Influence of surface modifications on pitting corrosion behavior of nickel-base alloy 718. Part 1: Effect of machine hammer peening

•Machine hammer peening (MPM) introduces smoother surface as well as nano-grains and nano-twins in the near surface region.•MPM leads to more severe work hardening and higher compressive residual stress .•MPM has a benificial effect on the corrosion resistance of nickel-base alloy 718. The effect of surface modifications induced by machine hammer peening on pitting corrosion behavior of nickel-base alloy 718 in a 3.5wt.% NaCl solution is investigated. Severe work hardening and high compressive residual stress are generated with surface smoothing and microstructure evolution in terms of formation of nano-grains and nano-twins in the near surface region after machine hammer peening. Electrochemical tests results show that machine hammer peening has a beneficial influence on the corrosion resistance, indicated by a significant increase of the critical pitting potential (+134mV) accompanied with lower corrosion current density and higher polarization resistance.