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Open AccessArticle

Resistance of Thermally Aged DSS 2304 against Localized Corrosion Attack

1
“Aldo Daccò” Corrosion and Metallurgy Study Centre, University of Ferrara, Via G. Saragat 4A, 44122 Ferrara, Italy
2
Terra & AcquaTech Laboratory, University of Ferrara, Via Saragat 1, 44122 Ferrara, Italy
*
Author to whom correspondence should be addressed.
Metals 2018, 8(12), 1022; https://doi.org/10.3390/met8121022
Received: 31 October 2018 / Revised: 28 November 2018 / Accepted: 4 December 2018 / Published: 5 December 2018
(This article belongs to the Special Issue Corrosion and Protection of Metals)
In this paper, the effects of thermal aging in the 650–850 °C range on the localized corrosion behaviour of duplex stainless steel (DSS) 2304 was investigated. Pitting corrosion resistance was assessed by pitting potential (Epitt) and critical pitting temperature (CPT) determination, while the degree of sensitisation (DOS) to intergranular corrosion (IGC) was evaluated by double loop electrochemical potentiokinetic reactivation (DL-EPR). The susceptibility to stress corrosion cracking (SCC), evaluated in standard NACE TM-0177 solution at pH 2.7 and 25 °C, with the addition of S2O32− at 10−3 M, resulted in general good agreement with pitting and IGC behaviour. In fact, as-received DSS 2304 aged for 5 min at 650 °C or 750 °C presented a high resistance to localized corrosion. The alloy corrosion behaviour was severely impaired with an aging time of 60 min at 650 °C and of 10 or 60 min at 750 °C, due to the precipitation of finely distributed M23C6-type chromium carbides at ferrite/austenite interphases, which determined the formation of chromium and molybdenum depleted areas. The behaviour of samples aged at 850 °C also depended on the aging time, but, at 60 min, the rediffusion of passivating elements produced a recovery of the alloy resistance to pitting, IGC and SCC. View Full-Text
Keywords: duplex stainless steel; pitting corrosion; intergranular corrosion; stress corrosion cracking; CPT; DL-EPR duplex stainless steel; pitting corrosion; intergranular corrosion; stress corrosion cracking; CPT; DL-EPR
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MDPI and ACS Style

Zanotto, F.; Grassi, V.; Balbo, A.; Monticelli, C.; Zucchi, F. Resistance of Thermally Aged DSS 2304 against Localized Corrosion Attack. Metals 2018, 8, 1022.

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