Surface morphology and passive film composition after pickling and electropolishing

In this work, a novel method of selecting the most favourable electropolishing (EP) conditions is presented as a compromise between the processing time and obtaining the lowest possible roughness value of S-a or S-q (commonly used parameters) as well as the gradual increase of parameters highlighted in this work S-sk and S-ku. The results showed that the most appropriate EP charge input should be higher than 1.2 Amin cm(-2) and lower than 2.3 Amin cm(-2). XPS highresolution spectra revealed that pickling and EP of the samples results in a decrease of the ratio of the iron oxides amount (at.-%) to the total amount of chromium oxides and hydroxides (at.-%) in the passive film. This ratio gradually decreases reaching the values 1.2, 1.0 and 0.7 for asreceived, pickled and electropolished samples, respectively. This result demonstrates iron dissolution of the outer surface layer by pickling and EP.