ASTM E399-2009 6250 Standard Test Method for Linear-Elastic Plane-Strain Fracture Toughness K Ic of Metallic Materials.pdf

1、Designation: E 399 09Standard 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 year

2、 of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method covers the deter

3、mination of fracturetoughness (KIc) of metallic materials under predominantlylinear-elastic, plane-strain conditions using fatigue precrackedspecimens having a thickness of 1.6 mm (0.063 in.) or greater2subjected to slowly, or in special (elective) cases rapidly,increasing crack-displacement force.

4、Details of test apparatus,specimen configuration, and experimental procedure are givenin the Annexes.NOTE 1Plane-strain fracture toughness tests of thinner materials thatare sufficiently brittle (see 7.1) can be made using other types ofspecimens (1).3There is no standard test method for such thin m

5、aterials.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 specificinformation on displacement gage and loading fixture design,special requirements for individual specimen configu

6、rations,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 requirements common to allspecimen configurations:SectionReferenced Documents 2Terminology 3Stress-Intensity Factor

7、 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 Applications 5.2Apparatus (see also 1.4) 6Tension Machine 6.1Fatigue Machine 6.2Loading Fixtures 6.3Displacement Gage, Measure

8、ment 6.4Specimen Size, Configurations, and Preparation (seealso 1.5)7Specimen Size Estimates 7.1Standard and Alternative Specimen Configurations 7.2Fatigue Crack Starter Notches 7.3.1Fatigue Precracking (see also 1.6) 7.3.2Crack Extension Beyond Starter Notch 7.3.2.2General Procedure 8Specimen Measu

9、rementsThickness 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 9.1Pmax/PQValidity Requirement 9.1.3Specimen Size Validity Requirements 9.1.4Reporting 10Precision and Bias 111.4 Spe

10、cific requirements related to test apparatus:Double-Cantilever Displacement Gage Annex A1Testing Fixtures Annex A2Bend Specimen Loading Fixture Annex A2.1Compact Specimen Loading Clevis Annex A2.21.5 Specific requirements related to individual specimenconfigurations:Bend Specimen SE(B) Annex A3Compa

11、ct 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 jurisdiction of ASTM Committee E08 on Fatigueand Fracture and is the direct responsibility of Subcommittee E08.07 on Fract

12、ureMechanics.Current edition approved July 1, 2009. Published August 2009. Originallyapproved in 1970. Last previous edition approved in 2008 as E 399 08.2For additional information relating to the fracture toughness testing of alumiinum alloys, see Practice B 645.3The boldface numbers in parenthese

13、s 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 Specific requirements related to special test procedures:Fatigue Precracking KIc Specimens Annex A8Hot-Pressed Beryllium

14、 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 standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility

15、 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 Documents2.1 ASTM Standards:4B 909 Guide for Plane Strain Fracture Toughness Testing ofNon-Stress Relieved Aluminum ProductsB 645

16、Practice for Linear-Elastic PlaneStrain FractureToughness Testing of Aluminum AlloysE4 Practices for Force Verification of Testing MachinesE 8/E 8M Test Methods for Tension Testing of MetallicMaterialsE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 337 Test Method for Mea

17、suring Humidity with a Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures)E 456 Terminology Relating to Quality and StatisticsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 1820 Test Method for Measurement of Fracture Tough-nessE 182

18、3 Terminology Relating to Fatigue and Fracture Test-ingE 1921 Test Method 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,KIIIFL3/2ma

19、gnitude of the ideal-crack-tip stress field (a stress-fieldsingularity), 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

20、 Values of K for modes I, II, and III are given as:KI5limr0syy2pr!1/2# (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-e

21、xtension resistance under conditions of crack-tip planestrain in Mode I 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 req

22、uire-ments) specified in Test Method E 399, that provides for themeasurement 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

23、-extension resistance,crack-tip plane strain, and mode in Terminology E 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(

24、s) preceding thehyphen represents the direction normal to the crack plane 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

25、propagation direction of the crack in relation to thematerials anisotropy, 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-

26、rolled plate, cross-rolled plate, pancake forging, and soforth) along with 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 dir

27、ections areidentified as in Fig. 1(a) and Fig. 1(b), which give examples 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 direct

28、ion3.1.3.3 Using the two-letter code, the first letter designatesthe direction 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

29、of crackpropagation is coincident with the direction of maximum grainflow (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,ind

30、icates the crack plane to be perpendicular to the principaldeformation (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 direction4For referenced ASTM standards, visit the ASTM website, www.astm.

31、org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.E399092(a) Rectangular SectionsSpecimens Aligned with Reference Directions(b) Rectangular SectionsSpecimens Not Aligned with R

32、eference Directions(c) Cylindrical Bars and TubesL = direction of maximum grain flowR = radial directionC = circumferential or tangential directionFIG. 1 Crack Plane IdentificationE399093intermediate between T and S, and the expected fracturedirection is in the L direction.3.1.3.5 For cylindrical se

33、ctions, where grain flow can be inthe longitudinal, radial or circumferential direction, specimenlocation and crack plane orientation shall reference originalcylindrical section geometry such that the Ldirection is alwaysthe axial direction for the L-R-C system, as indicated in Fig.1(c), regardless

34、of the maximum grain flow. Note that this is ageometry based system. As such, the direction of maximumgrain flow shall be reported when the direction is known.NOTE 2The same system is useful for extruded or forged parts havingcircular cross section. In most cases the L direction corresponds to thedi

35、rection of maximum grain flow, but some products such as pancake,disk, or ring forgings can have the R or C directions correspond to thedirection of maximum grain flow, depending on the manufacturingmethod.L = axial directionR = radial directionC = circumferential or tangential direction3.1.3.6 In t

36、he case of complex structural shapes, where thegrain flow is not uniform, specimen location and crack planeorientation shall reference host product form geometry and benoted on component drawings.3.1.3.7 Non-Wrought Productsfor non-wrought products,specimen location and crack plane orientation shall

37、 be definedon 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 pro

38、duct characteristicdirections 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

39、 factor rate, 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 t

40、ension or three-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 %

41、apparent crack 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 th

42、e KIcvalue determined 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 fa

43、ctor level at 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 Use

44、5.1 The property 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 t

45、ritensileplane 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 inc

46、reasing ligament 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

47、 cleavage fracture; 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 T

48、estMethod E 1921 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

49、this test method 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 mechanics 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