1、Designation:G7181(Reapproved 2014)Standard Guide forConducting and Evaluating Galvanic Corrosion Tests inElectrolytes1This standard is issued under the fixed designation G71;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,the year of
2、 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 guide covers conducting and evaluating galvaniccorrosion tests to characterize the behavior of two dissimilarmetals in
3、electrical contact in an electrolyte under low-flowconditions.It can be adapted to wrought or cast metals andalloys.1.2 This guide covers the selection of materials,specimenpreparation,test environment,method of exposure,and methodfor evaluating the results to characterize the behavior ofgalvanic co
4、uples in an electrolyte.NOTE1Additional information on galvanic corrosion testing andexamples of the conduct and evaluation of galvanic corrosion tests inelectrolytes are given in Refs(1)2through(2).1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are inc
5、luded in thisstandard.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 and health practices and determine the applica-bility of regulatory limitations prior to
6、use.2.Referenced Documents2.1 ASTM Standards:3G1 Practice for Preparing,Cleaning,and Evaluating Corro-sion Test SpecimensG3 Practice for Conventions Applicable to ElectrochemicalMeasurements in Corrosion TestingG4 Guide for Conducting Corrosion Tests in Field Applica-tionsG16 Guide for Applying Stat
7、istics to Analysis of CorrosionDataG31 Guide for Laboratory Immersion Corrosion Testing ofMetalsG46 Guide for Examination and Evaluation of Pitting Cor-rosion3.Significance and Use3.1 Use of this guide is intended to provide information onthe galvanic corrosion of metals in electrical contact in ane
8、lectrolyte that does not have a flow velocity sufficient to causeerosion-corrosion or cavitation.3.2 This standard is presented as a guide for conductinggalvanic corrosion tests in liquid electrolyte solutions,both inthe laboratory and in service environments.Adherence to thisguide will aid in avoid
9、ing some of the inherent difficulties insuch testing.4.Test Specimens4.1 MaterialTest specimens should be manufactured fromthe same material as those used in the service application beingmodeled.Minor compositional or processing differences be-tween materials or between different heats can greatly a
10、ffectthe results in some cases.4.2 Size and Shape:4.2.1 The size and shape of the test specimens are dependenton restrictions imposed by the test location.When determiningmaterial behavior in the laboratory,it is advisable to use thelargest specimens permissible within the constraints of the testequ
11、ipment.In general,the ratio of surface area to metal volumeshould be large in order to favor maximum corrosion loss perweight.Sufficient thickness should be employed,however,tominimize the possibility of perforation of the specimens duringthe test exposure.When modeling large components,the sizeof t
12、he specimens should be as large as practical.Whenmodeling smaller components,specimen size should be asclose as possible to that of the application being modeled.Surface area ratio in the test should be identical to theapplication being modeled.This ratio is defined as the surfacearea of one member
13、of the couple divided by the surface areaof the other member of the couple.Only the area in contactwith the electrolyte(wetted area)is used in this calculation.In1This guide is under the jurisdiction of ASTM Committee G01 on Corrosion ofMetals and is the direct responsibility of Subcommittee G01.11
14、on ElectrochemicalMeasurements in Corrosion Testing.Current edition approved May 1,2014.Published May 2014.Originallyapproved in 1981.Last previous edition approved in 2009 as G7181(2009).DOI:10.1520/G0071-81R14.2The boldface numbers in parentheses refer to a list of references at the end ofthis sta
15、ndard.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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C7
16、00,West Conshohocken,PA 19428-2959.United States1 low-resistivity electrolytes,maintaining proximity between thematerials being coupled may be more important than maintain-ing the exact area ratio.Also,with some couples,such ascopper coupled to aluminum,there may be effects of corrosionproducts washing from one electrode to another which mayhave to be considered in determining specimen placement.4.2.2 Laboratory tests are normally performed on rectangu-lar plates or on cylinders.When modeling se