It is well known, that the choice of electrolyte strongly influences the result of
this technologically important surface finishing process. Especially aqueous solutions
of NaCl, NaNO3 and NaClO3 have been studied with respect to their influence on the
anodic polarization, the substrate surface morphology and the overall metal removal
rate [56-59]. Most of the reported anodic dissolution experiments have been carried
out using pure metals, like iron and nickel, as substrates. For these systems
quantitative dissolution models have been proposed mainly on the basis of a mass
transport controlled ECM-process [60]. The diffusion layer in the liquid forming on the
substrate surface upon Electrochemical Machining and the formation of a very thin
salt layer directly on the substrate surface have been studied by many workers [61,
62]. However, not much is known about the complex dissolution behaviour of
technical carbon steels because of their heterogeneous microstructure based on the
steel matrix including metal carbides and non-metallic inclusion compounds like
oxides and sulfides.