Film hole cooling technology is an effective means to improve the temperature bearing capacity of turbine blades

while the recast layer on the hole wall caused by EDM processing of film holes is a serious threat to the service performance of film holes. In order to eliminate the recast layer

this paper puts forward a process method to eliminate the recast layer on the wall of EDM hole by secondary heat treatment. Experimentally

it was found that the recast layer of the hole wall obtained by EDM was γ single-phase organization

with internal holes and microcracks

and the phenomenon of compositional segregation existed. Subsequently

the heat treatment process of solid solution and aging of the film holes revealed that the original recast layer region formed a two-phase organization consistent with the matrix

with uniform composition distribution. At the same time

the original recast layer region was oriented in the same direction as the matrix

ensuring the overall single-crystal characteristics of the blade. The high-temperature tensile experiments show that the elimination of the recast layer avoids the hazards of the hole wall defects and changes the fracture mechanism

which improves the tensile strength and elongation of the film holes. Therefore

the proposed process of removing recast layer by EDM based on secondary heat treatment provides a reliable means for the manufacture of high-quality film holes.