Effect of nitrogen on the corrosion behavior of high-strength low-alloy steel in simulated marine atmosphere

Considered the fact that the study on how nitrogen influences the general corrosion behavior of high-strength low-alloy steel, we explored the effect of nitrogen on the corrosion of low-alloy high-strength steel in a simulated marine atmosphere from the aspects of corrosion rate analysis, corrosion products analysis, morphology analysis, and electrochemical analysis. Several experimental methods include electron backscattered diffraction, transmission electron microscopy, and inductively coupled plasma mass spectrometry were adopted. The findings reveal that the addition of nitrogen increases the yield strength by about 20 MPa and the tensile strength by about 40 MPa. The addition of 0.02 wt.% N to steel does not significantly improve the average corrosion resistance but slightly decreases the ratio of the maximum corrosion depth to the average corrosion depth. Nitrogen is present as ammonium ions and is enriched at the bottom of corrosion products. Overall, the alloying of 0.02 wt.% N slightly enhances the polarization resistance and increases the stability of corrosion products, whereas it has no obvious improvement on decreasing the corrosion rate. Graphical abstract: [Figure not available: see fulltext.].