Electrochemical investigation of passive film in pre-deformation AISI 304 stainless steels

The electrochemical measures in deformed AISI 304 stainless steels ranged from 0% to 24% were investigated. With the increasing of the strain α′-martensite was gradually increasing. Moreover, the morphologies and densities of dislocations changed with increasing strain. The Mott-Schottky plots showed that the maximum total of donor and acceptor densities in passive film occurred in borate buffer solution when ɛ-martensite was most, while in borate buffer solution with 5000 ppm Cl− the maximum total of donor and acceptor densities occurred when the content of α-martensite was most. These results were proven by further impedance spectroscopy experiments.

► With the increasing of the strain α′-martensite was gradually increasing. ► The acceptor density of all the specimens was always more than donor density in borate buffer solution. ► ɛ-Martensite had a detrimental effect on passive properties in borate buffer solution. ► The detrimental effect of α′-martensite was more prominent in borate buffer solution with Cl−.