ES2350064A1 - Combined method for the severe plastic deformation by hydraulic pressure and extrusion in constant angle channel (hidroecae). (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

In the present patent a novel method is proposed for obtaining materials with improved mechanical properties, as a consequence of their processing through an angular or polyangular channel, which enables both the severe plastic deformation of volumetric elements and slender parts, without modification significant of the cross-sectional shape of the same. The proposed process presents the novelty of combining a hydraulic system for obtaining a hydrostatic pressure in the fluid capable of generating the necessary pressure to perform the extrusion of materials through an extrusion matrix in angular or polyangular channel, resulting in the cross section of the processed material is substantially equal to that of the starting material. With the present invention, the buckling problems associated with the traditional angular channel extrusion processes are avoided. (Machine-translation by Google Translate, not legally binding)

Description

Combined method for plastic deformation Severe by hydraulic pressure and constant angular channel extrusion (HYDROECAE).

A method for severe plastic deformation by combining hydraulic pressure and equal channel angular extrusion (HYDROECAE) .

Sector of the technique to which the invention relates

The invention relates mainly to the sector metalworking, specifically to the area of material processing Metals by severe plastic deformation (ε) >> 1) in angular channel. In the present invention a method for processing parts, without significant modification of its cross section, using a process that combines a hydraulic system to generate a hydrostatic pressure, in a fluid, capable of generating the pressure necessary for the extrusion of materials in constant angular channel (ECAE). Present the novelty, in relation to other developed processes, to enable extrusion of all kinds of pieces, both slender and non-slender, which is not possible by conventional processes of angular channel extrusion, due to the buckling experienced by compression elements used and that makes the length processed may not be very large in such processes.

Prior art

As is known, the reduction of grain size in metallic materials it presents great interest from the point of industrial and technological view, since its refinement produces a significant improvement of mechanical properties. So, a size of submicron or nanometric grain can lead to obtaining low temperatures increases resistance, hardness, toughness and fatigue limit, among other properties. In addition, it is possible to have superplastic behaviors at higher temperatures, being able to experience very large deformations without fracture in the material.

In the processes of severe plastic deformation in angular channel (\ varepsilon >> 1) you have small changes in the cross section of the processed parts. This maintenance of the dimensions of the pieces means that there is no defined limit to the deformation that can be reached, provided when the material has sufficient ductility, being able, in addition, repeat the process repeatedly and thus get a high accumulated plastic deformation, which will lead to a fine tuning of the grain size of the material processed in relation to the material of departure.

The novelty of the present invention lies in the use of a compression method based on the application of a hydrostatic pressure in a fluid capable of generating the necessary thrust to process, by extrusion in angular channel, both parts that have been called as slender, that is, with one of its dimensions much larger than the other two, as not slender. This is not possible by conventional methods of angular channel extrusion (ECAE) due to the buckling experienced by the compression mechanisms (punches) used; Since, as is known, when a slender piece is subjected to compression efforts, it experiences a buckling effect that is manifested by the appearance of significant displacements, transverse to the main direction of compression, and that have limited the development industrial technology known as ECAE (Equal Channel Angular Extrusion). This process was initially proposed by VM Segal et al . in 1971, in the former Soviet Union (V. Segal, Mat. Sci. Eng., 1995, 157-164; V. Segal, V. Reznikov, A. Drobyshevskiy, V. Kopylov, Russian Metally, 1, 1981, 99 -105). It has been applied to a large number of materials, although the results obtained are, to a much greater extent, in the academic and research field than in the industrial field, as a result of the difficulty of processing materials with sufficient length to be used in structural applications, which is possible with the present invention.

As indicated above, one of the fundamental reasons for these limitations is found in the buckling that experiences the punch used to push the specimen, what causes that said punch, and consequently the test piece, does not may exceed a certain size, from which the amplitude Buckling prevents the device from working.

Through the ECAE technique, the material crosses a matrix that contains two channels of the same section (circular, square or polygonal) that intersect forming a angle generally 90º. Upon reaching the punch at that angle, the test tube is already completely located in the channel after the elbow, from where it is extracted. The material is thus deformed by a shear tension mechanism when crossing the angular channel. One time that the specimen has been processed, can be reintroduced by the channel input and repeat the process with the consequent deformation accumulation It is possible to use different routes in the ECAE process. For example, route A, in which the orientation of the test tube remains unchanged in successive passes; route B, in the one that the test tube rotates 90º in the successive passes, with respect to the longitudinal axis of the specimen; and route C, in which the specimen is rotates 180º also with respect to the longitudinal axis of the specimen. The resulting microstructural characteristics vary depending on of the process path. The process can repeat a number N of times, depending on the type of material and the deformations that They want to get.

In short, although the ECAE process presents interest because it makes it possible to obtain very high deformations, its industrial application has been limited by the small size of the specimens, because of the buckling of the punch that compress the specimen, which is avoided with the method proposed in the present invention

Some patents related to obtaining materials through severe plastic deformation in angular channel (C. J. Luis, P. A. González, J. Gil, J. Alkorta, ES2224787; M. Jarret, W. Dixon, May 1994, US Patent No. 5309748; V. Segal, R. Goforth, K. Hartwing, Mar 1995, US Patent No. 5400633; V. Segal, L. Segal, Feb 1997, US Patent No. 5600989; V. Segal, May 1996, US Patent No. 5513512; L. Semiatin, D. Délo, May 1999, US Patent No. 5904062).

However, these patents have not found any method that uses the technology proposed in the present invention, which uses a hydraulic system for application of a hydrostatic pressure in a fluid, capable of generate the necessary pressure for the extrusion of materials in matrices that have an angular channel geometry, or polyangular, of constant cross section.

Explanation of the invention.

The present invention allows to obtain severe plastic deformations (? >> 1) in the starting material (L1). It can be used both for Angular channel extrusion of slender and non-slender pieces. It comprises a deformation process in a polygonal canal, without limitation of starting material size, and that does not change significantly the cross section of the processed material, being applicable to very different sections (square, rectangular, circular, polygonal, etc.), both solid and hollow.

The invention comprises a hydraulic system to raise the pressure of a fluid in a high pressure chamber (1), which will generate, in turn, the pressure necessary for the material located at the entrance of the angular channel (L_ {1}) crosses the ECAE matrix and pass to the exit channel, being deformed by means of a shear tension mechanism in the presence of a hydrostatic pressure, as shown in the Figures 1-7.

The matrix by which the material is forced to pass contains an angular channel that includes one or more angles of any effective value to produce a shear stress effect to the metallic material. One of the preferred values for any of the angles of said channel is 90º, but the process is also effective using angular channels with angles of other values.

The process object of the present invention is applicable to starting materials with very different sections, such as it is observed in Figure 2. For example: preforms with section square or rectangular (5), preforms with circular section (6) or oval, or preforms with polygonal section. Such materials can present conformations of various possible sections such as example, bars, plates, sheets, plates, tubes, hollow profile, etc.

Also, the process can be carried out at room temperature or at controlled temperature, by use of matrices that can be heated so that they transmit the heat to the part that will be processed by ECAE.

Optionally, the processed material can be subjected to a subsequent heat treatment, for example, a Annealing that relieves stress and leads to a more grain form equiaxial or any other heat treatment (recrystallization, precipitation, etc.)

Description of the drawings

For a better understanding of the description, it they accompany some drawings in which the scheme of the processing system object of the invention and, on the other part, a case study of the processing of a piece Slender through the process that has been called HIDROECAE.

Figure 1 shows an application scheme of the angular channel hydroextrusion process (HIDROECAE) for the angular channel extrusion of slender pieces.

Figure 2 shows an enlarged detail of the Figure 1 showing that the section of the processed material can have any type of geometry (circular, rectangular, square, polygonal, etc.), the configurations being preferential where the section is circular, square or rectangular. It also shows the scheme of the system of compression of the HIDROECAE process, with a non-return valve (2) to prevent pressure loss in the high pressure chamber (1) and a system for sealing (consisting of a elastomer (4) and / or a sheet (3)) in the high pressure chamber (1), until the pressure necessary to perform the angular channel extrusion.

Figure 3 shows an enlarged view of the start of extrusion in which there is perforation of the sheet (3) (optional), which is extruded together with the material and a elastomer (4) (optional) to make a better seal in the high pressure chamber (1). This pressure will be the one that will generate the force necessary to extrude the material.

Figure 4 shows a scheme of the system compression of the HIDROECAE process, with a non-return valve (2) to prevent pressure loss in the high pressure chamber (1) and an elastomer (4) for sealing in the chamber of high pressure (1).

Figure 5 shows an outline of the process of HYDROECAE using an elastomer sheet (7) for the extrusion.

Figure 6 shows an outline of the process of HIDROECAE using two pressure chambers (1), for processing repetitive without removing the processed part from the ECAE matrices.

Figure 7 shows the scheme of the process of HYDROECAE, using a polyiangular extrusion die with two angles (equivalent to a two-stage process path C). He material that is at the entrance of the first angular channel (L_ {1}) crosses a first matrix with angular channel. Subsequently, the same material crosses a second matrix with angular channel, which It has an output length (L_ {2}).

Embodiments of the invention

Example one

Processing of slender pieces of rectangular section of the AA1070 by HIDROECAE

Be part of aluminum alloy plate 1070 (AA1070), (10000x4x1200) mm (length x height x width), at which It has been given a homogenizing treatment. Said alloy is processed by HIDROECAE at room temperature of 25ºC and using an angular channel extrusion die (ECAE) that It has an angle of 90º, between the input and output channels, and radios of agreement between the same input and output channels and 1.5 mm value. The extrusion speed used is 50 mm / min and for the generation of the necessary pressure, a pressure intensifier that increases the pressure in the previous chamber to the matrices in angular channel (1). Likewise, a valve is used non-return (2) and a system consisting of an elastomer (4) and a sheet (3), as shown in Figures 1-3, with in order to obtain the necessary seal to increase the pressure in the chamber (1) where the fluid that will exert is located the necessary pressure on the plate of the AA1070 so that it cross the angular channel. As a lubricant for the process of angular channel extrusion molybdenum disulfide is used (MoS_ {2}) spray previously applied on the matrices in angular channel, before placing the material on them, so which matrices are used divided by their middle plane and to which a closing pressure is applied by a hydraulic system. Dice that the material is under compressive stress, it will pass through the channel without experiencing the buckling that would suffer in a process of Conventional ECAE The matrices are at temperature ambient.

Example 2

Processing of hot slender parts of circular section of an aluminum alloy that has a constant creep stress 94 MPa at the process temperature and using a matrix of polyiangular channel extrusion (2 angles) that configure a C path of process

It starts from a bar of an alloy 2500 mm long and 50 mm diameter aluminum, which has been obtained by hot rolling. Said alloy is processed by HIDROECAE, at a temperature of 225ºC, and using a matrix polyangular that presents an angle of 90º, between the channels of input and output of each extrusion, that is, the output of the First extrusion stage is the input of the next, with a spatial arrangement that configures a process path C, just as shown in Figure 7. The radii of agreement are equal and with 5mm value The extrusion speed used is 100 mm / min and for the generation of the necessary pressure a pressure intensifier that increases the pressure in the chamber (1), to as the extrusion of the material in the matrix is performed polyangular Likewise, a non-return valve (2) and a system composed of an elastomer (4) and a sheet (3), according to detail shown in Figures 2-3, in order to get the tightness necessary to increase the pressure in the chamber (1) where the fluid that will exert the pressure is located necessary on the aluminum alloy plate considered so that it crosses the polyiangular canal (two angles). How lubricant is used a synthetic oil previously applied on the matrices in polygonal channel, before placing the material on them, for which matrices divided by their plane are used medium and to which a closing pressure is applied by means of a hydraulic system. Since the material is under stress compression, will pass through the channel without experiencing the buckling that I would suffer in a conventional ECAE process. The matrices are found at a temperature of 225 ° C. The extrusion process performed in this way it is equivalent to repeating the process of HYDROECAE, according to route C, without the need to extract the material from the matrices, as shown in Figure 7.

Example 3

Processed plate of laminated material of square section

It is part of a low alloy steel plate, for deep die cutting 2000 mm long, 1000 mm wide and 10 mm thick It is extruded into a matrix that has an inner radius 2 mm and 1.5 mm outer radius and an angle between the channel 90º entry and exit. The radios are tangent to the channel of input and output, respectively. The process is done using lubricant and at controlled temperature. The speed of The process used is 10 mm / min and the process of HIDROECAE by heating the matrices at a temperature of 200ºC. One time Once the process is done, it is extracted from the extrusion dies, rotates the material 180º, in relation to its longitudinal axis, and it Repeat the HYDROECAE process, prior introduction and lubrication of the material in the ECAE matrix.

Example 4

Repetitive processing of a 60 mm diameter aluminum shaft and 2000 mm in length

A HYDROECAE process is used to deform in angular channel an axis of the alloy 5052 of aluminum with object of accumulating shear deformation, through a matrix in angular channel, and using two HIDROECAE systems, as shown in Figure 6, in order to repeat the process of severe plastic deformation without removing the part from the extrusion die The process is used using a fluid that it is at a temperature of 80ºC and the matrices are preheated to 100ºC in order to carry out the HIDROECAE process at temperature controlled and above room temperature. The matrix in which the process is carried out presents a circular section of 60 mm of diameter and radii of agreement equal and with a value of 10 mm, between both channels

Example 5

Processing of a square section bar 50 mm side and 1500 mm length of a carbon steel

It is processed by a HYDROECAE process a square section bar of a low carbon steel in an angular channel extrusion die of rectangular section 50 mm x 50 mm that has an angle of intersection between the channel of entry and exit of the matrix of 85º and radios of agreement between 7.5 mm channels in the inner radius and 10 mm in the outer radius, both radii being tangent to the input and output channel of the matrix and the output channel being slightly lower than the channel of 49.90 mm x 49.90 mm inlet, according to the scheme shown in Figure 2. The process is done cold. At the end of the process, it becomes to introduce the piece by rotating it 180º in relation to its axis longitudinal and repeating the process of HYDROECAE. At the end of process a stress relief heat treatment is performed at The processed part.

Claims (40)

1. Method for severe plastic deformation in angular channel characterized by comprising a compression system of the starting material, based on the application of a pressure by means of a fluid that is confined in a chamber (1) in which the pressure is increased until it reaches the necessary value to cause extrusion of the starting material through an extrusion matrix in angular or polyangular channel, resulting in that the cross section of the processed material is substantially equal to that of the starting material. 2. Processing of materials by severe plastic deformation in a polyiangular channel according to claim 1, characterized in that the matrix through which the material is processed contains a channel of constant cross-section, comprising one or more angles of any value effective to produce an effect of deformation by shear stress in the processed material. 3. Processing of materials by severe plastic deformation in a polyangular channel according to any of claims 1-2, characterized in that two pressure chambers (1) are used, for repetitive processing without the need to extract the processed part from the ECAE matrices . 4. Processing of materials by severe plastic deformation in a polyangular channel according to any of claims 1-2, characterized in that several pressure chambers (1) are used, for repetitive processing without the need to extract the processed part from the ECAE matrices . 5. Processing of materials by severe plastic deformation in a polyangular channel according to any of claims 1-4, characterized by the use of an elastomer (4), located between the material to be processed and the pressure chamber (1), to guarantee the tightness 6. Processing of materials by severe plastic deformation in a polyangular channel according to any of claims 1-4, characterized by the use of a sheet (3), located between the material to be processed and the pressure chamber (1), to guarantee the tightness 7. Processing of materials by severe plastic deformation in a polyangular channel according to any of claims 1-4, characterized by the use of a sheet (3) and an elastomer (4), located between the material to be processed and the pressure chamber (1), to ensure tightness. 8. Processing of materials by severe plastic deformation in a polygonal channel according to any one of claims 1-4, characterized by the use of any type of system to ensure tightness. 9. Processing of materials by severe plastic deformation in a polyangular channel according to any of claims 1-8, characterized by the use of a hydraulic oil as a compression fluid. 10. Processing of materials by severe plastic deformation in a polyiangular channel according to any of claims 1-8, characterized by the use of a water-oil emulsion as a compression fluid. 11. Processing of materials by severe plastic deformation in a polyiangular channel according to any of claims 1-8, characterized by the use of a synthetic oil as a compression fluid. 12. Processing of materials by severe plastic deformation in a polyangular channel according to any one of claims 1-8, characterized by the use of a hydroforming fluid as a compression fluid. 13. Processing of materials by severe plastic deformation in a polyiangular channel according to any of claims 1-8, characterized by the use of any fluid as a compression fluid and at any temperature. 14. Processing of materials by severe plastic deformation in the polyangular channel, according to claims 1-13, characterized in that the exit channel of the matrix in which the material is processed is of the same dimension as the input channel. 15. Processing of materials by severe plastic deformation in the polyiangular channel, according to claims 1-13, characterized in that the inlet and outlet channels of the matrix, in which the material is processed, have different dimensions. 16. Processing of materials by severe plastic deformation in a polyangular channel according to any of the preceding claims 1-15, characterized in that preferably one or more of the angles comprised in the channel is 90 °. 17. Processing of materials by severe plastic deformation in a polyiangular channel according to any of claims 1-16, characterized in that the radii of agreement between channels are the same. 18. Processing of materials by severe plastic deformation in a polyiangular channel according to any of claims 1-16, characterized in that the inner radius of agreement between channels is smaller than the outer radius of agreement in the channels
them. 19. Processing of materials by severe plastic deformation in a polyiangular channel according to any of claims 1-16, characterized in that the outer radius of agreement between channels is smaller than the inner radius of agreement in channels. 20. Processing of materials by severe plastic deformation in a polyiangular channel according to any of claims 1-16, characterized in that the transition between the channels of the extrusion die is carried out with or without agreed radii. 21. Processed by severe plastic deformation in a polyiangular channel according to any of claims 1-20 characterized in that the process is carried out at room temperature. 22. Processed by severe plastic deformation in a polyangular channel according to any of claims 1-20, characterized in that the matrix can be heated to carry out the process at a temperature other than the ambient temperature. 23. Processing of materials by severe plastic deformation in a polyangular channel according to any of claims 1-22, characterized in that a slender material of circular, oval, square, rectangular, polygonal or other geometric cross-section is processed. 24. Processing of materials by severe plastic deformation in a polyiangular channel according to any of claims 1-22, characterized in that a slender material of solid cross-section is processed in a circular, oval, square, rectangular, polygonal or other geometric shape. 25. Processing of materials by severe plastic deformation in a polyiangular channel according to any of claims 1-22, characterized in that a slender material of hollow cross-section is processed in a circular, oval, square, rectangular, polygonal or other geometric shape. 26. Processing of materials by severe plastic deformation in a polygonal channel according to any of claims 1-22, characterized in that a non-slender material of solid cross-section is processed in a circular, oval, square, rectangular, polygonal or other geometric shape. 27. Processing of materials by severe plastic deformation in a polyangular channel according to any of claims 1-22, characterized in that a non-slender material of hollow cross-section is processed in a circular, oval, square, rectangular, polygonal or other geometric shape. 28. Processing of materials by severe plastic deformation in a polyiangular channel according to any of claims 1-27, characterized in that a predominantly longitudinal material is processed. 29. Processing of materials by severe plastic deformation in a polyiangular channel according to any of claims 1-27, characterized in that a predominantly two-dimensional or flat material is processed. 30. Processing of materials by severe plastic deformation in a polyiangular channel according to any of claims 1-27, characterized in that a volumetric material is processed. 31. Processing of materials by severe plastic deformation in a polygonal channel according to any of claims 1-27, characterized in that any geometric form of material is processed. 32. Processing of materials by severe plastic deformation in a polygonal channel according to any of claims 1-31, characterized in that the processed materials are metallic. 33. Processing of materials by severe plastic deformation in a polygonal channel according to any of claims 1-31, characterized in that the processed materials are polymeric. 34. Processing of materials by severe plastic deformation in a polygonal channel according to any of claims 1-31, characterized in that the processed materials are ceramic. 35. Processing of materials by severe plastic deformation in a polygonal channel according to any of claims 1-31, characterized in that the processed materials are non-metallic. 36. Processing of materials by severe plastic deformation in a polyangular channel according to any one of claims 1-35, characterized by comprising a subsequent stress relief heat treatment. 37. Processing of materials by severe plastic deformation in a polygonal channel according to any of claims 1-35, characterized by comprising a subsequent recrystallization heat treatment. 38. Processing of materials by severe plastic deformation in a polyangular channel according to any of claims 1-35, characterized by comprising a subsequent heat treatment of precipitation hardening. 39. Processing of materials by severe plastic deformation in a polygonal channel according to any of claims 1-35, characterized by comprising any other type of heat treatment. 40. Processing of materials by severe plastic deformation in a polygonal channel according to any of claims 1-39, characterized by comprising a subsequent surface treatment.