Electric heating – Metal heating – For deposition welding
Reexamination Certificate
2001-02-26
2002-10-15
Elve, M. Alexandra (Department: 1725)
Electric heating
Metal heating
For deposition welding
C219S13700R, C219S1370WM
Reexamination Certificate
active
06465755
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to the manufacture of repair material. In particular, the invention relates to the manufacture of repair material from alloys that are difficult to mechanically deform.
Turbine components, such as blades, nozzles, vanes, airfoils, tips and the like (hereinafter “turbine components”) are frequently formed from superalloys, for example, nickel-based superalloys, that have a directionally solidified single-crystal structure. The turbine components can be manufactured with defects, including cracks, surface defects, imperfections and holes. These defects must be repaired by various repair processes for reliable, proper, and dependable performance of the turbines. Turbine components also develop defects during service throughout their lifetime. These service and use related defects may occur by wear, oxidation, and erosion. Such defects include cracks, surface defects, imperfections, and holes. These turbine component defects must be repaired for proper, dependable, and reliable operation of the turbine.
A previous defect repair method provided a repair material that is comparable in chemistry to the turbine component's parent superalloy. Also, the repair material in the previous defect repair method may have been provided with an oxidation resistance that is comparable, or even superior, to the turbine component's parent superalloy. The repair material was melted, and re-solidified to the turbine component at the defect site. The process was intended to provide an integral repaired structure, with a turbine defect site proximate the defect melting and re-solidifying with the repair material. Thus, repair material and the turbine component material formed a solid, one-piece repaired member.
For repair of a turbine component by a welding repair process, such as tungsten inert gas (TIG) welding, the repair material is often provided in the form of a repair material wire. A weld wire has been previously manufactured by powder metallurgy processes in conjunction with mechanically working to a wire form. Powder metallurgy processes often produce high volume fractions of strengthening precipitates, such as gamma prime (&ggr;′) material. The &ggr;′ material in amounts up to about 70% by volume makes weld wire less ductile and hard to deform with low workability, and difficult to form into small diameter wires, and difficult to handle. The &ggr;′-containing material is difficult to mechanically deform at the temperatures commonly used for forming the weld wire, for example by a wire drawing process, is not ductile, will not exhibit substantial plastic deformation to the point where the material will not easily bend. This type of low-ductility repair material is not well suited for further thermo-mechanical processing.
Complex multiple canning and hot extrusion processes have been attempted for producing weld wire, however the combination of these processes is an extremely expensive manufacturing process. For example, weld wire produced by the combination of multiple canning and hot extrusion processes may be up to ten times more in value than the raw metal itself.
Therefore, a repair material for turbine components that is relatively inexpensively produced, ductile, easy to thermo-mechanically process. and readily capable of being mechanically deformed is needed.
SUMMARY OF THE INVENTION
The invention sets forth a process for the manufacture of repair material. The repair material is ductile and readily mechanically deformed, and can be used in the repair of turbine components. The process comprises providing a directionally solidified material, cold-swaging the directionally solidified material, and heat treating the cold-swaged material into the repair material. The repair material, after the step of cold-swaging with intermediate heat treatment, comprises a microstructure that is essentially free from cracks, for repairing the turbine component.
The invention also sets forth methods for repair of articles, such as turbine components, using a repair material. The repair material is ductile and readily mechanically deformed, and can be used in the repair of turbine components. The process comprises providing a directionally solidified material, cold-swaging the directionally solidified material, and heat treating the cold-swaged material into the repair material. The repair material, after the step of cold-swaging, comprises a microstructure that is essentially free from cracks, for repairing the turbine component.
Further, the invention sets forth a turbine component repaired using a repair material. The repair material for the turbine component is ductile and readily mechanically deformed, and can be used in the repair of turbine components. The repair material is formed by a process that comprises providing a directionally solidified material, cold-swaging the directionally solidified material, and heat treating the cold-swaged material into the repair material. The repair material, after the step of cold-swaging, comprises a microstructure that is essentially free from cracks, for repairing the turbine component.
REFERENCES:
patent: 4129462 (1978-12-01), Korenko
patent: 4213026 (1980-07-01), Duvall et al.
patent: 5106010 (1992-04-01), Stueber et al.
Hughes John Raymond
Jackson Melvin Robert
Mukira Charles Gitahi
Susi Allan Richard
White Raymond Alan
DiConza Paul J.
Elve M. Alexandra
Patnode Patrick K.
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