Experimental and analytical investigation on high chloride-attack resistibility of alloy corrosion-resistant steel Cr10Mo1

Abstract

The electrochemical performances of new alloy corrosion-resistant steel Cr10Mo1 subjected to chloride attack with various levels (0 M, 0.2 M, 1.0 M and 2.0 M, as NaCl), were evaluated by electrochemical techniques (linear polarization resistance, electrochemical impedance spectroscopy and potentiodynamic polarization). X-ray photoelectron spectroscopy (XPS) was used to characterize the composition and structure of the surface film on the steel, with transmission electron microscopy (TEM) visualizing the film layer. The electrochemical results show that as chloride increases, the steel never goes to corrosion domain even when chloride up to 2.0 M, although has a moderate decline in corrosion resistance. According to XPS and TEM analysis, the passive film on the steel presents a bilayer structure: an outer layer enriched in Fe oxides, and an inner layer rich in Cr species. With more chloride attacking, Fe oxides gradually decompose while Cr oxides remain good stability. The Cr oxides concentrated inner layer in the film acts as a protective barrier, supporting the alloy corrosion-resistant steel excellent corrosion resistance against high-concentration chloride.