Corrosion resistance of plasma-based low-energy nitrogen ion implanted austenitic stainless steel

Plasma-based low-energy ion implantation has emerged as a low-temperature surface engineering technique for low-energy implanting ions and then diffusing them into steel and alloy. This paper summarizes the pitting corrosion resistance and general corrosion resistance of the plasma-based low-energy ion implanted 1Cr18Ni9Ti austenitic stainless steel which was estimated by electrochemical polarization measurement and immersion corrosion test in the different NaCI and H2SO4 solutions. A high nitrogen face-centered-cubic phase (gamma(N)) was obtained on the implanted 1Cr18Ni9Ti stainless steel at the process temperatures of 300degreesC - 450degreesC. The gammaN, phase possessed a superior pitting corrosion resistance in 0.5% - 6% NaCl solutions, and an equivalent general corrosion resistance in 0.5 mol 1(-1) H2SO4 solution, compared with the original stainless steel. The effect of composition and microstructure of the gamma(N) phase oil the corrosion resistance was discussed. The nitrogen concentration in the gamma(N) phase mainly affected the pitting corrosion resistance and slightly affected the general corrosion resistance. The corrosion resistance mechanism of the gamma(N), phase was explored based on analysis of the passive films by Auger electron spectroscopy. The different role of supersaturated nitrogen of the gamma(N) phase in corrosion resistance indicated the different corrosion mechanism between the pitting corrosion resistance and general corrosion resistance.