At higher frequencies, the intercept corresponds to the solution resistance (Rs), and at lower frequency end corresponds to (Rt). The difference between these two values gives the charge transfer resistance (Rct). The value of Rct is a measure of the electron transfer across the surface and is inversely proportional to corrosion rate. The semicircle shaped Nyquist plots indicate the formation of a barrier on the surface and a charge transfer process mainly controlling the corrosion of carbon steel.