Method for reconditioning a hot gas path part of a gas turbine

Patent metadata

Field	Value
Publication number	US-2016069185-A1
Application number	US-201514851459-A
Country	US
Kind code	A1
Filing date	Sep 11, 2015
Priority date	Mar 19, 2013
Publication date	Mar 10, 2016
Grant date	—

Abstract

A method for reconditioning a hot gas path part of a gas turbine in order to flexibly adapt an operation regime of said gas turbine for subsequent operation intervals is disclosed. The method includes providing a hot gas path part to be reconditioned; removing a predetermined area of said hot gas path part, resulting in a cutout at said hot gas path part; and manufacturing a coupon for being inserted into said cutout to replace said removed area of said hot gas path part. The method further includes inserting said coupon into said cutout; and joining said hot gas path part with said inserted coupon. The coupon is manufactured by a selective laser melting (SLM) method resulting in a fine grain sized material with significantly improved low cycle fatigue (LCF) lifetime. The hot gas path part is coated, at least in an area comprising said inserted coupon, with a metallic overlay with improved thermo-mechanical fatigue (TMF) and oxidation lifetime.

First claim

1 . A method for reconditioning a hot gas path part of a gas turbine in order to flexibly adapt an operation regime of said gas turbine for subsequent operation intervals, comprising:
providing a hot gas path part to be reconditioned; removing a predetermined area of said hot gas path part, resulting in a cutout at said hot gas path part; manufacturing a coupon or section for being inserted into said cutout to replace said removed area of said hot gas path part; inserting said coupon or section into said cutout; and joining said hot gas path part with said inserted coupon or section; whereby said coupon or section is manufactured by a selective laser melting (SLM) method resulting in a fine grain sized material with significantly improved low cycle fatigue (LCF) lifetime; and whereby said hot gas path part is coated, at least in an area comprising said inserted coupon or section, with a metallic overlay with improved thermo-mechanical fatigue (TMF) and oxidation lifetime.

2 . The method as claimed in claim 1 , wherein said coupon or section is made of a higher oxidation resistant material than said hot gas path part.

3 . The method as claimed in claim 2 , wherein said coupon or section is made of a highly precipitation strengthened Ni base superalloy.

4 . The method as claimed in claim 3 , wherein said coupon or section is made of an MM247 alloy.

5 . The method as claimed in claim 4 , wherein said coupon or section is completely over-aluminized by chemical vapor deposition (CVD), physical vapor deposition (PVD) or a slurry process.

6 . The method as claimed in claim 1 , wherein, in order to introduce a self-healing property, said metallic overlay comprises an additional active phase containing a melting point depressant and/or a substance with a softening point or melting point below an operation temperature or within an operation temperature range of said hot gas path part.

7 . The method as claimed in claim 1 , wherein said metallic overlay is applied by
a) providing a powder material containing at least a fraction of sub-micron powder particles; and b) applying said powder material to the surface of said hot gas path part by means of a thermal spraying technique to build up a coating layer.

8 . The method as claimed in claim 7 , wherein said powder material is of the MCrAlY type with M=Fe, Ni, Co, or combinations thereof.

9 . The method as claimed in claim 7 , wherein said powder material contains powder particles of micron size and/or larger agglomerates, and that the sub-micron particles powder particles are in said coating layer distributed around the surface of said powder particles of micron size and/or said larger agglomerates.

10 . The method as claimed in claim 1 , wherein at least said area with said metallic overlay is additionally protected by applying a thermal barrier coating (TBC).

11 . The method as claimed in claim 1 , wherein said hot gas path part is a front stage vane of a gas turbine, said vane comprising an airfoil with a leading edge and a trailing edge, and that at least part of said trailing edge is replaced by said coupon.

12 . The method as claimed in claim 1 , wherein said hot gas path part is a front stage blade of a gas turbine, said blade comprising an airfoil with a leading edge and a trailing edge, and that at least part of said leading edge is replaced by said coupon.

Assignees

• Alstom Technology Ltd

Inventors

• Stankowski Alexander
• Zimmermann Julien Rene Andre
• Hoevel Simone
• Grasso Piero-Daniele
• Olliges Sven
• Duval Sophie Betty Claire

Classifications

• B33Y10/00

  Processes of additive manufacturing · CPC title

• F01D5/005 Primary

  Repairing methods or devices · CPC title

• B23K26/342

  Build-up welding · CPC title

• B23K26/0006

  taking account of the properties of the material involved (B23K26/32, B23K26/40 take precedence) · CPC title

• F05D2230/80

  Repairing, retrofitting or upgrading methods · CPC title