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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Microstructure by Thermal Attack under Vacuum of a Superduplex Stainless Steels and Electrochemical Behavior in H2S/CO2-Saturated Synthetic Seawater

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Author(s):
Souza, Elki C. [1] ; Fortulan, Carlos A. [2] ; Rollo, Joao M. D. A. [3]
Total Authors: 3
Affiliation:
[1] Univ Fed Tocantins, Dept Quim Ambiental, BR-77402970 Gurupi, TO - Brazil
[2] Univ Sao Paulo, Dept Engn Mecan, Escola Engn Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil
[3] Univ Sao Paulo, Dept Engn Mat, Escola Engn Sao Carlos, BR-13566590 Sao Carlos, SP - Brazil
Total Affiliations: 3
Document type: Journal article
Source: Journal of the Brazilian Chemical Society; v. 29, n. 9, p. 1803-1810, SEP 2018.
Web of Science Citations: 0
Abstract

Superduplex stainless steels (SSS) composed in both equal fraction ferritic-austenite phases, classically defined by ASTM A995M Gr.5A, in order to obtain a better relation of mechanical properties and corrosion properties, are applied as components for use in petrochemical industries in off-shore platforms. The corrosion resistance of stainless steels is due to the oxides formed on the surface, which is dependent on the temperature and environment in which they are exposed. This paper investigates a microstructure duplex during steps of thermal attack under vacuum at high temperatures through observation of the coloration and growth of oxide films. Some coloration was observed in the phases, austenite and ferrite, with the increase of the temperature to 1100 ºC, which is indicative of the presence of chromium and iron oxides. In the cooling occurs the stability of oxides present in the films. Electrochemical tests were conducted in H2S/CO2-saturated in two different concentrations of chloride sodium electrolyte, simulating a seawater environment. Potentiodynamic polarization curves indicate that pitting corrosion resistance and repassivation process in media of 3.5 and 9.0% (wt.%) NaCl are not affected by the presence of H2S/CO2 (40/60 ppm) at room temperature (25 ºC). (AU)