Designation:A646/A646M−06(Reapproved2016)StandardSpecificationforPremiumQualityAlloySteelBloomsandBilletsforAircraftandAerospaceForgings1ThisstandardisissuedunderthefixeddesignationA646/A646M;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1Thisspecificationcoverspremiumqualityalloysteelsemifinishedrolledorforgedbloomsandbilletsforreforgingintocriticalpartssuchasaircraftlanding-gearforgings.1.2Bloomsandbillets,hereinafterreferredtoasblooms,aresemifinishedsteelproducts,hotrolledorforgedtoapproxi-matecross-sectionaldimensions.Bloomsmaybesquare,round,hexagonal,octagonal,orrectangularinsection.Forthepurposesofthisspecification,minimumbloomsectionsizewillbe16in.2[103cm2].1.3Thisspecificationcoverstwobasicclassificationsofsteel:1.3.1ClassI—Vacuum-inductionmeltedorconsumable-electrodevacuummelted,orothersuitableprocesseswhichwillsatisfythequalityrequirementsofthisspecification.1.3.2ClassII—Air-meltedvacuumdegassed.1.3.3ClassIII—Airmeltedelectricfurnaceladlerefinedandvacuumdegassed.1.4Thevaluesstatedineitherinch-poundorSI(metric)unitsaretoberegardedseparatelyasstandards.Withinthetextandtables,theSIunitsareshowninbrackets.Thevaluesstatedineachsystemarenotexactequivalents;therefore,eachsystemshallbeusedindependentlyoftheother.Combiningvaluesfromthetwosystemsmayresultinnonconformancewiththespecification.1.5Unlesstheorderspecifiestheapplicable“M”specifica-tionthematerialshallbefurnishedtotheinch-poundunits.2.ReferencedDocuments2.1ASTMStandards:2A255TestMethodsforDeterminingHardenabilityofSteelA388/A388MPracticeforUltrasonicExaminationofSteelForgingsA788/A788MSpecificationforSteelForgings,GeneralRe-quirementsA604/A604MPracticeforMacroetchTestingofConsum-ableElectrodeRemeltedSteelBarsandBilletsE45TestMethodsforDeterminingtheInclusionContentofSteelE114Pract...
