US3286337A

US3286337A - Processes for shaping metals under high hydrostatic pressure

Info

Publication number: US3286337A
Application number: US388501A
Authority: US
Inventors: Sauve Charles
Original assignee: Commissariat a lEnergie Atomique CEA
Current assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date: 1963-08-20
Filing date: 1964-08-10
Publication date: 1966-11-22
Anticipated expiration: 1983-11-22
Also published as: NL6409614A; FR1376606A; BE651665A; LU46696A1; IL21843A; ES303279A1; GB1081896A

Description

Nov. 22, 1966 c. SAUVE 3,286,337

PROCESSES FOR SHAPING METALS UNDER HIGH HYDROSTATIC PRESSURE F'iled Aug. 10, 1964 5 Sheets-Sheet 1 4: 2- INVENTOR 0mm E5 SAM/E BY 16m ATTORNEY 5 Nov. 22, 1966 c. SAUVE r 3,236,337

PROCESSES FOR SHAPING METALS UNDER HIGHHYDROSTATIC PRESSURE Filed Aug. 10, 1964 5 SheecsSheet 2 FIGS FIG."

INVENTOR CHARLES 541/ v5 BY m ATTORNEYS 5 Sheets-Sheet 5 FIG. l3

Nov. 22, 1966 c. sAuvE PROCESSES FOR SHAPING METALS UNDER HIGH HYDRQSTATIC PRESSURE Fil ed Aug. 10, 1964 CHARLES SAUVE A'ITORNEYS //W m/ M/ 3,286,337 Patented Nov. 22, 1966 United States Patent Office 12 Claims. ((:1. 29-423 The present invention relates to processes for shaping metals under high hydrostatic pressure, particularly metals which are difficult to deform under conventional conditions. l

The conventional processes for the plastic deformation of metals by forging generally have as their object the shaping of such metals with a view to using them directly in the shape obtained or to permit the subsequent transformation thereof. 1

In many cases, metallurgists have found that themetal which had been deformed under a power hammer, a forging press, a rolling mill or a drawing press, had acquired new properties due to the influence of the high pressures to which it had been subjected. These new propertiesmay on the one hand he considered as'resulting from the disappearance of the basaltic metal flow structures (primary, course-grained structure) and from their replacement by a secondary structure, generally of a fine-grained type; simultaneously, diffusion phenomena may become effective during thermal treatment preceding or continuing the process of transformation by forging, the effect of such phenomena being to homogenize the' metal.

These new properties may on the one hand be considered as resulting from the high pressures exerted during the deformation which brings about either the elimination of the slag particles in operations involving the shingling of steels obtained by puddling, or the crushing and closure of the casting shrinkage holes, the walls of which are joined and welded together during the ingot forging operations. Generally speaking, it may be said that the compactness or density of a poured metallurgical product is increased :by the deformation operations.

Similarly, if consideration is given to a product consisting of fine agglomerated particles, such as those which can be obtained by the sintering of metallic or refractory powders or of a mixture of metallic powders and refractory powders, it is known that the apparent density of these products after sintering is a function of the diameter and of the number of porosities existing within the said products and that all the deformation operations to which the said sintered materials are subjected have as their result a diminution in the volume of the numerous porosities which they contain.

It is known that, in the various cases which we wish to discuss, the utilisation of a static pressure alone is insufiicient to diminish the pores, even when a considerable pressure is exerted and even when the entire material passes into the plastic state. It is also known that, in order to obtain a substantial reduction effect in respect of the pores or cavities, recourse has been had to the plastic deformation of the materials, i.e., plastic shaping has first of all been effected by stressing, this then being followed by the deformation thereof. It is during the sliding or shearing effects to which the metal is subjected that the reduction of the pores and other cavities takes place under the influence of the pressure which has rendered the metal plastic.

If consideration is now given to the system of tensions to which a body which it is desiredto shape by plastic deformation is subjected, it will be perceived that the tensions bringing about the flow are independent of the hydrostatic pressure. In other words, the cubic expansion and angular expansion undergone by the'material at each of its points during the deformation are proportional to the components of the deviation of the tensions, i.e., to the components of a tensor obtained by deducting the hydrostatic component from the tensor of the stresses. In this manner, the deformation of a metal may be effected by applying a predetermined pressure on a surface element of the metal, this being done furthermore in a manner which is absolutely independent of the ambient hydrostatic pressure, since it will be remembered that the plastic deformation is effected without change in volume and density. J

On the other hand, it will be well understood that if a material containing porosities is deformed under slight hydrostatic pressure, a small number of porosities i.e., only the largest will tend to be reduced, whereas, on the other hand, if the hydrostatic pressure is high, the number of porosities which will be reduced will be much greater and their diameter will be smaller after the operation has been completed.

Furthermore, it is known that, although certain metals, which crystallize in a cubic system exhibiting a large number of systems of sliding planes, will readily deform in the poly-crystalline state since, whatever the orientation of the grain, there is, practically speaking, always one or more active sliding planes. On the other hand, other metals, the crystalline system of which is less rich in respect of elements of symmetry, are difiicult to deform when they are in the poly-crystalline state, since certain grains which are badly orientated relatively to the direction of main deformation exhibit no active sliding planes in that direction. It is known that such metals, if they are forged without special precautions being taken and even at low welding rates, exhibit microscopic cracking providing a'sta'rting point for rupture, which gives rise to subsequent deformation. Of such metals, mention may in particular be made of beryllium which has two systems of sliding planes, the base planes and prismatic planes, and one sliding direction located in the base plane. On the other hand, it is known that the metals whose number of sliding systems is low are, as we have just shown, diflicult to deform if the deformation force is applied to them in certain directions. The crystal then tends to rock during the deformation in such manner as to adopt a preferential orientation. Such metals, when they have been subjected to a considerable degree of deformation, exhibit a preferential orientation or texture the result of which is to impart to them marked directional properties which it may be desirable to avoid.

Thus, it will be an easy matter to understand the special difficulties which the metallurgist is required to overcome when, having at his disposal a cast metal of coursegrained basaltic texture and which is highly anisotropic and the deformation of which is frequently accompanied by the appearance of fissures, he is required to transform it by means of an appropriate forging operation to a metal consisting of small equi-axial grains without preferential orientation and without fissure formation. Such are the ditficulties encountered in particular with poured beryllium.

It is the object of the present invention to render the processes for the shaping of metals of this kind under high hydrostatic pressure, such that they permit the elimination of possible porosity, the avoidance of the formation of fissures, the elimination of preferential orientation, and the obtaining of an equi-axial metal which is also finely crystallized and which may be worked at high temperature.

The invention consists mainlywhile simultaneously effecting the shaping under the hydrostatic pressure which is much higher than that necessary for effecting the deformation and which may reach as much as 12,000 barsin combining successive deformations, which are defined and limited in respect of their amplitude but are uniform in respect of the metal mass as a whole, and which are effected within a predetermined range, and also (where appropriate) annealing effected within predetermined cycles and for a predetermined period of time.

The invention consists furthermore, apart from this main arrangement, of certain other arrangements which are preferably utilized simultaneously and which may be considered either separately or in combination one with another, notably:

The metal to be deformed is disposed in a jacket made of a metal which is relatively less ductile at the temperature under consideration, and the shape and thickness of which are such that they oppose the proposed deformation,

The deformation is effected by forging,

The deformation is effected by rolling,

The deformation is effected by drawing,

The said deformation is effected in an envelope in which a high pressure obtains due to the influence of artificial means such as high-pressure gas, a non-compressible liquid or a second metal which has been rendered plastic by the application of the pressure supplied by the first metal to be deformed, the said liquid or second metal or (if appropriate) gas being able to flow only through a small calibrated orifice and being, if appropriate, adjustable in such manner that it becomes possible to obtain a predetermined hydrostatic pressure rate during the operations,

The above discussed operations are intercombined and/ or are combined with suitable annealing operations,

The said metal to be deformed is beryllium,

The said second metal is lead,

The said second metal is aluminium,

The said second metal is copper,

The said second metal is Armco iron.

The invention will, furthermore, be readily understood with the aid of the following supplementary description and of the accompanying drawings, which are givenpurely by way of example.

In the accompanying drawings:

FIGURES 1 and 2 are diagrammatic views showing a shaping operation effected by forging in a jacket made of less ductile metals.

FIGURES 3, 4, 5 and 6 are diagrammatic views showing shaping by rolling in a jacket made of less ductile metals;

FIGURES 7, 8, and 9 are diagrammatic views showing shaping by drawing in a jacket of less ductile metals.

FIGURE 10 is a diagrammatic view of shaping by forging in a high-pressure gas or non-compressible liquid;

FIGURE 11 is a diagrammatic view showing shaping by drawing in a high-pressure gas or a non-compressible liquid.

FIGURE 12 is a diagrammatic view showing shaping by drawing in the presence of a second plastic metal; and

FIGURES 13 and 14 are diagrammatic views showing shaping by forging in the presence of a second plastic metal.

FIGURES 1 and 2 show the jacketing of the metal 1 to be deformed with the aid of a metal 2 which is relatively less ductile at the temperature under consideration but is disposed in an envelope the shape and thickness of which are such that the proposed deformation is opposed, thus producing a high hydrostatic pressure in the interior. This method is illustrated by FIGURES 1 and 2 which show the two upsetting states of a small metal cylinder 1 within a metal 2 which is less ductile.

The method may also be illustrated by FIGURES 3, 4, 5, and 6, which show, respectively, operations involving the rolling'of a metal 1 within a metal 2 which 4 is less ductile, with regard to plates (FIGS. 3 and 4) with two rolling rolls and with regard to bars (FIGS. 5 and 6) with four rolling rolls.

The method is also illustrated by FIG. 7 which shows an operation involving the drawing of a metal 1 within a less ductile metal 2, this metal then being suitable for application to products of any desired section, the section of the less ductile material being, optionally, circular or of any other desired shape (FIGS. 8 and 9).

Mention may also be made, with reference to FIG- URES 10 and 11, of deformation operations such as forging by upsetting (FIG. 10) or drawing (FIG. 11) of a metal 1, when these deformations are effected within an envelope 3 in which a high pressure is set up by artificial means such as a highpressure gas. It is also possible to utilize a n-onc-ompressib-le liquid 4 which is permitted to escape through a small orifice 5 so as to compensate for possible variations in volume.

Mention may also be made of deformation operations such as the drawing, as illustrated in FIGURE 12, of a metal 1, which, after having been drawn, opens out within a container 6 disposed in which is a metal 7 which has been rendered plastic by the application of the pressure supplied by the metal 1 and which is able to flow only through a small calibrated orifice 8, so that the slight true resistance of the said plastic metal is multiplied by LnSo/Sl wherein S0 is the section of the plastic metal and SI that of the outlet orifice 8.

The metal 7 thus exerts a counter-pressure which may be varied by acting on the ratio So/Sl between the minimum values 5, 6 and maximum values 50, 60 or even 100.

The said metal 7 may be for example lead for temperatures below C., aluminium for temperatures between and 400 C., copper above this level or alternatively Anmco iron (an extremely pure grade of iron) for rapid forging operations.

Mention may also be made of an operation which is the reverse of what has been discussed herein above and wherein the metal 1, after having been thus elongated under a high hydrostatic pressure, is restored by upsetting to its original dimensions. This operation is effected in a container 9 of suitable dimensions (FIGURES 13 and 14). in which the metal 1 is surrounded by a more highly plastic metal ring 10 which is allowed to pass through calibrated orifices 11.

It is also possible to provide a combination of these operation-s by means of which there is obtained a billet of deformed metal without texture, the dimensions of which are, practically speaking, those of the initial billet or a combination of these two processes with annealing effected at a suitable temperature and for suitable periods of time, or a combination of these processes with one or more of the previously described processes.

I claim:

1. A process for shaping difficult to deform ductile metals under high hydrostatic pressure, comprising: confining a first ductile metal to be shaped in a first zone in a rigid container; confining a second ductile metal in a second zone in said rigid container in force-transmitting engagement with said first ductile metal; said second zone being configured to conform to the desired final shape of said first ductile metal, applying a pressure to said first ductile metal sufficiently high to force said first ductile metal to flow out of said first zone and into said second zone and to simultaneously force said second ductile metal to flow out of said second zone through at least one outlet orifice of predetermined size communicating with said second zone, said outlet orifice being of such a size as to require the application of a predetermined pressure to said second ductile metal by said first ductile metal to force said second ductile metal to flow therethrough.

2. A process as defined in claim 1 in which said pressure applied to said first ductile metal is a substantially uniform pressure which is higher than a pressure necesa metal ofiers a substantially uniform resistance to the flow of said first ductile metal during the entire time said first ductile metal is being forced to flow from said first into said second zone.

3. A process as defined in claim 1 in which said first and said second ductile metals are in the solid state.

4. A process as defined in claim 1 in which said pressure applied to said first ductile metal is substantially 12,000 bars.

5. A process as defined in claim 1 in which said second ductile metal is forced to flow out of said second zone through a plurality of outlet orifices of predetermined size.

6. A process as defined in claim 1 in which said pressure is applied to said first ductile metal on the side thereof opposite said second ductile metal.

7. A process as defined in claim 1 in which said second metal is more ductile than said first metal.

8. A process according to claim 1, in which said metal to be deformed 'is beryllium.

9. A process according to claim 1, in which said second metal is lead.

10. A process according to claim 1, in which said sec ond metal is aluminium.

11. A process according to claim 1, in which said second metal is copper.

12. A process according to claim 1, in which said second metal is Armco iron.

References Cited by the Examiner UNITED STATES PATENTS 1,685,915 10/ 1928 Geno 29423 1,891,234 12/1932 Langenberg 29421 X 2,653,494 9/ 1953 Creutz 72-46 X 2,770,874 11/1956 Lindow 29-421 2,993,269 7/ 1961 Kelley 29424 3,122,828 3/1964 Havel 72365 3,127,671 4/1964 Hayes 29-423 3,156,974 11/ 1964 Bobrowsky 2-9--421 X FOREIGN PATENTS 848,269 9/ 1960 Great Britain. 1,305,289 11/196'1 France.

JOHN F. CAMPBELL, Primary Examiner.

THOMAS H. EAGER, Examiner.

Claims

1. A PROCESS FOR SHAPING DIFFICULT TO DEFORM DUCTILE METALS UNDER HIGH HYDROSTATIC PRESSURE, COMPRISING: CONFINING A FIRST DUCTILE METAL TO BE SHAPED IN A FIRST ZONE IN A RIGID CONTAINER; CONFINING A SECOND DUCTILE METAL IN A SECOND ZONE IN SAID RIGID CONTAINER IN FORCE-TRANSMITTING ENGAGEMENT WITH SAID FIRST DUCTILE METAL; SAID SECOND ZONE BEING CONFIGURED TO CONFORM TO THE DESIRED FINAL SHAPE OF SAID FIRST DUCTILE METAL, APPLYING A PRESSURE TO SAID FIRST DUCTILE METAL SUFFICIENTLY HIGH TO FORE SAID FIRST DUCTILE METAL TO FLOW OUT OF SAID FIRST ZONE AND INTO SAID SECOND ZONE AND TO SIMULLTANEOUSLY FORCE SAID SECOND DUCTILE METAL TO FLOW OUT OF SAID SECOND ZONE THROUGH AT LEAST ONE OUTLET ORIFICE OF PREDETERMINED SIZE COMMUNICATING WITH SAID SECOND ZONE, SAID OUTLET ORIFICE BEING OF SUCH A SIZE AS TO REQUIRE THE APPLICATION OF A PREDETERMINED PRESSURE TO SAID SECOND DUCTILE METAL BY SAID FIRST DUCTILE METAL TO FORCE SAID SECOND DUCTILE METAL TO FLOW THERETHROUGH.