Corrosion Behavior of Passivated Martensitic and Semi-Austenitic Precipitation Hardening Stainless Steel

Abstract

This research aimed to conduct a passive layer state study on martensitic and semiaustenitic precipitation hardening stainless steels (PHSS) passivated in citric acid and nitric acid baths at 49 and 70◦C for 50 and 75 min and subsequently exposed in 5 wt.% NaCl and 1 wt.% H2SO4 solutions. Corrosion behavior of the passivated material was observed by using potentiodynamic polarization (PP) according to the ASTM G5-11 standard. The microstructural analysis was performed by optical microscopy and scanning electron microscopy (SEM), while the passivated layer was characterized by X-ray photoelectron spectroscopy (XPS). The results indicated that the semi-austenitic-NA-50 min-70◦C sample showed the best corrosion resistance behavior in both solutions. The XPS characterization confirmed that the martensitic and semi-austenitic surface film presented a mixture of chemical compounds, such as Cr2O3 and Fe(OH)O, respectively.