Current application and development trend in electrochemical measurement methods for the corrosion study of stainless steels

Carbon steels are prone to a high level of corrosion when exposed to harsh environments. Stainless steels, having better corrosion resistance, are therefore, used in many applications to mitigate the high risk of failure due to corrosion. However, stainless steels are also not 100% corrosion-resistant; hence, they may suffer uniform corrosion, pitting corrosion, and/or corrosion cracking. It is, therefore, necessary to evaluate the corrosion resistance of stainless steel prior to its large-scale applications. The two main techniques used in studying the corrosion behavior of stainless steels are the immersion and electrochemical tests. Due to the high corrosion resistance of stainless steels, analyzing its corrosion behavior using the immersion test method takes a long period. Consequently, the application of the immersion test method is highly limited. The electrochemical methods are, therefore, widely used due to its faster rate of evaluation of corrosion behavior and mechanisms. The most commonly used electrochemical methods in the corrosion assessment of stainless steels include the corrosion potential test, AC impedance test, potentiostatic test, and cyclic polarization test. This paper introduced these four electrochemical methods of corrosion evaluation of stainless steels. The advantages and disadvantages of various detection methods were also clarified. Long-period corrosion monitoring can be achieved with the implementation of corrosion potential and AC impedance methods, due to their nondestructive features. The polarization characteristic parameters of materials can be obtained by analyzing the potentiostatic or potentiodynamic polarization results. These help to evaluate the corrosion resistance of materials. Comprehensive utilization of various electrochemical methods is beneficial to the analysis of corrosion mechanisms. Given the current research status and trend of corrosion in stainless steel, the electrochemical method is projected to be mainly implemented in the control of the corrosion processes. Therefore, there is need for better detection technologies to achieve a better analysis of the corrosion processes of stainless steels.