Enhancing H13 die steel surface quality with ultrasonic-assisted powder EDM

H13 die steel, valued for its hardenability, high-temperature strength, and toughness, is extensively utilized in aerospace and automotive industries. However, electrical discharge machining (EDM) induces surface defects like recast layers, heat-affected zones, and debris globules, contributing to mold failures. This study examines H13 steel surfaces processed via ultrasonic-assisted mixed powder EDM using four working fluids with varying Al₂O₃ and diamond particle concentrations. COMSOL simulations based on Blake’s theory confirmed significant cavitation in the processing slit. SEM analysis revealed distinct surface morphologies, linking variations in debris globules, cracks, and discharge craters to particle properties. Results indicate that ultrasonic cavitation and particle characteristics (thermal conductivity, specific surface area) critically influence energy dissipation and surface morphology. Adjusting particle concentration effectively optimizes surface quality, demonstrating that particle selection and concentration control are key to enhancing EDM-processed workpiece performance.