Designation:B646−17StandardPracticeforFractureToughnessTestingofAluminumAlloys1ThisstandardisissuedunderthefixeddesignationB646;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheU.S.DepartmentofDefense.1.Scope*1.1Fracturetoughnessisakeypropertyforanumberofaluminumalloysutilizedinaerospaceandprocessindustries.Fracturetoughnesstestingisoftenrequiredforsupplierqualification,qualitycontrol,andmaterialreleasepurposes.Thepurposeofthispracticeistoprovideuniformtestproceduresfortheindustry,pointingoutwhichcurrentstan-dardsareutilizedinspecificcases,andprovidingguidelineswherenostandardsexist.Thispracticeprovidesguidancefortesting(a)sheetandotherproductshavingaspecifiedthick-nesslessthan6.35mm(0.250in.),(b)intermediatethicknessesofplate,forgings,andextrusionsthataretoothinforvalidplane-strainfracturetoughnesstestingbuttoothickfortreat-mentassheet,suchasproductshavingaspecifiedthicknessgreaterthanorequalto6.35mm(0.250in.)butlessthan25to50mm(1to2in.),dependingontoughnesslevel,and(c)relativelythickproductswhereTestMethodE399isappli-cable.1.2Thispracticeaddressesbothdirectmeasurementsoffracturetoughnessandscreeningtests,thelatterrecognizingthecomplexityandexpenseofmakingformalfracturetough-nessmeasurementsongreatquantitiesofproductionlots.1.3ThevaluesstatedinSIunitsaretoberegardedasthestandard.Thevaluesininch-poundunitsgiveninparenthesisareprovidedforinformationpurposesonly.1.4Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.1.5Thisinternationalstandardwasdevelopedinaccor-dancewithinternationallyrecognizedprinciplesonstandard-izationestab...
