To reveal the influence of electrical discharge machining (EDM) parameters on the pore wall microstructure of DD9 single crystal high-temperature alloy, this paper takes 2404554MICRO01 to MICRO05 series specimens as objects, and conducts 500 × microscopic observation and recast layer measurement on five sets of circular and horn holes, B119, B222, B716, B1503, and B1902. Extract 10 thickness measurement points for each operating condition, calculate the average thickness, maximum thickness, coefficient of variation, and local instability index. The results showed that the average thickness of the recast layer of the circular hole increased from 6.0 μ m to 16.4 μ m, and the maximum thickness of the B1503 circular hole reached 44 μ m, with a local instability index of 2.68. The average thickness of the horn hole under B119 is 9.1 μ m, and the coefficient of variation of the horn hole under B222 is 77.45%. Mechanism analysis shows that pulse heat input controls overall thickening, hole geometry amplifies local non-uniformity through discharge gaps and flushing disturbances, and the γ/γ ‘structure affects the re solidification interface and microcrack initiation.
