Unweldable superalloy component repair using electro-spark deposition with high strength filler material

Nickel-base superalloy components with high Al+Ti content are difficult to weld repair using high strength filler materials with conventional welding methods like TIG welding. A feasibility study of electro-spark deposition (ESD) for unweldable superalloy component repair with a high strength filler material was carried out. SEM analysis reveals that a fully dense, crack-free, metallurgical bonded deposition layer can be obtained on the K24 substrate. The as-deposited microstructure characterizes fine cellular structure and the post weld heat treatment precipitates fine γ′particles. The room temperature tensile testing and 975℃, 196MPa stress rupture life testing indicate that ESD makes positively contribution to mechanical performance of repaired specimens. Based on these results, ESD has the potential as an effective alternative to repair of damage and defects in superalloy components, but more efforts should be made before it can be applied in engineering repair.