Corrosion-fatigue of carbon steels in sweet and sour corrosion environments : Analysis of cyclic elastic and plastic strain effects on the electrochemical behavior by a transient corrosion current method

• The effects of cyclic stress and strain on corrosion-fatigue in sweet and sour corrosion were studied with an electrochemical approach. Cold-drawn and cold rolled carbon steel samples were mechanically cycled in a confined and CO2-saturated synthetic seawater solution, and their electrochemical response was acquired with a classic 3-electrode apparatus. The effect of elastic static stress was evaluated with the Linear Polarization Resistance (LPR) method. The effect of dynamic stresses, strain rate and plastic strain were evaluated by a potentiostatic method, at imposed steady-state Open Circuit Potential (OCP). Both methods show a linear dependency of the work electrode potential with respect to the applied stress. The latter method allowed the detection of an anodic contribution, proportional to the plastic deformation and to the strain rate. Using these findings, a time-domain model was built, in the form of a RLC circuit, associated to the electrochemical behavior. The calculations show a good agreement with the experimental results, and support the detected influences of stress, strain rate and plastic strain.

Nyckelord

Corrosion-fatigue

Electrochemistry

Stress enhanced corrosion

Time-domain modelling

Carbon steel

Cold rolling

Corrosion fatigue

Metal cladding

Plastic deformation

Resonant circuits

Steel sheet

Strain rate

Time domain analysis

Cold rolled carbon steels

Electrochemical behaviors

Electrochemical response

Electrode potentials

Linear polarization resistance

Open circuit potential

Potentiostatic methods

Time domain

Corrosion

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