1、Designation: B 930 03 (Reapproved 2008)Standard Test Method forRating Grain Size and Frequency of Abnormally LargeGrains in Cemented Tungsten Carbides (Hardmetals)1This standard is issued under the fixed designation B 930; the number immediately following the designation indicates the year oforigina
2、l 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. Scope1.1 This test method describes a procedure for measuringabnormally lar
3、ge grains and the frequency of those grains incemented tungsten carbides (hardmetals).1.2 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 a
4、nd determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B 243 Terminology of Powder MetallurgyB 406 Test Method for Transverse Rupture Strength ofCemented CarbidesB 657 Guide for Metallographic Identification of Micro-structure in Cemented Ca
5、rbidesB 665 Guide for Metallographic Sample Preparation ofCemented Tungsten Carbides3. Terminology3.1 DefinitionsDefinitions of powder metallurgy termscan be found in Terminology B 243.3.2 Definitions of Terms Specific to This Standard:3.2.1 E-Ratingthe number/cm2of grains larger than aspecified siz
6、e in a fully-etched specimen.3.2.2 L-Ratingthe size, in m, of the largest grain ob-served in a fully-etched specimen.4. Summary of Test Method4.1 A polished and fully etched specimen/specimens havinga minimum observable area of 0.5 cm2is examined using ametallograph. Abnormally large grains, compare
7、d to the finer-grained background material, are identified. These grains arecategorized as: (1) The number of grains larger than a specifiedsize, or (2) The largest grain observed, or both.5. Significance and Use5.1 The microstructure and grain growth of cemented tung-sten carbides affect the materi
8、als mechanical and physicalproperties. The grain size and distribution will affect thematerials wear resistance and fracture toughness. Abnormallylarge grains as compared to the background may introduce anarea of weakness in a sintered part.5.2 This test method may be used in acceptance testing ofce
9、mented tungsten carbide materials or the tungsten carbidepowder used in their manufacture. The specified grain size usedfor the E-Rating is to be agreed upon between purchaser andsupplier.6. Apparatus6.1 Metallographic Microscope, capable of magnificationsof up to 15003.6.2 Ordinary metallurgical la
10、boratory equipment.6.3 Equipment for specimen preparation as outlined inGuide B 665.7. Test Specimens7.1 Specimen SizeThe recommended specimen shall bethe standard transverse rupture specimen as specified in TestMethod B 406; that is, ground to the following dimensions:5.00 6 0.25 mm (0.200 6 0.010
11、in) thick by 6.25 6 0.25 mm(0.250 6 0.010 in) wide by 19.0 mm (0.750 6 in) long.Alternatively, the specimen shall be a size to provide aminimum 0.5 cm2surface area of examination, or it mayconsist of several samples that provide this minimum area.7.2 Specimen Preparation:7.2.1 Polish the specimen/sp
12、ecimens according to the pro-cedure described in Guide B 665, or other suitable metallo-graphic polishing procedure. If using the recommended speci-men, polish the 6.25 by 19.0 mm side.1This test method is under the jurisdiction of ASTM Committee B09 on MetalPowders and Metal Powder Products and is
13、the direct responsibility of Subcom-mittee B09.06 on Cemented Carbides.Current edition approved April 1, 2008. Published May 2008. Originallyapproved in 2003. Last previous edition approved in 2003 as B 930 03.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Custo
14、mer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.2.2 Etch the specimen according to
15、 the procedure de-scribed in Test Method B 657, or other suitable etchingprocedure that will reveal the tungsten carbide grain structure.8. Procedure8.1 Examine a fully-etched specimen at a minimum of2003 magnification.8.1.1 For E-ratingCount the number of grains larger thanthe specified size observ
16、ed in the full cross-section of thepolished and etched specimen/specimens. Divide this numberby the total area examined (1.2 cm2for the recommendedtransverse rupture specimen) to obtain a number of grains/cm2.8.1.2 For L-RatingMeasure the largest dimension of thelargest grain observed in the polishe
17、d and etched specimen/specimens.9. Report9.1 The report shall include the following:9.1.1 Reference to this test method,9.1.2 Complete identification of the test specimen,9.1.3 Details of any occurrence that may have affected theresults,9.1.4 The total area examined, in cm2,9.1.5 The E-Rating as gra
18、ins/cm2, rounded to the nearestwhole integer, and9.1.6 The L-Rating in m, rounded to the nearest wholeinteger.10. Precision and Bias10.1 No statement regarding precision and bias of this testmethod can be made at this time. Plans for an interlaboratorystudy are being formulated.11. Keywords11.1 abno
19、rmally large grains; cemented carbides; cementedtungsten carbide; E-rating; hardmetals; L-rating;microstructureASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advise
20、d 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 technical committee and must be reviewed every five years andif not revised, either re
21、approved 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 at a meeting of theresponsible technical committee, which you may attend. If y
22、ou 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 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).B 930 03 (2008)2
