JPH01278932A - Superplastic forging - Google Patents

Abstract

PURPOSE:To perform non-oxidizing superplastic forging by fixing a stock and forging dies in a sheet container having the same composition as the stock, discharging air in the container in a degree of vacuum exceeding a specified value, filling and closing the container with high-purity inert gas at a pressure exceeding a specified pressure for forging. CONSTITUTION:An alloy stock 11 is put between an upper die 2 and a lower die 3 and all of them are put in a container 4. They are heated by a heating mechanism to a specified temperature at which superplastic deformation is generated and the dies 2, 3 are compressed by punches 5, 6 for forging. The degree of vacuum in a discharging hole 7 exceeds 10<-5>Torr, inert gas having a purity >=99.99% is introduced to obtain a pressure exceeding 1.05 times the atmospheric pressure and protect the back flow of the atmosphere. A cavity part 8 makes a vacuum or an inert gas atmosphere. When a forging is performed in an indicated state, the volume of a superplastic alloy of initial charge is made larger than a die cavity. Accordingly, superplastic forging can be carried out to oxidizing stock such as Ti and Si base alloy without suffering from oxidation.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for superplastic forging of metal materials used in parts for jet engines, fields requiring high temperature and high strength, and the like.

<Conventional technology> Conventionally, metal materials used for jet engine parts and parts that require high temperature and high strength are made of superplastic forging materials in the atmosphere. Alternatively, a method of performing 13Th in an inert gas atmosphere such as At 1He has been used.

That is, the forging material has been forged while being exposed to the atmosphere, or the material has been subjected to superplastic forging in the presence of a forging die and the material in an atmospheric gas.

Among these, forging in an inert gas atmosphere such as Ar1He is usually carried out using a series of manufacturing equipment from heating to forging.

However, when such manufacturing equipment is used, the equipment cost is very high, and moreover, it is not suitable for high-mix, low-volume production.

<Problems to be Solved by the Invention> In the above-mentioned conventional atmosphere [a], since the material is naturally exposed to the atmosphere, it is inevitable that the material will be affected by oxidation and nitridation.

Also, when forging in an inert gas atmosphere, apart from the case of small materials such as test pieces, large (〉φ
In the case of the material No. 300), this large material and the mold had to be kept in a protective atmosphere, and the equipment became larger by the size of the protective chamber, resulting in an enormous equipment cost. Furthermore, it is difficult to maintain gas purity and airtightness in large equipment, and the purity tends to be poor.

For this reason, for example, in a mold using a cold alloy, a problem of elevation occurs, which is a big problem for the life of the mold.

Means for Solving the Problems> The present inventors have conducted various studies to solve the problems of the conventional forging method described above, and as a result, they have arrived at the present invention.

That is, this invention fixes a forging material and a forging die in a container made of a thin plate having the same composition or metal texture as the material to be superplastically forged, and the interior of the container is
Purity 99.9 after evacuating to a vacuum level of Torr or higher
The container is filled with an inert gas of 9% or more to a pressure of 1.5 times the atmospheric pressure or more and sealed, and then the container is forged to transform the forging material into an umbrella product. The present invention provides a superplastic forging method in a completely protective atmosphere with special characteristics.

Function> This invention has 5 A1 2.5 Sn Tj, 6 #
-4V T, 13Cr -11V 3N T
L, 4.5 Ml-5t%-L5Cr-TL etc., 2-7%N and Fe, Zn, t%, CILlTa
, SL, BL, Mn, Cr, and V in an amount of 1 to 15%, and the balance is T, which is useful as a superplastic forging of a high Ti alloy material.

The feature of this invention is to provide a new method for processing a sintered body having approximately 100% theoretical density by l-1IP sintering, extrusion, etc.

That is, in the present invention, as shown in FIG. 1, an alloy material 1 as described above is put into an upper mold 2 and a lower mold 3 which are divided into two parts, and the whole is put into a container 4.

Although not shown, the entire structure is heated by a heating mechanism to a temperature of about 800 to 1100° C. at which superplastic deformation occurs. Alternatively, a preheated material without a heating mechanism may be used.

After that, punches 5 and 6 are used to punch the upper and lower molds 2 and 3.
The material is then compressed to perform superplastic forging.

In the figure, reference numeral 7 indicates an exhaust hole, and after evacuation is performed to a degree of vacuum of 10-5 Torr or more before forging, an inert gas such as K is introduced into the container. It is necessary to fill the inert gas with an atmospheric pressure of 1.05@ or more, in order to prevent the atmosphere from flowing back into the container.

Note that the reference numeral 8 in the figure is a cavity, which is in a vacuum or inert gas atmosphere.

When forging in the condition shown in FIG. 1, the volume of the initially loaded superplastic alloy must be larger than the void in the mold.

This is because if this is not the case, the inside of the mold cannot be completely filled with the superplastic material. If there is too much material, it is preferable to provide a notch or the like in a part of the mold so that the excess material flows out of the mold.

Further, if the dimensional accuracy of the mold in the thickness direction is not very strict, a mold having a structure as shown in FIG. 2 can be used.

An object of the present invention is to easily and inexpensively perform superplastic working while preventing oxidation of a superplastic alloy at high temperatures.

When using a Ti-based superplastic alloy as described above as the material for superplastic forging, the mold material should be an N1 alloy containing 50% or more of NL and the balance containing Cr, Co, Nl, etc. IN-100 manufactured by International Nickel Corporation, Wasbaloy manufactured by United Technologies Corporation, υdilet 100 manufactured by Special Metals Corporation, etc.) are suitable. Furthermore, when a NL-based super heat-resistant alloy is used as a forging material, it is preferable to use a heavy alloy with higher temperature and strength.

That is, as for the characteristics required for the mold material, it is preferable that the material has higher strength than the superplastic material at the forging temperature, has high wear resistance, has little reaction with the superplastic material, and is easily peeled off.

The superplastic forging method of this invention is particularly superior because of the NL
This is the case for superplastic alloys.

In other words, mold materials suitable for N-based superplastic alloys include:
A cold alloy is preferable, but this alloy is easily oxidized, and when it comes into contact with the atmosphere or oxygen at high temperatures, an oxidized layer is formed on the surface, resulting in an extremely short mold life. However, by sealing as in this invention, oxidation can be prevented.

Furthermore, even in the case of T-based superplastic alloys, since the wood is easily oxidized, superplastic processing in the atmosphere is not desirable, and the method of the present invention is particularly effective.

<Example> Hereinafter, this invention will be explained in detail with reference to Examples.

φ made of 5 wt% M-2, 5 wt% Sr, -TL material
40×40 cylinder with the same 5% by weight #-2,5% Sr
Place it in a thin plate container of TL composition with a thickness of 2.
5 x 10”6
After evacuation to Torr, gas of 99.99% purity was filled to 1.12 times atmospheric pressure and sealed.

The composite thus created was heated to 800℃ under a load of 400℃.
It was compressed to a thickness of 20 mm using a ton press. The deformation strain rate was 2 x 10'3-'.

Since the oxygen concentration of the compressed material was exactly the same as the original, 0.12% by weight, it was confirmed that superplastic forging was possible in a completely protective atmosphere.

In the above embodiment, an example was described in which the inside of the container was evacuated and then replaced with Ar gas, but it is not necessarily necessary to evacuate the inside of the container. In the case of a container having such a structure, gas in the container can be replaced at normal pressure, which is more preferable.

<Effects of the Invention> As explained above, according to the method of the present invention, superplastic compression can be performed in a completely protective atmosphere, which improves the superplasticity of easily oxidized materials such as L- and NL-based cemented carbides. Forging can also be carried out without the risk of oxidation.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of superplastic compression processing in the method of the present invention, and FIG. 2 is an explanatory diagram showing another example. 1... Superplastic forging material 2... Upper mold 3.
...Lower mold 4...Container 5.6...
・Punch 7.7'...Exhaust hole applicant's agent Patent attorney Kazu 1) Showa 1 TIA Figure 2

Claims (1)

[Claims] A forging material and a forging die were fixed in a container made of a thin plate having the same composition or metal structure as the material to be superplastically forged, and the inside of the container was evacuated to a vacuum level of 10^-^5 Torr or more. After that, the container is filled with an inert gas with a purity of 99.99% or more until the pressure reaches 1.05 times the atmospheric pressure or more and sealed, and then the container is forged to deform the forging material and form the metal. Superplastic forging method in a completely protective atmosphere, characterized by the production of products.