Designation:B935−16StandardGuideforSteamTreatmentofFerrousPowderMetallurgy(PM)Materials1ThisstandardisissuedunderthefixeddesignationB935;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1Thisguideisintendedasanaidinestablishingandmaintainingaprocedureforthesteamtreatment,alsoreferredtoassteamblackening,ofsinteredferrousPMmaterialsandtheappropriateuseandevaluationofthesematerials.Addi-tionalinformationconcerningtheeffectofthisprocessonferrousPMmaterialpropertiesiscontainedinAppendixX1.1.2Withtheexceptionofthevaluesfordensityandthemassusedtodeterminedensity,forwhichtheuseofthegrampercubiccentimetre(g/cm3)andgram(g)unitsisthelong-standingindustrypractice,thevaluesininch-poundunitsaretoberegardedasstandard.ThevaluesgiveninparenthesesaremathematicalconversionstoSIunitsthatareprovidedforinformationonlyandarenotconsideredstandard.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:B243TerminologyofPowderMetallurgy3.SummaryofGuide3.1Anormalsequenceofstepsforbatchprocessingis:(1)preheattheload;(2)introduceasuperheatedsteam-richatmosphere;(3)heattheloadtotheprocessingtemperatureandmaintainthetemperatureforthedurationoftheprocessingcycle;and(4)cooltheloadtoatemperaturesuitableforhandling.Thisprocesswillproducealayerofblackironoxide(magnetite)onthesurfaceofthepartsandonthesurfacesoftheinterconnectedporositybythereaction.3Fe14H2O~gas!↔Fe3O414H2~gas!3.2Forcontinuoussteamtreatment,partsaretransportedthroughthefurnaceonacontinuousmeshbelt,andthethermalprofileofthefurnace(temperaturesettingsofthevariouszonesandthespeedofthemeshbelt)issettoe...
