1、Designation: C749 08 (Reapproved 2010)1An American National StandardStandard Test Method forTensile Stress-Strain of Carbon and Graphite1This standard is issued under the fixed designation C749; the number immediately following the designation indicates the year oforiginal adoption or, in the case o
2、f revision, the year 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.1NOTEUpdated units scope statement and Table 1 editorially in May 2010.1. Scope1.1 This test method covers
3、 the testing of carbon andgraphite in tension to obtain the tensile stress-strain behavior,to failure, from which the ultimate strength, the strain tofailure, and the elastic moduli may be calculated as may berequired for engineering applications. Table 2 lists suggestedsizes of specimens that can b
4、e used in the tests.NOTE 1The results of about 400 tests, on file at ASTM as a researchreport, show the ranges of materials that have been tested, the ranges ofspecimen configurations, and the agreement between the testers. SeeSection 11.NOTE 2For safety considerations, it is recommended that the ch
5、ainsbe surrounded by suitable members so that at failure all parts of the loadtrain behave predictably and do not constitute a hazard for the operator.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that
6、 are provided for information onlyand are not considered standard. Conversions are not providedin the tables and figures.1.3 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-p
7、riate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C565 Test Methods for Tension Testing of Carbon andGraphite Mechanical MaterialsC709 Terminology Relating to Manufactured Carbon andGraphiteE4 Practice
8、s for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 DefinitionsTh
9、e terms as related to tension testing asgiven in Terminology E6 shall be considered as applying to theterms used in this test method. See also Terminology C709.4. Summary of Test Method4.1 A tensile specimen (Fig. 1) is placed within a load trainassembly made up of precision chains and other machine
10、dparts (Fig. 2). A load is applied to the specimen provided withmeans of measuring strain until it is caused to fracture. Thistest yields the tensile strength, elastic constants, and strain tofailure of carbons and graphites.5. Significance and Use5.1 The round robin testing on which the precision a
11、nd biasfor this test method have been determined employed a range ofgraphites (see Table 2) whose grain sizes were of the order of1 mil to14 in. (0.0254 to 6.4 mm) and larger. This wide rangeof carbons and graphites can be tested with uniform gaugediameters with minimum parasitic stresses to provide
12、 qualitydata for use in engineering applications rather than simply forquality control. This test method can be easily adapted toelevated temperature testing of carbons and graphites withoutchanging the specimen size or configuration by simply utilizingelevated temperature materials for the load tra
13、in. This testmethod has been utilized for temperatures as high as 4352F(2400C). The design of the fixtures (Figs. 2-9 and Table 1) anddescription of the procedures are intended to bring about, onthe average, parasitic stresses of less than 5 %. The specimensfor the different graphites have been desi
14、gned to ensure1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.F0 on Manufactured Carbon and Graphite Products.Current edition approved May 1, 2010. Published May 2010. Originallyapproved in 1973
15、. Last previous edition approved in 2008 as C749 08. DOI:10.1520/C0749-08R10E01.2For referenced 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
16、onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.fracture within the gauge section commensurate with experi-enced variability in machining and testing care at differentfacilities. The constant gauge diameter permits
17、 rigorous ana-lytical treatment.5.2 Carbon and graphite materials exhibit significant physi-cal property differences within parent materials. Exact sam-pling patterns and grain orientations must be specified in orderto make meaningful tensile strength comparisons. See also TestMethods C565.6. Appara
18、tus6.1 Testing MachineThe machine used for tensile testingshall conform to the requirements of Practices E4. The testingmachine shall have a load measurement capacity such that thebreaking load of the test specimen falls between 10 and 90 %of the scale or load cell capacity. This range must be linea
19、r towithin 1 % over 1 % increments either by design or bycalibration.6.2 Strain Measurements:6.2.1 The axial strain can be measured at room temperatureby the use of strain gauges, mechanical extensometers, Tuck-erman gauges, optical systems, or other devices applied dia-metrically opposite in the ga
20、uge length portion of the speci-men. Two opposing gauges provide some compensation forbending and some assurance that it was not severe. Differentgraphites require different attachment procedures and extremecare is necessary. A proven device for mounting the specimenwith minimum damage and for enabl
21、ing the specimen toreceive different extensometers is shown in Fig. 10. Whenattaching strain gauges, the modification of the surface mayresult in a glue-graphite composite at the skin and thus theresulting strain values may be erroneous and typically low.When using clip-on extensometers, the knife e
22、dges can initiatefracture. Record, but do not include the fractures at theattachments in the averages. If more than 20 % of the failuresTABLE 1 List of Materials Shown in Fig. 2Assembly Item Quantity Name, Description, Material1A 101 2 Crosshead attachment yoke1 diax4long416 or 440 S.S.12 in.AgripsB
23、,C102 2 Chain316 dia, 700 pound tensile limit, 10 links longCarbonSteel103 4 Chain journal916 dia x12 long416 or 440 S.S.D104 4 Pin316 dia x 1Std Dowel105 2 Grip attachment yoke1 dia x 258 long416 or 440 S.S.D106 2 Pin14 shank dia with12 dia x34 long knurled head, total length212 , taper first half
24、inch at 10416 or 440 S.S.D107 2 Grip sleeve112 diax2516 long416 or 440 S.S.D108 2 Split sleeve1 diax1long416 or 440 S.S.D109 1 Specimen0.510 dia x 434 longCarbon110 Not Used1B . . . 2 Item 101Crosshead attachment yoke34 in.Agrips . . . 2 Item 102Chain. . . 4 Item 103Chain journal. . . 4 Item 104Pin.
25、 . . 2 Item 105Grip attachment yoke. . . 2 Item 106Pin111 2 Grip sleeve112 diax2516 long416 or 440 S.S.D112 2 Split sleeve1 diax1long416 or 440 S.S.D113 1 Specimen0.760 dia x 434 longCarbon114 Not Used1C 115 2 Crosshead attachment yoke112 diax4long416 or 440 S.S.D114 in.Agrips 116 2 Chain38 dia, 510
26、0 pound tensile limit, 10 links longCarbon Steel117 4 Chain journal58 dia x58 long416 or 440 S.S.D118 4 Pin38 diax112 longStd Dowel119 2 Grip attachment yoke112 diax258 long416 or 440 S.S.D120 2 Pin12 shank dia with34 dia x34 long knurled head, total length414 , taper first half inch at 10416 or 440
27、 S.S.D121 2 Grip sleeve178 diax358 long416 or 440 S.S.D122 2 Split sleeve112 diax214 long416 or 440 S.S.D123 1 Specimen114 diax934 longCarbon124 Not Used1D . . . 2 Item 115Crosshead attachment yoke2in.Agrips . . . 2 Item 116Chain. . . 4 Item 117Chain journal. . . 4 Item 118Pin125 2 Grip attachment y
28、oke214 diax258 long416 or 440 S.S.D126 2 Pin12 shank dia with34 dia x34 long knurled head, total length414 , taper first half inch at 10416 or 440 S.S.D127 2 Grip sleeve234 diax512 long416 or 440 S.S.D128 2 Split sleeve214 diax4long416 or 440 S.S.D129 1 Specimen2.000 dia x 1438 longCarbon130 Not Use
29、dA1 in. is equal to 25.4 mm.BPreload chain to yield using a load time recording.CCommercially available.DOr alternative high strength stainless steel.C749 08 (2010)12occur at the attachment location, change the strain monitoringsystem or attachment device.6.2.2 The circumferential strain can be meas
30、ured at roomtemperature by use of strain gauges applied circumferentially.Knowledge of the anisotropy in the billet and orientation of thespecimen is necessary in order to properly place the strain-measuring device. Generally, one can expect three values ofPoissons ratio for a nonisotropic material.
31、 Hence, the strainsensing devices must be sized and positioned carefully. Notethe limitations on strain gauges mentioned in 6.2.1.6.2.3 The diametral strains can be measured by most of thedevices with limitations mentioned in 6.2.1 and 6.2.2.6.3 Parasitic Stress MonitorAn optional parasitic stressmo
32、nitor can be inserted as an extension of one of the grips. Itshall be a steel rod about 4 in. long with strain gauges mountedat 90 angles to monitor axial bending moments on the rod andTABLE 2 Sample Sizes Used in Round-Robin Tests (Suggested Specimen Size)AMaterialBMax Grain Size,in.Sample, in.Spec
33、imenSize, in.RecommendedShank andMaximum Gauge,in.AXM-50 0.001 5 by 5 by 5, molded12 by 0.200C 12 by31634 by149326 0.001 20 by 10 by 2, molded12 by1434 by 0.312 by316C12 by31634 by149326A 0.001 20 by 10 by 2, molded12 by1412 by31634 by3834 by 0.334 by 0.334 by38ATJ 0.006 13, rounds, molded12 by1412
34、by1434 by3834 by1434 by3834 by1434 by38HLM 0.033 molded, 10 by 18 by 2512 by1434 by3834 by3834 by3834 by38CS 0.030 10, rounds, extruded 2 by 134 by3834 by3812 by1412 by14AGR 0.250 25, rounds, extruded 2 by 1 2 by 12by1 114 by582by1114 by58CGE 0.265 14, rounds, extruded 2 by 11434 by12 2by1Graphitar
35、. . . carbon-graphite, resin impregnated34 by1434 by14Grade 8612 by14C 12 by 0.212 by14Purebon P-59 . . . carbon-graphite, copper treated34 by1434 by1412 by14C 12 by31612 by14ABased on Research Report RR:C05-1000 (see Section 11).BIdentity of suppliers available from ASTM International Headquarters.
36、CGas-bearings.NOTEStandard Specimen:r1= r2,A1= A2/1.2,l1= D2/2, andl2= 2 in. (51 mm) or 8 D1, whichever is greater.FIG. 1 Double Reduction Used to Minimize Radii-FracturesC749 08 (2010)13thus on the specimen. The rod shall be sized so that the bendingmoment applied to the specimen being used can be
37、detected towithin a 5 % parasitic stress in the outer fiber of the specimen.The parasitic stress shall be calculated elastically by translatingthe moment and assuming that the specimen is a free-endbeam.6.4 Gripping DevicesGripping devices that conform tothose shown in Fig. 2 shall be used. The cent
38、erlines of allconnections must align to within the tolerances shown through-out the test.6.5 General Test ArrangementThe general arrangementof the specimen, flexible linkages, and crossheads shall be asshown in the schematic of Fig. 3.7. Test Specimens7.1 Test specimens shall be produced to the gene
39、ral con-figurations shown in Fig. 9. The selection of the proper ratio ofshank to gauge diameter is important to prevent excessivehead-pops or fracture of the specimen at the groove in theFIG. 2 Tensile Load Train AssemblyC749 08 (2010)14shanks. The ratios shown in Table 2 have been found satisfac-t
40、ory for this use. It is acceptable to double reduce gaugediameters as necessary (see Fig. 1) to eliminate head pops (orout-of-gauge fractures) or reduce them to an acceptable 20 %maximum of the total fractures. However, the reducing radiusmust be maintained near the values shown or excessive radiibr
41、eaks will be obtained.Also, the gauge diameter should not bereduced to less than three to five times the maximum particlessize in the material, or the failure mode may be atypical.7.2 Improperly prepared test specimens often cause unsat-isfactory test results. It is important, therefore, that care b
42、eexercised in the preparation of specimens both in minimizingend and side thrusts and in providing a quality surface. Eithertool cutting or grinding is acceptable.7.3 The gauge length of the specimen will be measuredfrom the axial center of the specimen. Gauge marks can beapplied with ink or layout
43、dope but no scratching, punching, ornotching of the specimen is permissible. The gauge length is tobe used in referencing the point of fracture within 0.1 in. (2.5mm). The total gauge length is defined as that section with thesmaller uniform diameter extending from radius tangent toradius tangent pl
44、us 10 %. The additional 10 % is intended toaccommodate the normal statistics of fracture for a materiallike graphite. However, at least 50 % of the specimens shouldfracture within the uniform diameter or the specimen should beredesigned and the system checked. Acceptable fracture loca-tions are show
45、n in Fig. 11.7.4 To determine the cross-sectional area, the diameter ofthe specimen at the smaller or constant diameter region shall beused. The dimension shall be recorded to the nearest 0.001 in.(0.0254 mm).8. Procedure8.1 CalibrationCalibrate the micrometres that are to beused for measurement of
46、diameters by measuring the dimen-sions of blocks provided by the NBS that are accurate within60.0001 in. (0.00254 mm). Calibrate all instrumentation andestablish shunt calibration for each recorded and each param-eter. Zero all recorders.8.2 SpecimenAdapt to the specimen the appropriate straininstru
47、mentation by bonding strain gauges to its surface, adapt-ing, or any other strain measuring system so that strain can bemeasured during the test. Place the specimen within the loadtrain. Make sure all instrumentation is properly calibrated andzeroed.8.3 LoadingApply the load at a predetermined const
48、antstress rate by following the appropriate load time curve eithermanually or automatically. Continuously apply the load untilfracture is induced.8.4 RecordingDuring the entire load application duration,record the output of the load cell on the vertical axis of an X-Yrecorder and the strain on the h
49、orizontal axis, and obtain apermanent record of the stress-strain curve for the specimenbeing tested during the entire test.FIG. 3 Schematic of Tensile System for Carbon and GraphiteDimensions,in. (mm)Item101 115A0.250 6 0.001 0.312 6 0.001(6.35 6 0.03) (7.92 6 0.03)B0.500 6 0.001 0.625 6 0.001(12.70 6 0.03) (15.88 6 0.03)C 1.000 (25.40) 1.500 (38.10)D316 (4.76)38
