are plastically processed in advance before being encapsulated in the HIP capsule.
The degree of processing is determined in consideration of the powder particle size, HIP treatment temperature and solution treatment temperature so that no residual powder particles are present in the sintered body. When the binding powder is used, it is preferable that the powder particles be subjected to flattening so as to cause a particle size change of 25% or more.

FIG. 1 is a graph showing the relationship between the maximum particle size of AF115 Ni-based superalloy powder after classification by sieving (ie, corresponding to the opening size of the mesh) and the amount of flattening until residual powder particles disappear. Therefore, it can be seen from the figure that when using a powder containing particles of 50 μm or more, it is necessary to give a processing amount of at least 25% or more according to the maximum particle size. In addition, the sintered compact sample was made of AF115 powder at 1000 atm, 1130
After HIP treatment at 3 ° C for 3 hours, solution treatment was performed at 1170 ° C.

The sintered body of the superalloy powder after the HIP treatment is solution-treated at a temperature at which the crystal grains are not coarsened, and then is aged. The solution treatment temperature is A
In the case of F115, it is about 1130 to 1170 ° C. The HIP treatment temperature is set to be equal to or lower than the solution heat treatment temperature by about 30 to 80 ° C. However, if the HIP treatment temperature is set equal, the HIP treatment furnace is rapidly cooled after the HIP treatment if it can be rapidly cooled. As a result, the solution treatment can also be used.

Next, specific examples will be given. Example 1 (1) AF115 superalloy was atomized and then classified with 150 mesh under. (2) The classified powder was put into a powder flattening apparatus, and subjected to cold flattening of 50% under vacuum to prevent oxidation. Then, the flattened powder was filled in a disk capsule under a vacuum and encapsulated. (3) After HIP treatment at 1000 atm and 1100 ° C. × 3 Hr, the sintered body was solution-treated at 1170 ° C. × 3 Hr and aged at 760 ° C. × 16 Hr. The metal structure of the obtained powder superalloy material was observed under a microscope. The results are shown in Fig. 2 (magnification 400 times). From the figure, it can be seen that there are no residual powder particles and the crystal grains are fine. Example 2 (1) After atomizing Rene 95, the powder classified and flattened in the same manner as in Example 1 was encapsulated under vacuum in a capsule having a convex cross-section and subjected to HIP treatment. HIP processing conditions are 1000 atm and 1100 ° C. × 3 Hr. (2) A capsule for a disk is manufactured by attaching a ring-shaped frame having a U-shaped cross section to the outer peripheral surface of the large diameter portion of the HIP-treated sintered body, and in the ring-shaped space in the frame, the same as in Example 1. The AF115 powder flat-processed into was filled in a vacuum and sealed. (3) This disk capsule is 1000atm, 1100 ℃ × 3Hr
After HIP treatment at 1,100 ° C. × 3 Hr solution treatment.
A sample was taken from each part of the composite powdered superalloy material and the metallographic structure was observed under a microscope. As a result, no residual powder particles were found and the crystal grains were fine in each part.

[0014]

As described above, according to the method for producing a powder superalloy material of the present invention, in order to prevent the powder particles having the solidification structure during the powder production from remaining in the sintered body, the powder superalloy material is preliminarily used. Since plastic processing is performed, the powder in the sintered body has strain energy, and even if the temperature during solution treatment is a low temperature at which coarsening of crystal grains does not occur, thermal energy due to heating during solution treatment is applied. And the above-mentioned strain energy are combined with each other to promote the movement of atoms, and the crystallized or extruded material of the solidification structure is dissolved in the matrix, and fine crystal grains are obtained by recrystallization. The material is obtained. Further, in the present invention, an extrusion device and a superplastic forging device are unnecessary, and since there is no forging process, the material yield is high and the economy is excellent.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the maximum grain size of superalloy powder and the amount of flattening required to eliminate residual powder grains.

FIG. 2 is a photograph of the metallographic structure of the powder superalloy material according to the example (40
0 times).

FIG. 3 Photograph of metallographic structure of powdered superalloy material according to conventional example (40
0 times).

FIG. 4 is a metallographic photograph (400 times) of a comparative example subjected to solution treatment at high temperature.

Claims (2)

[Claims] 1. A method for producing a powdered superalloy material, which comprises subjecting an atomized powder of a superalloy to hot isostatic pressing, and subjecting the obtained sintered body to a solution treatment at a temperature at which coarsening of crystal grains does not occur. A method for producing a powder superalloy material, which comprises subjecting powder particles to plastic working in advance in order to prevent powder particles having a solidified structure during powder production from remaining in the aggregate. 2. The method for producing a powder superalloy material according to claim 1, wherein the flattening process is applied to the powder particles so as to change the particle size by 25% or more.