The influence of mechanical stress on the electrochemical properties of ferritic steel SAE 1008 and austenitic stainless steel 301LN was studied using Scanning Kelvin Probe and Localized Electrochemical Impedance Spectroscopy (LEIS) techniques. The probe-working electrode Volta potential difference was mapped in situ under load. It was found that the influence of elastic deformation on the potential was small. Plastic deformation decreased the potential of steel by 150–300 mV, whereas the relaxation of the load from the plastic domain increased the Volta potential. However, some locations, which can contain residual stress, remained at low potential. The pre-strained surfaces were characterized by X-ray Photo Electronic Spectroscopy and by Atomic Force Microscopy. Distribution of the capacitance across strained and strain-free surfaces was studied by LEIS in boric/borate electrolyte. The plastic stress increases the capacitance and decreases the ability of the steels to passivate the surface indicating that emerging of pile-ups of dislocations create defective oxide films.

The interplay between mechanical stresses and electrochemical reactions may lead to stress corrosion cracking or hydrogen embrittlement for many materials. In this work, the effect of the tensile stress on the electrochemical properties of AISI 304 stainless steel was studied using scanning Kelvin probe (SKP) in air and scanning electrochemical microscopy (SECM) in an aqueous 0.5 M Na₂SO₄ electrolyte. The measurements were performed under load- and load-free conditions. No influence of the elastic stress on the electrochemical potential of the steel was found. In contrast, the plastic strain induces dislocations and dislocation pile-ups, which emerge to the surface. The formation of new active surfaces is accompanied by an increase in the roughness and a 150–200 mV decrease in the steel potential. After activation, the potential increased due to passivation of the emerging surfaces by a newly grown oxide film, which took place under both the load and load-free conditions and followed a time dependence of φ = A log t + B. Formation and then passivation of the new surfaces increased and then decreased the reduction current of the mediator in the SECM measurements. The effect of residual stress stored in the steel due to the development of dislocations on the reactivity of the re-passivated surface was investigated.

The aim of the present work was to study the influence of the stress on the electrode potential of the austenitic stainless steel 301LN using Scanning Kelvin Probe (SKP). It was found that elastic deformation reversibly ennobles the potential whereas plastic deformation decreases the potential in both tensile and compressive deformation mode and this decrease is retained even 24 h after removal of the load. To interpret the stress effects, different surface preparations were used and the composition and thickness of the passive film were determined by GDOES. Slip steps formed due to plastic deformation were observed using AFM. The effect of plastic strain on the potential is explained by the formation of dislocations, which creates more a defective passive film.