1、Designation:C59893(Reapproved 2013)Standard Test Method forAnnealing Point and Strain Point of Glass by BeamBending1This standard is issued under the fixed designation C598;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of
2、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.Scope1.1 This test method covers the determination of the anneal-ing point and the strain point of a glass by measuring the rateof m
3、idpoint viscous bending of a simply loaded glass beam.2However,at temperatures corresponding to the annealing andstrain points,the viscosity of glass is highly time-dependent.Hence,any viscosities that might be derived or inferred frommeasurements by this procedure cannot be assumed to repre-sent eq
4、uilibrium structural conditions.1.2 The annealing and strain points shall be obtained fol-lowing a specified procedure after direct calibration of theapparatus using beams of standard glasses having knownannealing and strain points such as those supplied and certifiedby the National Institute of Sta
5、ndards and Technology.31.3 This test method,as an alternative to Test Method C336is particularly well suited for glasses that for one reason oranother are not adaptable for flame working.It also has theadvantages that thermal expansion and effective lengthcorrections,common to the fiber elongation m
6、ethod,areeliminated.1.4The values stated in metric units are to be regarded asthe standard.The values given in parentheses are for informa-tion only.1.5 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 stan
7、dard 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:4C336 Test Method for Annealing Point and Strain Point ofGlass by Fiber Elongation3.Terminology3.1 Definitions:3.1.1 annealing r
8、angethe range of glass temperature inwhich stresses in glass articles can be relieved at a commer-cially desirable rate.For purposes of comparing glasses,theannealing range is assumed to correspond with the tempera-tures between the annealing point(A.P.)and the strain point(St.P.).3.1.2 annealing po
9、intthat temperature at which internalstresses in a glass are substantially relieved in a matter ofminutes.During a test in accordance with the requirements ofthis test method,the midpoint rate of viscous deflection of thetest beam is measured by an extensometer with suitablemagnification during cool
10、ing at a rate of 4 6 1C/min.Thenominal deflection rate at the annealing point ideally is asfollows:Deflection rate,cm/min52.67310211L3M!/Ic(1)where:L=support span,cm;M=centrally applied load,g;andIc=cross-section moment of inertia of test beam,cm4(seeAppendix X1).3.1.3 strain pointthat temperature a
11、t which internalstresses in a glass are substantially relieved in a matter ofhours.The strain point is determined by extrapolation of theannealing point data and is the temperature at which theviscous deflection rate is 0.0316 times that observed at theannealing point.1This test method is under the
12、jurisdiction of ASTM Committee C14 on Glassand Glass Products and is the direct responsibility of Subcommittee C14.04 onPhysical and Mechanical Properties.Current edition approved Oct.1,2013.Published October 2013.Originallyapproved in 1967.Last previous edition approved in 2008 as C598 93(2008).DOI
13、:10.1520/C0598-93R13.2Hagy,H.E.,“Experimental Evaluation of Beam Bending Method of Deter-mining Glass Viscosities in the Range 108to 1015Poises,”Journal of the AmericanCeramic Society,Vol 46,No.2,1963,pp.9597.3NIST Special Publication 260.4For referenced ASTM standards,visit the ASTM website,www.ast
14、m.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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.Significance an
15、d Use4.1 This test method offers an alternate procedure to TestMethod C336 for determining the annealing and strain pointsof glass.It is particularly recommended for glasses notadaptable to flame working.Also fewer corrections are neces-sary in data reduction.5.Apparatus5.1 The apparatus shall consi
16、st of a furnace,a means ofcontrolling its temperature and cooling rate,a specimen holderand loading rod,and a means of observing the rate of midpointviscous deflection of the glass beam.5.1.1 FurnaceThe furnace shall be electrically heated byresistance-wire windings of either platinum-rhodium or 80-20Ni-Cr alloys.A cutaway drawing of a typical furnace is shownin Fig.1.Dimensions and details of the furnace constructionare not critical,but a cylindrical furnace of height of 255 mm(10 in.),outside
