Corrosion study of Laser surface hardening of AISI420 steel

In this study, the surface of the samples were hardened by pulsed Nd:YAG laser. After determination of optimal parameters of laser transformation hardening of mentioned steel and improving in hardness compared to previous studies by pulsed Nd:YAG laser, the pitting corrosion behavior of hardened and as received surfaces were compared. SEM and Optical microscopic studies were done to study the microstructure. Cyclic polarization tests were used to study the electrochemical corrosion behavior. The result showed that in the result of solid- state transformation and refining of carbides in the steel matrix, improvement in the depth and surface hardness was obtained and the hardness of about 700 Vickers in the surface was gained. The polarization curves showed increased 113mV in potential. It was observed that this steel didn’t have repassivation capability even after laser surface hardening.