1、Designation: E399 122Standard Test Method forLinear-Elastic Plane-Strain Fracture Toughness KIcofMetallic Materials1This standard is issued under the fixed designation E399; 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.1NOTE3.1.3 was editorially revised in May 2013
3、.2NOTENote 2 of Fig. A2.2 was editorially revised in October 2013.1. 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 (0.063 in
4、.) 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 sufficiently br
5、ittle (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 specifici
6、nformation 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 requ
7、irements common to allspecimen configurations:SectionReferenced Documents 2Terminology 3Stress-Intensity Factor 3.1.1Plane-Strain Fracture Toughness 3.1.2Crack Plane Orientation 3.1.4SectionSummary of Test Method 4Significance and Use 5Significance 5.1Precautions 5.1.1 5.1.5Practical Applications 5.
8、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 7.3.1Fatigu
9、e 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 9.1Pma
10、x/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 Ann
11、ex 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 jurisdictio
12、n of ASTM Committee E08 on Fatigueand Fracture and is the direct responsibility of Subcommittee E08.07 on FractureMechanics.Current edition approved Nov. 15, 2012. Published January 2013. Originallyapproved in 1970. Last previous edition approved in 2009 as E399 092. DOI:10.1520/E0399-12E02.2For add
13、itional information relating to the fracture toughness testing of alumiinum alloys, see Practice B645.3The boldface numbers in parentheses refer to the list of references at the end ofthis standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Un
14、ited States11.6 Specific 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 informati
15、ononly.1.8 This standard 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. Refer
16、enced Documents2.1 ASTM Standards:4B909 Guide for Plane Strain Fracture Toughness Testing ofNon-Stress Relieved Aluminum ProductsB645 Practice for Linear-Elastic PlaneStrain FractureToughness Testing of Aluminum AlloysE4 Practices for Force Verification of Testing MachinesE8/E8M Test Methods for Ten
17、sion Testing of Metallic Ma-terialsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE337 Test Method for Measuring Humidity with a Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures)E456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting
18、 an Interlaboratory Study toDetermine the Precision of a Test MethodE1820 Test Method for Measurement of Fracture ToughnessE1823 Terminology Relating to Fatigue and Fracture TestingE1921 Test Method for Determination of ReferenceTemperature, To, for Ferritic Steels in the TransitionRange3. Terminolo
19、gy3.1 Definitions:Terminology E1823 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), for a particular mode of crack displacement, in ahomogeneous, linear-elastic body.3.1.1.1 K is a function
20、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:KI5limr0yy2r!1/2# (1)KII5limr0xy2r!1/2# (2)KIII5limr0yz2r!1/2# (3)where r is the distance directly forward from the crack tip to
21、the location where the significant stress is calculated.3.1.2 plane-strain fracture toughness, KIcFL-3/2thecrack-extension 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. Th
22、e stress intensity factor, KIc, is measured using theoperational procedure (and satisfying all of the validity require-ments) specified in Test Method E399, that provides for themeasurement of crack-extension resistance at the onset (2% orless) of crack extension and provides operational definitions
23、 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 E1823.3.1.3 crack mouth opening displacement (CMOD), VmLcrack opening displacement resulting from the total deforma-t
24、ion (elastic plus plastic), measured under force at the locationon a crack surface that has the largest displacement per unitforce.3.1.4 crack plane orientationidentification of the planeand direction of crack extension in relation to the characteristicdirections of the product. A hyphenated code de
25、fined inTerminology E1823 is used wherein the letter(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).3.1.4.1 Wrought Productsthe fracture toughness ofwrought material d
26、epends on, among other factors, the orien-tation and 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, pr
27、oduct form shall be identified (for example,straight-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-matio
28、n.3.1.4.2 For rectangular sections, the reference directions 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 = dire
29、ction of least deformationS = third orthogonal direction3.1.4.3 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 thew
30、idth direction of a plate and the expected direction of crackpropagation is coincident with the direction of maximum grainflow (or longitudinal) direction of the plate.3.1.4.4 For specimens tilted in respect to two of the refer-ence axes as in Fig. 1(b), crack plane orientation is identified4For ref
31、erenced ASTM standards, visit the ASTM website, www.astm.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.E399 1222(a) Rectangular SectionsSpecimens Aligned with Reference Dir
32、ections(b) Rectangular SectionsSpecimens Not Aligned with Reference Directions(c) Cylindrical Bars and TubesL = direction of maximum grain flowR = radial directionC = circumferential or tangential directionFIG. 1 Crack Plane IdentificationE399 1223by a three-letter code. The designation L-TS, for ex
33、ample,indicates 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 directionintermediate between T and S, and the expected fractured
34、irection is in the L direction.3.1.4.5 For cylindrical sections, 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 fo
35、r the L-R-C system, as indicated in Fig.1(c), regardless 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 se
36、ction. In most cases the L direction corresponds to thedirection 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 directi
37、onC = circumferential or tangential direction3.1.4.6 In the 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.3.1.4.7 Non-Wrought Productsfor non-wrought pro
38、ducts,specimen location and crack plane orientation shall be definedon the part drawing.The result of a fracture toughness test froma non-wrought product shall not carry an orientation designa-tion.3.1.4.8 Discussionwhen products are to be compared onthe basis of fracture toughness, it is essential
39、that specimenlocation and orientation with respect to product characteristicdirections be comparable and that the results not be generalizedbeyond these limits.3.2 Definitions of Terms Specific to This Standard:3.2.1 stress-intensity factor rate, K(FL-3/2t-1)change instress-intensity factor, K, per
40、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 three-point bending. Details of thetest specimens and exp
41、erimental 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 crack extension) is established bya specified deviation fr
42、om 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 determined by this test methoddepends upon the establish
43、ment 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 which specimen fatigue precracking isconducted is lim
44、ited 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 property KIcdetermined by this test method char-acterizes t
45、he 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 tritensileplane strain, and (2) the crack-tip plastic zone is smallc
46、ompared 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 ligament size.Notwithstanding these variations, however, KI
47、cis 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 fracture; for example, ferritic steels in theductile-to-b
48、rittle 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 E1921 and E1820. Likewise this test method does notapply
49、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 E1820.5.1.3 The value of KIcobtained by 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 mec
