Effect of Temperature and Salinity on the Localized Corrosion of Stainless Steel 316L

Abstract

Cyclic polarization test was used to determine the breakdown potential of passive film for stainless steel 316L at different temperatures (20°C, 30°C, 40°C, 50 °C) and different salinity (15%, 25%, and 35%). The results show the highest breakdown potential occur at low temperature and low salinity indicate that incresing the temperature and salt content in seawater will increasing the corrosion attack on 316L. Increasing the temperature from 20°C to 50°C was decrease the Ebvalue for 75%. Before and after testing, visible pits and hardness for each sample were observed by using Scanning Electron Microscopy (SEM) and Vickers hardness testing. It was found that at temperature 20°C, it can be seen that number of pits is more but the pits size is a bit tiny. However, the number of pits reduce as the temperature and salinity increased but the size of the pit become larger and wide which indicate that pitting has propagate during that period. Furthermore, increasing the temperature from 20°C to 50°C also lead to increased the hardness different value which indicate that reducing in hardness properties of 316L at increasing salinity because of corrosion attack.