Electrochemical Behavior of Corrosion on Borided and Non-borided Steel Immersed in NaCl 3.5% and HCl Solutions

This paper assesses the ability of borided and non-borided Z80 WCrV 18-04-01 steel to resist corrosion by employing linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) methods. The steel samples were subject to boriding using the powder boriding method for different durations (1 hour, 2 hours, and 8 hours) at a temperature of 1223 K. Structural analysis of the borided steel surfaces revealed the presence of a double layer of FeB / Fe2B on the Z80 WCrV 18-04-01 steel. The properties of linear polarization resistance and electrochemical impedance spectroscopy were evaluated on the surfaces of both borided and non-borided steels amples by immersing them in corrosive solutions of 1M HCl (pH = 0.13) and 3.5% NaCl saline. The measurements of electrochemical impedance spectroscopy were analyzed over a 7-day exposure period in both corrosive solutions. Equivalent electrical circuits were used to model the impedance curves acquired for both the borided and non-borided steel samples. The findings from both electrochemical methods suggest that the boride layers formed on the surfaces of the steel provide effective protection against corrosive effects in both environments, but this protection is observed only during the first day of immersion.