2024年4月22日发(作者：google香港)

Designation:E1457

−

13

StandardTestMethodfor

MeasurementofCreepCrackGrowthTimesandRatesin

Metals

1

ThisstandardisissuedunderthefixeddesignationE1457;thenumberimmediatelyfollowingthedesignationindicatestheyearof

originaladoptionor,inthecaseofrevision,rinparenthesesindicatestheyearoflastreapproval.A

superscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.

1.1Thistestmethodcoversthedeterminationoftimefora

creepcracktogrowoninitialload(CCI)anditssubsequent

creepcrackgrowth(CCG)ratesinmetalsatelevatedtempera-

turesusingpre-crackedspecimenssubjectedtoelevatedtem-

testsarevalidatedforeitherbasematerial(homogenous

properties)ormixedbase/weldmaterialwithinhomogeneous

thetime(CCI),

t

0.2

toaninitialcrackextensionδa

i

=0.2mmfromtheonsetof

firstappliedforceandCCGrate,a˙orda/dtareexpressedin

termsofthemagnitudeofcreepcrackgrowthrelating

parameters,C**definedasthesteadystate

determinationofthecracktipstressesderivedinprincipalfrom

C*(t)andC

t

(1-14).

2

Thecrackgrowthderivedinthismanner

isidentifiedasamaterialpropertywhichcanbeusedin

modelingandlifeassessmentmethods(15-25).

1.1.1Thechoiceofthecrackgrowthcorrelatingparameter

C*,C*(t),C

t

,orKdependsonthematerialcreepproperties,

esofmaterial

behavioraregenerallyobservedduringcreepcrackgrowth

tests;creep-ductile(

1-14)andcreep-brittle(26-37).Increep

ductilematerials,wherecreepstrainsdominateandcreepcrack

growthisaccompaniedbysubstantialtime-dependentcreep

strainsatthecracktip,thecrackgrowthrateiscorrelatedby

thesteadystatedefinitionsofC

t

orC*(t),definedasC*(see

1.1.4).Increep-brittlematerials,creepcrackgrowthoccursat

uently,thetime-dependentcreep

strainsarecomparabletoordominatedbyaccompanying

uchsteadystate

creep-brittleconditions,C

t

orKcouldbechosenasthe

correlatingparameter(8-14).

1.1.2Inanyonetest,tworegionsofcrackgrowthbehavior

maybepresent(9,10).Theinitialtransientregionwhere

ThistestmethodisunderthejurisdictionofASTMCommitteeE08onFatigue

andFractureandisthedirectresponsibilityofSubcommitteeE08.06onCrack

GrowthBehavior.

CurrenteditionapprovedFeb.1,ally

eviouseditionapprovedin2000asE1457–07

ε4

.DOI:

10.1520/E1457-13.

2

Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof

thisstandard.

1

elasticstrainsdominateandcreepdamagedevelopsandinthe

steadystateregionwherecrackgrowsproportionallytotime.

Steady-statecreepcrackgrowthratebehavioriscoveredby

tionspecificrecommendationsaremade

in

11.7astohowthetransientregionshouldbetreatedinterms

steadystate,aunique

correlationexistsbetweenda/dtandtheappropriatecrack

growthraterelatingparameter.

1.1.3Increepductilematerials,extensivecreepoccurs

whentheentireun-crackedligamentundergoescreepdefor-

nditionsaredistinctfromtheconditionsof

small-scalecreepandtransitioncreep(

1-7).Inthecaseof

extensivecreep,theregiondominatedbycreepdeformationis

significantinsizeincomparisontoboththecracklengthand

l-scale-creeponlyasmall

regionoftheun-crackedligamentlocaltothecracktip

experiencescreepdeformation.

1.1.4Thecreepcrackgrowthrateintheextensivecreep

regioniscorrelatedbytheC*(t)-

t

parameter

correlatesthecreepcrackgrowthrateinthesmall-scalecreep

andthetransitioncreepregionsandreduces,bydefinition,to

C*(t)intheextensivecreepregion(

5).Henceinthisdocument

thedefinitionC*isusedastherelevantparameterinthesteady

stateextensivecreepregimewhereasC*(t)and/orC

t

arethe

parameterswhichdescribetheinstantaneousstressstatefrom

thesmallscalecreep,transientandthesteadystateregimesin

ommendedfunctionstoderiveC*forthe

differentgeometriesisshownin

AnnexA1isdescribedin

AnnexA2.

1.1.5Anengineeringdefinitionofaninitialcrackextension

sizeδa

i

isusedinordertoquantifytheinitialperiodofcrack

een

shown(

38-40)thatthisinitialperiodwhichexistsatthestartof

thisearlyperiodthecracktipundergoesdamagedevelopment

aswellasredistributionofstressespriorreachingsteadystate.

Recommendationismadetocorrelatethisinitialcrackgrowth

perioddefinedast

0.2

atδa

i

=0.2mmwiththesteadystateC*

whenthecracktipisunderextensivecreepandwithKfor

uesforC*andKshouldbe

calculatedatthefinalspecifiedcracksizedefinedasa

o

+δa

i

wherea

o

initialsizeofthestartercrack.

Copyright©ASTMInternational,100BarrHarborDrive,POBoxC700,WestConshohocken,States

Copyright by ASTM Int'l (all rights reserved); Tue Jun 10 22:37:10 EDT 2014

1

Downloaded/printed by

Shanghai Jiaotong Univ (Shanghai Jiaotong Univ) pursuant to License Agreement. No further reproductions authorized.

E1457−13

ingthe

tensileresidualstresseffectintoaccountwillproduceC*

valueslowerthanexpectedeffectivelyproducingafaster

crackingratewithrespecttoaconstantC*.Thiswouldproduce

conservativeestimatesforlifeassessmentandnon-

ldalsobe

notedthatdistortionduringspecimenmachiningcanalso

indicatethepresenceofresidualstresses.

1.1.9Stressrelaxationoftheresidualstressesduetocreep

andcrackextensionshouldalsobetakenintoconsideration.

Nospecificallowanceisincludedinthisstandardfordealing

rthemethodofcalculatingC*

presentedinthisdocumentwhichusedthespecimen’screep

displacementratetoestimateC*inherentlytakesintoaccount

theeffectsdescribedaboveasreflectedbytheinstantaneous

rextracaution

shouldstillbeobservedwiththeanalysisofthesetypesoftests

asthecorrelatingparametersKandC*shownin

AnnexA2

eventhoughitisexpectedthatstressrelaxationathigh

temperaturescouldinpartnegatetheeffectsduetoresidual

4presentsthecorrectcalculationsneededto

deriveJandC*forweldmenttestswhereamiss-matchfactor

needstobetakenintoaccount.

1.1.10Specimenconfigurationsandsizesotherthanthose

listedinTableA1.1whicharetestedunderconstantforcewill

donebycompar-

ingdatafromrecommendedtestconfiheless,

useofothergeometriesareapplicablebythismethodprovided

dataarecomparedtodataobtainedfromstandardspecimens

(asidentifiedinTableA1.1)andtheappropriatecorrelating

parametershavebeenvalidated.

1.2ThevaluesstatedinSIunitsaretoberegardedasthe

h-poundunitsgiveninparenthesesarefor

informationonly.

1.3Thisstandarddoesnotpurporttoaddressallofthe

safetyconcerns,ifany,e

responsibilityoftheuserofthisstandardtoestablishappro-

priatesafetyandhealthpracticesanddeterminetheapplica-

bilityofregulatorylimitationspriortouse.

ncedDocuments

2.1ASTMStandards:

3

E4PracticesforForceVerificationofTestingMachines

E74PracticeofCalibrationofForce-MeasuringInstruments

forVerifyingtheForceIndicationofTestingMachines

E83PracticeforVerificationandClassificationofExten-

someterSystems

E139TestMethodsforConductingCreep,Creep-Rupture,

andStress-RuptureTestsofMetallicMaterials

E220TestMethodforCalibrationofThermocouplesBy

ComparisonTechniques

E399TestMethodforLinear-ElasticPlane-StrainFracture

ToughnessK

Ic

ofMetallicMaterials

ForreferencedASTMstandards,visittheASTMwebsite,,or

contactASTMCustomerServiceatservice@ualBookofASTM

Standardsvolumeinformation,refertothestandard’sDocumentSummarypageon

theASTMwebsite.

3

1.1.6TherecommendedspecimensforCCIandCCGtest-

ingisthestandardcompacttensionspecimenC(T)(seeFig.

A1.1

)whichispin-loadedintensionunderconstantloading

vissetupisshownin

Fig.A1.2(see7.2.1for

details).Additionalgeometrieswhicharevalidfortestingin

thisprocedureareshownin

retheC-ringin

tensionCS(T),middletensionM(T),singlenotchtension

SEN(T),singlenotchbendSEN(B),anddoubleedgenotch

bendtensionDEN(T).In

Fig.A1.3,thespecimens’side-

grooving-positionformeasuringdisplacementattheforce-line

(FLD)crackmouthopeningdisplacement(CMOD)andalso

andpositionsforthepotentialdrop(PD)inputandoutputleads

endedloadingforthetensionspecimensis

figurations,sizerangeandinitialcrack

sizeandtheirextentofside-groovingaregivenin

TableA1.1

ofAnnexA1,(40-44).Specimenselectionwillbediscussedin

5.9.

1.1.7Thestate-of-stressatthecracktipmayhavean

influenceonthecreepcrackgrowthbehaviorandcancause

ensize,

geometry,cracklength,testdurationandcreeppropertieswill

affectthestate-of-stressatthecracktipandareimportant

mendedsize

rangeoftestspecimensandtheirside-groovingaregivenin

eenshownthatforthisrange

thecrackingratesdonotvaryforarangeofmaterialsand

loadingconditions(

40-44).Suggestingthatthelevelof

constraint,fortherelativelyshorttermtestdurations(lessthan

oneyear),doesnotvarywithintherangeofnormaldatascatter

ritisrecom-

mendedthat,withinthelimitationsimposedonthelaboratory,

thattestsareperformedondifferentgeometries,specimensize,

asesacomparisonof

thedatafromtheaboveshouldbemadebytestingthestandard

C(T)earthatincreased

confidenceinthematerialscrackgrowthdatacanbeproduced

bytestingawiderrangeofspecimentypesandconditionsas

describedabove.

1.1.8Materialinhomogeneities,residualstressesandmate-

rialdegradationattemperature,specimengeometryandlow-

forcelongdurationtests(mainlygreaterthatoneyear)can

influencetherateofcrackinitiationandgrowthproperties

(

39-47).Incaseswhereresidualstressesexist,theeffectcanbe

significantwhentestspecimensaretakenfrommaterialthat

characteristicallyembodiesresidualstressfieldsorthedam-

agedmaterial,mpleweldments,orthickcast,

forged,extruded,components,plasticallybentcomponentsand

complexcomponentshapes,oracombinationthereof,where

enstakenfromsuch

componentthatcontainresidualstressesmaylikewisecontain

residualstresseswhichmayhavealteredintheirextentand

tionofspeci-

mensinitselfpartiallyrelievesandredistributestheresidual

stresspattern;however,theremainingmagnitudecouldstill

causesignificanteffectsintheensuingtestunlesspost-weld

heattreatment(PWHT)iseresidual

stressesaresuperimposedonappliedstressandresultsin

crack-tipstressintensitythatisdifferentfromthatbasedsolely

Copyright by ASTM Int'l (all rights reserved); Tue Jun 10 22:37:10 EDT 2014

2

Downloaded/printed by

Shanghai Jiaotong Univ (Shanghai Jiaotong Univ) pursuant to License Agreement. No further reproductions authorized.