1、Designation: B 645 07Standard Practice forLinear-Elastic PlaneStrain Fracture Toughness Testing ofAluminum Alloys1This standard is issued under the fixed designation B 645; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f 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.INTRODUCTIONLinear-elastic plane-strain fractu
3、re toughness testing of aluminum alloys is performed essentially inaccordance with Test Method E 399. However, there is a need, in the application of Test Method E 399for quality assurance testing, to deal with the interpretation of the results for material qualification andrelease in cases where al
4、l requirements for valid measurements of plane-strain fracture toughnesscannot be met. It is the purpose of this practice to provide consistent methods of dealing with thosesituations.1. Scope*1.1 This practice is applicable to the fracture toughnesstesting of all aluminum alloys, tempers, and produ
5、cts, espe-cially in cases where the tests are being made to establishwhether or not individual lots meet the requirements ofspecifications and should be released to customers.1.2 Test Method E 399 is the basic test method to be usedfor plane-strain fracture toughness testing of aluminum alloys.The p
6、urpose of this practice is to provide supplementaryinformation for plane-strain fracture toughness of aluminumalloys in three main areas:1.2.1 Specimen sampling,1.2.2 Specimen size selection, and1.2.3 Interpretation of invalid test results.1.3 The values stated in SI units are to be regarded as thes
7、tandard. The values given in parentheses are provided forinformation only.1.4 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
8、 the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B 646 Practice for Fracture Toughness Testing of Alumi-num AlloysE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE 399 Test Method for Linear-Elasti
9、c Plane-Strain FractureToughness KICof Metallic MaterialsE 561 Test Method for K-R Curve DeterminationE 1823 Terminology Relating to Fatigue and Fracture Test-ing3. Terminology3.1 GeneralTerms, definitions, symbols, and orientationdesignations in Test Method E 399 and Terminology E 1823are applicabl
10、e herein.3.2 The following additional definitions are applicable:3.2.1 invalid plane-strain fracture toughnesstest result,KQ, that does not meet one or more of the validity requirementsin Test Method E 399 and, where so characterized, is of novalue in judging the true plain-strain fracture toughness
11、 of amaterial but may, under certain conditions, adequately guaran-tee the materials fracture toughness for lot release purposes.1This practice is under the jurisdiction of ASTM Committee B07 on LightMetals and Alloys and is the direct responsibility of Subcommittee B07.05 onTesting.Current edition
12、approved Sept. 1, 2007. Published September 2007. Originallyapproved in 1978. Last previous edition approved in 2002 as B 64502.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informatio
13、n, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.2 valid plane-strain, fracture toughnesstest res
14、ultmeeting all the validity requirements in Test Method E 399,that is, a value of KIc.4. Summary of Practice4.1 This practice supplements Test Method E 399 and Prac-tice B 646 in three main areas:4.1.1 Specimen sampling,4.1.2 Specimen size selection, and4.1.3 Interpretation of results that fail the
15、validity require-ments in Test Method E 399 in one of the following areas inorder to determine if the invalid results are usable for lotrelease:4.1.3.1 Pmax/PQrequirements,4.1.3.2 Specimen size requirements, and4.1.3.3 Fatigue precracking requirements.5. Significance and Use5.1 This practice for pla
16、ne-strain fracture toughness testingof aluminum alloys may be used as a supplement to TestMethod E 399. The application of this practice is primarilyintended for quality assurance and material release in caseswhere valid plane-strain fracture toughness data cannot beobtained per Test Method E 399.5.
17、2 It must be understood that the interpretations andguidelines in this practice do not alter the validity requirementsof Test Method E 399 or promote the designation of data thatare invalid according to Test Method E 399 to a “valid”condition. This practice is primarily concerned with caseswhere it
18、is not possible or practical to obtain valid data, butwhere material release judgments must be made againstspecified fracture toughness values. Where it is possible toobtain a valid plane-strain fracture toughness value by replace-ment testing according to Test Method E 399, that is thepreferred app
19、roach.6. Apparatus6.1 All apparatus shall be in conformance with Test MethodE 399.7. Sampling7.1 Sampling requirements stated in the individual materialspecifications shall be followed. In the absence of specificrequirements in the individual material specifications, speci-mens shall be taken at the
20、 following locations:7.1.1 Specimens from plate shall be from the mid-thickness,until the plate thickness is twice the standard specimenthickness for that particular product (that is, the specimenthickness selected for lot release and quality assurance testingwhich typically yields a valid KIcfor th
21、at particular alloy andproduct), at and beyond which the specimen shall be centeredat the quarter-thickness location.7.1.2 Specimens from forgings, extrusions, and rod shall betaken from the center of the cross section as far as is practical.NOTE 1Considerable care should be taken in specifying the
22、locationof specimens within the thickness of the thick plate, forgings, extrusions,or rod because fracture toughness may vary appreciably with locationthrough the thickness.8. Test Specimen Configuration and Dimensions8.1 Specimen size requirements stated in the individualmaterial specifications sha
23、ll be followed. In the absence ofspecific requirements, the specimen types, general configura-tion, and size requirements in Test Method E 399 are appli-cable herein with the following supplemental recommenda-tions and requirements:8.1.1 For aluminum products, the recommended minimumspecimen ligamen
24、t length is:W a! $5KQ/sYS!2(1)rather than the required minimum of:W a! $2.5KQ/sYS!2(2)in Test Method E 399.NOTE 2Experimental studies3have shown that more uniform valuesof KQare obtained for high toughness aluminum alloys when theconditions of Eq 1 are met.8.1.2 In all cases, the specimen W/B ratio
25、shall be greaterthan or equal to 2 and less than or equal to 4 based on nominalspecimen dimensions. Other specimen dimensional propor-tions in Test Method E 399 shall also be maintained.NOTE 3Specimens meeting this requirement correspond to the stan-dard (W/B = 2) or alternative specimen geometries
26、(2# W/B #4) in TestMethod E 399.8.1.3 When the minimum size requirement of:W a! $2.5KQ/sYS!2in Test Method E 399 cannot be met due to product dimen-sional constraints, the specimen shall be machined such thatthe W dimension is maximized to the nearest 12.7 mm (0.5 in.)at the specified test location
27、while still meeting the require-ments of 8.1.2.NOTE 4It is not practical for W to vary continuously (that is,non-discretely) since many C(T) specimen dimensions are proportional toW. Each change in W requires a different machining or testing setup.Therefore, it is required that W be maximized to the
28、 nearest 12.7 mm (0.5in.).8.1.4 When the requirement Pmax/PQ# 1.1 cannot be metdue to product dimensional constraints, the specimen shall bemachined such that the B dimension is maximized up to arequired maximum thickness of 63.5 mm (2.5 in.) at thespecified test location. The specimen ligament leng
29、th should bemaintained at:W a! $2.5KQ/sYS!2(3)or as large as possible while still meeting the requirements of8.1.2.NOTE 5The upper limit on specimen thickness has been establishedbecause of practical limitations on how large a specimen can be routinelymachined and tested for lot release purposes in
30、a production environmentusing standard test equipment. The producer may test thicker specimensprovided the testing capability and sufficient material are available, andthe specimen proportions adhere to the requirements in 8.1.2.3Kaufman, J. G., “Experience in Plane Strain Fracture Toughness per AST
31、ME 399,” Developments in Fracture Mechanics Test Methods Standardization, ASTMSTP 632, ASTM, 1977, pp. 3-24.B6450728.1.5 When it is not possible to meet either the:W a! $2.5KQ/sYS!2(4)or the:Pmax/PQ#1.1 (5)requirements, then both the W and B dimensions shall bemaximized in accordance with requiremen
32、ts in 8.1.2, 8.1.3, and8.1.4.NOTE 6For aluminum products where the size requirement in eitherEqs 4 or 5 cannot be consistently met because of high toughness, evenwhen B and W are maximized, other measures of fracture toughness suchas KR25described in Practice B 646 or the K-R curve as described in T
33、estMethod E 561 should be considered for evaluating fracture toughness forlot release purposes.NOTE 7Test Method E 399 permits the use of side-grooved specimensin certain specimen types. Side-grooved specimens may allow for validKICvalues to be obtained for high toughness alloys or thin products tha
34、totherwise would have invalidities due to excessive plasticity. For lotacceptance testing, side-grooved specimens shall not be used unlessspecifically allowed by the product specification or by agreement betweenproducer and user. Side-grooves increase the level of constraint withrespect to the recom
35、mended specimen. The increased constraint promotesa more uniform stress state along the crack front and inhibits shear lipdevelopment.As a result, a KICvalue obtained from testing a side-groovedspecimen is expected to be lower than a KICvalue obtained from testingthe recommended specimen, particular
36、ly for thin products or tests exhib-iting Type I behavior. For use of side-grooves in lot acceptance testing,minimum KICvalues specific to side-grooved specimens may need to beestablished.9. Fatigue Precracking9.1 Fatigue precracking shall be performed and fatiguecrack front measurements shall be ma
37、de in accordance withTest Method E 399.10. Procedure10.1 The test procedure, analysis of test record, and calcu-lations shall be made in accordance with Test Method E 399.11. Interpretation of Results11.1 AKQvalue that satisfies all of the validity requirementsof Test Method E 399 is a valid KICin a
38、ccordance with thispractice. A KQvalue that does not meet all of the requirementsof Test Method E 399 is not a valid KICvalue in accordancewith Test Method E 399 or this practice, but is usable for lotrelease purposes if all of the appropriate requirements in thissection are met.11.2 For a KQvalue h
39、aving invalidities in accordance withTest Method E 399, all of the secondary conditions in 11.3,11.4, and 11.5 must be met for each of those invalidities for theKQvalue to be usable for lot release.11.3 Invalidities Related to Specimen Size and Pmax/PQRequirements:11.3.1 In all cases, the specimen W
40、/B ratio must meet therequirements in 8.1.2. Otherwise, a replacement test shall beperformed using a specimen meeting those requirements.11.3.2 If a KQvalue is invalid because the specimen doesnot meet the:W a! $2.5KQ/sYS!2requirement but the test record meets the:Pmax/PQ#1.1requirement, the KQvalue
41、 may be usable for lot release if thespecimen width W is maximized according to 8.1.3.11.3.3 If a KQvalue is invalid because the test record doesnot meet the:Pmax/PQ#1.1requirement but the specimen size does meet the:W a! $2.5KQ/sYS!2requirement, the KQvalue may be usable for lot release if thethick
42、ness is maximized according to 8.1.4.11.3.4 If a KQvalue is invalid because it fails to meet boththe:Pmax/PQ#1.1 (6)requirement and the:W a! $2.5KQ/sYS!2(7)requirement, the KQvalue may be usable for lot release if thewidth W and the thickness B are maximized according to 8.1.5.NOTE 8Under the condit
43、ions in 11.3.2, 11.3.3, and 11.3.4, the KQvalue may not represent or approximate KIc, but it does represent ameasure of the materials resistance to fracture. KQvalues obtained underthese conditions may also depend significantly on the specimen geometryand dimensions. Therefore, both the specified va
44、lue and the qualificationtesting should be based on a specimen of the same geometry anddimensions.11.4 Invalidities Related to Fatigue Precracking:11.4.1 If the maximum stress intensity in the final stage ofprecracking (Kfmax) exceeds the limit of 60% of KQallowed inTest Method E 399, but still sati
45、sfies the requirement that:Kfmax/E#0.00032 m0.002 in.!,the KQvalue may be usable for lot release if Kfmaxis no morethan 80% of KQ. Otherwise, a replacement test shall beperformed.11.4.2 If the crack length a determined in accordance withTest Method E 399 is outside the range allowed in E 399(0.45W t
46、o 0.55W), the KQvalue may be usable for lot releaseif the crack length a is within the range 0.4W to 0.6W.Otherwise, a replacement test shall be performed.11.5 Other Invalidities: To be usable for lot release, a KQvalue must also satisfy all other validity requirements in TestMethod E 399 not covere
47、d in 11.3 and 11.4. Otherwise, areplacement test shall be performed.11.6 Annex A1 provides a flowchart to help the userunderstand how to interpret an invalid KQvalue from E 399 todetermine if it is usable for lot release according to thisPractice.12. Report12.1 The record shall include all informati
48、on required byTest Method E 399 and individual reasons for invalid resultsbeing considered usable for lot release in accordance with thispractice.12.2 The complete record is not normally required formaterial certification and lot release purposes. Such records areusually retained by the producer for
49、 future audit by thepurchaser.B64507312.3 For the purpose of determining conformance with aspecified limit in a material or product specification, the valueof KIc(or KQwhen usable for lot release) obtained in the testshall be rounded “to the nearest unit” in the last right handsignificant digit used in expressing the limiting value inaccordance with the rounding method of Practice E29. For alimit specified as a whole number, all digits shall be consideredsignificant including zeros.12.4 Replacement TestsAtest specimen may be di
