JP3369627B2 - Method of manufacturing fine crystal grain super heat resistant alloy member - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a super heat-resistant alloy member mainly used for disks of jet engines for aircraft and gas turbine engines.

[0002]

2. Description of the Related Art The super heat-resistant alloy members used for the above-mentioned applications are required to have high tensile strength and fatigue strength at high temperatures, and refinement of crystal grains is an effective method therefor. Various so-called thermomechanical treatments, in which the combination of machining and heat treatment is strictly controlled, have been studied in order to refine the crystal grains of the superheat-resistant alloy member. Japanese Unexamined Patent Publication (Kokai) No. 46-6003 discloses that ASTM No. 718, Incoloy 901, Waspaloy, and other super heat-resistant alloys are processed by heat treatment and recrystallization heat treatment. A method for obtaining 10 or more fine crystal grains is shown. Here, a method of using an intermetallic compound which is stable above the recrystallization temperature of the alloy and has an action of suppressing the growth of crystal grains is described.

Taking Inconel 718 as an example, this intermetallic compound is a phase which is usually called δ phase and is composed of Ni 3 Nb. After the δ phase precipitation treatment at 871 to 927 ° C., it is forged at a δ phase solid solution temperature of 996 ° C. or lower. , From the δ phase solid solution temperature 14
It is a method of obtaining a fine crystal grain by carrying out a solution treatment at a temperature lower by ~ 28 ° C. Further, in JP-A-3-64435, primary forging is performed at 1025 to 1100 ° C., and then 1030 ° C.
By performing the secondary forging at the following temperature, the precipitation treatment of the δ phase can be omitted and the grain size ASTM No. It is stated that fine grains of 8 or more can be obtained.

[0004]

However, when the above method is applied to the actual production of a super heat-resistant alloy, particularly to a production method for applying a large forging ratio at a high strain rate such as die forging,
It has been found that it is not always easy to obtain fine crystal grains over the entire surface of the member. As a result of various studies on the cause, the inventors have found that the solid solution of the δ phase, which has a crystal grain growth suppressing effect, is considerably advanced where the crystal grains are partially coarse. This suggests that even though the heating temperature before finish forging was not higher than the δ phase solid solution temperature, the temperature was partially raised above the δ phase solid solution temperature during forging.

In the case of processing at a relatively low strain rate such as press forging, the temperature rise during such processing is relatively small.
However, in order to finish a member having a complicated shape by press forging, a large-capacity press is required and a large amount of equipment is required. Therefore, it is desired to manufacture by die forging which can be efficiently produced by a relatively small equipment. An object of the present invention is to control the hot plastic working conditions with a large strain rate such as stamping and forging to obtain a structure of fine crystal grains, and a method for producing a super heat resistant alloy member having high tensile strength and fatigue strength. Is to provide.

[0006]

The first aspect of the present invention is that 0.1% or less of C that precipitates a δ phase, which is an intermetallic compound , Si0.
5% or less, Mn 0.5% or less, Ni 40-60%, Cr
15-25%, Mo2-4%, Al0.2-1.0%,
Ti 0.5-1.5%, Nb + Ta 4.0-6.0%,
B 0.001-0.01%, balance Fe and impurities
In the final forging performed by heating the super-heat-resistant Ni-Fe alloy alloy to a temperature below the solid solution temperature of the intermetallic compound, the grain size ASTM No. 6 using the above materials, and the materials without the temperature of the forging in the finish forging exceeds the solid solution temperature of the intermetallic compound by heating due to processing focusing
Gastric row forging finishing so as to fine Akiratsubu, the finish
At least part of the forging process is stamping and forging, and
The grain size ASTM No. is characterized in that the forging ratio of each die forging is 3 or less in terms of height ratio . It is a method for producing a fine crystal grain super heat resistant alloy member having 7 or more grains.

The second aspect of the present invention is the δ phase which is an intermetallic compound.
0.1% or less of C, 0.5% or less of Si, Mn
0.5% or less, Ni 40-60%, Cr 15-25%,
Mo2-4%, Al0.2-1.0%, Ti0.5-
1.5%, Nb + Ta 4.0-6.0%, B0.001
~ 0.01%, Ni-F consisting of balance Fe and impurities
The super heat-resistant alloy of e-based alloy is below the solid solution temperature of the intermetallic compound.
Grain size AST in finish forging performed by heating below
MNo. Using 6 or more materials, and crystal grains of said materials
To stop the forging in the finish forging process so as to refine
After that, repeat the heating and forging process at least once.
At least part of the finish forging is stamped forging
And the forging ratio of each stamping forging is 3 or less in height ratio.
Grain size ASTM No. 7 or more
It is a manufacturing method of the above-mentioned fine grain super heat-resistant alloy member.

[0008]

As described above, the skeleton of the present invention has a specific composition.
In superalloys of Ni-Fe based alloy, less the
In some of the processes, the temperature of the object to be forged during finish forging using stamping forging does not exceed the solid solution temperature of the δ phase, which is an intermetallic compound that has the effect of suppressing grain coarsening due to the temperature rise due to processing. It is to perform finish forging. In the case of the same material, the temperature rise due to processing increases as the forging ratio increases and the strain rate increases. Therefore, high strain rate like die forging,
In the case of a forging method with a high forging ratio, the temperature rise is particularly large. In the present invention using stamping and forging, it is necessary to adjust the forging ratio to prevent this. The simplest way to do this is to reduce the finish forging ratio. The forging ratio in the case of stamping and forging is complicated and difficult to accurately represent, but in the case of forming a disk-shaped member from a cylindrical material, the height of the cylinder before forging relative to the height of the disk after forging is If the forging ratio is the value of the ratio, it is necessary to set the forging ratio to 3 or less.

However, the small finish forging ratio means that the driving force for grain refinement by recrystallization during the finish forging and / or the subsequent solution treatment is small. For this reason, it is necessary to considerably reduce the crystal grain size of the material before finish forging.
STM No. Limited to 6 or more. Further, when the ingot used is small, the diameter of the stamping and forging material is also small. In this case, it is difficult to reduce the total forging ratio to 3 or less. If this is forged at one time, the temperature of the object to be forged partially exceeds the δ phase solid solution temperature due to the temperature rise during processing as described above. Therefore, in such a case, it is necessary not to complete the finish forging all at once, but to temporarily stop the forging before reaching the δ phase solid solution temperature and heat it again for forging.

In this case, it is possible to use both press forging and die forging, but in the case of die forging, it is necessary to set the individual forging ratio to 3 or less. Further, performing the finish forging in several times in this way has a smaller driving force than the case of performing the finish forging at the same time in order to refine the crystal grains by recrystallization during the finish forging and / or the subsequent solution treatment. , The grain size of the material is ASTM No. It is necessary to reduce the size to 6 or more.

[0011] manufacturing method described herein, Ri superalloys der to deposit δ phase which is an intermetallic compound, having a following composition
It is important to use C0.
1% or less, Si 0.5% or less, Mn 0.5% or less, Ni
40-60%, Cr 15-25%, Mo 2-4%, Al
0.2-1.0%, Ti 0.5-1.5%, Nb + Ta
4.0-6.0%, B0.001-0.01%, balance F
This is the case when applied to an alloy (Inconel 718) composed of e and impurities.

[0012]

EXAMPLES Ni-Fe compounds having the composition (% by weight) shown in Table 1
150m in diameter by melting a super heat-resistant alloy of gold and slab forging
m rod and used as a forging material. This was finish-forged into a disk shape having a diameter of 300 mm and a height of 50 mm. At this time, the forging ratio was adjusted by changing the height of the forging material as shown in Table 2. Table 2 shows the grain sizes of the raw materials, finish forging conditions, and the grain sizes and mechanical properties of the obtained disks in the present invention and comparative examples.
The grain size of the material is ASTM No. Although it is 6.5, this is intentionally changed by heat treatment to Comparative Example 2. 4.
It was coarsely used up to 5. In the fatigue test, the fatigue strength was determined by rotating bending fatigue test at 500 ° C. for 10 ⁷ times.

[0013]

[Table 1]

[0014]

[Table 2]

According to the present invention, the grain size No.
A fine crystal grain of 7.0 or more was obtained, and there was almost no difference depending on the location. It also has good mechanical properties. on the other hand,
In Comparative Example 1, the forging ratio of 3.5 was applied in one forging, so that the central portion was heated to the δ phase solid solution temperature or higher and fine crystal grains were not obtained. Further, in Comparative Example 2, the forging condition matches the condition of the present invention, but the grain size of the material is N
o. The crystal grain size of the product was uniform because it was as coarse as 4.5, but No. It has not reached 7 or more. Comparative Example 3
Is the grain size No. Since the forging heating temperature of the material of 6.5 was not less than the δ phase solid solution temperature, the crystal grains became coarse during the heating, and it was not possible to obtain fine crystal grains in the final member. The mechanical properties in these comparative examples are
In each case, since the crystal grains are coarse, the value is lower than that of the present invention.

[0016]

As described above, according to the present invention, it is possible to efficiently manufacture a fine grain super heat resistant alloy member which has hitherto been difficult by stamping and forging, and to obtain a super heat resistant alloy member having high tensile strength and fatigue strength. It is possible to obtain.

Continuation of front page (51) Int.Cl. ⁷ identification code FI C22F 1/00 650 C22F 1/00 650A 650D 651 651B 683 683 694 694A (56) Reference JP-A-4-190941 (JP, A) Sho 60-92458 (JP, A) JP-A 61-153254 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22F 1/10 C21D 8/00-8/10 B21J 5 / 00 C22C 19/00-19/05 C22C 30/00

Claims (2)

(57) [Claims] 1. A C which precipitates a δ phase which is an intermetallic compound.
0.1% or less, Si 0.5% or less, Mn 0.5% or less,
Ni 40-60%, Cr 15-25%, Mo 2-4%,
Al 0.2-1.0%, Ti 0.5-1.5%, Nb +
Ta 4.0 to 6.0%, B 0.001 to 0.01%, balance
In the final forging performed by heating the super-heat-resistant alloy of Ni—Fe alloy composed of Fe and impurities to the solid solution temperature of the intermetallic compound or less, grain size ASTM No. Finishing is performed by using 6 or more materials and by refining the crystal grains of the material without exceeding the solid solution temperature of the intermetallic compound due to the temperature rise of the forging object during finish forging. <Br /> have rows up forging, at least part of the process of the finish forging
It is stamping forging, and the forging ratio of each stamping forging is the height ratio.
Grain size ASTMN, characterized by 3 or less
o. 7. A method for producing a fine grain super heat resistant alloy member having 7 or more grains. 2. C which precipitates a δ phase which is an intermetallic compound
0.1% or less, Si 0.5% or less, Mn 0.5% or less,
Ni 40-60%, Cr 15-25%, Mo 2-4%,
Al 0.2-1.0%, Ti 0.5-1.5%, Nb +
Ta 4.0 to 6.0%, B 0.001 to 0.01%, balance
In the final forging performed by heating the super-heat-resistant alloy of Ni—Fe alloy composed of Fe and impurities to the solid solution temperature of the intermetallic compound or less, grain size ASTM No. Use 6 or more materials and refine the crystal grains of the materials.
After temporarily interrupted forged at sea urchin finishing forging process, carried out over at least once the process of forging and heating again, the finish forging
At least part of the manufacturing process is stamping and forging, and
The grain size ASTM No. is characterized in that the forging ratio of the die forging is 3 or less in terms of height ratio . 7. A method for producing a fine grain super heat resistant alloy member having 7 or more grains.