Electrical arc–grinding hybrid machining: Hybrid electrode stability, thermo-mechanical–grinding coupled modeling, and high-quality surface machining of GH4099

Electrical arc machining of high-temperature alloys is attractive for its high material removal rate but is limited by poor surface quality. To improve the post-machining surface finish while avoiding re-positioning errors across multiple operations, this work proposes electrical arc–grinding hybrid machining (EA-GHM), in which the electrode is replaced after the arc step to perform subsequent finishing, enabling high-quality machining of high-temperature alloys. We first design and fabricate a compatible hybrid electrode and verify its high-temperature thermal stability; we elucidate the degradation evolution of the coated abrasives under different media; and, based on high-temperature friction–wear theory and experiments, we clarify the temperature dependence of abrasive thermal behavior and wear, thereby confirming electrode stability. We then build a sequentially coupled temperature–stress field model for single and stochastic arc discharges and, on this basis, couple the diamond-grinding process to reveal the synergistic removal mechanism; single rotational discharge–grinding experiments are conducted to validate the model. Finally, comparative tests show that EA-GHM reduces the surface roughness of high-temperature alloys to below 0.5 μm, markedly improving surface quality and providing a new route to high-quality manufacturing after arc machining.