CH673658A5 - - Google Patents

Description

DESCRIPTION

Technical field

Oxide dispersion hardened superalloys based on nickel, which thanks to their excellent mechanical properties are used at high temperatures in the construction of thermal machines. Preferred use as a blade material for gas turbines.

The invention relates to the improvement of the mechanical properties of oxide dispersion-hardened nickel-based superalloys with overall optimal properties with regard to high-temperature strength, long-term stability and ductility. The focus is on creep behavior and fatigue strength at high material temperatures.

In particular, it relates to a process for producing a workpiece consisting of a single crystal with a preferred longitudinal direction from an oxide dispersion-hardened nickel base superalloy, starting from powder-metallurgically produced, hot-kneaded fine-grained starting material, the latter first being subjected to an extrusion and then a zone annealing process.

PRIOR ART xo Oxide dispersion-hardened superalloys are produced by powder metallurgy, generally compacted by extrusion or hot isostatic pressing of a powder mixture and annealed to coarse grains, optionally also thermally aged. They are then sold as semi-finished products in the form of rods or plates with pronounced coarse stem crystals oriented in the longitudinal direction. In this direction, the longitudinally oriented stem crystals produced by zone annealing have the best properties in terms of creep resistance. In the transverse direction, however, the semi-finished product and the workpiece made from it have numerous grain boundaries due to comparatively poor properties: creep and fatigue strength, corrosion resistance, fracture toughness, ductility are low. Attempts are therefore being made to produce semifinished products which have as few grain boundaries as possible in the transverse direction, ie which have “thicker” grains. This inevitably leads to the demand for the single crystal, in which there are no grain boundaries which impair the high-temperature properties. 30 However, all previous attempts to achieve this goal with conventional methods have failed.

The following literature is cited on the prior art:

- G.H. Gessinger, Powder Metallurgy of Superalloys, Butterworths, London, 1984

35 - R.F. Singer and E. Doctor, Conf. Proc. "High Temperature Materials for Gas Turbines", Liège, Belgium, October 1986

- J.S. Benjamin, metal. Trans. 1970,1, 2943-2951

- M.Y. Nazmy and R.F. Singer, Effect of inclusions on tensile ductility of a nickel-base oxide dispersion strengthened

4o superalloy, Scripta Metallurgica, Vol. 19, pp. 829-832, 1985, Pergamon Press Ldt.

- T.K. Glasgow, "Longitudinal Shear Behavior of Several Oxide Dispersion Strengthened Alloys", NASA TM-78973 (1978).

45 - R.L. Cairns, L.R. Curwick, and J.S. Benjamin, Grain Growth in Dispersion Strenghtened Superalloys by Moving Zone Heat Treatments, Metallurgical Transactions A, Vol. 6 A, January 1975, p 179-188.

The invention is based on the object of specifying a method for producing a workpiece consisting of a single crystal with a preferred longitudinal direction from an oxide-dispersion-hardened nickel-based superalloy. It is assumed that the powder-metallurgically produced, hot-melted, fine-grained raw material, the powder first being compressed by extrusion. The process is intended to enable single crystals of large dimensions, such as are required for the production of gas turbine blades for industrial plants, to be realized.

This object is achieved in that, in the method mentioned at the outset, the workpiece is worked out of the extruded starting material in such a way that its preferred longitudinal axis includes an arbitrary angle a with the extrusion direction and that the workpiece produced in this way is at least partially so by a zone annealing heating device is passed that the extrusion direction in the workpiece with that on the tem

temperature / displacement gradient of the vertical recrystallization front, which is also the temperature front, encloses an angle β from 0 to 600, and that the temperature / displacement gradient in the workpiece in the heating zone is at least 5 ° C./mm.

WAY OF IMPLEMENTING THE INVENTION The invention is described on the basis of the exemplary embodiments explained in more detail by the figures:

It shows:

1 is a plan view of a section of strictly pressed raw material with the longitudinal axis of the workpiece perpendicular or oblique to the extrusion direction,

2 schematically shows the position of a workpiece according to FIG. 1 in the zone annealing process for vertical passage through the induction coil,

3 schematically shows the position of a workpiece according to FIG. 2 in the zone annealing process for oblique passage through the induction coil,

4 is a perspective view of the position of the workpiece in the extruded material,

5 is a perspective view of the vertical passage of the workpiece through the induction coil during zone annealing,

6 is a perspective view of the inclined passage of the workpiece through the induction coil during zone annealing,

7 is a plan view of a section of strictly pressed primary material with the longitudinal axis of the workpiece parallel to the extrusion direction,

8 schematically shows the position of a workpiece according to FIG. 7 in the zone annealing process for oblique and for transverse passage through the induction coil,

9 shows a representation in longitudinal section with a perspective for vertical passage of the workpiece through the zone annealing device,

10 is a representation in longitudinal section with perspective for obliquely passing the workpiece through the zone annealing device,

11 is a perspective view of the transverse passage of a narrow side of a workpiece according to FIG. 7 through the induction coil of a first zone glow heating device,

12 shows a section through a workpiece according to FIG. 7 after transversely passing a narrow side through the induction coil of a first zone annealing heating device,

13 shows a section through a workpiece according to FIG. 7 during the vertical longitudinal passage through the induction coil of a second zone glow-heating device at the beginning of the process,

14 shows a section through a workpiece according to FIG. 7 during the vertical longitudinal passage through the induction coil of a second zone annealing heating device towards the end of the process.

Fig. 1 shows the top view (plan view) of a section of strictly pressed primary material with the longitudinal axis of the workpiece perpendicular or oblique to the extrusion direction. 2 is the extrusion direction indicated by arrow s, which coincides with the longitudinal axis of the primary material 1. Workpieces, the position of which is shown, are worked out from the primary material 1. 6 is the longitudinal axis of the workpiece to be cut out. 3 is a workpiece whose longitudinal axis 6 is perpendicular

3,673,658

to extrusion direction 2 (angle a = 90 °). 4 is a workpiece, the longitudinal axis 6 of which is oblique to the extrusion direction 2 (45 ° <a <90 °).

Fig. 2 shows schematically the position of the workpiece during the zone annealing process in the case of the workpiece being passed vertically through the induction coil of the heating device. 8 is the induction coil of the zone glow heating device, the plane of which in the present case is penetrated perpendicularly by the longitudinal axis 6 of the workpiece (angle <p io = 90 °). The level of the induction coil 8 coincides with the direction 7 of the recrystallization front r (= temperature front). The left side of the figure relates to a workpiece 3 with an angle a to the extrusion direction of 90 °. The angle 15 β (not shown) between extrusion direction s and recrystallization front r, which is decisive for the formation of single crystals, is 0 ° here, since the directions coincide. The right side of the figure represents a workpiece 4 with an angle a deviating from 90 ° (in the present case, for example, 60 °). The angle β is 30 ° here. 20 The arrow v represents the feed direction 9 of the workpiece 3 or 4 during zone annealing.

3 schematically shows the position of the workpiece during zone annealing in the event that the workpiece is passed obliquely through the induction coil of the heating device 25. 8 is the induction coil, the plane of which is penetrated obliquely by the longitudinal axis 6 of the workpiece (45 x <p <90 °). 7 is the direction of the recrystallization front r. The angle ß can be clearly seen. Otherwise, the representations and reference numerals correspond to those in FIG. 2.

In Fig. 4, the position of the workpiece to be machined in the extruded material is shown in perspective. 1 is the extruded, fine-grained primary material (semi-finished product) in the form of a rod of rectangular cross-section. 2 is the extrusion direction lying in the longitudinal axis (arrow s). 3 is a prismatic workpiece intended for the production of an airfoil of a gas turbine blade, the longitudinal axis 6 of which is perpendicular to the extrusion direction 2 (angle a = 90 °). The shape of the finished workpiece is indicated by the airfoil profile on the end faces.

Fig. 5 is a perspective view of the vertical passage of the workpiece through the induction coil in zone annealing. 3 is the workpiece, the longitudinal axis 6 of which is perpendicular to the extrusion direction 2 of the primary material 45 (angle a = 90 °). 8 is the induction coil of the zone glow heater. The feed direction 9 (arrow v) of the workpiece 3 is perpendicular to the plane of the induction coil 8 (direction 7 of the recrystallization front r) and coincides with the longitudinal axis 6 of the former (angle cp so = 90 °). The angle ß not shown is 0 °.

Fig. 6 is a perspective view of the oblique passage of the workpiece through the induction coil in zone annealing. 3 is the workpiece, the longitudinal axis 6 of which is perpendicular to the extrusion direction 2 (arrow s) of the half-55 (angle a = 90 °). 8 is the induction coil of the zone glow heater. 6 is the longitudinal axis of the workpiece 3, which is skewed on the plane of the induction coil 8 (direction 7 of the recrystallization front r) and coincides with the feed direction 9 (arrow v) of the workpiece 3 (45 <(p <90 °; im In this case, angle cp is approximately 60 °. The angle ß between 2 and 7 (arrows s and r) is approximately

30 °.

7 shows the top view (plan view) of a section of extruded primary material with the longitudinal axis of the workpiece parallel to the extrusion direction. 1 is extruded, fine-grained primary material (semi-finished product) in the form of a prismatic body, a rod or plate of rectangular cross section. 2 is the strand indicated by arrow s

673 688 4

Press direction, which speak with the longitudinal axis of the primary material 1 that of FIG. 9. The cover plate 10 which coincides. A workpiece 5 is made from the primary material 1. FIG. 9 has been omitted.

worked out, whose location is shown. 6 is the longitudinal axis. FIG. 11 relates to a perspective view of the axis of the workpiece 5 to be cut out, which coincides with the transversal passage of a narrow side of one of the extrusion directions 2 (not shown 5 workpiece according to FIG. 7 through the induction coil of one

Angle a = 0 °). first zone glow heater. 5 is a prismatic

8 schematically shows the position of a workpiece, the workpiece whose longitudinal axis 6 coincides with the extrusion direction according to FIG. 7 in the zone annealing process for oblique and for 2 (arrow s). 8 indicates the induction coil of a transverse passage through the induction coil of the zone glow heater in the form of a loop, the

Heater. 8 is the induction coil of the zone glow-precise shape and dimension of the respective workpiece 5

Heating device whose level is adapted to the direction 7 of the recri. 9 is the feed direction (arrow v), which coincides with the installation front r (= temperature front). That is perpendicular to the longitudinal axis 6 of the workpiece 5. The Rich

The left-hand side of the figure relates to a crooked recess 7 of the recrystallization front r (= temperature front) leading through the induction coil 8, the feed direction of the left-hand narrow side of the workpiece 5 being essentially 9 (arrow v) in the extrusion direction 2 (arrow s) lies. This is in the extrusion direction 2. The corresponding temperature

The longitudinal axis 6 of the workpiece 5 forms with the direction 7 of the temperature / displacement gradient 12 (arrow G) is perpendicular to the

Recrystallization front (arrow r) the angle <p (in the aforementioned directions. The approximately dynamic case 135 °). The limit 16 for fine crystal formation between the fine-grained material and the already existing angle β between the arrows s and v is thus the single crystal produced is indicated by a dashed line.

45 °. The right side of the figure represents a transversal pointing.

perform by the induction coil 8. The work in Fig. 12 is a section through a workpiece according to Fig. 7 piece 5 is transversely so that its longitudinal direction 6, which coincides with the extrusion direction 2 after the transverse passage of a narrow side, parallel to by the induction coil of a first zone glow-heating level of the induction coil 8, d. H. shown to direction 7 of the direction of recr. The left narrow side of the workpiece 5 comes to rest (arrow r). After passing through the loop-shaped induction direction 9 (arrow v), the feed 25 is perpendicular to the longitudinal axis 6. The ionizing coil 8 of the zone glow-heating device at an angle (p (not shown) is 0 °. crystal 15 recrystallized, while the remaining part still consists of a bend, not shown, angle β (between the arrows s fine-grained raw material 14. The other reference and r) are 0 characters correspond to those of FIG. 11.

"". n, "• y •• 1. ...". T-,, 30 Fig. 13 shows a step through a workpiece according to

. is a representation in longitudinal section with a perspective view? for vertical longitudinal passage tive for vertical passage of the workpiece through, 0,,. T a w 1 • -, ~ TT. .

"...." • •,. t 7,. . , through the induction coil of a second zone glow heater

the zonengluh facility. The conditions correspond. -a • * n t-> .. ,, ,, „

, _,. ,,? t- .. - ..,,, v .. _. . direction at the beginning of the process. 11 and 12

2, lmks and FIG. 5.3 is pretreated workpiece 5, in a second step the workpiece with,, u,. T a 1 1 o •?

^ _, _r.,. _. t •• i_ ^ a xxt 1 3S in this way through the induction coil 8 of a second zone glow

Extrusion direction 2 (arrow s). The longitudinal axis 6 of the factory TT. . ... c ■ T ..,,

, ... ça ■ l. o Heating device that its longitudinal axis 6 coincides with the rwr t iS 6 QS (vn ^ fanSPress ^ c feed direction 9 (arrow v). The already to

(Angle a = 90 °). 8 is the induction coil of the zone glow. Single crystal recrystallized narrow side makes

TT • • * t • 1 tll / j 4 • 4 1,. \ vlllvlli Jj'lllA.lXolclll 1J 1 vaI Ijlulllolvl Lv Uwillilctlüvllv llluvill

Heating device, the level (indicated by arrow r),. . . A c A ^ r • i ••.

«Rj t- v wT 1 1% x ^ the beginning, which stands vertically on the longitudinal axis 6 of the workpiece 3 from unchanged fine-grained. . 11l4L. r3 .... »• *, ... T c,

(Angle cp = 90 °). The feed direction 9 (arrow v) of the nfstfende fn & T61.1 workpiece 5 is

. , T "t.? “After the orientation of the single crystal 15.

Workpieces coincide with its longitudinal axis 6. The i * * •• u »...

. ,. . . , t,, q. . nom-4. • »lj 1 The latter grows, so to speak, in the fine-grained material not shown ß here 0 0 is a cover 14 no. The direction 7 ^ er recrystallization front r is plate, 11 em furnace to keep warm or to achieve a, e, T .. °.

'. . . ,, .... j S, i i r? t perpendicular to the longitudinal axis 6 of the workpiece and has no slow cooling of the workpiece 3. The temperature D, ° ...

temperature / path gradient 12 (arrow G) in the middle of the cross- 4 * more to the original extrusion direction,

t. a txT i i o r-ii. • a t •• u t t which is why it is no longer shown; to confuse the workpiece 3 falls m along its longitudinal axis 6. In., ° °

to avoid

Part of the figure shows a curve 13. It gives inFig. 14 is a section through a workpiece according to FIG. 7

the temperature T of the workpiece 3 in the longitudinal axis 6m when passing it vertically longitudinally through the

Function of the feed or the location x again. One can T j w i • ^ ". . •,.

j A,, ...,, 1.j. . so take induction coil of a second zone glow heater from this that the workpiece is very quickly (gradient versus the end of the process represents. The single crystal

G high) to the recalculation temperature and 15 has grown at the expense of the fine-cored raw material and then kept there for a certain time. 14. Otherwise the same reference numerals apply as in relatively slow cooling. pjg 13

10 shows a representation in longitudinal section with perspective 55

tive for oblique passage of the workpiece through the embodiment 1

Zone glow device. The ratios correspond to those - see Fig. 1,2 left side, 4 and 9!

3 on the left and FIG. 6. The workpiece 3 with the primary material 1 was a powder metallurgy

Extrusion direction 2 and the longitudinal axis 6 (angle a = oxide dispersion hardened nickel-based superalloy with the

90 °) is moved in the direction of its longitudinal axis 6: feed 60 trade name MA 6000 from INCO in front. The alloy

direction 9 (arrow v). The level of the induction coil 8 has the following composition:

skewed on the longitudinal axis 6 of the workpiece 3 (45 <<p <90 0;

in the present case angle cp approx. 60 °). The temperature /

Path gradient 12 (arrow G) is perpendicular to the plane of Cr = 15% by weight

Induction coil 8 and thus takes with the longitudinal axis 6 (= es W = 4.0 wt .-%

Feed direction 9) the angle 90 ° -cp (in the present Mo = 2.0% by weight

Case approx. 30 °). The angle β between the arrows s and v AI = 4.5% by weight

is also 30 ". All other reference numerals ent- Ti = 2.5 wt .-%

5

673658

Ta =

C.

B

Zr = Y2O3 = Ni =

2.0% by weight 0.05% by weight 0.01% by weight 0.15% by weight

1.1% by weight rest% by weight

The raw material 1 was in a fine-grained state in the form of an extruded rod with a rectangular cross section and had the following dimensions:

Width = 180 mm thickness = 65 mm

Length = 1000 mm (extrusion direction s)

A section 110 mm wide was cut off from the bar transversely to the extrusion direction s (a = 90 °), so that the dimensions of the workpiece 3 to be treated were as follows:

Temperature of 1290 ° C, which was 15 ° C below the solidus temperature.

Embodiment 3 s See Fig. 7,8 left side!

A powder-metallurgically produced oxide dispersion-hardened nickel-based superalloy of the following composition was present as primary material 1:

xo Cr =

20.0% by weight

AI =

6.0% by weight

Mo =

2.0% by weight

W =

3.5% by weight

Zr =

0.19% by weight

15 B =

0.01% by weight

C.

0.01% by weight

Y2O3 =

1.1% by weight

Ni =

rest

20th

Width = 110 mm (extrusion direction s)

Thickness = 65 mm

Length = 180 mm (perpendicular to the extrusion direction s) 25

Profile radius

-V

Cross-sectional area 71

-V

110-65

= 48 mm

The primary material 1 was in the fine-grained state as an extruded rod of rectangular cross-section. A workpiece 5 was cut from the rod, the longitudinal axis 6 of which coincided with the extrusion direction 2 (arrow s) and had the following dimensions:

Width = 160 mm thickness = 45 mm

Length = 280 mm (extrusion direction s)

The workpiece 3 was then subjected to a zone annealing process, the feed direction 9 lying parallel to the edge measuring 180 mm in the longitudinal axis 6 and thus being perpendicular to the original extrusion direction 2 (arrow s) of the starting material 1 (cp = 90 °). The angle β was therefore 0. The constant feed rate v was 4 mm / min, the average heating rate in the middle of the workpiece 3 for a temperature of 1160 ° C. 43 ° C./min. The workpiece 3 reached a temperature of 1275 ° C. on its circumference in the plane of the induction coil 8. The temperature / displacement gradient 12 (arrow G) in the middle in the feed direction 9 reached the value of 10.7 ° C./min at 1200 ° C.

Embodiment 2

See Fig. 1,2 right side!

An oxide dispersion-hardened nickel-based superalloy with the composition according to Example 1 was in the form of a rod. A workpiece 4 of the following dimensions was cut out of it obliquely to the extrusion direction s at an angle a of 60 °:

Width = 100 mm thickness = 50 mm length = 220 mm

The workpiece 4 was subjected to a zone annealing process, the angle cp = 90 ° and the angle β = 300. The feed rate was 2.5 mm / min, the average heating rate in the middle of the workpiece 4 for a temperature of 1180 ° C 50 ° C / min. The temperature / displacement gradient 12 (arrow G) at 1200 ° C. in the middle in the feed direction 9 of the workpiece 4 was 20 ° C./min. The workpiece 4 reached a maximum on the circumference

30 The angle a was thus 0 °. The workpiece 5 was subjected to a zone annealing process, the feed direction 9 being parallel to the edge measuring 280 mm in the longitudinal axis 6. The plane of the induction coil 8 (= direction 7 of the recrystallization front r) was such that the angle 35 was cp = 1400 and the angle β = 40 °. The feed speed v was 3 mm / min, the heating speed in the middle of the workpiece 5 averaged 47 ° C / min. The temperature / path gradient 12 (arrow G) perpendicular to the recrystallization front 7 (arrow r) was in the middle of the workpiece 5 at a temperature of 1200 ° C. in the heating area on average 10 ° C./mm. The maximum temperature was 1280 ° C.

Embodiment 4 45 See FIGS. 7, 11, 12, 13, 14!

An oxide-hardened nickel-based superalloy was present as primary material 1 in the form of an extruded rod in the fine-grained state. The alloy had the following composition:

50

Cr =

17.0% by weight

AI =

6.0% by weight

Mo =

2.0% by weight

w =

3.5% by weight

55 Ta =

2.0% by weight

Zr =

0.15% by weight

B

0.01% by weight

C.

0.05% by weight

Y2O3 =

1.1% by weight

60 Ni

rest

65

A workpiece 5 was cut from the rod, the longitudinal axis 6 of which coincided with the extrusion direction 2 (arrow s) and had the following dimensions:

Width = 120 mm thickness = 65 mm

Length = 350 mm (extrusion direction s)

673658

Profile radius = ^ Q ^ rschnittflà ^ = ^ 1 ^ 65 = 50mm

The workpiece 5 was heat-treated in a first method step according to FIGS. 11 and 12. One of its narrow sides, with its longitudinal axis 6 set transversely, was passed through the induction coil 8, which is designed as a loop, of a first zone annealing heating device. The feed direction 9 (arrow v) was both perpendicular to the longitudinal axis 6 and to the extrusion direction 2 (arrow s). The direction 7 of the recrystallization front r at the head end of the workpiece 5 was approximately parallel to the extrusion direction 2, as a result of which optimal conditions for the production of a single crystal 15 were present. The corresponding temperature / path gradient 12 (arrow G) was approximately perpendicular to the recrystallization front r. The remaining part of the workpiece 5 remained in the state of the fine-grained starting material 14. In a second process step, the workpiece 5 was turned through 90 ° and, according to FIGS. 13 and 14, its longitudinal axis 6 was passed longitudinally through the induction coil 8 of a second zone annealing heating device. The head end of the workpiece 5, which had already been recrystallized into a single crystal 15, was introduced into the induction coil. The feed direction 9 (arrow v) and the longitudinal axis 6 of the workpiece 5 coincided and were perpendicular to the direction 7 of the recrystallization front r (= plane of the induction coil). The single crystal 15 grew, as it were, into the remaining part consisting of fine-grained primary material 14. The extrusion direction 2 has been omitted in FIGS. 13 and 14 valid for the second method step, since it no longer plays a role here. The maximum temperature during recrystallization was 1280 ° C. The heating rate was 45 ° C / min, the feed rate v approx. 3 mm / min. The temperature / displacement gradient at 1200 ° C in the middle of the workpiece 5 was 15 ° C / mm.

The invention is not restricted to the exemplary embodiments. It is generally a method of producing one from a single crystal with preferred

Workpiece 3, 4, 5 consisting of an oxide dispersion hardened nickel-based superalloy, starting from powder-metallurgically produced, hot-kneaded, fine-grained primary material 1, the latter first being subjected to an extrusion and then a zone annealing process, in that the workpiece 3, 4, 5 is extruded from the extruded material The primary material 1 is worked out so that its preferred longitudinal axis 6 forms an arbitrary angle a with the extrusion direction 2 and the workpiece 3, 4, 5 produced in this way is at least partially passed through a zone annealing heating device such that the extrusion direction 2 in the workpiece 3, 4, 5 forms an angle β of 0 to 60 ° with the recrystallization front 7, which is perpendicular to the temperature / path gradient 12 and which is also the temperature front, the temperature / path gradient 12 in the workpiece 3, 4, 5 in the heating zone is at least 5 ° C / mm.

In one embodiment, the recrystallization front 7 is perpendicular to the moving longitudinal axis 6 of the workpiece 3, 4, 5 and the temperature / path gradient 12 is 7 to 20 ° C./mm. In another embodiment, the recrystallization front 7 is inclined to the longitudinal axis 6 and the temperature / path gradient is 10 ° C / mm.

In a further embodiment, the workpiece 5 is worked out of the extruded material 1 in such a way that its preferred longitudinal axis 6 forms an angle a of 0 ° with the extrusion direction 2, and the workpiece 5 produced in this way is first used in only one of its first steps Narrow sides are guided through a first zone annealing heating device in such a way that the extrusion direction 2 essentially forms an angle β of 00 with the recrystallization front 7, the workpiece 5 recrystallized in this way on a narrow side to form a single crystal 15 in a second step in a second step Zone annealing heating device is carried out such that its preferred longitudinal axis 6 coincides with the feed direction 9 and the zone annealing process is started on the narrow side of the workpiece 5 that has already been recrystallized into a single crystal 15 and the angle <p between the longitudinal axis 6 of the workpiece 5 and d he recrystallization front 7 can be any.

6

5

10th

15

20th

25th

30th

35

40

B

3 sheets of drawings

Claims (4)

673658 PATENT CLAIMS Process for the production of a workpiece (3, 4, 5) consisting of a single crystal with a preferred longitudinal direction from an oxide dispersion hardened nickel-base superalloy, starting from powder-metallurgically produced, hot-kneaded fine-grained primary material (1), the latter firstly using an extrusion and then a zone annealing process is subjected to, characterized in that the workpiece (3, 4, 5) is worked out of the extruded primary material (1) in such a way that its preferred longitudinal axis (6) with the extrusion direction (2) includes any angle a and that this is on it Workpiece (3, 4, 5) produced in this way is at least partially passed through a zone annealing heating device in such a way that the extrusion direction (2) in the workpiece (3, 4, 5) is perpendicular to the temperature / displacement gradient (12) Recrystallization front (7), which is also the temperature front, an angle β of 0 to 60 ° closes, and that the temperature / displacement gradient (12) in the workpiece (3, 4, 5) in the heating zone at least 5 ° C / mm. 2. The method according to claim 1, characterized in that the recrystallization front (7) during zone annealing is perpendicular to the longitudinal axis (6) of the workpiece (3, 4, 5) and the temperature / path gradient (12) 7 to Is 20 ° C / mm. 3. The method according to claim 1, characterized in that the recrystallization front (7) is oblique to the preferred longitudinal axis (6) of the workpiece (3, 4, 5) during zone annealing and the temperature / displacement gradient (12) 10 ° C / mm is. 4. The method according to claim 1, characterized in that the workpiece (5) is worked out from the extruded material (1) such that its preferred longitudinal axis (6) with the extrusion direction (2) includes an angle a of 0 ° and that Workpiece (5) produced in this way is first passed in a first step with only one of its narrow sides through a first zone annealing heating device such that the extrusion direction (2) in the workpiece (5) essentially has an angle β of 0 ° with the recrystallization front (7), and that the workpiece (5) recrystallized in this way on a narrow side to form a single crystal (15) is passed in a second step through a second zone annealing heating device in such a way that its preferred longitudinal axis (6) coincides with the feed direction ( 9) coincides and that the zone annealing process on the narrow side of the workpiece (5) that has already been recrystallized to form a single crystal (15) is started, whereby the angle <p between the longitudinal axis (6) of the workpiece (5) and the recrystallization front (7) can be arbitrary.