GAS TURBINE HOT GAS COMPONENT REPAIR METHOD

• US 20090255117A1
• Filed: 04/08/2009
• Published: 10/15/2009
• Est. Priority Date: 04/09/2008
• Status: Active Grant

• Current Assignee: Ansaldo Energia IP UK Limited (Ansaldo Energia SPA)
• Original Assignee: Alstom Technology Ltd. (Alstom SA)
• Inventors: Schnell, Alexander, Bissig, Hans, Kurtz, Rainer, Hovel, Simone, Ambrosy, Gunter, Stankowski, Alexander, Hoebel, Matthias
• Granted Patent: US 8,156,649 B2
• Time in Patent Office: Days
• US Class Current: 29/889.100
• CPC Class Codes: B23K 1/0018 Brazing of turbine parts
• CPC Class Codes: B23K 1/0056 soldering by means of beams, e.g. lasers, E.B.
• CPC Class Codes: B23K 10/00 Welding or cutting by means of a plasma
• CPC Class Codes: B23K 2101/001 Turbines
• CPC Class Codes: B23K 26/0093 combined with mechanical machining or metal-working covered by other subclasses than B23K combined welding or cutting procedures or apparatus B23K28/02
• CPC Class Codes: B23K 28/02 Combined welding or cutting procedures or apparatus
• CPC Class Codes: B23K 9/0026 specially adapted for particular articles or work
• CPC Class Codes: B23P 6/005 using only replacement pieces of a particular form
• CPC Class Codes: F01D 5/005 Repairing methods or devices
• CPC Class Codes: F05D 2230/235 TIG or MIG welding
• CPC Class Codes: F05D 2230/80 Repairing, retrofitting or upgrading methods
• CPC Class Codes: Y10T 29/49318 Repairing or disassembling
• CPC Class Codes: Y10T 29/49728 and by a metallurgical operation, e.g., welding, diffusion bonding, casting
• CPC Class Codes: Y10T 29/49732 by attaching repair preform, e.g., remaking, restoring, or patching

Abstract

A gas turbine engine hot gas component repair method for defects that do not extend through the thickness of the component is provided. First defects are removed by machining a cavity in the surface of a component. Coupons, fittable within the cavities are manufactured, are for example coated with brazing medium on an inner surface and then joined to the component by joining means such as laser metal forming. The joint holds the coupon during later heat treatment, thereby eliminating a need for holding aids. Before heat treatment, a further brazing medium can be applied to the surface of the coupon overlapping onto the component. A single heat treatment, brazing the coupon to the component and, brazing the brazing medium to the outer surface of the coupon can, then be used to complete the repair.

Claims

1. A gas turbine engine hot gas component repair method for defects that do not extend through a thickness of the component, comprising:

a) machining at least one cavity in a surface of the component to remove at least one defect from the component;

b) manufacturing at least one coupon fittable within the cavity;

c) applying a brazing medium to the coupon to enable brazing of the coupon to the component;

d) fitting the coupon as a fitted coupon into the cavity;

e) joining the fitted coupon to the component at an outer edge of the fitted coupon;

f) applying foil or sheet brazing medium to the fitted coupon to achieve a thickness requirement of the component; and

g) subjecting the component to a thermal cycle wherein the foil or sheet brazing medium is brazed to an outer surface of the coupon.

2. The method of claim 1, wherein the brazing medium is a binder free brazing medium.

3. The method of claim 1, wherein step f) includes applying the foil or sheet brazing medium to neighboring surfaces of the fitted coupon.

4. The method of claim 1, wherein before step c), the method comprises:

machining a surface of the coupon.

5. The method of claim 1, wherein the joining of step e) comprises:

laser metal forming or electron beam welding, and a resulting joint is heat treated as part of step g).

6. The method of claim 1, wherein the joining of step e) comprises

TIG welding, and a resulting joint is heat treated as part of step g).

7. The method of claim 1, wherein the joining is along discrete points.

8. The method of claim 6, wherein joining comprises:

laser metal forming along an outer edge of the coupon to create a near final shape joint.

9. The method of claim 1, comprising:

re-contouring after step g).

10. The method of claim 1, wherein the component is made from single crystal or directionally solidified material.

11. The method of claim 1, wherein the component is made from cast material.

23. The method of claim 1, comprising:

before step e), subjecting the component to an initial thermal cycle wherein the coupon is brazed to the component.

12. A gas turbine engine hot gas component repair method for defects that do not extend through a thickness of the component, comprising:

a) machining at least one cavity in a surface of the component to remove at least one defect from the component;

b) manufacturing at least one coupon fittable within the cavity;

c) applying a brazing medium to the coupon to enable brazing of the coupon to the component;

d) fitting the coupon as a fitted coupon into the cavity;

e) joining the fitted coupon to the component at an outer edge of the fitted coupon;

f) applying foil or sheet brazing medium to the fitted coupon to achieve a thickness requirement of the component; and

g) subjecting the component to a single thermal cycle wherein the foil or sheet brazing medium is brazed to an outer surface of the coupon and the coupon is brazed to the component.

13. The method of claim 12, wherein the brazing medium is a binder free brazing medium.

14. The method of claim 12, wherein step f) includes applying the foil or sheet brazing medium to neighboring surfaces of the fitted coupon.

15. The method of claims 12, wherein before step c), the method comprises:

machining a surface of the coupon.

16. The method of claim 12, wherein the joining step of step e) comprises:

laser metal forming or electron beam welding, and a resulting joint is heat treated as part of step g).

17. The method of claim 12 wherein the joining step of step e) comprises:

TIG welding, and the resulting joint is heat treated as part of step g).

18. The method of claim 12, wherein the joining is along discrete points.

19. The method of claim 17, wherein joining comprises:

laser metal forming along an outer edge of the coupon to create a near final shape joint.

20. The method of claim 12, comprising:

re-contouring after step g).

21. The method of claim 12, wherein the component is made from single crystal or directionally solidified material.

22. The method of claim 12, wherein the component is made from cast material.