Electrochemical Corrosion Resistance of AISI H13 Steel Machined by Electro Discharge Machining

Electro discharge machining (EDM) technique is widely used in the die and mold industries for its distinct advantages in machining hard metals. Nevertheless, the properties of EDM treated steel, especially its corrosion resistance, have not been well understood or clearly identified. In this paper, electrochemical corrosion behavior of EDM treated AISI H13 steel in NaOH solution was investigated, with the diamond polished being reference specimen. The corrosion resistance of the specimens was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests. The morphology and microstructure of the machined surface layer were also observed. Electrochemical experimental results revealed that EDM treated specimen has a weaker resistance to corrosion compared with diamond polished one. This weakening is considered to be correlated to differences in surface morphology and subsurface microstructure.