ASTM_G_112_-_92_2015.pdf

Designation:G11292(Reapproved 2015)Standard Guide forConducting Exfoliation Corrosion Tests in Aluminum Alloys1This standard is issued under the fixed designation G112;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 This guide differs from the usual ASTM standard in thatit does not address a specific test.Rather,it is an introductoryguide for new users of other standard exfoliation test methods,(see Terminology G15 for definition of exfoliation).1.2 This guide covers aspects of specimen preparation,exposure,inspection,and evaluation for conducting exfoliationtests on aluminum alloys in both laboratory accelerated envi-ronments and in natural,outdoor atmospheres.The intent is toclarify any gaps in existent test methods.1.3 The values stated in SI units are to be regarded as thestandard.The inch-pound units given in parentheses are forinformation only.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 use.2.Referenced Documents2.1 ASTM Standards:2G1 Practice for Preparing,Cleaning,and Evaluating Corro-sion Test SpecimensG15 Terminology Relating to Corrosion and Corrosion Test-ing(Withdrawn 2010)3G34 Test Method for Exfoliation Corrosion Susceptibility in2XXX and 7XXX Series Aluminum Alloys(EXCO Test)G50 Practice for Conducting Atmospheric Corrosion Testson MetalsG66 Test Method for Visual Assessment of ExfoliationCorrosion Susceptibility of 5XXX Series Aluminum Al-loys(ASSET Test)G85 Practice for Modified Salt Spray(Fog)TestingG92 Practice for Characterization of Atmospheric Test Sites2.2 ASTM Adjuncts:Illustrations of Appearance Classifications(6 glossy pho-tos)43.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 panela flat,rectangular specimen normally takenwith the test surface parallel to the longitudinal and long-transverse dimensions of fabricated product.For thin sheet andextrusions,the thickness may be the full thickness of the part.3.1.2 samplea portion of a large piece,or an entire pieceout of a group of many pieces,that is submitted for evaluationand considered representative of the larger piece or population.For castings and forgings,this may be an extra portion orprolongation,or in the case of small parts,an entire extra piecetaken from a specific lot.3.1.3 specimenthe actual test piece to be corrosion tested.Frequently this has a specific shape with prescribed dimen-sional tolerances and finishes.3.1.4 test planethe plane in the thickness of the samplethat is being tested.Generally this is the fabricated surface orsome specified interior plane.Interior planes typically used are:(a)T/10=10%of the thickness removed,(this is representa-tive of a minimal machining cut to obtain a flat surface),(b)T/4=quarter plane,25%of the thickness removed,and(c)T/2=midplane,50%of the thickness removed.4.Significance and Use4.1 Although there are ASTM test methods for exfoliationtesting,they concentrate on specific procedures for test meth-odology itself.Existent test methods do not discuss materialvariables that can affect performance.Likewise they do notaddress the need to establish the suitability of an acceleratedtest for alloys never previously tested nor the need to correlateresults of accelerated tests with tests in outdoor atmospheresand with end use performance.4.2 This guide is a compilation of the experience of inves-tigators skilled in the art of conducting exfoliation tests and1This guide is under the jurisdiction of ASTM Committee G01 on Corrosion ofMetals and is the direct responsibility of Subcommittee G01.05 on LaboratoryCorrosion Tests.Current edition approved Nov.1,2015.Published December 2015.Originallyapproved in 1992.Last previous edition approved in 2009 as G11292(2009).DOI:10.1520/G0112-92R15.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from ASTM International Headquarters.Order Adjunct No.ADJG003402.Original adjunct produced in 1980.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 assessing the degree and significance of the damage encoun-tered.The focus is on two general aspects:guides to techniquesthat will enhance the likelihood of obtaining reliableinformation,and tips and procedures to avoid pitfalls that couldlead to erroneous results and conclusions.4.