Effect of carbon dioxide and temperature on passive film parametersof superduplex stainless steel

Abstract

Superduplex stainless steel has been frequently employed in new sites of Brazilian Pre-Salt. In these environments, chloride concentration, temperature and carbon dioxide are normally present in higher levels than those at sea water at room temperature. In these conditions, it is expected that the passive films of stainless steel also show modifications. To better understand such modifications, samples of superduplex stainless steel UNS S32750 were submitted to electrochemical impedance measurements in brine media, at two temperatures and under presence/absence of carbon dioxide. The electrochemical impedance results were initially tested using the Kramers-Kronig transform and subsequently fitted by equivalent circuit employing constant phase elements -CPE. Moreover, to quantify the effect of each factor (temperature, chloride, carbon dioxide and microstructure) on the equivalent circuit, their parameters were tested applying statistical analysis. Significant effect of carbon dioxide and temperature was found on related parameters of passive film for heat-treated samples.

Microbiologically influenced corrosion of galvanized steel by Desulfovibrio sp. and Desulfosporosinus sp. in the presence of Ag–Cu ions

“…determined after 2, 24, 48 and 72 h were 1.270 Â 10 À4 , 0.122 Â 10 À4 , 0.124 Â 10 À4 , 0.107 Â 10 À4 respectively and for Desulfosporosinus sp. they were 6.990 Â 10 À4 , 2.602 Â 10 À4 , 1.399 Â 10 À4 and 1.140 Â 10 À4 respectively, and these values falls by the middle of the determined range [28].…”

“…with AgeCu ions determined after 2, 24, 48 and 72 h were 0.894 Â 10 À4 , 0.503 Â 10 À4 , 0.788 Â 10 À4 , 0.716 Â 10 À4 respectively, and for Desulfosporosinus sp. were 0.603 Â 10 À4 , 0.870 Â 10 À4 , 0.538 Â 10 À4 and 0.950 Â 10 À4 , respectively, and these values falls by the middle of the determined range [28]. the test coupon exposed to Desulfovibrio sp., and (c) the test coupon exposed to Desulfosporosinus sp.…”

UQ eSpace

“…In 2205 DSS in presence of H 2 S, the reduction in pH and presence of carbon dioxide will increase susceptibility to SCC [29]. When pH is lower than 2.7 the main corrosion mechanism will be hydrogen induced cracking and there may be hydrogen entry into the steel.…”