Enhancements of Passive Film and Pitting Resistance in Chloride Solution for 316LX Austenitic Stainless Steel After Sn Alloying

Abstract

In the present work, the electrochemical behavior and properties of the passive film of a new Sn-alloyed 316LX austenitic stainless steel were investigated. With the increase in Sn content in 316LX austenitic stainless steel from 0 to 0.21%, the critical pitting temperature value increased from 32.6 to 38.8°C, and the pitting potential increased from 0.252 V SCE to 0.317 V SCE . Electrochemical impedance spectroscopy results showed that the corrosion resistance of passive film rose with the increase in Sn content, indicating a more stable passive film. The Mott-Schottky measurement revealed an n-type passive film with a decreased carrier concentration on the 316LX austenitic stainless steel surface. The Cr, Sn 2? and Sn 4? (SnO, SnOHCl or SnO 2 ) enrichments were observed in the passive layer by X-ray photoelectron spectroscopy. The enrichment of Sn and Cr in the passive film can account for the enhanced pitting resistance of 316LX austenitic stainless steel in chloride solution.

Unravelling the Fe Effect on the Corrosion of Chromium Coatings: Chemical Composition and Semiconducting Properties

“…93,94 Moreover, having a Cr oxide layer doped with other elements also has a negative impact in the corrosion resistance in comparison to a purely constituted Cr oxide film. 95 Apparently, there is a critical value between 5 and 27 % of Fe content in the alloy (Table II) that triggers the formation of a native duplex oxide layer (Fe100 and Fe400 samples, Fig. 5) rather than a pure Cr oxide-based layer (Fe0 and Fe8 samples, Fig.…”

Enhancement in intergranular corrosion resistance of the stabilised ultra-pure 430LX ferritic stainless steel by tin addition

“…SnO 2 is a p-type semiconductor, with low electronic conductivity and high corrosion resistance, blocking aggressive ions [38]. As proposed in previous studies, the presence of SnO 2 is sufficient to suppress the active dissolution and decrease the corrosion rate of the stainless steels [5,12].…”

“…The corrosion resistance of FSSs depends greatly on chromium and molybdenum contents. However, these alloying elements are rather pricey and greatly raise the production cost of FSSs [4,5]. In recent years, small amounts of tin element have been added into FSSs to improve the corrosion resistance.…”

Comparison Study on the Semiconductive and Dissolution Behaviour of 316L and Alloy 625 in Hydrochloric Acid Solution

“…The selective coefficients of Ni and Cr were lower than 1, which indicated that Ni and Cr species were relatively stable in acid solutions. Due to the low stability of iron oxides, the selective dissolution of Fe was very commonly reported [6,12,21,56]. Cr was the key element in the passive film.…”

“…In general, 316L and Alloy 625 could be spontaneously passivated owing to the formation of a protective film on their surface. In recent years, passive films have been characterized by numerous techniques, including atomic force microscopy (AFM) [5], X-ray photoelectron spectroscopy (XPS) [6,7], transmission electron microscopy (TEM) [8], and secondary ion mass spectrometry (SIMS) [9][10][11][12][13]. Agreements have been reached that the passive films were dominated by Cr, Fe, Mo and Ni species.…”