1、Designation: B 665 03Standard Guide forMetallographic Sample Preparation of Cemented TungstenCarbides1This standard is issued under the fixed designation B 665; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide prescribes a method for preparing cementedcarbides for metallographic examination.1.2 This standard does not purport
3、 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:B 390 P
4、ractice for Evaluating Apparent Grain Size andDistribution of Cemented Tungsten Carbides2B 657 Test Method for Metallographic Determination ofMicrostructure in Cemented Tungsten Carbides23. Significance and Use3.1 This sample preparation procedure may be used toprepare metallographic samples for Tes
5、t Method B 657 andPractice B 390. It does not include all variations of samplepreparation.4. Selection of Specimen4.1 Cemented tungsten carbides are very often in the formof relatively small pieces; it is possible to select and mount theentire piece in such manner as to permit examination of theenti
6、re cross section. When pieces are too large for this,however, they should be sectioned, using a diamond cutoffwheel, to allow viewing as much of a representative crosssection as possible. For micrographs, the area selected shouldrepresent, as nearly as possible, the entire cross section.5. Procedure
7、5.1 There are several acceptable methods for preparingcemented tungsten carbide surfaces for microscopical exami-nation. Basically, they all use diamond wheels for grinding anddiamond powders for lapping. The grinding practices differ, toa minor degree, with respect to grit size of diamond. In allpr
8、actices, however, the final polish is produced by extremelyfine diamond powder lapping, and in all practices care must beexercised to retain the microstructure in its true form and toavoid pull-out of the softer matrix material (usually cobalt).While it is accepted that other procedures may be useds
9、uccessfully, this procedure has proved satisfactory in manylaboratories.5.1.1 MountingWhere possible, specimens should bemounted in a plastic material such as phenol-formaldehyde orpoly(methyl methacrylate) to facilitate polishing withoutrounding the edges. Larger specimens may be polished withoutmo
10、unting. When specimens are too large they may be sec-tioned using a diamond cut-off wheel or they may be fractured(appropriate safety precautions should be used when fracturingspecimens). The area selected for examination should repre-sent, as nearly as possible, the entire cross section.5.1.2 Rough
11、 GrindingThe surface to be examined may beground flat on a surface grinder with a resin-bonded diamondwheel (100 to 220 grit) operated at 5000 to 5500 surface feetper minute (25 to 28 m/s). After the surface is flat, severalclean-up passes are required; the maximum depth of cut shouldbe 0.0005 in. (
12、13 m) per pass and copious amounts of coolantshould be used.5.1.3 PolishingPolishing in three steps using diamondpowder or paste on a synthetic short-napped cloth (the reverseside of photographic paper, or manila file folders may also beused). When automatic polishing equipment is used, a resin-bond
13、ed diamond disk may be substituted in the roughing lap.For manual polishing, speeds of 500 to 600 rpm should beused; automatic polishing generally requires speeds of 100 to200 rpm.5.1.3.1 Roughing LapFor the roughing lap, use NISTGrade 20 diamond powder3(15 to 25 m) dispersed in lightspindle oil. Co
14、mmercial diamond paste and thinner will pro-vide similar results.1This guide is under the jurisdiction of ASTM Committee B09 on MetalPowders and Metal Powder Productsand is the direct responsibility of Subcommit-tee B09.06 on Cemented Carbides.Current edition approved April 10, 2003. Published May 2
15、003. Originallyapproved in 1979. Last previous edition approved in 1997 as B 66592 (1997).2Annual Book of ASTM Standards, Vol 02.05.3Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 3460, Gaithersburg, MD 20899-3460.1Copyright ASTM International, 100 Barr Har
16、bor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.1.3.2 Second LapFor the second lap, use Grade 6diamond powder (4 to 8 m) or an equivalent paste.5.1.3.3 Finishing LapFor the finish lap, use Grade 1diamond powder (less than 2 m) or an equivalent paste.NOTE 1Best results are o
17、btained by applying considerable pressure tothe specimen in all lapping operations. Lack of adequate pressure willresult in pulling out the softer matrix material. It is also essential that thespecimen and operators hands be thoroughly cleaned between allgrinding or polishing steps; ultrasonic clean
18、ing is recommended.6. Precision and Bias6.1 The nature of this guide precludes any statement ofprecision and bias.7. Keywords7.1 cemented carbides; cemented tungsten carbides;microstructureASTM International takes no position respecting the validity of any patent rights asserted in connection with a
19、ny item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technica
20、l committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration
21、at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor
22、 Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).B665032
