Corrosion resistance of Cd coating on 30CrMnSi bolts surface

This study examines the corrosion resistance variability of cadmium (Cd) coatings on high-strength steel bolts due to different surface post-treatments using sodium nitrate immersion, sodium chloride immersion, and accelerated salt spray tests. We enhance this analysis with open circuit potential (OCP) measurements to evaluate corrosion potential, and electrochemical impedance spectroscopy (EIS). Linear sweep voltammetry (LSV) is used to obtain Tafel curves. Scanning electron microscopy (SEM) was used to observe the corroded area of the cadmium coating. Our findings reveal that the Cd coating exhibits a larger capacitive arc in a 3.5%NaNO 3 solution, indicating a more pronounced passivation effect and differing corrosion rates depending on the surface treatments. Moreover, Cd coatings exhibit better corrosion resistance after treatment by immersion in grinding solution.