Effect of Chloride Salt Bath on Electrochemical Behavior and Morphology of 304L and 316L Stainless steels

Stainless steels (SSs) are highly valued for their exceptional properties, making them suitable for a wide range of applications. This study investigates the corrosion behavior of SS304L and SS316L in a chloride salt bath using chemical methods (weight loss) and electrochemical techniques (potentiodynamic polarization). The SS304L and SS316L undergo immersion in a chloride salt bath mixture consisting of 50% KCl and 50% NaCl at temperatures of 250, 350, and 450°C for 3h. Also, the immersion time at 350 °C for both stainless steels was investigated from 0.5 h to 3 h with an interval of 0.5 h. The potentiodynamic polarization (PDP) assessment was conducted at room temperature to assess the samples' corrosion behavior after exposure to the salt bath. Corrosion rates (CR) were then determined under different conditions to evaluate the samples' susceptibility to corrosion. The SEM and EDX analyses were employed to examine the corrosion products under various conditions. It was observed that the existence of Mo, Ni, and Cr content after PDP testing contributed to the protective layer formation and so inhibited further degradation. Before immersion, SS316L alloys exhibited the lowest corrosion rate (0.107 mm/y) but the CR values increased with an increase in the temperature of the salt bath before the PDP test. However, the SS316L samples for different conditions have lower CR values than SS304L. The SEM images confirmed the results of the PDP test.