Marie Touzet

An EIS study and auger analysis on 304L stainless steel in hot chloride media before and after a sample straining

Abstract Interface development of 304L stainless steel in Scheil reagent has been studied on nonstrained samples or on samples subjected to a plastic straining. Electrochemical impedance spectroscopy (EIS) was used for this work. Continuous changes in the layer formed on the material have been observed in this electrolyte. The Auger analyses have shown a very different film constitution and thickness before and after straining. Inhomogeneities of the film displayed by EIS diagrams have been confirmed by the formation of pits observed by SEM.

The characterization of damage in SCC by an electrochemical impedance and statistical study of multiple cracking

Abstract To build a realistic predictive model, it is essential to understand how the damage is developed. The evolution of this damage on 304L steel in Scheil reagent during slow strain rate tests has been studied for 4 various strain rates. An observation of the distribution of crack traces (number, size and morphology) has shown that the damage is closely linked to the strain rate. Interrupted CERTs have been realised for two strain rates. For each strain rate, electrochemical impedance measurements at fixed frequency (100 mHz) and histograms of the distribution of the crack traces have been carried out. The linked use of two techniques to characterize the damage in stress corrosion studies gives very interesting results. The evolution of the phase of the electrochemical impedance is closely linked to the initiation rate of cracks. Density of cracks that have reached a given size could be a new definition of the critical damage in stress corrosion studies when multiple cracks exist.

Microstructure, Mechanical and Corrosion Behaviour of AN AA2024-T3 FSW Joint

The FSW weld consists of three distinct microstructural zones. The microstructure inside each zone is directly impacted by the FSW process parameters. The aim of this article is to correlate microstructure, microhardness and corrosion sensitivity of a AA-2024-T3 FSW joint for one processing parameter set. A microstructural analysis has been conducted in each weld zone by the combination of TEM observations, chemical and DSC analysis. Moreover, a small electrochemical cell was used to estimate the corrosion sensitivity of the distinct zones by localized open circuit potential measurements all along the weld. Mechanical properties were evaluated using Vickers microhardness measurements. The results show a direct correlation between mechanical property evolution, local corrosion process involved and microstructure modification.