ASTM_C_1025_-_15.pdf

Designation:C102515An American National StandardStandard Test Method forModulus of Rupture in Bending of Electrode Graphite1This standard is issued under the fixed designation C1025;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 determination of the modulus ofrupture in bending of specimens cut from graphite electrodesusing a simple square cross section beam in four-point loadingat room temperature.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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:2C651 Test Method for Flexural Strength of ManufacturedCarbon and GraphiteArticles Using Four-Point Loading atRoom TemperatureC783 Practice for Core Sampling of Graphite ElectrodesE4 Practices for Force Verification of Testing MachinesE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions:3.1.1 electrode graphite,na type of manufactured graph-ite with less restrictive controls on homogeneity and purity,commonly produced to carry current in electric arc furnaces,asa consumable item in electrical discharge machining,and as astructural material in plastic-injection molds.3.1.2 flexural strength,nproperty of solid material thatindicates its ability to withstand a flexural or transverse load,obtained through a measurement of the ultimate load-carryingcapacity of a specified beam in bending.3.1.3 modulus of rupture in bending,nthe value of maxi-mum stress in the extreme fiber of a specified beam loaded tofailure in bending.4.Significance and Use4.1 This test method provides a means for determining themodulus of rupture of a square cross section graphite specimenmachined from the electrode core sample obtained according toPractice C783,with a minimum core diameter of 57 mm.Thistest method is recommended for quality control or qualityassurance purposes,but should not be relied upon to comparematerials of radically different particle sizes or orientationalcharacteristics.For these reasons as well as those discussed in4.2 an absolute value of flexural strength may not be obtained.4.2 Specimen SizeThe maximum particle size and maxi-mum pore size vary greatly for manufactured graphiteelectrodes,generally increasing with electrode diameter.Thetest is on a rather short stubby beam,therefore the shear stressis not insignificant compared to the flexural stress,and the testresults may not agree when a different ratio or specimen size isused.5.Apparatus5.1 The testing machine shall conform to the requirementsof Sections 14 and 17 of Practices E4.5.2 The four-point loading fixture shall consist of bearingblocks or roller assemblies which ensure that forces applied tothe beam are normal only and without eccentricity.(See TestMethod C651.)The directions of loads and reactions may bemaintained parallel by judicious use of linkages,rockerbearings,and flexure plates.Eccentricity of loading can beavoided by the use of spherical or cylindrical bearings.Provision must be made in fixture design for relief of torsionalloading to less than 5%of the nominal specimen strength.Refer to Fig.1 for a suggested four-point fixture with asemi-articulating roller configuration.5.3 The bearing block diameter shall be between110and120of the specimen support span,12 mm to 6 mm.A hardenedsteel bearing block,roller assembly,or its equivalent isnecessary to prevent distortion of the loading member.1This 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 1984.Last previous edition approved in 2010 as C1025 91(2010)1.DOI:10.1520/C1025-15.2For 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 6.Test Specimen6.1 SamplingA core sample(minimum of 57 mm diam-eter and 165 mm long)shall be obtained from the electrode inaccordance with Practice C783.6.2 PreparationA test specimen shall be prepared fromt