Abstract
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.
Highlights
To cite this version: Andrej Nazarov, Vincent Vivier, D Thierry, F Vucko, Bernard Tribollet
The results showed that prior tensile plastic deformation increased slightly the thickness of iron oxide layer, from about 2.2 nm to about 2.7 nm
It was demonstrated that scanning Kelvin probe (SKP) and local electrochemical impedance spectroscopy (LEIS) are local electrochemical techniques that are able to visualize the distribution of the residual stress with similar spatial resolution
Summary
To cite this version: Andrej Nazarov, Vincent Vivier, D Thierry, F Vucko, Bernard Tribollet. The residual stress from plastic deformation or wear accelerates the corrosion rate.[1] In the classic film rupture model, tensile stress breaks the passive film creating anodic locations at the bottom of the crack,[2,3] which propagates through an activation/passivation process This model was developed to the “slip dissolution-film rupture model” pointing out the importance of formation of dislocations and metal dissolution through dislocation slip lines.[3,4] The slip dissolution-film rupture model of crack advance was discussed in details previously.[5] This model can predict the crack growth rate for the stainless steels, nickel alloys, and low-alloy steels in high temperature water.[6]. A calorimetric study[10] showed that residual energy from cold work was less than 7 calories per gram without any significant impact on Gibbs potential during the deformation
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