Abstrait

Responses to indentation and to impedance spectroscopy of plastically compressed steels. Part 2: Case of a Fe-Ni-Cr steel

Pierre-Yves Girardin, Adrien Frigerio, Patrice Berthod

As in the first part of this study impedance spectroscopy was used in this second part to characterize the influence of permanent deformation in compression on the corrosion behaviour, in the same sulphuric acid solution, of a secondmodel iron-based alloy – a ternary Fe-Ni-Cr alloy, base of many stainless austenitic steels – always for the two main orientations of surface with respect to the deformation axis. Preliminary to the EIS experiments, XRD runs and Vickers indentations showed the same effects of the plastic deformation in compression on diffraction patterns and on hardness. The Nyquist plots obtained were also similar to semi-circles and the corresponding charge transfer resistances and double layer capacitance were determined. In contrast with what was observed for pure iron in the same conditions (except the deformation rates really achieved because of the much higher strength of the simplified austenitic stainless steel studied here by comparison to pure iron) the transfer resistance rather tended here to decrease when the permanent compression deformation increased, and to be higher for the perpendicular orientation than for the parallel orientation.