ASTM_D_6208_-_07_2020.pdf

Designation:D620807(Reapproved 2020)Standard Test Method forRepassivation Potential of Aluminum and Its Alloys byGalvanostatic Measurement1This standard is issued under the fixed designation D6208;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 A procedure to determine the repassivation potential ofaluminum alloy 3003-H14(UNSA93003)(1)2as a measure ofrelative susceptibility to pitting corrosion by conducting agalvanostatic polarization is described.Aprocedure that can beused to check experimental technique and instrumentation isdescribed,as well.1.2 The test method serves as a guide for similar measure-ment on other aluminum alloys and metals(2-5).1.3 The values stated in SI units are to be regarded asstandard.The values given in parentheses after SI units areprovided for information only and are not considered standard.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:3D1193 Specification for Reagent WaterD3585 Specification for ASTM Reference Fluid for CoolantTestsG3 Practice for Conventions Applicable to ElectrochemicalMeasurements in Corrosion TestingG15 Terminology Relating to Corrosion and Corrosion Test-ing(Withdrawn 2010)4G46 Guide for Examination and Evaluation of Pitting Cor-rosionG107 Guide for Formats for Collection and Compilation ofCorrosion Data for Metals for Computerized DatabaseInput3.Terminology3.1 DefinitionsTerms used in this test method can befound in Practice G3 and Terminology G15.3.2 Symbols:3.2.1 EBbreak potential;potential at which the passivealuminum oxide layer breaks down.3.2.2 EGprotection potential,as measured in this galvano-static method;potential at which oxide layer repassivates.3.2.3 Jcurrent density,in A/m2.4.Summary of Test Method4.1 The test method described is an adaptation of themethod described in FORD Motor Company standards(6).4.2 An aluminum alloy specimen is polarized at fixedcurrent density for 20 min.in a solution of coolant andcorrosive water containing chloride.The potential as a functionof time is recorded.4.3 The maximum potential,EB,reached upon polarizationis determined,as is the minimum potential following themaximum potential,EG.4.4 Visual examination of the specimen may be made usingGuide G46 as a guide after disassembly and rinsing.5.Significance and Use5.1 This test method is designed to measure the relativeeffectiveness of inhibitors to mitigate pitting corrosion ofaluminum and its alloys,in particular AA3003-H14,rapidlyand reproducibly.The measurements are not intended to1This test method is under the jurisdiction of ASTM Committee D15 on EngineCoolants and Related Fluids and is the direct responsibility of SubcommitteeD15.06 on Glassware Performance Tests.Current edition approved Feb.1,2020.Published February 2020.Originallyapproved in 1997.Last previous edition approved in 2014 as D620807(2014).DOI:10.1520/D620807R20.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.3For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.4The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.correlate quantitatively with other test method values or withsusceptibility to localized corrosion of aluminum observed inservice.Qualitative correlation of the measurements and sus-ceptibility in service has been established(1).5.2 Themaximumpotentialreacheduponinitialpolarization,EB,is a measure of the resistance to breakdown ofthe aluminum oxide film.Lower susceptibility to initiation ofpitting corrosion is indicated by a more noble potential.(SeePractice G3 and