METHOD FOR REPAIRING GAS TURBINE BLADES AND GAS TURBINE BLADE

• US 20120000890A1
• Filed: 06/13/2011
• Published: 01/05/2012
• Est. Priority Date: 06/14/2010
• Status: Abandoned Application

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: ITO, Shoko, HINO, Takehisa, SAKAI, Yoshiaki
• Application Number:
  US13/159,105
• Publication Number:
  US 20120000890A1
• Time in Patent Office: Days
• US Class Current: 219/76.1
• CPC Class Codes: B23P 6/007 using only additive methods, e.g. build-up welding
• CPC Class Codes: F01D 5/005 Repairing methods or devices

Abstract

A method for repairing gas turbine blades includes: a thickness-reduced portion removing step S101 of working a surface of a blade tip 10a into a flat surface 13 by removing a thickness-reduced portion 12 of the blade tip 10a; a build-up welding step S102 of forming a built-up portion 14 with a predetermined thickness by melting powder of a build-up material higher in ductility than a base material forming the gas turbine blade 10 by a laser beam and building up the melted powder in multiple layers on the blade tip 10a whose surface is worked into the flat surface 13; a forming step S103 of working the built-up portion 14 into the same shape as a shape that the blade tip 10a originally has before suffering a thickness loss; and a heat-treatment step S104 of removing a residual strain caused by laser welding in the build-up welding step S102.

Claims

1. A method for repairing gas turbine blades which repairs a thickness-reduced portion of a blade tip of a gas turbine blade, the method comprising:

a thickness-reduced portion removing step of working a surface of the blade tip into a flat surface by removing the thickness-reduced portion of the blade tip;

a build-up welding step of forming a built-up portion with a predetermined thickness by melting powder of a build-up material higher in ductility than a base material forming the gas turbine blade by a laser beam and building up the melted powder in multiple layers on the blade tip whose surface is worked into the flat surface;

a forming step of working the built-up portion into the same shape as a shape that the blade tip originally has before suffering a thickness loss; and

a heat-treatment step of removing a residual strain caused by laser welding in the build-up welding step.

3. The method for repairing gas turbine blades according to claim 1, wherein a coating layer is formed on a blade surface of the gas turbine blade, the method further comprising:

a coating layer removing step of removing the coating layer prior to the thickness-reduced portion removing step; and

a coating step of forming a coating layer on the blade surface of the gas turbine blade, after the heat treatment step.

5. The method for repairing gas turbine blades according to claim 1,

wherein the build-up material is made of a Ni-base superalloy whose Al content is less than an Al content of a base material forming the gas turbine blade.

10. A gas turbine blade, being repaired by the method for repairing gas turbine blades according to claim 1.

2. A method for repairing gas turbine blades which repairs a thickness-reduced portion of a blade tip of a gas turbine blade, the method comprising:

a thickness-reduced portion removing step of working a surface of the blade tip into a flat surface by removing the thickness-reduced portion of the blade tip;

a first build-up welding step of forming a first built-up portion with a predetermined thickness by melting powder of a first build-up material higher in ductility than a base material forming the gas turbine blade by a laser beam and building up the melted powder in multiple layers on the blade tip whose surface is worked into the flat surface;

a second build-up welding step of forming a second built-up portion with a predetermined thickness by melting powder of a second build-up material more excellent in oxidation resistance than the first build-up material by a laser beam and building up the melted powder in multiple layers on the first built-up portion in a stacked manner;

a forming stop of working the first built-up portion and the second built-up portion into the same shape as a shape that the blade tip originally has before suffering a thickness loss; and

a heat-treatment step of removing a residual strain caused by laser welding in the first build-up welding step and the second build-up welding step.

4. The method for repairing gas turbine blades according to claim 2, wherein a coating layer is formed on a blade surface of the gas turbine blade, the method further comprising:

a coating layer removing step of removing the coating layer prior to the thickness-reduced portion removing step; and

a coating step of forming a coating layer on the blade surface of the gas turbine blade, after the heat treatment step.

6. The method for repairing gas turbine blades according to claim 2,

wherein the first build-up material is made of a Ni-base superalloy whose Al content is less than an Al content of a base material forming the gas turbine blade.

7. The method for repairing gas turbine blades according to claim 2,

wherein the second build-up material is made of one material selected from a group consisting of the same material as the base material forming the gas turbine blade, MCrAlY (M:

Co and Ni), and an Al alloy.

8. The method for repairing gas turbine blades according to claim 6,

wherein the second build-up material is made of one material selected from a group consisting of the same material as the base material forming the gas turbine blade, MCrAlY (M:

Co and Ni), and an Al alloy.

9. The method for repairing gas turbine blades according to claim 2,

wherein a thickness of the second built-up portion after the forming step is 50 μ

m to 300 μ

m.

11. A gas turbine blade, being repaired by the method for repairing gas turbine blades according to claim 2.