Influence of Grain Size on Corrosion Resistance and Electrochemical behaviour of Mild Steel

Abstract

Corrosion of mild steel is one of the biggest issues faced in today's world, and leads to huge losses every year. Mild steel, an alloy with a very vast range of applications, is very susceptible to corrosion and thus, it is important to study the factors that govern corrosion in mild steel and how to control this corrosion. In this study, the effect of heat treatment, microstructure, grain size and hardness of mild steel on its rate of corrosion under a natural environment is studied. The microstructures of mild steel that underwent heat treatment for various time periods were characterized using optical microscope and their grain sizes were determined by intercept method. The corrosion resistances of these samples were found using Electrochemical Impedance Spectroscopy (EIS). The study suggests that, as time of heat treatment increases, grain size increases, hardness decreases and corrosion rate decreases. The conclusion obtained from the results of this study is found to match with those predicted by theory.