ASTM_G_139_-_05_2015.pdf

Designation:G13905(Reapproved 2015)Standard Test Method forDetermining Stress-Corrosion Cracking Resistance of Heat-Treatable Aluminum Alloy Products Using Breaking LoadMethod1This standard is issued under the fixed designation G139;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 test method covers procedures for evaluation ofstress corrosion cracking(SCC)resistance by the breaking loadtest method,a concept which uses residual strength as themeasure of damage evolution(in this case environmentallyassisted cracking).1.2 This test method covers specimen type and replication,test environment,stress levels,exposure periods,final strengthdetermination,and statistical analysis of the raw residualstrength data.1.3 The test method was developed for use with heat-treatable aluminum alloys,that is,2XXX alloys and 7XXXwith 1.2 to 3.0%Cu,and test specimens oriented in theshort-transverse direction relative to grain structure(1,2).2However,the residual strength measurements and the statisticsused to analyze the data are not specific to heat-treatablealuminum alloys and can be used for other specimen orienta-tions and different types of materials.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:3E8 Test Methods for Tension Testing of Metallic MaterialsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodG44 Practice for Exposure of Metals andAlloys byAlternateImmersion in Neutral 3.5%Sodium Chloride SolutionG47 Test Method for Determining Susceptibility to Stress-Corrosion Cracking of 2XXX and 7XXX AluminumAlloy ProductsG49 Practice for Preparation and Use of Direct TensionStress-Corrosion Test SpecimensG64 Classification of Resistance to Stress-Corrosion Crack-ing of Heat-Treatable Aluminum Alloys3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 censora statistical term indicating that the valuefrom an individual observation may fall outside of the rangethat can be measured because of test procedures or conditions.3.1.2 samplethe nominally uniform,bulk material fromwhich individual stress-corrosion cracking specimens are ob-tained.4.Summary of Test Method4.1 This test method describes a procedure for using re-sidual strength after exposure to a corrosive environment toevaluate stress corrosion cracking susceptibility in heat treat-able aluminum alloy product forms such as sheet,plate,extrusions,forgings,and bar.These products generally aremost susceptible to SCC in the long transverse direction ofsheet,the short transverse direction of plate,extrusions andforgings,and the transverse direction of rod and bar stock.Inthis test,tensile bars or direct tension sheet specimens,pre-pared according to Practice G49,are exposed to 3.5 weight%aqueous sodium chloride solution(Practice G44),are removedbefore they fail and are tension tested to determine the amountof corrosion damage that has occurred.The average retainedstrength is then calculated and the Box-Cox Transformationcan be used for statistical analysis of the results.4.2 The procedure calls for exposure of unstressed speci-mens which are used to factor out the effects of pitting,intergranular,and general corrosion.These phenomena de-grade residual strength but do not require applied stress fortheir occurrence.1This test method is under the jurisdiction of ASTM Committee G01 onCorrosion of Metals and is the direct responsibility of Subcommittee G01.06 onEnvironmentally Assisted Cracking.Current edition approved Nov.1,2015.Published December 2015.Originallyapproved in 2005.Last previous edition approved in 2011 as G13905(2011).DOI:10.1520/G0139-05R15.2The boldface numbers in parentheses refer to the list of references at the end ofthe 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.Significance and Use5.1 The test method was developed for use with highstrength aluminum alloys(2XXX and Cu containing 7XXX)that are normally tested in 3.5 weight%NaCl by alternateimmersion.However,the concept which uses residual strengthasameasureofdamageevolution(inthiscaseenvironmentally-assisted cracking)can,in principle,be appliedto any alloy and environmental system.5.2 This test method has been develop