Laser processing and gas tungsten arc welding are the processes commonly used for turbine repair. However, these processes can cause a range of metallurgical issues in the repaired component, including microcracking in the heat-affected zone and local loss of properties. Electro-spark deposition is a process that occurs at rapid cooling rates, mitigating a number of these metallurgical concerns.
Critical Factors Affecting the Quality of Electro-spark Deposits on Nickel-base Superalloys, a paper by EWI associates Liya Amanuel and Jerry Gould, covers some key processing issues known to affect deposition rates and resulting surface quality, including changes to the electric circuitry (that affect pulse shape) and quality of the shielding used