Designation:D6491−09StandardPracticeforEvaluationofAgingResistanceofPrestressedPrepaintedMetalInaDryHeatTest1ThisstandardisissuedunderthefixeddesignationD6491;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thispracticecanbeusedtoevaluatetheresistanceofaprestressedprepaintedmetalpaneltocracking,orlossofadhesion,orboth,afteracceleratedheataging.Mostcoilcoatedproductsareformedandbentintospecificshapestoproduceafinalproduct.Theseoperationsintroducestresses,whichmayberelievedbycrackingofthecoatingafteraging.1.2ThevaluesstatedinSIunitsaretoberegardedasthestandard.Thevaluesgiveninparenthesesareforinformationonly.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2D4145TestMethodforCoatingFlexibilityofPrepaintedSheet3.Apparatus3.1GravityorForcedAirLaboratoryOven,capableofmaintainingatemperatureof6063°C(14065°F).3.2BenchVise,withsmoothjawsorinserts,130mm(5in.)permanentlymountedonaworktableorbench,oralternativeequipmentcapableofmakingtheappropriatebends.3.3BendingDiesorTestShims,(optional).3.410Xmagnifier,(optional).3.5AdhesiveTape.4.TestSpecimens4.1Cutsamples75mm(3in.)wide(acrossthebenddirection)bywhateverlengthisnecessarytomaketheappro-priatenumberofbends.Thedirectionofthebendmaybetransverseorlongitudinaltothe“rollingdirection”ofthemetal—orasagreeduponbetweencustomerandvendor.5.Procedure5.1Performthefabricationatroomtemperature,2561°C(7762°F).Alltestspecimensshouldbeequilibratedtothesametemperaturebeforefabricating.Differentfabricationtemperaturesmaybeused,whenneeded,tomeetcustomerorvendorrequirements,orboth.5.2Preparethre...
