Designation:F436−11StandardSpecificationforHardenedSteelWashers1ThisstandardisissuedunderthefixeddesignationF436;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheU.S.DepartmentofDefense.1.Scope*1.1Thisspecificationcoversthechemical,mechanical,anddimensionalrequirementsforhardenedsteelwashersforusewithfastenershavingnominalthreaddiametersof1⁄4through4in.Thesewashersareintendedforgeneral-purposemechani-calandstructuralusewithbolts,nuts,studs,andotherinternallyandexternallythreadedfasteners.ThesewashersaresuitableforusewithfastenerscoveredinSpecificationsA325,A354,A449,andA490.1.2Thewashersaredesignatedbytypedenotingthemate-rialandbystyledenotingtheshape.1.2.1Thetypesofwasherscoveredare:1.2.1.1Type1—Carbonsteel.1.2.1.2Type3—Weatheringsteel.AtmosphericcorrosionresistanceandweatheringcharacteristicsarecomparabletothatofsteelscoveredinSpecificationsA588/A588MandA709/A709M.Theatmosphericcorrosionresistanceofthesesteelsissubstantiallybetterthanthatofcarbonsteelwithorwithoutcopperaddition.See5.1.Whenproperlyexposedtotheatmosphere,thesesteelscanbeusedbare(uncoated)formanyapplications.1.2.1.3ThisspecificationprovidesforfurnishingType3tochemicalcompositionoraCorrosionIndex(CRI)of6orhigheratthesuppliersoption.1.2.2Thestylesofwasherscoveredare:1.2.2.1Circular—Circularwashersinnominalboltsizes1⁄4through4in.suitableforapplicationswheresufficientspaceexistsandangularitypermits.1.2.2.2Beveled—Beveledwashersaresquareorrectangular,innominalsizes1⁄2through11⁄2in.,withabeveled1to6ratiosurfaceforusewithAmericanstandardbeamsandchannels.1.2.2.3Clipped—Clippedwashersarecircularorbeveledforusewherespacelimitationsnecessitatethatonesidebeclipped.1.2.2.4ExtraThick—Extrathickwashersarecircularwash-ersinnominalsizes1⁄2through11⁄2...
