Grinding-Electrode-Assisted Short Electric Arc Machining of GH4099: A Composite Approach to Surface Integrity

This study introduces a composite method that integrates a diamond-coated tubular grinding electrode with short electric arc machining (SEAM) for GH4099. Mechanical micro-grinding and arc erosion act concurrently within the inter-electrode gap, enabling an in situ "erode-dress" coupling in which the grinding action levels nascent craters and promotes debris evacuation while SEAM supplies localized thermal-electrical energy for removal. A design-of-experiment scheme probes discharge and grinding factors, and performance is evaluated by material removal behavior, electrode wear, and surface integrity. Within a robust window (12-24 V; 500-2000 r/min), the composite process sustains stable discharges without catastrophic melting at 24 V and yields dense, uniform textures. Representative surfaces show controllable areal roughness (Sa ≈ 14-27 µm across 80#-600#), reflecting a practical finishing-efficiency trade-off. Multi-scale characterization (3D topography, cross-sectional metallography, SEM) evidences suppression of recast steps, macro-protrusions, and irregular pits, with more evenly distributed, shallower grinding traces compared to those with single-mode SEAM. The comparative analyses clarify discharge stabilization and recast-layer mitigation mechanisms, establishing a feasible pathway to high-quality, high-efficiency composite SEAM of GH4099 without resorting to overly aggressive electrical conditions.