1、Designation:B40696(Reapproved 2015)Standard Test Method forTransverse Rupture Strength of Cemented Carbides1This standard is issued under the fixed designation B406;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last rev
2、ision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This test method2covers the determination of t
3、hetransverse rupture strength of cemented carbides.1.2 The values stated in inch-pound units are to be regardedas the standard.The SI values in parentheses are provided forinformation only.1.3 This standard does not purport to address the safetyconcerns,if any,associated with its use.It is the respo
4、nsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2.Referenced Documents2.1 ASTM Standards:3B276 Test Method for Apparent Porosity in Cemented Car-bides2.2 ISO Standard:4ISO-3327 HardmetalsD
5、etermination of Transverse Rup-ture Strength3.Significance and Use3.1 This test method is used as a means of determining thequality of cemented carbide grade powders by measuring theirsintered strength.It is performed on test specimens prepared tospecified shape,dimensions,and surface finish;test sp
6、ecimensmay be prepared from finished parts if size permits.There is noknown standard material for this test method.The transverserupture strength of cemented carbides is not a design value.3.1.1 Most commercial cemented carbides have mechanicalbehavior that is best classified as brittle(negligible d
7、uctility).Fracture strengths are dependent on internal or surface flaws.Examples of incoherent internal flaws are macropores,Type Bporosity(see Test Method B276),and inclusions of foreignparticles.Such flaws are randomly distributed spatially and insize within the sintered material.This imparts a st
8、atisticalnature to any transverse rupture strength measurement.3.1.2 The stress distribution in a beam in three-point loadingis non-uniform.It increases linearly along the span to amaximum at the center,and varies linearly through any sectionfrom compression on the top to tension on the bottom.Thema
9、ximum tensile stress therefore occurs at center span in thebottom most fibers of the sample,and is defined as thetransverse rupture strength at failure.Failure is initiated at arandom flaw site,which is most probably not coincident withthe maximum stress.This imparts an additional statisticalnature
10、to transverse rupture strength measurements.4.Apparatus4.1 Either a specially adapted machine for applying the loador a special fixture suitable for use with a conventionalload-applying machine may be used.In either case,theapparatus shall have the following parts:4.1.1 Two ground-cemented-carbide c
11、ylinders 0.250 60.001 in.(6.35 6 0.02 mm)in diameter,at least 0.500 in.(13mm)in length with the long axes parallel,and center to centerspacing of 0.563 6 0.005 in.(14.3 6 0.1 mm).4.1.2 Amovable member(free to move substantially only ina line perpendicular to the plane established by the axes of thet
12、wo cylinders)containing a 0.4 6 0.05-in.(10 6 1.3-mm)cemented-tungsten-carbide ball or a ground-cemented-carbidecylinder of the same dimensions as,and with axis parallel to,those of the two previously mentioned cylinders(see 4.1.1).This ball or cylinder shall be so positioned that movements ofthe me
13、mber will cause the ball or cylinder to contact aspecimen placed on the two lower cylinders at the midpoint ofthe span between them.4.1.3 The apparatus shall be so constructed that the appli-cation of a sufficient load to the movable member to effectbreaking of a specimen will not cause appreciable
14、deflection ofthe line of movement of the movable member and the planeestablished by the two fixed cylinders.The apparatus shall becapable of applying sufficient load to break the specimen.Theapparatus shall be capable of registering the load required1This test method is under the jurisdiction of AST
15、M Committee B09 on MetalPowders and Metal Powder Products and is the direct responsibility of Subcom-mittee B09.06 on Cemented Carbides.Current edition approved Oct.1,2015.Published October 2015.Originallyapproved in 1963.Last previous edition approved in 2010 as B406 96(2010).DOI:10.1520/B0406-96R1
16、5.2This test method is comparable to ISO-3327.3For 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.4Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1(within 6