Corrosion fatigue behaviour of nitrogen‐implanted steel in water

Abstract
The corrosion fatigue behaviour of nitrogen implanted iron in neutral solutions has been investigated utilizing the oscillating cantilever beam method, by means of electrochemical (Ecorr vs. time plots, Rp measurements) and S. E. M. techniques.The calculated corrosion rate under stagnant conditions is lowered for the implanted iron at all nitrogen doses with respect to untreated iron. The surface oxide layers achieve enhanced protecting capacity.Consequently under a cyclic load of 25.4 kg mm−2, at a frequency of 16.6 Hz, cracks nucleation is delayed. The time to breaking of implanted specimens is considerably lower in our experimental conditions compared to untreated iron. The increase in the crack growth rate is consistent with the detrimental action of structural damage following implantation. The fracture morphology is also discussed.