1、Designation: B657 11B657 18Standard Guide forMetallographic Identification of Microstructure in CementedCarbides1This standard is issued under the fixed designation B657; 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. Scope*1.1 This guide covers apparatus and procedures for the metallographic identification of microstructures in cemented carbi
3、des.1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitatio
4、ns prior to use. Precautions applying to use of hazardous laboratory chemicals should beobserved for chemicals specified in Table 1.1.3 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for t
5、he Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2B665 Guide for Metallographic Sample Preparation of Cemented Tungsten Carbides2.2 ISO Standard:3ISO 4499
6、HardmetalsMetallographic Determination of Microstructure3. Terminology3.1 Definitions of Symbols:Symbol Definition phase tungsten carbide phase binder (for example, Co, Ni, Fe) phase carbide of a cubic lattice (for example, TiC, TaC, NbC)that may contain other carbides (for example, WC) insolid solu
7、tion-type phases multiple carbides of tungsten and at least one metal of thebinder4. Significance and Use4.1 The microstructure of a cemented carbide affects the materials mechanical and physical properties. This guide is notintended to be used as a specification for carbide grades. Producers and us
8、ers may use the microstructural information as a guidein developing their own specifications.5. Apparatus5.1 Metallographic Microscope capable of magnifications up to 1500 times.5.2 Ordinary metallurgical laboratory equipment.5.3 Equipment for specimen preparation as outlined in Guide B665.1 This gu
9、ide is under the jurisdiction of ASTM Committee B09 on Metal Powders and Metal Powder Products and is the direct responsibility of Subcommittee B09.06on Cemented Carbides.Current edition approved Oct. 1, 2011April 1, 2018. Published October 2011April 2018. Originally approved in 1979. Last previous
10、edition approved in 20052011 asB657 05.B657 11. DOI: 10.1520/B0657-11.10.1520/B0657-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary
11、 page on the ASTM website.3 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous versi
12、on. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes secti
13、on appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16. Specimen Preparation6.1 A suitable procedure is described in Guide B665.7. Procedure7.1 Examine the microstructure by gradual development of the
14、phases by etching. Examples of suitable etching techniques aregiven in Table 1. Examples of the appearance of some expected phases, in fine, medium, and coarse grain sizes, are given in Fig.1.7.2 Determine the presence of -type phases by lightly etching half the section with Technique 1 (see Table 1
15、). Examine theentire section at low magnification and, if necessary, at magnifications up to 1500 times. Phases of -type are colored orange tobrown in the etched portion, and white to light gray in the unetched portion. -Phase may also etch lightly and appear brownishin the etched portion, but will
16、have a brown/gold color even in the unetched portion, thereby differentiating it from -phase. Theother phases remain unetched. Etching by Technique 1 does not preclude subsequent etching by Technique 2. Note and record theexistence of -type phases and their distribution.7.3 Determine the presence of
17、 phases by etching with Technique 2 (Table 1). This phase appears light yellowish brown andhas a typically rounded shape (see Fig. 1). Examine the etched section and note and record the existence of a phase.7.4 Determine the presence of phase in the same etched specimen as in 7.3. The phase appears
18、gray, angular (idiomorphic),and straight-slided (see Fig. 2). Examine the etched section and note and record the presence of phase.TABLE 1 Etching TechniquesNOTE 1The separate solutions of potassium hexacyanoferrate (III) and potassium or sodium hydroxide may be stored for a long time, but must befr
19、eshly mixed each day when used.NOTE 2The times in the conditions for etching are for concentrations listed. Deviation from these concentrations will affect times required to revealdesired structures.EtchingTech-niqueComposition of Etchants Conditions of Etching Objectiveof Etching1 Freshly prepared
20、mixture of equal quantities of10 %(mass mass) aqueous solutions of K3Fe(CN)6 (III)(potassium ferricyanide) and potassiumor sodium hydroxideEtch at approximately 20C for 2 to 10 s. Flush the test-piecesection with water immediately, without removing the oxide layer. Drythe surface carefully with acet
21、one or alcohol without wiping.Identification of phase2 A Same as 1A Etch at approximately 20C for 2 to 4 min.Swabbing surface may enhance the effects of etchant.Identification of , ,and phasesFIG. 1 Phase Fine, All 8.5%Co, 8.5% Co, 5.9% TiC, 5.5% TaC, 2.4% NbC, balance WCB657 1827.5 Identify the pha
22、se in the same etched specimen as 7.3 and 7.4. This phase remains white and is usually the continuous,interstitial phase between the and grains.NOTE 1This procedure follows essentially ISO 4499.FIG. 1 Phase Medium (continued)FIG. 1 Phase Coarse (continued), All 8.5%Co, 8.5% Co, 5.9% TiC, 5.5% TaC, 2
23、.4% NbC, balance WC (continued)B657 1838. Report8.1 The report shall include complete identification of the specimen and the phases present.FIG. 2 Phase Fine, All 10% cobalt, balance WCFIG. 2 Phase Medium (continued)B657 1849. Keywords9.1 cemented carbides; hardmetals; microstructure; powder metallu
24、rgySUMMARY OF CHANGESCommittee B09 has identified the location of selected changes to this standard since the last issue(B657 05B657 11) that may impact the use of this standard. (Approved October 2011.)April 2018.)(1) Replaced original micrographsAddition of Note 2 withto Table 1new digital images
25、containing micron bars(2) The chemical composition of the pictured materials have been listed in the “Figure” headings.”Added comment concerningswabbing of surface.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this
26、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 technical committee and must be r
27、eviewed 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 at a meeting of therespons
28、ible 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 Drive, PO Box C700, West
29、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). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 2 Phase Coarse (continued), All 10% cobalt, balance WC (continued)B657 185
