Corrent, one can use inert graphite as well as cathode.

thank you very much for your support 

Dear Ayman

In the electrochemical cell of electrochemical etching of a stainless steel sample ( as a working electrode) , it is necessarily to have a counter (auxiliary) electrode such as platinum (cathode) electrode or a high density-graphite electrode.   The purpose of the counter electrode is to act as a dump site for electrons which are produced from the anodic dissolution (oxidation/electrochemical etching) of atoms of the stainless steel surface.    Therefore, counter electrodes ,i.e., as platinum or graphite, are known to have  high exchange current rate at equilibrium potential, i.e., reversible reaction of the electrode materials.   Consequently, the counter electrode normally attains a zero net of the exchange current which makes the counter electrode inert during the electrochemical etching of the stainless steel.   In other words, counter electrodes don't electrochemically polarized.