1、Designation: C749 08 (Reapproved 2010)1C749 13 An 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 th
2、e case of 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.1 NOTEUpdated units scope statement and Table 1 editorially in May 2010.1. Scope Scope*1.1 This te
3、st method covers the testing of carbon and graphite in tension to obtain the tensile stress-strain behavior, to failure,from which the ultimate strength, the strain to failure, and the elastic moduli may be calculated as may be required for engineeringapplications. Table 2 lists suggested sizes of s
4、pecimens that can be used in the tests.NOTE 1The results of about 400 tests, on file atASTM as a research report, show the ranges of materials that have been tested, the ranges of specimenconfigurations, and the agreement between the testers. See Section 11.NOTE 2For safety considerations, it is rec
5、ommended that the chains be surrounded by suitable members so that at failure all parts of the load trainbehave predictably and do not constitute a hazard for the operator.1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematicalconver
6、sions to SI units that are provided for information only and are not considered standard. Conversions are not provided inthe tables and figures.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this stand
7、ard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C565 Test Methods for Tension Testing of Carbon and Graphite Mechanical MaterialsC709 Terminology Relating to Manufactured Carbon
8、and GraphiteE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method3. Ter
9、minology3.1 DefinitionsThe terms as related to tension testing as given in Terminology E6 shall be considered as applying to the termsused in this test method. See also Terminology C709.4. Summary of Test Method4.1 A tensile specimen (Fig. 1) is placed within a load train assembly made up of precisi
10、on chains and other machined parts(Fig. 2). A load is applied to the specimen provided with means of measuring strain until it is caused to fracture. This test yieldsthe tensile strength, elastic constants, and strain to failure of carbons and graphites.5. Significance and Use5.1 The round robin tes
11、ting on which the precision and bias for this test method have been determined employed a range ofgraphites (see Table 2) whose grain sizes were of the order of 1 mil to 14 in. (0.0254 to 6.4 mm) and larger. This wide range of1 This test method is under the jurisdiction of ASTM Committee D02 on Petr
12、oleum Products Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.F0 on Manufactured Carbon and Graphite Products.Current edition approved May 1, 2010Oct. 1, 2013. Published May 2010November 2013. Originally approved in 1973. Last previous edition approved in
13、20082010 asC749 08. 08 (2010)1. DOI: 10.1520/C0749-08R10E01.10.1520/C0749-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on t
14、he ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users c
15、onsult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohock
16、en, PA 19428-2959. United States1carbons and graphites can be tested with uniform gauge diameters with minimum parasitic stresses to provide quality data for usein engineering applications rather than simply for quality control. This test method can be easily adapted to elevated temperaturetesting o
17、f carbons and graphites without changing the specimen size or configuration by simply utilizing elevated temperaturematerials for the load train. This test method has been utilized for temperatures as high as 4352F (2400C). The design of thefixtures (Figs. 2-9 and Table 1) and description of the pro
18、cedures are intended to bring about, on the average, parasitic stresses ofless than 5 %. The specimens for the different graphites have been designed to ensure fracture within the gauge sectioncommensurate with experienced variability in machining and testing care at different facilities. The consta
19、nt gauge diameterpermits rigorous analytical treatment.5.2 Carbon and graphite materials exhibit significant physical property differences within parent materials. Exact samplingpatterns and grain orientations must be specified in order to make meaningful tensile strength comparisons. See also Test
20、MethodsC565.6. Apparatus6.1 Testing MachineThe machine used for tensile testing shall conform to the requirements of Practices E4. The testingmachine shall have a load measurement capacity such that the breaking load of the test specimen falls between 10 and 90 % ofthe scale or load cell capacity. T
21、his range must be linear to within 1 % over 1 % increments either by design or by calibration.6.2 Strain Measurements:TABLE 1 List of Materials Shown in Fig. 2Assembly Item Quantity Name, Description, Material1A 101 2 Crosshead attachment yoke1 dia x 4 long416 or 440 S.S.12 in. A gripsB,C 102 2 Chai
22、n316 dia, 700 pound tensile limit, 10 links longCarbonSteel103 4 Chain journal916 dia x 12 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 with 12 dia x 34 long knurled head, total length212, taper first half inch at 10
23、416 or 440 S.S.D107 2 Grip sleeve112 dia x 2516 long416 or 440 S.S.D108 2 Split sleeve1 dia x 1 long416 or 440 S.S.D109 1 Specimen0.510 dia x 434 longCarbon110 Not Used1B . . . 2 Item 101Crosshead attachment yoke34 in. A grips . . . 2 Item 102Chain. . . 4 Item 103Chain journal. . . 4 Item 104Pin. .
24、. 2 Item 105Grip attachment yoke. . . 2 Item 106Pin111 2 Grip sleeve112 dia x 2516 long416 or 440 S.S.D112 2 Split sleeve1 dia x 1 long416 or 440 S.S.D113 1 Specimen0.760 dia x 434 longCarbon114 Not Used1C 115 2 Crosshead attachment yoke112 dia x 4 long416 or 440 S.S.D114 in. A grips 116 2 Chain38 d
25、ia, 5100 pound tensile limit, 10 links longCarbon Steel117 4 Chain journal58 dia x 58 long416 or 440 S.S.D118 4 Pin38 dia x 112 longStd Dowel119 2 Grip attachment yoke112 dia x 258 long416 or 440 S.S.D120 2 Pin12 shank dia with 34 dia x 34 long knurled head, total length414, taper first half inch at
26、 10416 or 440 S.S.D121 2 Grip sleeve178 dia x 358 long416 or 440 S.S.D122 2 Split sleeve112 dia x 214 long416 or 440 S.S.D123 1 Specimen114 dia x 934 longCarbon124 Not Used1D . . . 2 Item 115Crosshead attachment yoke2 in. A grips . . . 2 Item 116Chain. . . 4 Item 117Chain journal. . . 4 Item 118Pin1
27、25 2 Grip attachment yoke214 dia x 258 long416 or 440 S.S.D126 2 Pin12 shank dia with 34 dia x 34 long knurled head, total length414, taper first half inch at 10416 or 440 S.S.D127 2 Grip sleeve234 dia x 512 long416 or 440 S.S.D128 2 Split sleeve214 dia x 4 long416 or 440 S.S.D129 1 Specimen2.000 di
28、a x 1438 longCarbon130 Not UsedA 1 in. is equal to 25.4 mm.B Preload chain to yield using a load time recording.C Commercially available.D Or alternative high strength stainless steel.C749 1326.2.1 The axial strain can be measured at room temperature by the use of strain gauges, mechanical extensome
29、ters, Tuckermangauges, optical systems, or other devices applied diametrically opposite in the gauge length portion of the specimen. Two opposinggauges provide some compensation for bending and some assurance that it was not severe. Different graphites require differentattachment procedures and extr
30、eme care is necessary. A proven device for mounting the specimen with minimum damage and forenabling the specimen to receive different extensometers is shown in Fig. 10. When attaching strain gauges, the modification ofthe surface may result in a glue-graphite composite at the skin and thus the resu
31、lting strain values may be erroneous and typicallylow. When using clip-on extensometers, the knife edges can initiate fracture. Record, but do not include the fractures at theattachments in the averages. If more than 20 % of the failures occur at the attachment location, change the strain monitoring
32、 systemor attachment device.TABLE 2 Sample Sizes Used in Round-Robin Tests (Suggested Specimen Size)AMaterialB Max Grain Size,in. Sample, in. SpecimenSize, in.RecommendedShank andMaximum Gauge,in.AXM-50 0.001 5 by 5 by 5, molded 12 by 0.200C 12 by 31634 by 149326 0.001 20 by 10 by 2, molded 12 by 14
33、34 by 0.312 by 316C12 by 31634 by 149326A 0.001 20 by 10 by 2, molded 12 by 14 12 by 31634 by 3834 by 0.3 34 by 0.334 by 38ATJ 0.006 13, rounds, molded 12 by 14 12 by 1434 by 38 34 by 1434 by 38 34 by 1434 by 38HLM 0.033 molded, 10 by 18 by 25 12 by 14 34 by 3834 by 3834 by 3834 by 38CS 0.030 10, ro
34、unds, extruded 2 by 134 by 38 34 by 3812 by 1412 by 14AGR 0.250 25, rounds, extruded 2 by 1 2 by 12 by 1 114 by 582 by 1114 by 58CGE 0.265 14, rounds, extruded 2 by 11434 by 12 2 by 1Graphitar . . . carbon-graphite, resin impregnated 34 by 14 34 by 14Grade 86 12 by 14C 12 by 0.212 by 14Purebon P-59
35、. . . carbon-graphite, copper treated 34 by 14 34 by 1412 by 14C 12 by 31612 by 14A Based on Research Report RR:C05-1000 (see Section 11).B Identity of suppliers available from ASTM International Headquarters.C Gas-bearings.NOTE 1Standard Specimen:r1 = r2,A1 = A2/1.2,l1 = D2/2, andl2 = 2 in. (51 mm)
36、 or 8 D1, whichever is greater.FIG. 1 Double Reduction Used to Minimize Radii-FracturesC749 1336.2.2 The circumferential strain can be measured at room temperature by use of strain gauges applied circumferentially.Knowledge of the anisotropy in the billet and orientation of the specimen is necessary
37、 in order to properly place thestrain-measuring device. Generally, one can expect three values of Poissons ratio for a nonisotropic material. Hence, the strainsensing devices must be sized and positioned carefully. Note the limitations on strain gauges mentioned in 6.2.1.6.2.3 The diametral strains
38、can be measured by most of the devices with limitations mentioned in 6.2.1 and 6.2.2.6.3 Parasitic Stress MonitorAn optional parasitic stress monitor can be inserted as an extension of one of the grips. It shallbe a steel rod about 4 in. long with strain gauges mounted at 90 angles to monitor axial
39、bending moments on the rod and thuson the specimen. The rod shall be sized so that the bending moment applied to the specimen being used can be detected to withina 5 % parasitic stress in the outer fiber of the specimen.The parasitic stress shall be calculated elastically by translating the momentan
40、d assuming that the specimen is a free-end beam.FIG. 2 Tensile Load Train AssemblyC749 1346.4 Gripping DevicesGripping devices that conform to those shown in Fig. 2 shall be used. The centerlines of all connectionsmust align to within the tolerances shown throughout the test.6.5 General Test Arrange
41、mentThe general arrangement of the specimen, flexible linkages, and crossheads shall be as shownin the schematic of Fig. 3.7. Test Specimens7.1 Test specimens shall be produced to the general configurations shown in Fig. 9. The selection of the proper ratio of shankto gauge diameter is important to
42、prevent excessive head-pops or fracture of the specimen at the groove in the shanks. The ratiosshown in Table 2 have been found satisfactory for this use. It is acceptable to double reduce gauge diameters as necessary (seeFig. 1) to eliminate head pops (or out-of-gauge fractures) or reduce them to a
43、n acceptable 20 % maximum of the total fractures.However, the reducing radius must be maintained near the values shown or excessive radii breaks will be obtained.Also, the gaugediameter should not be reduced to less than three to five times the maximum particles size in the material, or the failure
44、mode maybe atypical.7.2 Improperly prepared test specimens often cause unsatisfactory test results. It is important, therefore, that care be exercisedin the preparation of specimens both in minimizing end and side thrusts and in providing a quality surface. Either tool cutting orgrinding is acceptab
45、le.7.3 The gauge length of the specimen will be measured from the axial center of the specimen. Gauge marks can be applied withink or layout dope but no scratching, punching, or notching of the specimen is permissible. The gauge length is to be used inreferencing the point of fracture within 0.1 in.
46、 (2.5 mm). The total gauge length is defined as that section with the smaller uniformdiameter extending from radius tangent to radius tangent plus 10 %. The additional 10 % is intended to accommodate the normalstatistics of fracture for a material like graphite. However, at least 50 % of the specime
47、ns should fracture within the uniformdiameter or the specimen should be redesigned and the system checked. Acceptable fracture locations are shown in Fig. 11.FIG. 3 Schematic of Tensile System for Carbon and GraphiteC749 1357.4 To determine the cross-sectional area, the diameter of the specimen at t
48、he smaller or constant diameter region shall be used.The dimension shall be recorded to the nearest 0.001 in. (0.0254 mm).8. Procedure8.1 CalibrationCalibrate the micrometres that are to be used for measurement of diameters by measuring the dimensions ofblocks provided by the NBS that are accurate w
49、ithin 60.0001 in. (0.00254 mm). Calibrate all instrumentation and establish shuntcalibration for each recorded and each parameter. Zero all recorders.8.2 SpecimenAdapt to the specimen the appropriate strain instrumentation by bonding strain gauges to its surface, adapting,or any other strain measuring system so that strain can be measured during the test. Place the s
