Effects of nitric acid passivation on the corrosion behavior of ZG06Cr13Ni4Mo stainless steel in simulated marine atmosphere

Abstract

ZG06Cr13Ni4Mo martensitic stainless steel was nitric acid‐passivated to improve its corrosion performance. The effects of nitric acid passivation on the surface morphology, chemical composition, electrochemical properties, semiconductor behavior, and long‐term corrosion performance of the stainless steel were investigated using various analytical techniques. An in‐depth analysis of X‐ray photoelectron spectroscopy (XPS) showed that the passive film formed after the acid passivation process showed high thickness and a duplex character as it consisted of a hydroxide layer and an oxide layer. The oxide layer affected the corrosion resistance and thickness of the passive film. The thickness of the passive film was calculated theoretically as well as experimentally by fitting the electrochemical impedance spectroscopy and XPS results. The electrochemical tests revealed that the dramatic increase in the corrosion resistance of the stainless steel after the passivation was due to the formation of a thick, low‐disorder passive film rather than Cr enrichment. The removal of inclusions resulted in higher pitting resistance, whereas the increased roughness showed a negative effect on the corrosion behavior of the stainless steel. During the wet–dry cyclic tests, the modification of the passive film was examined. The passivated stainless steel exhibited good corrosion resistance for up to 50 days of exposure in the simulated environment.

Corrosion Behavior of Sensitized AISI 304 Stainless Steel in Acid Chloride Solution

“…For this specimen, the positive effect of the high-temperature oxides chemical removal was registered [ 16 , 17 ]. Nitric acid as a part of the pickling solution could strengthen the passive surface film [ 30 , 31 , 32 ], which partially retained its protectiveness. This was reflected in the curve with a narrow passivity region.…”

Evolution of Passive Film on 304 Stainless Steel During Nitric Acid Passivation

“…The results are consistent with those reported previously for stainless steel. [37][38][39] The behavior of the p-type semiconductor corresponds to the inner Cr-rich oxide layer in the passive film, while the behavior of the n-type semiconductor can be related to the outer Fe-rich oxide layer. As time prolongs, both N A and N D decrease first and then increase after 2.67 h. This indicates that the doping species density of the sample passivated for 2.67 h was lower than that of other samples.…”

Electrochemical polishing versus mechanical polishing of AISI 304: surface and electrochemical study

“…Mott-Schottky (M-S) analysis was employed to characterize the semiconductive property of the passive films to determine their quality [23][24][25]. Donor and acceptor densities were utilized previously to determine the quality of the stainless in 0.2% NaCl, where the passivated specimen showed lower densities compared to untreated specimen [24,26,27].…”