US 5,822,852 A · Method for replacing blade tips of directionally solidified and single crystal turbine blades

Abstract

A method for repairing a blade tip of a turbine blade of a gas turbine engine. The method is particularly directed to replacing the squealer tip (14) of a directionally solidified (DS) or single crystal (SX) turbine blade (10), and can be carried out using a brazing or welding technique. The method generally entails the step of machining the tip (14) to remove any damaged, worn, oxidized or eroded portions thereof sustained by the blade (10) during engine operation. A DS or SX superalloy replacement tip (18) is then placed on the surface generated by the machining operation. If a brazing operation is used, a brazing alloy composition (16) is first applied to the blade tip or replacement tip (18) prior to placement of the replacement tip (18). The brazing alloy composition (16) is composed of at least two alloys, one of which having a melting point lower than the recrystallization temperature and solvus temperature of the superalloy of the turbine blade (10), such that heating causes the brazing alloy composition (16) to flow and thereby join the replacement tip (18) to the blade tip of the turbine blade (10). Alternatively, if a welding operation is employed, the joining operation entails transmitting current through the turbine blade (10) and replacement tip (18) to resistance weld the replacement tip (18) to the blade tip of the blade (10).

Claims20

Dependent claims

A method for replacing a tip on a directionally solidified or single crystal turbine blade, the method comprising the steps of:

providing a directionally solidified or single crystal turbine blade of a superalloy, the turbine blade having a blade tip;
removing a portion of the blade tip to generate an attachment surface;
placing a replacement tip on the attachment surface, the replacement tip being a directionally solidified or single crystal superalloy material;
and
applying heat to join the replacement tip to the turbine blade.

2 more elements

A method for replacing a squealer tip on a directionally solidified or single crystal turbine blade of a gas turbine engine, the method comprising the steps of:

providing a directionally solidified or single crystal turbine blade of a superalloy, the turbine blade having a squealer tip at a blade tip thereof;
machining the squealer tip to remove any damaged, worm, oxidized or eroded portions thereof, such that an attachment surface is generated at the blade tip;
providing a brazing alloy composition formed of a mixture of two alloy powders, one of the alloy powders containing a melting point depressant such that the brazing alloy composition flows at a temperature lower than a recrystallization temperature and a solvus temperature of the superalloy of the turbine blade;
applying a replacement tip to the attachment surface of the blade tip so that the brazing alloy composition is between the replacement tip and the attachment surface, the replacement tip being a directionally solidified or single crystal superalloy material;
and
heating the brazing alloy composition and the replacement tip to cause the brazing alloy composition to flow and thereby join the replacement tip to the blade tip of the turbine blade.

3 more elements

Dependencies are inferred from the claim text.

Method for replacing blade tips of directionally solidified and single crystal turbine blades

Life of this patent

Method for replacing blade tips of directionally solidified and single crystal turbine blades

Life of this patent

Abstract

Claims20