ASTM E399-2006e2 780 Standard Test Method for Linear-Elastic Plane-Strain Fracture Toughness K Ic of Metallic Materials.pdf

1、Designation: E 399 06e2Standard Test Method forLinear-Elastic Plane-Strain Fracture Toughness KIcofMetallic Materials1This standard is issued under the fixed designation E 399; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye

2、ar of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.e1NOTEEq A3.4 was editorially corrected in

3、 April 2007.e2NOTEFigure A4.1 was editorially corrected in April 2008.1. Scope1.1 This test method covers the determination of fracturetoughness (KIc) of metallic materials under predominantlylinear-elastic, plane-strain conditions using fatigue precrackedspecimens having a thickness of 1.6 mm (0.06

4、3 in.) or greater2subjected to slowly, or in special (elective) cases rapidly,increasing crack-displacement force. Details of test apparatus,specimen configuration, and experimental procedure are givenin the Annexes.NOTE 1Plane-strain fracture toughness tests of thinner materials thatare sufficientl

5、y brittle (see 7.1) can be made using other types ofspecimens (1).3There is no standard test method for such thin materials.1.2 This test method is divided into two parts. The first partgives general recommendations and requirements for KIctesting. The second part consists of Annexes that give speci

6、ficinformation on displacement gage and loading fixture design,special requirements for individual specimen configurations,and detailed procedures for fatigue precracking. Additionalannexes are provided that give specific procedures for beryl-lium and rapid-force testing.1.3 General information and

7、requirements common to allspecimen configurations:SectionReferenced Documents 2Terminology 3Stress-Intensity Factor 3.1.1Plane-Strain Fracture Toughness 3.1.2Crack Plane Orientation 3.1.3SectionSummary of Test Method 4Significance and Use 5Significance 5.1Precautions 5.1.1-5.1.5Practical Application

8、s 5.2Apparatus (see also 1.4) 6Tension Machine 6.1Fatigue Machine 6.2Loading Fixtures 6.3Displacement Gage, Measurement 6.4Specimen Size, Configurations, and Preparation (seealso 1.5)7Specimen Size Estimates 7.1Standard and Alternative Specimen Configurations 7.2Fatigue Crack Starter Notches 7.3.1Fa

9、tigue Precracking (see also 1.6) 7.3.2Crack Extension Beyond Starter Notch 7.3.2.2General Procedure 8Specimen MeasurementsThickness 8.2.1Width 8.2.2Crack Size 8.2.3Crack Plane Angle 8.2.4Specimen TestingLoading Rate 8.3Test Record 8.4Calculation and Interpretation of Results 9Test Record Analysis 9.

10、1Pmax/PQValidity Requirement 9.1.3Specimen Size Validity Requirements 9.1.4Reporting 10Precision and Bias 111.4 Specific requirements related to test apparatus:Double-Cantilever Displacement Gage Annex A1Testing Fixtures Annex A2Bend Specimen Loading Fixture Annex A2.1Compact Specimen Loading Clevis

11、 Annex A2.21.5 Specific requirements related to individual specimenconfigurations:Bend Specimen SE(B) Annex A3Compact Specimen C(T) Annex A4Disk-Shaped Compact Specimen DC(T) Annex A5Arc-Shaped Tension Specimen A(T) Annex A6Arc-Shaped Bend Specimen A(B) Annex A71This test method is under the jurisdi

12、ction of ASTM Committee E08 on Fatigueand Fracture and is the direct responsibility of Subcommittee E08.07 on FractureMechanics.Current edition approved Dec. 15, 2006. Published February 2007. Originallyapproved in 1970. Last previous edition approved in 2005 as E 399 05.2For additional information

13、relating to the fracture toughness testing of alumi-inum alloys, see Practice B 645.3The boldface numbers in parentheses refer to the list of references at the end ofthis standard.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.1.6 S

14、pecific requirements related to special test procedures:Fatigue Precracking KIc Specimens Annex A8Hot-Pressed Beryllium Testing Annex A9Rapid-Force Testing Annex A101.7 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.8 This s

15、tandard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.

16、1 ASTM Standards:4B 909 Guide for Plane Strain Fracture Toughness Testing ofNon-Stress Relieved Aluminum ProductsB 645 Practice for Plane-Strain Fracture Toughness Testingof Aluminum AlloysE4 Practices for Force Verification of Testing MachinesE8 Test Methods for Tension Testing of Metallic Material

17、sE 337 Test Method for Measuring Humidity with a Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures)E 456 Terminology Relating to Quality and StatisticsE 1820 Test Method for Measurement of Fracture Tough-nessE 1823 Terminology Relating to Fatigue and Fracture Test-ingE 1921 Test Meth

18、od for Determination of Reference Tem-perature, To, for Ferritic Steels in the Transition Range3. Terminology3.1 Definitions:Terminology E 1823 is applicable to this testmethod:3.1.1 stress-intensity factor, K, KI,KII,KIIIFL3/2magnitude of the ideal-crack-tip stress field (a stress-fieldsingularity)

19、, for a particular mode of crack displacement, in ahomogeneous, linear-elastic body.3.1.1.1 K is a function of applied force and test specimensize, geometry, and crack size, and has the dimensions of forcetimes length-3/2.3.1.1.2 Values of K for modes I, II, and III are given as:KI5limr0syy2pr!1/2#

20、(1)KII5limr0txy2pr!1/2# (2)KIII5limr0tyz2pr!1/2# (3)where r is the distance directly forward from the crack tip tothe location where the significant stress is calculated.3.1.2 plane-strain fracture toughness, KIcFL-3/2 thecrack-extension resistance under conditions of crack-tip planestrain in Mode I

21、 for slow rates of loading under predominantlylinear-elastic conditions and negligible plastic-zone adjust-ment. The stress intensity factor, KIc, is measured using theoperational procedure (and satisfying all of the validity require-ments) specified in Test Method E 399, that provides for themeasur

22、ement of crack-extension resistance at the onset (2% orless) of crack extension and provides operational definitions ofcrack-tip sharpness, onset of crack extension, and crack-tipplane strain.3.1.2.1 See also definitions of crack-extension resistance,crack-tip plane strain, and mode in Terminology E

23、 1823.3.1.3 crack plane orientationidentification of the planeand direction of crack extension in relation to the characteristicdirections of the product. A hyphenated code defined inTerminology E 1823 is used wherein the letter(s) preceding thehyphen represents the direction normal to the crack pla

24、ne andthe letter(s) following the hyphen represents the anticipateddirection of crack extension (see Fig. 1).3.1.3.1 Wrought Productsthe fracture toughness ofwrought material depends on, among other factors, the orien-tation and propagation direction of the crack in relation to thematerials anisotro

25、py, which depends, in turn, on the principaldirections of mechanical working and grain flow. Orientationof the crack plane shall be identified wherever possible. Inaddition, product form shall be identified (for example,straight-rolled plate, cross-rolled plate, pancake forging, and soforth) along w

26、ith material condition (for example, annealed,solution treated plus aged, and so forth). The user shall bereferred to product specifications for detailed processing infor-mation.3.1.3.2 For rectangular sections, the reference directions areidentified as in Fig. 1(a) and Fig. 1(b), which give example

27、s forrolled plate. The same system is used for sheet, extrusions, andforgings with nonsymmetrical grain flow.L = direction of principal deformation (maximum grain flow)T = direction of least deformationS = third orthogonal direction3.1.3.3 Using the two-letter code, the first letter designatesthe di

28、rection normal to the crack plane, and the second letterthe expected direction of crack propagation. For example, inFig. 1(a), the T-L specimen fracture plane normal is in thewidth direction of a plate and the expected direction of crackpropagation is coincident with the direction of maximum grainfl

29、ow (or longitudinal) direction of the plate.3.1.3.4 For specimens tilted in respect to two of the refer-ence axes as in Fig. 1(b), crack plane orientation is identifiedby a three-letter code. The designation L-TS, for example,indicates the crack plane to be perpendicular to the principaldeformation

30、(L) direction, and the expected fracture directionto be intermediate between T and S. The designation TS-Lmeans that the crack plane is perpendicular to a directionintermediate between T and S, and the expected fracturedirection is in the L direction.3.1.3.5 For cylindrical sections with principal d

31、eformationparallel to the longitudinal axis of the cylinder, the referencedirections are identified as in Fig. 1(c), which depicts a drawn4For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume

32、information, refer to the standards Document Summary page onthe ASTM website.E39906e22(a) Rectangular SectionsSpecimens Aligned with Reference Directions(b) Rectangular SectionsSpecimens Not Aligned with Reference Directions(c) Cylindrical Bars and TubesL = direction of maximum grain flowR = radial

33、directionC = circumferential or tangential directionFIG. 1 Crack Plane IdentificationE39906e23bar. The same system is useful for extrusions or forged partshaving circular cross section.L = direction of maximum grain flowR = radial directionC = circumferential or tangential direction3.1.3.6 In the ca

34、se of complex structural shapes, where thegrain flow is not uniform, specimen location and crack planeorientation shall reference component geometry and be notedon component drawings.3.1.3.7 Non-Wrought Productsfor non-wrought products,specimen location and crack plane orientation shall be definedon

35、 the part drawing.The result of a fracture toughness test froma non-wrought product shall not carry an orientation designa-tion.3.1.3.8 Discussionwhen products are to be compared onthe basis of fracture toughness, it is essential that specimenlocation and orientation with respect to product characte

36、risticdirections be comparable and that the results not be generalizedbeyond these limits.3.2 Definitions of Terms Specific to This Standard:3.2.1 crack mouth opening displacement (CMOD), VmLcomponent of clip gage displacement taken at the crackstarter-notch mouth.3.2.2 stress-intensity factor rate,

37、 K(FL-3/2t-1)change instress-intensity factor, K, per unit time.4. Summary of Test Method4.1 This test method covers the determination of the plane-strain fracture toughness (KIc) of metallic materials byincreasing-force tests of fatigue precracked specimens. Force isapplied either in tension or thr

38、ee-point bending. Details of thetest specimens and experimental procedures are given in theAnnexes. Force versus crack-mouth opening displacement(CMOD) is recorded either autographically or digitally. Theforce at a 5 % secant offset from the initial slope (correspond-ing to about 2.0 % apparent crac

39、k extension) is established bya specified deviation from the linear portion of the record (1).The value of KIcis calculated from this force using equationsthat have been established by elastic stress analysis of thespecimen configurations specified in this test method. Thevalidity of the KIcvalue de

40、termined by this test methoddepends upon the establishment of a sharp-crack condition atthe tip of the fatigue crack in a specimen having a size adequateto ensure predominantly linear-elastic, plane-strain conditions.To establish the suitable crack-tip condition, the stress-intensity factor level at

41、 which specimen fatigue precracking isconducted is limited to a relatively low value.4.2 The specimen size required for test validity increases asthe square of the materials toughness-to-yield strength ratio.Therefore a range of proportional specimens is provided.5. Significance and Use5.1 The prope

42、rty KIcdetermined by this test method char-acterizes the resistance of a material to fracture in a neutralenvironment in the presence of a sharp crack under essentiallylinear-elastic stress and severe tensile constraint, such that (1)the state of stress near the crack front approaches tritensileplan

43、e strain, and (2) the crack-tip plastic zone is smallcompared to the crack size, specimen thickness, and ligamentahead of the crack.5.1.1 Variation in the value of KIccan be expected withinthe allowable range of specimen proportions, a/W and W/B. KIcmay also be expected to rise with increasing ligam

44、ent size.Notwithstanding these variations, however, KIcis believed torepresent a lower limiting value of fracture toughness (for 2 %apparent crack extension) in the environment and at the speedand temperature of the test.5.1.2 Lower values of KIccan be obtained for materials thatfail by cleavage fra

45、cture; for example, ferritic steels in theductile-to-brittle transition region or below, where the crackfront length affects the measurement in a stochastic mannerindependent of crack front constraint. The present test methoddoes not apply to such materials and the user is referred to TestMethod E 1

46、921 and E 1820 . Likewise this test method doesnot apply to high toughness or high tearing-resistance materialswhose failure is accompanied by appreciable amounts ofplasticity. Guidance on testing elastic-plastic materials is givenin Test Method E 1820.5.1.3 The value of KIcobtained by this test met

47、hod may beused to estimate the relation between failure stress and cracksize for a material in service wherein the conditions of highconstraint described above would be expected. Backgroundinformation concerning the basis for development of this testmethod in terms of linear elastic fracture mechani

48、cs may befound in Refs (1) and (3).5.1.4 Cyclic forces can cause crack extension at KIvaluesless than KIc. Crack extension under cyclic or sustained forces(as by stress corrosion cracking or creep crack growth) can beinfluenced by temperature and environment. Therefore, whenKIcis applied to the desi

49、gn of service components, differencesbetween laboratory test and field conditions shall be consid-ered.5.1.5 Plane-strain fracture toughness testing is unusual inthat there can be no advance assurance that a valid KIcwill bedetermined in a particular test. Therefore, compliance with thespecified validity criteria of this test method is essential.5.1.6 Residual stresses can adversely affect the indicatedKQand KIcvalues. The effect can be especially significant forspecimens removed from as-heat treated or otherwise non-stress relieved stock, from weldmen