Title:
Stress corrosion cracking of duplex stainless steels in caustic solutions

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dc.contributor.advisor Singh, Preet M.
dc.contributor.author Bhattacharya, Ananya en_US
dc.contributor.committeeMember Carter, W. Brent
dc.contributor.committeeMember Gokhale, Arun, M.
dc.contributor.committeeMember Neu, Richard
dc.contributor.committeeMember Sanders, Thomas H., Jr.
dc.contributor.department Materials Science and Engineering en_US
dc.date.accessioned 2009-01-22T15:40:10Z
dc.date.available 2009-01-22T15:40:10Z
dc.date.issued 2008-11-19 en_US
dc.description.abstract Duplex stainless steels (DSS) with roughly equal amount of austenite and ferrite phases are being used in industries such as petrochemical and pulp and paper mills. However, many DSS grades have been reported to undergo corrosion and stress corrosion cracking in some aggressive environments such as chlorides and sulfide-containing caustic solutions. Although stress corrosion cracking of duplex stainless steels in chloride solution has been investigated and well documented in the literature, SCC mechanisms for DSS in caustic solutions were unknown. Microstructural changes and environmental factors, such as pH of the solution, temperature, and resulting electrochemical potential also influence the SCC susceptibility of duplex stainless steels. In this study, the role of material and environmental parameters on corrosion and stress corrosion cracking of duplex stainless steels in caustic solutions were investigated. Results showed that the austenite phase in the DSS is more susceptible to crack initiation and propagation in caustic environment, which is different from that in the low pH chloride environment where the ferrite phase is the more susceptible phase. This study also showed that alloy composition and microstructural changes in duplex stainless steels due to different heat treatments could affect their SCC susceptibility. Moreover, corrosion rates and SCC susceptibility of DSS was found to increase with addition of sulfide to caustic solutions. Corrosion films on DSS indicated that the metal sulfide compounds formed along with oxides at the metal surface in the presence of sulfide containing caustic environments made the steel susceptible to SCC initiations. The overall results from this study helped in understanding the mechanism of SCC in caustic solutions. Favorable slip systems in the austenite phase of DSS favors slip-induced local film damage thereby initiating a stress corrosion crack. Repeated film repassivation and breaking, followed by crack tip dissolution results in crack propagation in the austenite phase of DSS alloys. Result from this study will have a significant impact in terms of identifying the alloy compositions, fabrication processes, microstructures, and environmental conditions that may be avoided to mitigate corrosion and stress corrosion cracking of DSS in caustic solutions. en_US
dc.description.degree Ph.D. en_US
dc.identifier.uri http://hdl.handle.net/1853/26491
dc.publisher Georgia Institute of Technology en_US
dc.subject Stress corrosion cracking en_US
dc.subject Duplex stainless steel en_US
dc.subject Caustic en_US
dc.subject Microstructure en_US
dc.subject.lcsh Steel, Stainless
dc.subject.lcsh Stress corrosion
dc.subject.lcsh Microstructure
dc.title Stress corrosion cracking of duplex stainless steels in caustic solutions en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.advisor Singh, Preet M.
local.contributor.corporatename School of Materials Science and Engineering
local.contributor.corporatename College of Engineering
relation.isAdvisorOfPublication 436052a4-5726-4887-bdbf-e726647a6d26
relation.isOrgUnitOfPublication 21b5a45b-0b8a-4b69-a36b-6556f8426a35
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
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