1、Designation: B 276 05e1Standard Test Method forApparent Porosity in Cemented Carbides1This standard is issued under the fixed designation B 276; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in
2、 parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.e1NOTECorrected adjunct information in November 2006.1. Scope*1.1 This tes
3、t method specifies procedures for the metallo-graphic determination of apparent porosity in cemented car-bides.NOTE 1The term “apparent porosity” is construed to mean allmicrostructures observed on a properly prepared, unetched surface,including structures resulting from uncombined carbon, non-metal
4、licinclusions, etc., as well as true, inherent porosity.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 and determine the applica-bilit
5、y of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B 243 Terminology of Powder MetallurgyB 665 Guide for Metallographic Sample Preparation ofCemented Tungsten Carbides2.2 ASTM Adjunct:3ADJB0276A Apparent Porosity (4 prints of 4 photomicro-graphs each)3. Terminology3.
6、1 DefinitionsDefinition of powder metallurgy terms canbe found in Terminology B 243.4. Significance and Use4.1 Cemented carbide materials may contain small voidsthat, depending on the application, may affect the performanceof the product. To assist users in specifying the maximumacceptable level of
7、porosity, this test method illustrates a broadrange of porosity levels for each of three porosity types. Thistest method is not intended to be used as a specification, but thelevels shown here may be cited in specifications written byproducers and users of cemented carbides.5. Interferences5.1 Lack
8、of adequate pressure on the specimen duringpolishing may result in material being torn from the surface ofthe specimen. This condition may be erroneously interpreted asporosity.6. Apparatus6.1 A metallographic microscope permitting observationand measurement up to a magnification of 2003.6.2 Equipme
9、nt for the metallographic preparation of testspecimens.7. Specimen Preparation7.1 Where possible, specimens should be metallographi-cally mounted in a plastic material, so that they can be polishedwithout rounding the edges. Larger specimens may be polishedwithout mounting. When the specimens are to
10、o large, theyshall be sectioned using a diamond cut-off wheel or byfracturing (appropriate safety precautions shall be utilizedwhen fracturing a specimen). The area selected for examina-tion should represent, as nearly as possible, the entire crosssection.7.2 The specimen shall be prepared for metal
11、lographicexamination. A suitable procedure is described in PracticeB 665.The surface to be examined shall be unetched and free ofgrinding and polishing marks.8. Procedure8.1 Pore size shall be defined as the maximum dimension ofthe pore. Make special reference to the presence of cracks andslits, as
12、well as nonmetallic inclusions.8.2 Classification of Type “A” and “C” apparent porosity isbased entirely on comparison of the microstructures found withthe illustrations in Figs. 1, 3 and 4 of ADJB0276A3with due1This test method is under the jurisdiction of ASTM Committee B09 on MetalPowders and Met
13、al Powder Products and is the direct responsibility of Subcom-mittee B09.06 on Cemented Carbides.Current edition approved Dec. 1, 2005. Published December 2005. Originallyapproved in 1954. Last previous edition approved in 2000 as B 276 91 (2000).2For referenced ASTM standards, visit the ASTM websit
14、e, 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.3Available from ASTM International Headquarters. Order Adjunct No.ADJB0276A.1*A Summary of Changes section appears
15、 at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.consideration to the difference in field of view of the micro-scope compared to the area of the illustrations. This can beaccomplished by scanning the specim
16、en surface under themicroscope at the appropriate magnification, and noting whichof the illustrations most nearly represents the fields observed.Choose an area fully representative of the specimen surface forcomparison with the illustrations.NOTE 2The illustrations in Figs. 14 of ADJB0276A represent
17、 only aportion of the field of view typically observed in modern microscopes.Typically, the field of view of a microscope is 6.53 larger than the areain these figures. The exact relationship between the area observed at anygiven magnification in the microscope and the area of the illustrations canbe
18、 determined using the method in Annex A1.8.2.1 Classify pores #10 m as Type A (see Fig. 1 ofADJB0276A), and examine at a magnification of 2003. Reportthe porosity level by reference to the appropriate illustrationwith consideration to the relationship of area between theillustration and that observe
19、d in the microscope, and designateas A02, A04, A06, or A08. If the level of Type A pores is lessthan 50 % of that shown in the illustration for A02, thendesignate this as A00. If the porosity is not uniform over thearea of the test-piece section being examined, identify thelocation of the section, f
20、or example, as top, bottom, edge, rim(case), core, and so forth.8.2.2 Classify pores in the range from 10 to #25 m asType B (see Fig. 2 of ADJB0276A), and examine at amagnification of 1003.8.2.2.1 If the number of “B” pores appears to be less thanor equal to that represented by B02, with considerati
21、on to therelationship of area between the illustrations in Fig. 2 ofADJB0276A and that observed in the microscope (see A1.3),count the number of “B” pores in a representative area ($0.25cm2). Divide this count by the area examined (see A1.3)toobtain the number of “B” pores/cm2. If this number is les
22、s than70 pores/cm2, designate this as B00-#, where # is the numberof “B” pores/cm2so obtained. If the number is greater than orequal to 70 pores/cm2, designate this as B02. If no “B” poresare observed, designate this as B00-0.8.2.2.2 If the number of “B” pores appears to be greater thanthat represen
23、ted by B02, with consideration to the relationshipof area between the illustrations in Fig. 2 of ADJB0276A, andthat observed in the microscope (see A1.4), classify the “B”porosity as B04, B06, or B08 with reference to the illustrationsin Fig. 2 ofADJB0276A. If the porosity is not uniform over theare
24、a of the test-piece section being examined, identify thelocation of the section, for example, as top, bottom, edge, rim(case), core, and so forth.8.2.3 Count and report pores larger than 25 m as thenumber of pores per cm2. Choose the size ranges as follows:25 to #75 m, 75 to #125 m, and over 125 m.8
25、.2.4 Classify porosity resulting from uncombined carbonas Type C (see Figs. 3 and 4 of ADJB0276A), and examine ata magnification of 100 or 2003. Report the porosity level byreference to the appropriate illustration with consideration tothe relationship of area between the illustrations in Figs. 3 an
26、d4 of ADJB0276A, and that observed in the microscope, anddesignate as C02, C04, C06, or C08. If the porosity ofuncombined carbon is not uniform over the area of thetest-piece section being examined, identify the location of thesection, for example as top, bottom, edge, rim (case), core, andso forth.
27、 If no uncombined carbon is observed, designate this asC00.9. 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 Results obtained, and9.1.4 Details of any occurrence that may have affected theresult.10. Precis
28、ion and Bias10.1 A precision and bias statement cannot be made for thistest method.11. Keywords11.1 apparent porosity; cemented carbides; hardmetals; mi-crostructure; powder metallurgyANNEX(Mandatory Information)A1. DETERMINATION OF THE FIELD OF VIEW OF MICROSCOPEA1.1 Using a metallograph, view a st
29、age micrometer.A1.2 Determine the diameter (D) of the field of view to aprecision of 0.002 cm.A1.3 Calculate the area of the field of view using theformula:A 5pD/2!2(A1.1)where:A = area of field of view, cm2, andD = diameter of field of view, cm.A1.4 Determine the number of photomicrographs equiva-l
30、ent to the field of view of the microscope at the appropriatemagnification using the following:At 1003:# photographs = A/0.00676 cm2using ADJB0276AAt 2003:# photographs = A/0.0017cm2using ADJB0276AB27605e12SUMMARY OF CHANGESCommittee B09 has identified the location of selected changes to this standa
31、rd since the last issue, B 276 91(2000), that may impact the use of this standard. (Approved Dec. 1, 2005.)(1) Removed 6.1, ordinary laboratory apparatus.(2) Removed Note 2 and placed this sentence in 7.2.(3) Modified 8.2 to specify that porosity type A and C areclassified by comparison to ADJB0276A
32、, while consideringthe relationship of the area of the illustration to the field ofview of the microscope. The term photomicrographs andfigures have been replaced by the term illustrations.(3) The illustrations that were attached to this test methodhave been removed, as well as all reference to them
33、. Porositycan only be evaluated with reference to the illustrations inADJB0276A, and all sections of this test method have been sorevised.All ratings must consider the relationship of the area ofthe illustrations in ADJB0276A to that of the field of view ofthe microscope used.(4) The size range of p
34、orosity typeA, B, and larger have beenreclassified as: “A”#10 m, “B” 10 to#25 m, 25 to#75,75 to #125 m, and over 125 m.(5) Porosity of type “A” has been reclassified to indicate thata rating of A00 is anything that has less than 50 % of “A”porosity compared to A02 of Fig. 1 of ADJB0276A.(6) Porosity
35、 of type “B” that is less than 50 % of thatcompared to B02 of Fig 2 of ADJB0276A is rated as B00-#,where # is the number of “B” pores/cm2.(7) Section 8.3 has been removed.(8) AnAnnex has been added for determination of the field ofview of microscope.(9) The illustrations in ADJB0276A have had a micr
36、onmarker added to each field. The vol% porosity has beenremoved from each field. The note (this figure is reprinted fromISO 4505) has been removed from all figures.(10) Figure 1, Type A Apparent Porosity (3100) has beenremoved from ADJB0276A.ASTM International takes no position respecting the validi
37、ty of any patent rights asserted in connection with any 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 subjec
38、t to revision at any time by the responsible technical 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 Headquarte
39、rs. Your comments will receive careful consideration 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
40、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).B27605e13
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