PROCESS FOR PRODUCING A FORGED COMPONENT FROM A TiAl ALLOY AND COMPONENT PRODUCED THEREBY

Abstract

A process for producing a component from a TiAl alloy by two-stage isothermal forging and to a component produced thereby. The process comprises a first isothermal forging of a component precursor at a temperature of at least about 1180 C., an intermediate annealing of the forged precursor at a temperature ranging from about 1130 C. to 1170 C. for about 1 to 8 hours and a subsequent second isothermal forging at a temperature of at least about 1180 C. with a degree of forming which is lower than the degree of forming in the first isothermal forging.

Claims

1. A process for producing a component from a TiAl alloy by two-stage isothermal forging, wherein the process comprises: (a) first isothermal forging of a component precursor at a temperature of at least 1180 C. and with a first total degree of forming; (b) intermediate annealing of the forged precursor of (a) at a temperature ranging from 1130 C. to 1170 C. for 1 to 8 hours; (c) second isothermal forging of the intermediately annealed precursor of (b) at a temperature of at least 1180 C. and with a second total degree of forming which is lower than the first total degree of forming.

2. The process of claim 1, wherein the TiAl alloy is a TNM alloy.

3. The process of claim 1, wherein the temperature in (a) is at least 1190 C.

4. The process of claim 1, wherein the temperature in (a) is at least 1200 C.

5. The process of claim 1, wherein the temperature in (c) is at least 1190 C.

6. The process of claim 4, wherein the temperature in (c) is at least 1200 C.

7. The process of claim 1, wherein the degree of forming in (a) is at least 0.55.

8. The process of claim 4, wherein the degree of forming in (a) is at least 0.6.

9. The process of claim 1, wherein the temperature in (b) ranges from 1135 C. to 1165 C.

10. The process of claim 4, wherein the temperature in (b) ranges from 1140 C. to 1160 C.

11. The process of claim 1, wherein (b) is conducted for at least 1.5 hours and/or for no longer than 7.5 hours.

12. The process of claim 1, wherein after (c) at least one further heat treatment is conducted.

13. The process of claim 12, wherein the further heat treatment is conducted at a temperature above a solvus temperature of the TiAl alloy.

14. The process of claim 12, wherein the further heat treatment is conducted at a temperature below a solvus temperature of the TiAl alloy.

15. The process of claim 12, wherein the further heat treatment is conducted at a temperature in the range from a solvus temperature to 30 C. above the solvus temperature of the TiAl alloy.

16. The process of claim 12, wherein the further heat treatment is conducted at a temperature of from 10 C. to 50 C. below the solvus temperature of the TiAl alloy.

17. The process of claim 12, wherein the further heat treatment is conducted for from 20 to 180 minutes.

18. The process of claim 12, wherein the further heat treatment is followed by a cooling.

19. The process of claim 18, wherein the cooling is followed by a further heat treatment.

20. A component produced by the process of claim 1.

Description

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0026] A material for a component produced in accordance with the invention may, for example, have a composition in the range of from 42 at. % to 45 at. % of titanium, from 3.5 at. % to 4.5 at. % of niobium, from 0.75 at. % to 1.5 at. % of molybdenum, and also from 0.05 at. % to 0.15 at. % of boron, the remainder being aluminum and unavoidable impurities.

[0027] The material of the component is first forged by a first isothermal forging step at approximately 1200 C. with a degree of forming of approximately 0.6.

[0028] Next, the forged material is cooled to room temperature by means of air cooling and then heated at approximately 1150 C. for 4 hours, followed by a second isothermal forging step at approximately 1200 C. to (near) net shape.

[0029] The component thus produced can, in a first variant, be subjected to a (second) heat treatment at a temperature above the solvus temperature (for example at approximately 1290 C.) for, by way of example, 20 to 40 minutes.

[0030] Thereafter, the component is cooled rapidly, for example by means of fan cooling. This fan cooling is effected in air or in an oven, the temperature being lowered to below about 600 C. and then raised to approximately 850 C. and held at this temperature for approximately 6 hours.

[0031] The -TiAl microstructure that was established at the temperature of the second heat treatment, that is to say at a temperature of approximately 1290 C., is largely frozen in as a result.

[0032] In a second variant for the second heat treatment, the component is heated to below the y solvus temperature. By way of example, the component is heated at approximately 1235 C. for about an hour and subsequently cooled (fan cooling). The temperature is lowered to below 600 C. during the fan cooling and then raised again to approximately 850 C.

[0033] Although the present invention has been described in detail on the basis of the working example, it is clear to those skilled in the art that modifications are possible in such a way that individual features can be omitted, or different combinations of features can be implemented, without departing from the scope of protection of the claims. In particular, the disclosure of the present invention includes all combinations of the individual features presented above.