ASTM_C_749_-_15.pdf

Designation:C74915An 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 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.Scope*1.1 This test method covers 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 be used in the tests.NOTE1The 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.NOTE2For safety considerations,it is recommended that the chainsbe 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 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-priate 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 MaterialsE4 Practices 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 Definitions:3.1.1 The terms as related to tension testing as given inTerminology E6 shall be considered as applying to the termsused in this test method.3.1.2 modulus of elasticity,nthe ratio of a force applied toa material to the increment of dimensional change along theforce axis,commonly defined as the ratio of tensile stress totensile strain.3.1.3 tensile strength,nproperty of solid material thatindicates its ability to withstand a uniaxial tensile load,converted to unit stress based on the original cross-section areaof the tensile test specimen.3.1.4 ultimate tensile strength,nthe maximum tensilestress applied in stretching a specimen to rupture.4.Summary of Test Method4.1 A tensile specimen(Fig.1)is placed within a load trainassembly made up of precision chains and other machinedparts(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 and biasfor this test method have been determined employed a range ofgraphites(see Table 2)whose grain sizes were of the order of1 mil to14in.(0.0254 mm to 6.4 mm)and larger.This widerange of carbons and graphites can be tested with uniformgauge diameters with minimum parasitic stresses to providequality data for use in engineering applications rather thansimply for quality control.This test method can be easilyadapted to elevated temperature testing of carbons and graphi-tes without changing the specimen size or configuration bysimply utilizing elevated temperature materials for the loadtrain.This test method has been utilized for temperatures ashigh as 4352 F(2400 C).The design of the fixtures(Figs.2-9and Table 1)and description of the procedures are intended tobring about,on the average,parasitic stresses of less than 5%.The specimens for the different graphites have been designed1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.F0 on Manufactured Carbon and Graphite Products.Current edition approved Oct.1,2015.Published November 2015.Originallyapproved in 1973.Last previous edition approved in 2013 as C749 13.DOI:10.1520/C0749-15.2For 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 onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 to ensure fracture within