ASTM_G_5_-_14.pdf

Designation:G514Standard Reference Test Method forMaking Potentiodynamic Anodic PolarizationMeasurements1This standard is issued under the fixed designation G5;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers an experimental procedure forchecking experimental technique and instrumentation.Iffollowed,this test method will provide repeatable potentiody-namic anodic polarization measurements that will reproducedata determined by others at other times and in other labora-tories provided all laboratories are testing reference samplesfrom the same lot of Type 430 stainless steel.1.2 UnitsThe values stated in SI units are to be regardedas standard.No other units of measurement are included in thisstandard.1.3 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1338 Guide for Identification of Metals and Alloys inComputerized Material Property DatabasesG3 Practice for Conventions Applicable to ElectrochemicalMeasurements in Corrosion TestingG107 Guide for Formats for Collection and Compilation ofCorrosion Data for Metals for Computerized DatabaseInput3.Significance and Use3.1 The availability of a standard procedure,standardmaterial,and a standard plot should make it easy for aninvestigator to check his techniques.This should lead topolarization curves in the literature which can be comparedwith confidence.3.2 Samples of a standard ferritic Type 430 stainless steel(UNS S43000)used in obtaining standard reference plot areavailable for those who wish to check their own test procedureand equipment.33.3 Standard potentiodynamic polarization plots are shownfor a lot of material originally purchased in 1992.This testmethod is not applicable for standard material purchasedbefore 1992.These reference data are based on the results fromdifferent laboratories that followed the standard procedure,using that material in 1.0 N H2SO4.The four sigma probabilitybands for current density values are shown at each potential toindicate the acceptable range of values.3.4 This test method may not be appropriate for polarizationtesting of all materials or in all environments.3.5 This test method is intended for use in evaluating theaccuracy of a given electrochemical test apparatus,not for usein evaluating materials performance.Therefore,the use of theplots in Fig.1 is not recommended to evaluate alloys other thanType 430,or lots of Type 430 other than those availablethrough Metal Samples.The use of the data in this test methodin this manner is beyond the scope and intended use of this testmethod.Users of this test method are advised to evaluate testresults relative to the scatter bands corresponding to theparticular lot of Type 430 stainless steel that was tested.4.Apparatus4.1 The test cell should be constructed to allow the follow-ing items to be inserted into the solution chamber:the testelectrode,two auxiliary electrodes,a Luggin capillary withsalt-bridge connection to the reference electrode,inlet andoutlet for an inert gas,and a thermometer.The test cell shall beconstructed of materials that will not corrode,deteriorate,orotherwise contaminate the test solution.1This test method is under the jurisdiction of ASTM Committee G01 onCorrosion of Metals and is the direct responsibility of G01.11 on ElectrochemicalMeasurements in Corrosion Testing.Current edition approved Nov.1,2014.Published December 2014.Originallyapproved in 1969.Last previous edition approved in 2013 as G5132.DOI:10.1520/G0005-14.2For 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.3These standard samples are available from Metal Samples,152 Metal SamplesRd.,Mumford,AL 36268.Generally,one sample can be repolished and reused formany runs.This procedure is suggested to conserve the available material.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 NOTE1Borosilicate glass and TFE-fluorocarbon have been foundsuitable.4.1.1 A suitable cell is shown in Fig.2(1).4A 1-L,round-bottom flask has been modified by the addition ofvarious necks to permit the introduction of electrodes,gas inletand outlet tubes,and a thermometer.The Luggin probe-saltbridge separates the bulk solution from the saturated calomelrefere