Effect of water jet cavitation peening on electrochemical corrosion behavior of nickel-based alloy 600 in NaCl solution

Abstract

Surface roughness, residual stress, grain boundary microstructure of the surface layer, the electrochemical corrosion behavior and the surface chemical state after the electrochemical test in alloy 600 in 3.5 wt% NaCl medium was investigated. After the WJP treatment, the surface roughness was increased and residual compressive stress was introduced. A low angle grain boundary layer and a lamellae-shaped layer were formed on the surface. A passivation film with higher Cr content was formed on the WJP treated surface after the electrochemical test. After the WJP treatment, the electrochemical corrosion potential changed from −151 ± 4.6 mV to −133 ± 3.1 mV, the corrosion current density changed from 0.298 ± 0.003 μA/cm2 to 0.052 ± 0.001 μA/cm2, the pitting potential increased from 258 ± 13 mV to 350 ± 8 mV, and the film resistance increased from 4283 ± 158 Ω/cm2 to 124,850 ± 187 Ω/cm2. The superior corrosion resistance was attributed to the change in stress state and microstructure of the surface layer.