ICS21.200CCSJ17

AssociationStandard

T/CSTM00833E—2022

Specificationofdrivinggearforgingforrailtransport

軌道交通用驅(qū)動(dòng)齒輪鍛件技術(shù)規(guī)范

(EnglishTranslation)

Issueddate:2023-07-25

Implementationdate：2023-10-25

IssuedbyChineseSocietyforTesting&Materials，Zhongguancun

Contents

Scope 4

Normativereferences 4

Termsanddefinitions 5

Classification 8

Smelting 8

Nameandchemicalcomposition 8

Technicalrequirements 9

Forging 11

Forgingsclassification 11

Technologicalprocess 11

Processrequirements 11

Forgingproducts 12

Deliverystatus 12

Mechanicalpropertiesandsampling 12

Macrostructure 22

Microstructure 22

Hardenability 23

Ultrasonicflawdetection 27

Shapeanddimensions 28

Appearance 28

Marking 28

Others 29

Determination 29

Retest 29

Reheattreatment 29

Inspectionsrules 29

AnnexA(Informative)Specimensformechanicalproperties 31

Bibliography 33

T/CSTM00833E—2022

T/CSTM00833E—2022

II

III

Foreword

CSTM/FC991isinchargeofthisEnglishtranslation.IncaseofanydoubtaboutthecontentsofEnglishtranslation,theChineseoriginalshallbeconsideredauthoritative.

ThisdocumentisdraftedinaccordancewiththerulesgivenintheGB/T1.1—2020Directivesforstandardization―Part1:RulesforthestructureanddraftingofstandardizingdocumentsandGB/T20001.10—2014Rulesfordraftingstandards―Part10:Productstandards.

Attentionisdrawntothepossibilitythatsomeoftheelementsofthisdocumentmaybethesubjectofpatentrights.Theissuingbodyofthisdocumentshallnotbeheldresponsibleforidentifyinganyorallsuchpatentrights.

ThisdocumentwasjointlyproposedbyCSTM/FC99,Integratedstandardization,andSAC/TC52(TheNationalTechnicalCommitteeforGearStandardization).

ThisdocumentwaspreparedbyCSTM/FC99,Integratedstandardization.

1ChineseSocietyforTesting&Materials,Zhongguancun--abbreviatedasCSTM.FieldCommittee--abbreviatedasFC.

Introduction

Technologiesofrailtransportequipmenthaveundergoneseveralstagesfromthe“l(fā)eapfrogdevelopmentofrailway”proposedbytheMinistryofRailwaysofthePRCin2003totheCRH380Agearboxdrivingdevicebeinglistedasanationalkeynewproductin2014.Themaintechnicaldifficultiesareasfollows:

Duetothefastrunningspeedofthetrain,itneedstofacetheextremelyharshoperatingenvironmentsuchashightemperature,severecold,humidity,sandanddust,etc.

Inthenarrowspaceunderthetrain,therearegaugerestrictionsanddistancerequirementsbetweenthegroundandtherailsurface;

Thesingle-stagetransmissionratioislarge.

Inviewoftheabovecharacteristics,railtransportgearproductsneedtomeet(super)highreliabilityrequirements,andforgingsasthesourcecomponentsneedtobestrictlyregulated.Thisdocumentlistsspecificationsmainlyconcerningthefollowingaspects:

Thesmeltingleveldirectlyaffectsthefinalperformanceofproducts,anddifferentsmeltingrequirementsareputforwardforproductsofdifferentuses.ThegearcarburizedsteelisCr－Mnsteelseries.Duringthemanufacturingprocess,itssurfaceneedstobecarburizedbychemicalheattreatment.However,withhighgearcarburizationtemperature(930℃)andlongcarburizationtime(3h-6h),theaustenitegraintendstogrow,andthegraincoarsenessormixedcrystalphenomenonareoftenobserved.Theseleadtoanincreaseingearquenchingdeformationandcrackingtendency.Atthesametime,itsignificantlyreducesthestructuralstrengthofthegear,whichleadstostressconcentration,andtendstobringaboutbrittlefractureofthegear.Thisdocumentspecifiestherangeofaluminumandnitrogenratio,whichisconducivetoreducingthephenomenonofmixedcrystal.As17CrNiMo6HintheDINstandardisalsowidelyusedinactualproduction,consideringtheinterchangeabilityofthetwomaterials,thecontentofMnin18Cr2Ni2MoHisadjustedfrom0.50-0.90to0.45-0.65.

Appropriateforgingratioandpostforgingheattreatmentcanhelptoimprovethedefectssuchasporosity,pores,shrinkagecavityandbandedstructureintheingot,andcanalsofullybreakthesegregationandinclusionsintheingottomakethestructureuniform.Thisdocumentgivestheforgingprocessandbasicprocessrequirementsfordifferenttypesofforgings,whichisconducivetoobtainingforgingswithstablequality.

Forthemechanicalpropertytestandtypetestofdifferentparts,specificsamplingpositionsandsamplingdirectionsaregiventoavoidinconsistencybetweentests.

Inultrasonicflawdetection,differentacceptancemethodsareadoptedfordifferentforgings,whichismoreeconomicalandreasonable.

Atpresent,thoughdomesticstandardsconcerninggearforgings,suchasGB/T37683—2019Largegearandgirthgearforgings—Technicalspecification,GB/T39430—2020Specificationsfortheblanksofhighreliabilitygears,TB/T2989—2015Gearforrailwaylocomotiveandpowercar,YB/T4741—2019Steelsforgearsofrailwayindustry,havereferredtosmelting,forging,testingandotheraspects,theyarenotspecificallyfordrivinggearforgingsforrailtransport.Thisdocumentprovidesdetailedprocessandinspectionrequirements,whichareconvenientforpracticaloperation.

T/CSTM00833E—2022

T/CSTM00833E—2022

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Specificationofdrivinggearforgingforrailtransport

ScopeThisdocumentspecifiestheclassification,smelting,forging,productsanddeterminationofdrivinggearforgingsforrailtransport,aswellasthebodysamplingdiagramscorrespondingtogearforgingswithdifferentshapes.

Thisdocumentisapplicabletothemanufacturingandinspectionofgearforgingsusedfortractiondrivesonrail-orientedtransportationequipment(high-speedEMUs,locomotivesandurbanrailtrains,etc.).Othergearforgingswithhighreliabilityrequirementsandsimilarappearancesanddimensionscanalsobeusedforreference.

Normativereferences

Thefollowingreferenceddocumentsareindispensablefortheapplicationofthisdocument.Fordatedreferences,onlytheeditioncitedapplies.Forundatedreferences,thelatesteditionofthereferenceddocument(includinganyamendments)applies.

GB/T222PermissibletolerancesforchemicalcompositionofsteelproductsGB/T223(Allparts)Methodsforchemicalanalysisofiron,steelandalloyGB/T225Steel—Hardenabilitytestbyendquenching(Jominytest)

GB/T226Testmethodformacrostructureanddefectofsteelbyetching

GB/T228.1Metallicmaterials—Tensiletesting—Part1:Methodoftestatroomtemperature

GB/T229Metallicmaterials—Charpypendulumimpacttestmethod

GB/T231.1Metallicmaterials—Brinellhardnesstest—Part1:Testmethod

GB/T1979Standarddiagramsformacrostructureanddefectofstructuralsteels

GB/T4336 Carbonandlow-alloysteel—Determinationofmulti-elementcontents—Sparkdischargeatomicspectrometricmethod(routinemethod)

GB/T5611Foundryterminology

GB/T6394—2017Determinationofestimatingtheaveragegrainsizeofmetal

GB/T8541Terminologyofforgingandstamping

GB/T10561 Steel—Determinationofcontentofnonmetallicinclusions—Micrographicmethodusingstandardsdiagrams

GB/T11261 SteelandironDeterminationofoxygencontentThepulseheatinginertgasfusion-infra-redabsorptionmethod

GB/T20123 Steelandiron—DeterminationoftotalcarbonandsulfurcontentInfraredabsorptionmethodaftercombustioninaninductionfurnace(routinemethod)

GB/T20124 Steelandiron—Determinationofnitrogencontent—Thermalconductimetricmethodafterfusioninacurrentofinsertgas(Routinemethod)

GB/T32818Metallurgicalequipment—Terminology

JB/T5000.15—2007 Heavymechanicalgeneraltechniquesandstandards—Part15:Non-destructiveinspectionofforgedsteel

YB/T153 Standarddiagramsformacrostructureanddefectinqualitycarbonstructuralsteelandalloystructuralsteelcontinuouscastingblank

Termsanddefinitions

ThetermsanddefinitionsdefinedinGB/T32818,GB/T5611andGB/T8541andlistedbelowapplytothisdocument.

3.1

alternating-currentelectricarcfurnace

completesetofequipmentforsmeltingbysupplyingalternatingcurrentfromthefurnacetransformertogenerateelectricarcbetweentheelectrodesandthecharge,thusmeltingthecharge.

[SOURCE:GB/T32818—2016,5.3.1,modified]

3.2

converter

metallurgicalfurnacewithtiltablefurnacebodyforblowingmoltenironandotherchargeintomoltensteel.Thefurnacebodyisacylindricaltank,whichcanberotatedaroundahorizontalaxisperpendiculartoitscenterlinetoperformvarioussmeltingoperationsandcompletemetallurgicalfunctionssuchasdecarburization,desulfurization,anddephosphorization.

[SOURCE:GB/T32818—2016,5.5.1]

3.3

ladle(heating)furnaceLF

devicecharacterizedbysubmergedarcheatinginreducingatmosphere,formingsyntheticslagandstirringbyblowingArfromunderneath,andwithgooddesulfurizationandalloyingfunctions.Whetheravacuumsystemisequippedisdeterminedbytheprocessneeds,anditisoftenoperatedintandemwiththeRH(doubletubevacuumcirculationdegassing),DH(vacuumliftingdegassingfordehydrogenation,deoxidizationanddenitrificationinsteel)orVD(vacuumdegassing)devicestorefinehighpurityalloysteel.

[SOURCE:GB/T32818—2016,5.6.10,modified]

3.4

vacuumdegasserVD

devicefordegassing,adjustingthecompositionofmoltensteel,homogenizingthetemperatureofmoltensteelandremovinginclusionsundertheconditionofvacuumandpressurereductionandwiththehelpofblowinginertgasintothemoltensteelfromthebottomoftheladletostirthemoltensteel(orsettinganelectromagneticstirrertostirthemoltensteel)

[SOURCE:GB/T32818—2016,5.6.3]

3.5

RH-vacuumdegasser

doublepipevacuumcirculationdegassingdevice.Itmainlyincludes:avacuumchamber,anairextractionsystem,avacuumchargingsystem,anelectrodeheatingsystem,avacuumchamberbakingsystem,avacuumchamberorladleliftingsystem,avacuumchamberreplacementsystem,theEICsystem,etc.

Note1toentry:Whiledegassing,insertthecirculatingflowpipe(riseranddowncomer)intothemoltensteel,enablethemoltensteeltoenterthevacuumchamberthroughtheriserbyvacuumdifferentialpressure,andblowinthedrivinggas(nitrogenorargon)atthesametime.Usethebubblepumpprincipletoleadthemoltensteeltocontinuouslycirculatefromtheladle,throughtheriser,thevacuumchamberandthedowncomerandbacktotheladle,andremovethegas(hydrogen)inthevacuumchamber.

[SOURCE:GB/T32818—2016,5.6.2,modified—Note1toentryhasbeenadded.]

3.6

continuouscasting

processinwhichmetaliscontinuouslypouredintoawater-cooledmetalmoldandsolidifiedintometalblanks

Note1toentry:Themolddeterminesthesectionshapeoftheprofileandisthelinkconnectingthesteelmakingandrolling.

[SOURCE:GB/T5611—2017,7.6.1—Note1toentryhasbeenmodified.]

3.7

diecasting

processinwhichsteelingotswithgoodsurface,pureinterioranddensestructureareformedaftersolidificationofthemoltensteelpouredintothecavitymold

3.8

riser

feederhead

headofthemoldcastingingotandelectroslagingotwithfunctionsoffeeding,collectingslag,exhausting,reducingingotsegregation,concentratinginclusionsandpurifying,etc

[SOURCE:GB/T5611—2017,5.3.34,modified]

3.9

gate

runninggate

jointofingotandingotmoldformedduringmoltenmetalcasting

3.10

electroslagremelting

methodofsmeltingthechargeagainusingtheresistanceheatgeneratedwhenanelectriccurrentpassesthroughthemoltenslag

Note1toentry:Thesteelingotafterelectroslagremeltinghashighpurity,lowsulfurcontent,lessnon-metallicinclusions,smoothsurface,clean,uniformanddensetexture,anduniformmetallographicstructureandchemicalcomposition.Itsas-castmechanicalpropertiescanreachorexceedtheindexesofforgingsmadeofthesamesteel.

3.11

basewad

partoftheelectrodeblankthatbeginstomeltduringelectroslagremelting

3.12

principlestrain

maindirectionofthemetaldeformationflowduringforging

3.13

forgingratio

methodofexpressingthedegreeofdeformationduringforging,whichisusuallyexpressedbythecross-sectionalarearatio,lengthratioorheightratiobeforeandafterdeformation

[SOURCE:GB/T8541—2012,5.1.39]

3.14

opendieforging

processwheredirectionofthegapbetweenthetwohalvesofthedieisperpendiculartothedirectionofthediemovement,andthegapdecreasescontinuouslyintheprocess

[SOURCE:GB/T8541—2012,5.2.1,modified]

3.15

closeddieforging

processwheredirectionofthegapbetweenthetwohalvesofthedieisparalleltothedirectionofthediemovement,andthesizeofthegapstaysunchangedintheprocess

[SOURCE:GB/T8541—2012,5.2.2,modified]

3.16

loosetoolingforging

processofproducingdieforgingswithmovablediesonfreeforgingequipment[SOURCE:GB/T8541—2012,5.2.17]

3.17

flatdieforgingfreeforging

processofobtainingforgingsofthedesiredgeometryandinternalqualityusingonlysimpleuniversaltoolsorbydirectlydeformingtheblankbetweentheupperandloweranvilsoftheforgingequipment

[SOURCE:GB/T8541—2012,5.1]

3.18

axialspecimen

sampletakennearthetoothandalongtheaxialdirectionofthepart(alsotheaxialdirectioninthecrystallizationprocessoftheingot,electroslagingot,andcontinuouscastingblank),asshowninFigure1b)

3.19

transversespecimen

sampletakennearthetoothandalongthediameterdirectionofthepartasshowninFigure1

3.20

tangentialspecimen

sampletakennearthetoothandalongthecircumferentialdirectionofthepart,asshowninFigure1

Ringparts

Shaftparts

Key:

axialspecimen,A

tangentialspecimen,T

transversespecimen,C

Figure1—Samplingdirectionformechanicalpropertiesofforgings

Classification

Accordingtotheoperatingconditions,operatingcharacteristicsandsmeltingrequirements,gearforgingsaredividedintothefollowingfourgroups:

GroupⅠ:applicabletopowerdispersiveEMUswithaspeednotlessthan200km/h,whicharecharacterizedwithhighrunningspeed,bettercontactfatiguepropertiesofmaterials,orfrequentstarting.

GroupⅡ:applicabletopowerlocomotives,passengerlocomotives,andheavy-dutyfreightlocomotivesofEMUswithaspeedrangingfrom160km/hto200km/h,whicharecharacterizedwithlargetractionforceandgoodbendingfatiguepropertiesofmaterials.

GroupⅢ:applicabletopowervehicleswithaspeednotgreaterthan160km/h,suchassubway,lightrailandothervehicles,whicharecharacterizedwithfrequentstartingandbraking,andgoodimpactresistanceofmaterials.

GroupⅣ:applicabletoengineeringvehiclessuchasthoseusedinrailrepairandrescue.

Smelting

Nameandchemicalcomposition

ThesuppliershallconductsmeltinganalysisoneachheatofsteelandtheanalysisresultsshallcomplywithprovisionsinTable1andTable2.

Whentheuserhasrequirementsforfinishedproductanalysis,thesuppliershallcarryoutfinishedproductanalysisoftheforgings,andtheallowabledeviationshallconformtotheprovisionsinGB/T222.

Table1—Steelnameandchemicalcomposition

Masspercent(%)

Steelname

Chemicalcomposition

C

Si

Mn

Cr

Ni

Mo

Cu

Ca

Ti

18Cr2Ni2MoH

0,15to0,21

0,17to0,37

0,45to0,65

1,50to1,80

1,40to1,70

0,25to0,35

≤0,10

≤0,0010

≤0,010

20CrMnMoH

0,17to0,23

0,17to0,37

0,90to1,20

1,10to1,40

≤0,30

0,20to0,30

20CrNi2MoH

0,17to0,23

0,20to0,35

0,40to0,70

0,35to0,65

1,60to2,00

0,20to0,30

20Cr2Ni4H

0,17to0,23

0,17to0,37

0,30to0,60

1,25to1,65

3,25to3,65

—

Table2—Sulfur,phosphorusandotherelements

Masspercent(%)

Forgingstype

Chemicalcompositiona.bNotgreaterthan

P

S

Al

H

O

N

GroupⅠ

0,015

0,005

0,025to0,050

0,00015

0,0015

0,007to0,012

GroupⅡ

0,020

0,010

0,00020

0,0020

GroupⅢ

0,020

0,010

0,00020

0,0020

GroupⅣ

0,025

0,015

0,00020

0,0025

aThesumofthefiveharmfulelementsofPb,Sn,Sb,BiandAsshallnotexceed0,035%.

bThealuminum-nitrogenratio(Al/N)forfinishedproductanalysisshallbecontrolledwithintherangefrom2,5to4,0.

Technicalrequirements

Technologicalprocess

Theprocessisasfollows:

Converteroralternating-currentelectricarcfurnacesmelting;

LFrefining;

VDorRHvacuumdegassing;

Continuouscastingordiecasting;

Electroslagremelting(ifnecessary).

Processrequirements

Alternating-currentelectricarcfurnaceorconvertersmelting

Deoxidizerisaddedduringthetappingprocessfromtheprimarysmeltingfurnace,andthedeoxidizationisprecededtoreducethedeoxidizationpressureandtheformationofinclusionsinthesubsequentprocess.

Thetappingportshallbeequippedwithaslidingplatedeviceforslagblocking(orpneumaticslagblockingdevice,etc.),toautomaticallyblocktheslagduringthetappingprocess,soastopreventthemoltensteelfrombeingpollutedbythetappingslag.

LFrefining

Thewholeprocessofwhiteslagoperationshallbecarriedout,andthediffusionanddeoxidizationshallbecontinuedtoensuregooddeoxidization,sothattheinclusionscanbefullyfloatedandadsorbedbytheslag.

Beforetheendofrefining,thecompositionshallbeadjustedtothecontrolrangetopreventtheadditionofalloyinthesubsequentprocessfromaffectingthepurityofmoltensteel.

Vacuumdegassing

RH(orVD)shallbeequippedwithhydrogendeterminationequipmenttoensurethatthehydrogencontentaftervacuumtreatmentmeetstherequirements.

Aftervacuumbreaking,calciumcontainingsubstancesshallnotbeusedtomodifythemoltensteel,andsufficientsoftblowingtimeshallbeguaranteedtopromotethefloatingofinclusions.

Continuouscasting

Electromagneticstirring,endstirringorsoftreduction1andotherequipmentandprocessesshallbeused.Thecrystallizershallbeequippedwithcontrolequipmenttokeeptheliquidlevelchangingsmoothly.

Thewholeprocessofpouringshallbeprotectedagainstoxidation.

Blankidentification

Eachcontinuouslycastblankshallbeindependentlyidentifiedtoensurethetraceabilityoftheproductionprocess.

Diecasting

Whenpouringtheingotbythebottompouringmethod2,theingotmoldandtherunnerbrickshallbecleanedbeforepouring,andgasprotectionmeasuresshallbetakenduringthepouringprocess.

Diecastingsteelingotsshallbemanagedasingotdiscs.

Electroslagremelting

Airtightnessprotectionshallbeprovidedintheprocesstoreducethedegreeofsuctionandalloyburningduringremelting.

Allslagshallbebakedathightemperaturetoremovecrystalwater;

Electrodemeltingrateshouldbe400kg/h-550kg/h(determinedaccordingtotheingottypeandworkingconditions);

Intheprocessofelectroslagremelting,theAl/NratioshallbecontrolledinaccordancewiththerequirementsinTable2;

EachheatofelectrodeblankandelectroslagingotheadandtailshallbesampledforcompositionanalysisandAlcontentburninglossanalysis.

Processofapplyingpressuretotheblankduringblankdischargingtoimprovethestructureoftheblanketc.

Ingotcastingcanbedividedintotheuppercastingmethodandthelowercastingmethod.Thelowercastingmethod,alsoknownasthebottomcastingmethod,referstothecastingprocessinwhichthemoltensteelpassesthroughthecenterconduit,therunnerbrickandthenisinjectedfromthebottomupwardtotheinsideofthesteelingotmold.

Forging

Forgingsclassification

Accordingtotheshapeoftheparts,forgingscanbedividedintothefollowingfourcategories:

Shaftforgings:theoverallshapeoftheforgingisasolidcylinder,andtheratiooflengthtodiameterisgreaterthan1,0,seeFigure2;

Discforgings:theoverallshapeoftheforgingisahollowroundcakewithaweb,theratiooflengthtodiameterislessthan1,0,andtheratioofoutsidediametertoinnerdiameterisgreaterthan1,5,seeFigure3;

Ringforgings:theoverallshapeoftheforgingisahollowroundcake,theratiooflengthtodiameterislessthan1,0,andtheratioofoutsidediametertoinnerdiameterislessthan1,5,seeFigure4;

Cylinderforgings:theoverallshapeoftheforgingisahollowcylinder,andtheratiooflengthtodiameterisgreaterthan1,0,seeFigure5.

Technologicalprocess

Accordingtotheshapeofdifferentparts,thefollowingprocessroutesshallbeselected:

Shaftforgings:breakingdown/unloading→heating→freeforging+opendieforging→postforgingheattreatment→(finishing→roughmachining→)inspection;

Discforgings:breakingdown/unloading→heating→freeforging+closeddieforging(oropendieforging)→postforgingheattreatment→(finishing→roughmachining→)inspection;

Ringforgings:breakingdown/unloading→heating→freeforging(includingcounterboring)+opendieforging→postforgingheattreatment→(finishing→roughmachining→)inspection;

Cylinderforgings:breakingdown/unloading→heating→freeforging(includingpunching)+opendieforging→postforgingheattreatment→(finishing→roughmachining→)inspection.

Processrequirements

Basicrequirementsareasfollows:

Forgingsareforgedfromrawmaterialssuchasdie-castingots,electroslagingots,continuouslycastblanks,forgingstock/materialsorrolledmaterials.Continuouslycastblanksshallnotbeusedforshaftparts.

Theriser,thegate,thebasewadetc.shallbecutoffduringtheforgingprocessaccordingtothetotalweightoftheingot.Forthedie-castingot,therisershallbecutoffnotlessthan14%(accountingforthetotalmass),andthegatenotlessthan6%(accountingforthetotalmass);fortheelectroslagingot,theriserendshallbecutoffnotlessthan8%(accountingforthetotalmass),andthebasewadendnotlessthan4%(accountingforthetotalmass).

Whenusingelectroslagsteelingotsanddie-castingots,theforgingratioofpartsshallnotbelessthan5;whenusingrolledmaterials,theforgingratioofpartsshallnotbelessthan3;whenusingcontinuouslycastblanks,theforgingratioofthepartsshallnotbelessthan7;forgingratiosarecalculatedandaccumulatedonlywhentheyareinthesamedeformationdirectionandthesamedeformationmode.

Forsmallbatchproducts,freeforging(suchasBWmethod,crossforgingmethod,etc.)maybeused;forlargebatchproducts,dieforging(loosetoolingforging,opendieforging,closeddieforging)shouldbeused;largeforgingsshallbeforgedonaforgingpresswithsufficientcapacitytoensuredeformationpenetrationanduniformstructure.

Eachstepinthetechnologicalprocessshallatleastmeetthefollowingrequirements:

Breakingdown:thesizeandweightoftheblankshallbedeterminedaccordingtotheproductspecification;

Heating:theinitialforgingtemperatureis1180℃to1240℃,andtheholdingtimeshallconformtoFormula(1);

Freeforging:deformation,punching,ringrolling,counterboring,upsettinganddrawingperformedaccordingtotherequirementsoftheworkpiece;

Dieforging:heatingtheblanktothespecifiedtemperatureandputtingitintothemoldtopressitintoashapeclosetothefinishedpart;

Postforgingheattreatment:selectingappropriatepostforgingheattreatmentprocessaccordingtodifferentsteeltypesandforgingsections.

tsd

(1)

where

t istheholdingtime,expressedinminutes(min);

s istheheatingcoefficient,generallyrangingfrom0,7to1,expressedinminutespermillimeter(min/mm);

d istheequivalentofblanks,expressedinmillimeters(mm).

Forgingproducts

Deliverystatus

Deliverystatusshallbeindicatedinproductdrawingsorspecialtechnicaldocuments.

TheheattreatmentsystemandhardnessrequirementsafterforgingshallmeettherequirementsinTable3.

Heattreatmenttemperature:

Normalizing:itshallbeheatedto900℃to960℃andfullyinsulated,anddifferentcoolingsystemsshallbeselectedaccordingtothesectionsize;

Tempering:hightemperaturetempering,withatemperatureof650℃to680℃,shallbeadopted.

Gearforgingsshallgenerallybesuppliedaftersurfacesandblastingorroughmachining.Otherrequirementsshouldbeagreeduponbytheuserandthesupplier.

Thehardnessdeviationofthesameforgingshallnotexceed40HBW.

Table3—Supplystatusandheattreatmentsystem

Steelname

Supplystatus

Brinellhardnessvalue

HBW

18Cr2Ni2MoH

Normalizing&tempering

≤229

20CrMnMoH

20CrNi2MoH

20Cr2Ni4H

Mechanicalpropertiesandsampling

Mechanicalproperties

Whensamplingintheprincipalstraindirectionoftheforgingbody,themechanicalpropertiesofthespecimenshallconformtoprovisionsinTable4.

Table4—Mechanicalpropertiesintheprincipalstraindirection

SteelName

Heattreatmentsystem

Mechanicalproperties

Specimendiameterc

mm

Quenching

Tempering

Tensilestrength

Rm

MPa

Yieldstrength

Rp0.2

MPa

Elongationafterfracture

A

%

Reductionofarea

Z

%

Impactabsorbedenergy

a,b

KU2

J

Quenching

temperature℃

Coolant

Temperingtemperature

℃

Coolant

First

quenching

Second

quenching

Notgreaterthan

18Cr2Ni2MoH

880

840

Oil

180

Water,

air

1180

980

12

55

60

25

20CrMnMoH

850

-

Oil

180

Water,

air

1180

885

10

45

55

25

20CrNi2MoH

880

810

Oil

180

Water,

air

980

770

13

45

63

25

20Cr2Ni4H

880

780

Oil

180

Water,

air

1180

1080

10

45

63

25

Theallowableadjustmentrangeofheattreatmenttemperaturelistedinthetableis:±15℃forquenchingand±20℃for

low-temperaturetempering.

aWhentherearemorethantwotestmethodsforimpactabsorbedenergy,eitheronecanbeselected.

bWhenthreeimpactsamplesaretakenfromaforging,thesinglevalueofoneofthesamplesisallowedtobelowerthanthespecifiedvalue,butshallnotbelowerthan70%ofthespecifiedvalue,andthearithmeticmeanofthesinglevaluesofthethreesamplesshallnotbelowerthanthespecifiedvalue.

cWhentheforgingsectionissmallerthanthesizeoftheheat-treatedsample,theactualsectionsizeoftheforgingcanbetaken.

Bodysampling

General

Thebodysamplingisdividedintotwotypes:mechanicalpropertyspecimensandtypespecimens.Therequirementsareasfollows:

Mechanicalpropertyspecimens:fortheinspectionofthesamebatchofproducts,selectasingleproductbodyforsampling,includingonetensilespecimenandthreeU-notchimpactspecimens;

Typetestspecimens:forthefirstpieceofnewproducts,thebodysamplingshallincludetensilespecimensintwodirections(axialandtangential)andimpactspeci