EP3544753A1

EP3544753A1 - Method for machining a workpiece from a metallic material

Info

Publication number: EP3544753A1
Application number: EP17808370.5A
Authority: EP
Inventors: Alexander Kopp
Original assignee: Meotec GmbH and Co KG
Current assignee: Meotec GmbH
Priority date: 2016-11-23
Filing date: 2017-11-15
Publication date: 2019-10-02
Anticipated expiration: 2037-11-15
Also published as: EP3544753B1; DE102016122575B4; ES2865549T3; DE102016122575A1; US20200061689A1; WO2018095774A1

Abstract

The invention relates to a method for machining a workpiece from a metallic material, in which the workpiece is machined by means of ECAP, characterized in that the workpiece, after the machining by means of ECAP, is post-processed by means of hammering, whereby a diameter reduction is achieved. As a result, material properties of the material of the workpiece and in particular the strength and the hardness can be considerably enhanced.

Description

Method for machining a workpiece made of a metallic material

The invention relates to a method for machining a workpiece made of a metallic material, wherein the workpiece is machined by means of ECAP.

Methods are known for machining workpieces, which are summarized under the abbreviation SPD. The abbreviation SPD stands for "Severe Plastic Deformation." These are processes in which a metal workpiece is subjected to a very large plastic deformation in order to produce an ultra-fine grained texture (UFG). The microstructure can achieve an average particle size of less than 1 μm and often has large orientation angles at the grain boundaries. SPD techniques include ECAP ("Equal Channel Angular Pressing"), Accumulative Roll-Bonding (ARB), High Pressure Torsion (HPT), Repetitive Corrugation and Straightening (RCS), CEC (" Cyclic Extrusion Compression ")," torsion extrusion "," Severe Torsion Straining "(STS)," Cyclic Closed-Die Forging "(CCDF) and" Super Short Multi-pass Rolling "(SSMR).

The ECAP is a method in which a workpiece is pressed through at least two channels merging into one another, wherein the channels have an identical cross-section and the transition between the channels at an arbitrary angle, preferably between 80 ° and 140 °, angled , The plastic deformation of the material of the workpiece during the pressing of the transition between the channels can lead to a significant refinement of the material structure and thereby to improved material properties. A machining of a workpiece by means of ECAP is described, for example, in US Pat. No. 5,513,512 A, US Pat. No. 6,399,215 B1 and EP 2 366 808 A2, in which the machined workpieces at least partially consist of (pure) titanium and / or serve for the production of medical implants.

Medical implants are often made of pure titanium, which has a very good biocompatibility. A disadvantage of such implants, however, may be the relatively low mechanical strength of this material. Although this can be significantly increased by the use of titanium alloys, but this usually at the expense of biocompatibility and thus possibly the residence time of the implants consisting thereof in a human or animal body. The devices used in the above-mentioned publications for carrying out ECAP are limited in terms of dimensions and in particular with regard to the length of the workpieces to be machined. This is in particular in the limited stroke of the stamp, by means of which the workpieces are pressed through the channels of the respective tools justified. To eliminate this disadvantage, according to US Pat. No. 7,152,448 B2, a device should be suitable in which the workpiece has a first, part-circular channel which transitions at an angle into a second, straight channel, wherein the first channel is bounded radially on the inside by a disk-shaped driving element that can be driven in rotation is. By means of a rotation of the driving element, the workpiece is to be moved by friction in a continuous process through the first channel and pressed into the second channel. As a result, it should be possible to process workpieces of basically any length using ECAP in a continuous process.

In the publication by Brother et al., "Severe Plastic Deformation by Equal Channel Angular Swaging" in Materials Science Forum, Vols. 667-669, pp. 103 to 107 (ISSN: 1662-9752), there is described a method called ECAS, which describes the Principles of ECAP and hammering ("rotary swaging"), however, in which the characteristic of conventional hammering rotating the workpiece is not performed relative to the tools. Furthermore, in the ECAS method, the modified hammering is always performed simultaneously with the ECAP. A diameter reduction for the workpiece is not achieved in the ECAS method.

US 2007/0256764 A1 discloses a machining of a workpiece by means of a method designated as ECAE which is comparable to ECAP and in which the workpiece or the ECAE tool is set into vibration during machining. This vibration generation does not lead to a deformation of the workpiece, in particular not to a diameter reduction. In the vibration generation also no forming strokes of forming tools.

In the publication by Pachla et al., "Effect of severe plastic deformation realized by hydrostatic extrusion and rotary swaging on the properties of CP Ti grade 2" in Journal of Materials Processing Technology 221 (2015), pp. 255 to 268, a method is disclosed described a hydrostatic extrusion with a post-processing a workpiece combined by hammering. The hammering is performed to improve the surface quality of the workpiece.

Based on this prior art, the object of the invention was to provide a method by which, in particular, mechanical material properties of a workpiece machined by means of ECAP can be further improved.

This object is achieved by means of a method according to the patent claim 1. Advantageous embodiments of the method according to the invention and advantageous uses of a workpiece produced according to the invention are objects of the further claims and / or emerge from the following description of the invention.

A method for machining a workpiece, which consists of or comprises at least one metallic material, wherein the workpiece is machined by means of ECAP, according to the invention is characterized in that the workpiece is machined after machining by means of ECAP by means of hammering, wherein a permanent) diameter reduction (due to plastic deformation of the material of the workpiece) is achieved. Surprisingly, it was found that in this way mechanical material properties of the material of a previously machined by ECAP workpiece and in particular its tensile strength and / or hardness can be significantly improved or increased. This finding was surprising, in particular, because other processes for reshaping post-processing, for example rolling, a previously machined by ECAP workpiece these improvements do not always cause, but on the contrary, depending on the degree of deformation even improvements in the mechanical material properties, previously realized by ECAP were, again reduce. Even if an improvement occurs, usually only the strength is increased, while the ductility is set down seriously and breaks brittle in overload or with very little deformation. Such materials are not suitable as construction materials.

As already stated, a machining by means of ECAP is basically characterized in that a workpiece is pressed through at least two, but also three or more channels merging into one another, wherein the channels preferably have an identical cross-section and the transition between the channels is angled. The plastic deformation of the material of the workpiece during passage of the transition between the channels can lead to a significant refinement of the material structure and thereby to improved material properties. In particular, this can significantly increase the tensile strength and / or the hardness of the material compared with the initial state (before processing by means of ECAP).

Fig. 1 shows a schematic representation of an exemplary processing of a workpiece 1, which is pressed by means of a punch 2 by two angled merging into each other channels of a tool 3 and thereby realizable refinement of the material structure.

A particularly pronounced improvement in the material properties can be achieved by a multiple and especially two-fold ECAP. This can also take place in a machining pass, if the tool used for ECAP has at least three channels, two of which each turn into one another correspondingly angled, as shown by way of example in FIG. 2.

Preferably, it can be provided that the deformation of the workpiece by means of hammering takes place in several passes, wherein each deformation has a degree of deformation of 0.05 to 2, preferably from 0.1 to 0.5 and particularly preferably from 0.15 to 0.3 ,

Furthermore, it can be provided that the deformation of the workpiece by means of hammering at a temperature (of the workpiece) of between 10 ° C to 600 ° C, preferably from 12 ° C to 380 ° C and more preferably from 14 ° C to 250 ° C takes place. Optionally, a deformation of the workpiece by means of hammering at a temperature of the workpiece of> 100 ° C and / or of <350 ° C may be advantageous.

Hammering, which is also known as kneading or swaging (when machining cross-sectionally round workpieces), is characterized in that two or more tools (3) which are arranged on the circumference of the workpiece (1) directed radially in the direction of a workpiece center Apply forming strokes while the workpiece (1) rotates relative to the tools (3) around the workpiece center, as shown schematically in Fig. 3. A relative movement between the workpiece (1) and the tools (3) along a Longitudinal axis of the workpiece (1) allows a continuous or discontinuous forming machining of workpieces (1) whose dimensions along the longitudinal axis are greater than the corresponding dimensions of the tools (3). The relative movement between the workpiece (1) and the tools (3) along the longitudinal axis (4) of the workpiece (1) can preferably be realized by (only) moving the workpiece (1) longitudinally axially. Alternatively or additionally, however, a corresponding movement of the tools (3) can also be provided. The strokes executed by the tools (3) can in particular be made relatively short (eg between 0.25 mm and 3 mm, in particular between 0.3 and 1.5 mm) and relatively high-frequency (eg 1000 per minute and more). Furthermore, it may be provided that the tools (3) surround the workpiece (1) almost completely, ie with only minimal distances between the tools, on the circumference.

Hammering may be provided according to the invention in embodiments in which the workpiece (1) is hot, semi-warm or cold formed. By means of hammers a wide variety of external and internal geometries of the workpiece (1) can be formed. This can be realized by the use of thorns and by different relative movements of the tools (3) relative to the workpiece (1).

An advantage of hammering is that with each tool stroke only a brief forming takes place at one point (tool engagement). As a result, there are fewer stresses in the component than, for example, in extrusion molding, where the entire cross section of the workpiece is pressed through a bottleneck. The material can be subjected to greater deformation during hammering because of this advantage, without the formation of cracks or excessive embrittlement.

A preferred use of a method according to the invention is the production of a resorbable or non-resorbable medical implant, for example a dental implant or dental implant. Alternatively, such a medical implant may also be in the form of a screw, a plate, a nail, a wire, a foil or a scaffold, in particular a stent. The achievable by means of a method according to the invention improvement of the mechanical material properties may have a positive effect especially in implants Since the primary purpose of the post-processing of the workpiece by means of hammering in the context of a method according to the invention is an improvement of the mechanical material properties, it can be provided to use a method according to the invention to produce a blank or a semifinished product, ie a workpiece intended for further processing.

In particular, the purpose of reworking the workpiece by means of hammering in the context of a method according to the invention may be to achieve a diameter reduction for the workpiece. As a result of a limitation of the workpiece length in ECAP by the punch stroke of the ECPA device used only limited length blanks or workpieces, often less than 500 mm, in particular less than 300 mm, can usually be produced. Thereby, the further processing, for example for the production of screws, nails, plates, scaffolds or stents, on corresponding devices, e.g. Lathes, long lathes, laser cutting devices, etc., mostly uneconomical. In many cases, these devices have automatic conveyors, such as automated spindle bores, through which long rods or tubes are to be continuously fed to the machining process.

A method according to the invention therefore makes it possible by means of hammering to produce workpieces, for example blanks or semi-finished products, e.g. Rods, pipes, etc., whose lengths after hammering> 500 mm, preferably> 1000 mm and particularly preferred may be 2000 mm and can be further processed so economically.

The workpiece or the semifinished product or the blank can then additionally be further machined, for example by machining, to produce a component with a defined final contour, for example a resorbable or non-resorbable medical implant, for example a dental implant or dental implant. Alternatively, such a medical implant may also be in the form of a screw, a plate, a nail, a wire, a foil or a scaffold, in particular a stent.

On the other hand, hammering also fundamentally allows shaping of a machined workpiece, which is characterized by great freedom of form and very good dimensional stability (eg achievable tolerances of <0.03 mm). Accordingly, it can also be provided, a method according to the invention for the production to use a component that are generated by the hammering already defined end contours of the component. A further post-processing can be omitted, whereby the cost of producing such a component can be kept low.

In one possible embodiment according to the invention, the hammering is carried out by means of a so-called double rotor (see Fig. 4). This means that the tools and the component guided, for example, by rollers, rotate either in synchronism or in the opposite direction relative to each other. As a result, the self-rotation of the workpiece is largely avoided and it can be realized a very high rate.

This procedure can be advantageously provided in particular for a large-scale production (eg production of at least 1000 identical components), while a production of blanks in a small series production (production of less than 1000 identical components) may be advantageous because then the additional costs associated with a For example, machining subsequent processing of the blanks may be less than the cost of several rotary swaging tools by means of which correspondingly different shapes for the components can be realized. However, a production of blanks can also be advantageously provided in a large-scale production.

In a preferred embodiment of a method according to the invention, it may be provided that the metallic material comprises titanium (pure titanium (Ti) or a titanium alloy) and / or magnesium (pure magnesium (Mg) or a magnesium alloy), in particular resorbable magnesium. The improvement of the mechanical material properties of the material achievable by the inventive reworking by means of hammering could, at least for pure titanium and titanium alloys, in particular for a preferred titanium alloy, in addition to titanium (at least or exclusively) still zirconium (Zr), preferably a mass fraction of about 10%. up to about 20%, in particular from about 12% to about 14% and specifically of about 13%.

Furthermore, titanium and magnesium, but in particular titanium, because of their good biocompatibility, are particularly advantageously used as material for medical implants, which can preferably be produced by means of a method according to the invention. In principle, the method according to the invention may be advantageously suitable for the machining of workpieces made of metallic materials, it being possible with particular preference for light metals (for example magnesium (Mg) or aluminum (Al)) or their alloys to be used. For example, the method according to the invention is also suitable for producing semi-finished products or blanks made of resorbable magnesium or magnesium alloys, from which implants can also be produced, for example by subsequent turning, laser cutting or other methods.

Furthermore, it can be provided that the temperature of the workpiece during processing by means of ECAP is at least 200.degree. C., at least 350.degree. C., at least 450.degree. C. or at least or approximately 500.degree. In particular, a temperature of between 200 ° C and 350 ° C may be advantageous for a magnesium or magnesium alloy workpiece. For a workpiece made of pure titanium or a titanium alloy, on the other hand, a temperature of at least 450 ° C. and in particular of 500 ° C. may be advantageous. If the temperature of such a titanium workpiece during machining by means of ECAP is less than 450 ° C. and in particular less than 500 ° C., pronounced crack formation in the workpiece as a result of machining by means of ECAP can occur.

In a further preferred embodiment of a method according to the invention, it can be provided that the machining by means of ECAP comprises at least four, six or eight machining passes. As a processing passage while a pressing of the workpiece is understood by an angled transition between two channels. For this purpose, it may be provided that the workpiece is pressed by a tool having more than two channels, wherein each two adjacent channels form an angled transition and at least two, preferably all transitions are aligned differently (see Fig .. 2). Additionally or alternatively, it may also be provided that the workpiece between the processing passages in each case by a defined angle, which may be preferably 90 ° or 60 ° or 45 °, was rotated about the longitudinal axis (in particular with the same direction of rotation). The term "rotated" refers to the alignment of the workpiece relative to the used ECAP tool between two machining passages, and it is particularly preferred that the rotations of the workpiece between the machining passages lead to alignments covering a total of at least or exactly 360 ° , In the context of a method according to the invention, it can further be provided that the workpiece is additionally pressure-formed (in particular extruded) before and / or after the machining by means of ECAP. Thereby, a further improvement of mechanical material properties and / or a reduction of dimensions of the workpiece can be realized. Such additional pressure conversion can be provided, in particular, before the workpiece is reworked by means of hammering.

Further preferably, it can be provided that the workpiece is additionally heat-treated. As a result, it is likewise possible to achieve a further improvement and / or a targeted adjustment of material properties of the material. The heat treatment may be provided before or after the processing by means of ECAP and before or after the post-processing by means of hammering and before or after an optionally provided additional pressure forming. The selected temperature for the heat treatment may depend on the chosen material and may for example be between 480 ° C and 780 ° C for titanium or a titanium alloy, while for magnesium or a magnesium alloy, the temperature may be between 120 ° C and 580 ° C. While both the number of such heat treatment steps and the duration may vary, cooling in air or by contact with another medium, for example water, oil or a gas, for example argon, is possible.

The indefinite articles ("a", "an", "an" and "an"), in particular in the patent claims and in the description generally describing the claims, are to be understood as such and not as numerical words. Corresponding to this concretized components are thus to be understood that they are present at least once and may be present more than once.

The improvements which can be achieved by means of a method according to the invention with regard to specific material characteristics of the material of a machined workpiece are illustrated below by means of comparative experiments.

The material used for the workpieces to be machined in the comparative experiments was an alloy consisting of titanium and zirconium in a proportion by mass of 13% (Ti-13% Zr). In the initial state, the workpieces formed of solid material had a circular cross section with diameters of 10 mm or 16 mm. Two of these workpieces in the initial state (Hereinafter referred to as "starting workpieces") were provided as comparative samples.

For the machining of workpieces by means of ECAP, an ECAP tool was used whose straight and circular cross-section channels have a (over the longitudinal extent constant) cross-sectional diameter of 12 mm, wherein the channels at a (forming) angle of 120 ° into each other , The workpieces were rotated by 90 ° between individual machining passages during machining by means of ECAP.

Due to the cross sectional diameters of the channels of the ECAP tool of 12 mm, those workpieces having a diameter of 16 mm in the initial state were turned down to 12 mm before machining by ECAP (hereinafter referred to as "solid material workpieces") , which had a diameter of 10 mm in the initial state, but in each case with a tube sleeve made of pure titanium and with an outer diameter of 12 mm jacketed (hereinafter referred to as "sleeve workpieces").

Most of the sleeve workpieces were machined at a temperature of 500 ° C in two, four or six processing passes by ECAP. After four machining passes, cracks occurred in the material of individual workpieces and in particular in the material of the tubular sleeve. When these sleeve workpieces were subjected to further machining passes, ends of the sleeve workpieces broke off regularly. For experimental purposes, a sleeve workpiece was machined at 450 ° C in four processing passes by ECAP. However, it came to even more pronounced cracking.

A first series of eight solid workpieces was machined at a temperature of 500 ° C in four passes through ECAP. After being processed by ECAP, these solid material workpieces had significantly better surface qualities than the correspondingly machined sleeve workpieces. Seven of these ECAP machined solid workpieces were provided for post-processing, either by hammering or by rolling, while one was provided as a comparative sample.

It was also attempted to lower the forming temperature to 450 ° C in one of the solid material workpieces. Four were made with this solid material workpiece Machining runs performed. However, it also came here to a strong cracking and breaking off the ends.

Therefore, solid material workpieces of a second series were also processed at a forming temperature of 500 ° C by means of ECAP; in this case, however, with more processing passes than the first series. It turned out that more than six machining passes would not be expedient, since even at six machining passes, in some cases, small pieces at the ends of the solid material workpieces break off and the improvement in the mechanical properties is only slight. In the case of a solid material workpiece of this second series, machining had to be stopped by means of ECAP due to massive cracking after five processing passes.

Finally, five solid-material workpieces of the second series were processed by ECAP and intended for further use. Four of them were intended for rework, either by hammering or by rolling, while again one should be used as a reference sample.

During post-processing by hammering, the diameter was reduced in several steps at room temperature (about 21 ° C):

In the post-processing by rolling, a diameter reduction at room temperature (about 21 ° C) in a first forming step from 12 mm to 8 mm (θ = 0.81) and in a second forming step from 8 mm to 6 mm (θ = 0, 58).

Subsequently, the post-processed and comparative workpieces were subjected to either one or more hardness tests or a tensile test As part of the hardness test, the Vickers hardness (HV) should be determined. For this purpose, the workpieces intended for the hardness test and embedded and polished for each were measured with a force of 10 kp (= HV10) according to EN ISO 6507-1 by means of a hardness tester (DuraScan 80 from EMCO-TEST Prüfmaschinen GmbH). An average of at least five individual tests (impressions) was formed per workpiece.

The workpieces intended for the tensile tests, which were only machined by means of ECAP, as well as the starting workpieces, were reduced by turning to a diameter of 6 mm. For these, a parallel measuring length of 30 mm (form B6x30 according to DIN 50125) was furthermore provided. The workpieces intended for the tensile tests, which were additionally rolled or hammered after machining by means of ECAP, already had a diameter reduction to a diameter of only 4 mm as a result of this post-processing. For these a parallel measuring length of 20 mm (form B4x20) was provided. In all the tension tests Anfangsdehngeschwindigkeit Con t 3 x 10 ^"4 ^{s' 1.}

The following table summarizes the results of the hardness tests:

Type of workpiece: ECAP- ECAP- NachbearHV10: Standard:

Bdg. Temp. Processing

Starting workpiece 252 3.6

(10mm)

Sleeve workpiece 2 500 ° C - 290 2.2

Sleeve workpiece 4 500 ° C - 300 1 .3

Sleeve workpiece 6 500 ° C - 304 1 .3

Sleeve workpiece 4 450 ° C - 309 8.0

Starting workpiece 239 1 .5

(16 mm)

Solid material workpiece 4 500 ° C - 319 1 .3

Solid material workpiece 6 500 ° C - 328 1 .6

Solid material workpiece 4 500 ° C Rollers 302 9.3

Solid material workpiece 4 500 ° C Hammering 338 10.7

ECAP book: ECAP machining passes; Standard deviation: Stabndarc deviation

These results show that the hardness of the material increases as the number of ECAP machining passes increases, with the largest increase in the first machining passes. For the solid material workpieces, the hardness increase is more pronounced than for the sleeve workpieces (+ 33% after four machining runs compared to + 38% after six machining passes).

For the workpieces that have been additionally rolled or hammered after machining by means of ECAP, the following summary statements can be made: Rolling reduces hardness in the present case, while hammering leads to a further increase in hardness. In both cases, however, the hardness distribution is not homogeneous. The additionally rolled workpieces are softer in the middle of the cross section, while the additionally hammered workpieces are harder in the middle than at the edge (see the following table). At the workpieces exclusively machined by ECAP, such inhomogeneities were not observed.

In order to make the hardness distribution visible, a location-dependent measurement with a lower load (HV1) was additionally performed on selected workpieces. These measurements show a small inhomogeneity with a starting workpiece (16 mm) with a slightly increased hardness at the edge, a largely homogeneous hardness distribution of a workpiece exclusively machined by ECAP (4 x ECAP at 500 ° C), in comparison with a reduction of the hardness in the center a reworked by rolling workpiece and in turn compared to the exclusively machined by ECAP workpiece an increase in hardness in the center of a post-machined workpiece by hammering.

The following table summarizes the results of the tensile tests. The following applies: The elongation characteristics are plastic strains (ie without the elastic strain) and all stresses are engineering stresses (technical stresses).

AW: initial workpiece; HW: sleeve workpiece; VW: solid material workpiece;

SG: yield strength; ZF: tensile strength; GD: Equal expansion;

BD: elongation at break; BE: fracture neck

A comparison of these results shows that the trends seen in the hardness tests also apply to the results of the tensile tests. The material of the workpieces becomes significantly stronger by machining with ECAP (eg + 48% in the tensile strength after four processing cycles). Hammering further increases strength (+ 30% tensile strength compared to ECAP alone) while rolling reduces it again. The stronger the material of the workpieces is, however, the lower is the respective ductility. While the elongation at break of exclusively workpieces machined by means of ECAP is more than 10%, this decreases by subsequent hammering to about 5%. Subsequent rolling leads to a very strong embrittlement. In the overall result, the following can be stated: The strength and hardness of the starting material (Ti-13% Zr) could be significantly increased by machining with ECAP, whereby a ductility greater than 10% could be maintained. Further processing of the previously ECAP machined workpieces has shown that rolling does not give good results, since both strength and ductility have been greatly reduced. Here, the reduction in ductility was expected, as this is a known effect in a cold deformation, especially in rolling and is referred to as work hardening or cold embrittlement. The reduction in strength through rolling was unexpected and is likely to be due to overstressing due to locally greatly increased stresses in the deformation of the material causing, for example, internal dislocation and microcracking. On the other hand, hammering further increased the strength (yield strength and tensile strength greater than 1300 MPa) and merely resulted in a tolerable reduction in ductility.

A use example of a method according to the invention lies in the production of a semifinished product which is subsequently provided for the production of dental implants on a lathe. For this purpose, a Ti13Zr workpiece was machined in four machining passes at 500 ° C by means of ECAP and subsequent hammering, whereby the hammering reduced the diameter of the cylindrical workpiece from 20 mm to 5 mm. The length of the workpiece increased from 150 mm to 2400 mm. As a result of the machining according to the invention, an improvement in the tensile strength from originally 750 MPa to 1300 MPa and a change in the elongation at break of 25% (as cast and rolled) to 5% were achieved.

A further example of an application of a method according to the invention is the production of a semifinished product, which is subsequently provided for the production of absorbable pins (pins) of magnesium on a lathe. For this purpose, a workpiece made of ZX00 (magnesium + <1% zinc + <1% calcium) was processed in four processing cycles at 250 ° C by means of ECAP and subsequent hammering, wherein by hammering a reduction of the diameter of the cylindrical workpiece from 20 mm to 4 mm was achieved. The length of the workpiece increased from 150 mm to 3750 mm. The processing according to the invention results in an improvement of the tensile strength from originally 220 MPa to 400 MPa and a change in the elongation at break of 17% (as cast and rolled) to 8%.

Claims

claims:

1 . A method of machining a workpiece from a metallic material, wherein the workpiece is machined by means of ECAP, characterized in that the workpiece is machined after machining by means of ECAP by means of hammering, wherein a diameter reduction is achieved.

2. The method according to any one of the preceding claims, characterized in that the deformation of the workpiece by means of hammering is carried out in several steps, each forming a degree of deformation of 0.05 to 2, preferably from 0.1 to 0.5 and particularly preferably from 0 , 15 to 0.3 has.

3. The method according to any one of the preceding claims, characterized in that the deformation of the workpiece by means of hammering at a temperature of 10 ° C to 600 ° C, preferably from 12 ° C to 380 ° C, more preferably from 14 ° C to 250 ° C takes place.

4. The method according to any one of the preceding claims, characterized in that the material comprises titanium and / or magnesium.

5. The method according to any one of the preceding claims, characterized in that the material comprises zirconium, preferably in a mass fraction of about 10% to about 20%, in particular from about 12% to about 14%.

6. The method according to any one of the preceding claims, characterized in that the temperature of the workpiece during processing by means of ECAP at least 200 ° C, at least 350 ° C, at least 450 ° C or at least 500 ° C.

Method according to one of the preceding claims, characterized in that the machining by means of ECAP comprises at least four, six or eight machining passes.

8. The method according to any one of the preceding claims, characterized in that the workpiece is additionally pressure-formed before and / or after processing by means of ECAP.

9. The method according to any one of the preceding claims, characterized in that the workpiece is additionally heat treated.

10. The method according to any one of the preceding claims, characterized by the production of a workpiece having a length> 500 mm or> 1000 mm or> 2000 mm.

1 1. Use of a method according to one of the preceding claims for the production of a blank.

12. Use of a method according to one of claims 1 to 10 for the production of a medical implant.

13. Use according to claim 12, characterized by the production of a dental implant, in particular a dental implant.

14. Use according to claim 12 or 13 characterized by the production of an implant in the form of a screw, a plate, a nail, a wire, a pin, a foil, a scaffold or a stent.