简介:Thesystematiclaboratorystudiesontherolesofsulfate-reducingbacteria(SRB)inthestresscorrosioncracking(SCC)susceptibilityofX80steelsubjectedtocathodicpotentialhavebeenconductedinanearneutralpHsoilsolutionbyslowstrainratetests.ThecathodicpotentialandSRBincreaseindividuallytheSCCsusceptibilityofthesteelinthesoilsolution.ThepositiveroleoftheSRBactivitiesinSCCsusceptibilitydependsontheprolongationofpre-incubationtime,andtheSCCsusceptibilityofthesteelincreasesundermorenegativepotentials.What’smore,theappliedpotentialsandthepresenceofSRBworktogetherinpromotingtheSCCsusceptibilityofthesteel.But,thecombinedactionbecomeslimitedwithdecreasingcathodicpotentials.Therelationshipsbetweentheplasticitylossandthepermeablehydrogenconcentrationwereestablishedforthesteelinthesoilsolution,regardlessofunderopencircuitpotentialorcathodicpotentials,inboththesterileandSRBinoculatedconditions.Therelationshipsarepracticallysignificantfortheselectionofsafecathodicprotection(CP)potentialsinthepresenceofSRBinsoilenvironment.
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简介:ConstantloadtestsinNS4solutionpurgedwithN2-5%CO2gasmixturewereconductedonAmericanPetroleumInstitute(API)X80pipelinesteelappliedinthe2ndWest-EastGasPipelineprojectwithandwithoutpreload.TheresultsshowthatcrackscouldinitiateandpropagateinX80pipelinesteelinnear-neutralpHenvironmentunderaconstantloadcondition.Thelifeofcrackinitiationandpropagationincreasedwithdecreasingappliedstress.Preloaddidnotchangeitscorrosionbehaviorobviously.However,preloadreducedthetimeforcrackinitiation.