JPH02122004A - Manufacturing method of aluminum powder forgings - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing an aluminum alloy powder forging.

[Conventional technology]

The method for producing aluminum alloys with complex shapes is as follows:
Examples include precision casting, molten metal forging, and injection molding and powder forging using powdered aluminum.

Precision casting and molten metal forging have the advantage of being able to easily create complex shapes, being highly productive and low cost, but because they are melting methods, the alloy composition and structure are limited and the requirements for the product are limited. Currently, it is no longer possible to meet the harsh characteristics of

In terms of product characteristics, with the recent development of rapid solidification methods, At alloy powder containing many alloying elements such as Fe5Ni and 31, which have low solid solubility limits, has come to be manufactured. Aluminum alloys with unprecedented properties (eg, low coefficient of thermal expansion and high heat resistance) are being developed by, for example, hot extrusion according to processes.

However, it has been difficult to obtain aluminum alloys with complex shapes by conventional hot extrusion.

[Problem to be solved by the invention]

Due to the above circumstances, an attempt was made to produce a high value-added aluminum alloy with complex shapes and excellent properties by powder forging using A1 alloy powder, especially rapidly solidified A1 alloy powder. In addition to easily creating molds, the rapidly solidified A1 alloy powder is particularly difficult to process and has low plastic deformability, so defects such as cracks and underfilling are likely to occur on the surface and in highly processed areas. There is a problem in that gas is trapped inside the forged product and causes internal defects such as pores, cracks, and poor bonding between powders.

Therefore, an object of the present invention is to overcome such problems and provide a method for manufacturing an aluminum powder forged material having a complex shape, no defects, excellent mechanical properties, etc., high performance, and high added value.

[Means to solve the problem]

In order to achieve the above object, in the method for producing an aluminum powder forged material of the present invention, aluminum alloy powder is shaped, this powder compact (forged preform) is placed in a container made of aluminum or aluminum alloy, and
After degassing while heating to 400C or more in a vacuum higher than Torr, the powder compact is sealed in a container, and then hot forged with a processing degree of 30% or more to achieve a theoretical density ratio of 98% or more. Features.

In order to obtain a high-performance alloy with excellent properties, the aluminum alloy powder to be used is preferably A7 alloy powder produced by the rapid solidification method and containing a large amount of alloying elements such as Fe, Ni, and Si, but ordinary A1 alloy powder is preferable. Needless to say, it can also be used. It is also possible to mix the A1 alloy powder with other powders, such as hard particles such as ceramics.

[Effect]

In the method of the present invention, a compact of A1 alloy powder is sealed in a container made of Al or A1 alloy, which is soft and has good deformability, and then hot forged, so the surface of the powder compact is restrained and back pressure is applied. This makes it possible to suppress the occurrence of cracks on the surface and at the same time expand the plastic deformation limit as a whole, thereby eliminating the occurrence of defects. In addition, enclosing the powder in a container has the advantage of reducing the sticking of the powder compact to the mold and preventing the forging lubricant from penetrating into the powder compact, thereby increasing the lubricating effect.

The thicker the container made of AI or A1 alloy, the stronger the degree of restraint and the easier it is to handle large deformations, but on the other hand, a thick l or A1 alloy layer will be present in the final product after forging, making it more difficult to handle after cutting, etc. The removal process becomes complicated and costs increase. For this reason, the thickness of the container made of AI or A7 alloy is preferably selected to be 1 mm or less after forging.

As mentioned above, in powder forging, residual gas in the powder compact tends to cause internal defects, but especially when the powder compact is sealed in a container, the occurrence of internal defects is unavoidable because the gas does not escape. Therefore, in the method of the present invention, it is important to degas the container before sealing it. In this degassing step, 1) In order to separate and discharge HO, H, etc. adsorbed on the alloy powder, and to promote the decomposition and discharge of impurities on the A/alloy surface, the temperature is heated to 400C or higher and the temperature is higher than 1O-2torr. It must be done in a vacuum. Generally, the longer the degassing time, the better, but it can be set as appropriate depending on the thickness of the powder compact, the amount of residual gas, etc. Note that it is preferable to increase the density of the powder compact as much as possible and reduce the amount of residual gas in advance.

The degree of processing of the A1 alloy powder compact sealed in the container as described above must be 30% or more. In general, stable AIO@ is formed on the surface of A1 alloy powder, which limits mass transfer, and normal sintering does not cause sufficient diffusion and does not allow strong bonding between powders, but the method of the present invention By setting the workability during hot forging to 30% or more, stable high-strength A can be obtained regardless of the alloy composition or the thickness of the AIO film.
1 forged alloy is obtained. The reason for this is that large plastic deformation occurs due to forging with a workability of 30% or more, and the AIO film is destroyed by the relative movement of the powder at that time, and the exposed new surface contributes to bonding.

Also, A! obtained by forging! The theoretical density ratio of the alloy is 98
% or more is because if it is less than 98%, the difference in durability test (creep) from 98% or more becomes clearly worse.

〔Example〕

Example 1 Alloy composition A7-20Si-2 by air atomization method
Ni-3C! Create u-0.8Mg (wt%) 1 alloy powder (100 mesh or less) and compression mold this powder using a mold at 3.5t4 to create a powder compact with a diameter of 501 + 1ff x length of 30 mm. did. The theoretical density ratio of this powder compact was about 73%.

The obtained powder compact was placed in a 1-alloy can with a thickness of about Q and 5 mm, and heated at 450C under a vacuum degree of 10''.
Degassed for 1.5 hours and sealed, then heated at 420C for 1 hour in N gas, processing degree 10%, 20%,
Upset forging was performed at 30% and 50%.

Table 1 shows the forging results and tensile strength test results for each sample obtained.

Table 1 Sample Workability Forging result Tensile strength Theoretical density ratio x 1
10% No cracks 17 to 97m
97%*2 20 19 9
84 50 Internal defects 20
99 (Note) ×...Sample 1.2 is a comparative example.

From the above results, we found that by forging after degassing and sealing the can, the occurrence of cracks was suppressed and the processing rate was 30%.
It can be seen from the above that the strength is improved. In addition, processing degree is 50%
The reason why internal defects occurred in these materials was because the deformability of the material was small.

In addition, because of the specific axis, the same powder compact as above was heated as it was at 420C in \N gas for 1 hour without degassing and sealing, and the processing degree was 10%, 20%, 30%, and 5
Upset forging was performed at 0%. As a result, the one with a working degree of 10% was forged without cracking, but the tensile strength was as low as 16 kqhj, and the other cases with working degrees of 20%, 30%, and 50% all had cracks.

Example 2 The same A1 powder compact as in Example 1 was placed in an Al can with a thickness of 0.5 mm, degassed for 1 hour at the pressure and vacuum shown in Table 2 below, and then sealed. This was heated for 42 hours in N2 gas.
After heating at 0C for 1 hour, it was forged at a workability of 40% to obtain a forged material with a theoretical density ratio of 99.5%.

No cracks were observed in any of the forged materials obtained. Therefore, the internal structure of each forged material was further investigated, and the results are shown in Table 2 along with the results of measuring tensile strength and elongation.

Table 2 x 5 300; 10-325 0.6
With microbore *6 350i10 = 26
0.57 400i10= 27
1.0 Good 8 450i10=
26 1.0*9 400;10'-'
26 0.810 400;10”-
' 27 1.0 (Note) *...Sample 5.
6.9 is a comparative example.

The above results show that if the temperature and degree of vacuum during degassing are insufficient, the elongation of the forged material is poor and internal defects are likely to occur.

〔Effect of the invention〕

According to the present invention, since the aluminum alloy powder is sealed and hot forged, it is possible to suppress the occurrence of cracks on the surface and at the same time expand the plastic deformation limit, and since a degassing process is performed before the can is sealed, the aluminum alloy powder can be hot-forged. It is possible to eliminate internal defects and obtain a strong bond between powders.

As a result, from aluminum alloy powder, especially rapidly solidified aluminum alloy powder, aluminum powder forged material having a complex shape, no defects, excellent mechanical properties, etc., high performance, and high added value can be manufactured with high productivity.

teenager condyle Reason Man Man Sumitomo Electric Industries, Ltd. Patent attorney Nakamura Katsujro” 7; ・-1/

Claims (2)

[Claims] (1) Molding aluminum alloy powder, placing this powder compact in a container made of aluminum or aluminum alloy,
After degassing while heating to 400℃ or higher in a vacuum higher than 10^-^2torr, the powder compact is sealed in a container and then hot forged at a working degree of 30% or higher to achieve a theoretical density ratio of 98%. A method for producing an aluminum powder forged material, characterized by the above. (2) Containers made of aluminum or aluminum alloy:
The method for producing an aluminum powder forged material according to claim 1, characterized in that the layer is formed by forging to a thickness of 1 mm or less.