Electrochemical corrosion behavior of alloy 31 using dynamic electrochemical impedance spectroscopy

Abstract

Potentiodynamic anodic polarisation and Dynamic Electrochemical Impedance Spectroscopic (DEIS) measurements were carried out on type 316L stainless steel (SS) and alloy 31 in natural sea water in order to assess the pitting corrosion resistance. DEIS measurements were performed over a wide range of potentials covering the corrosion potential, passive region, breakdown region and dissolution region. It was shown that the impedance measurements in potentiodynamic conditions allow instantaneous investigation of changes in passive layer with potential. The impedance spectra of various potential regions were also discussed. From the above studies, the pitting corrosion resistance of the alloys 31 was higher than 316L SS; due to the higher contents of nitrogen, chromium and molybdenum.