Monitoring corrosion fatigue crack formation on drill steel using electrochemical impedance spectroscopy: Experiment and modeling

•Fatigue and electrochemical tests can be conducted simultaneously in a novel setup.•Fatigue crack can be recognized and monitored based on evolution of phase angle.•The established crack model is in good agreement with the experimental data. The corrosion fatigue crack formation on drill steel was studied using electrochemical impedance spectroscopy in a novel experimental setup, where the fatigue testing and electrochemical measurement could be conducted simultaneously. Results show that the corrosion fatigue crack formation in 3.5 % NaCl solution can be real time monitored based on changes in phase angle over time, i.e., the evolution of the peak value of phase shift angle and the frequency where the phase shift angle peak appears. A corrosion fatigue crack impedance model was established and it is found that modeling results are in good consistency with the experimental data.