1、Designation: B 311 08Standard Test Method forDensity of Powder Metallurgy (PM) Materials ContainingLess Than Two Percent Porosity1This standard is issued under the fixed designation B 311; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revi
2、sion, 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.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This test method c
3、overs the determination of density forpowder metallurgy (PM) materials containing less than twopercent porosity and for cemented carbides. This test method isbased on the water displacement method.NOTE 1A test specimen that gains mass when immersed in waterindicates the specimen contains surface-con
4、nected porosity. Unsealedsurface porosity will absorb water and cause density values higher than thetrue value. This test method is not applicable if this problem occurs.1.2 With the exception of density values, for which theg/cm3unit is the industry standard, the values stated in SI unitsare to be
5、regarded as the standard. Values in inch-pound unitsare shown in parentheses and result from conversion inaccordance with IEEE/ASTM Standard SI 10.1.3 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 sta
6、ndard 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:2B 243 Terminology of Powder Metallurgy2.2 IEEE/ASTM Standard:SI 10 American National Standard for Use of the Interna-tional S
7、ystem of Units (SI): The Modern Metric System2.3 ISO Standard:3369 Impermeable Sintered Metal Materials andHardmetalsDetermination of Density3NOTE 2The water density table in ISO 3369 differs from the tablecontained in this test method.3. Terminology3.1 Definitions of powder metallurgy (PM) terms ca
8、n befound in Terminology B 243. Additional descriptive material isavailable in the Related Material section of Vol. 02.05 of theAnnual Book of ASTM Standards.4. Summary of Test Method4.1 Using an analytical balance, the test specimen is firstweighed in air and then in water. The density is determine
9、d bycalculation using Archimedes principle.5. Significance and Use5.1 For PM materials containing less than two percentporosity, a density measurement may be used to determine ifthe part has been densified, either overall or in a critical region,to the degree required for the intended application. D
10、ensityalone cannot be used for evaluating the degree of densificationbecause chemical composition and heat treatment affect thepore-free density.5.2 For cemented carbides, a density measurement is nor-mally used to determine if there is any significant deviation incomposition of the carbide grade. F
11、or straight tungstencarbide-cobalt grades, the relationship is straightforward. Forcomplex carbide grades (for example, grades containing tan-talum carbide or titanium carbide, or both, in addition totungsten carbide-cobalt), the situation is more complicated. Ifthe measured density is beyond the sp
12、ecified limits, thecomposition is outside of the specified limits. A measureddensity within the specified limits does not ensure correctcomposition; compensation between two or more constituentscould result in the expected density with the wrong composi-tion. Density alone cannot be used for evaluat
13、ing a cementedcarbide grade.6. Apparatus6.1 Analytical Balance precision single-pan analyticalbalance that will permit readings within 0.01 % of the testspecimen mass. The analytical balance shall be supported in a1This test method is under the jurisdiction of ASTM Committee B09 on MetalPowders and
14、Metal Powder Products and is the direct responsibility of Subcom-mittee B09.11 on Near Full Density Powder Metallurgy Materials.Current edition approved Dec. 1, 2008. Published January 2009. Originallyapproved in 1956 . Last previous edition approved in 2002 as B 311 93(2002)1.2For referenced ASTM s
15、tandards, 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.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Fl
16、oor, New York, NY 10036, http:/www.ansi.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.manner to eliminate mechanical vibrations and be shieldedfrom air drafts. S
17、ee Table 1.6.2 Weighing LiquidDistilled or deionized water to which0.05 to 0.1 volume percent of a wetting agent has been addedto reduce the effects of surface tension.NOTE 3Degassing the water by evacuation, boiling, or ultrasonicagitation helps to prevent air bubbles from collecting on the test sp
18、ecimenand specimen support when immersed in water.6.3 Water ContainerA glass beaker or other suitabletransparent container should be used to contain the water.NOTE 4A transparent container makes it easier to see air bubblesadhering to the test specimen and specimen support when immersed inwater.NOTE
19、 5For the most precise density determination, the water con-tainer should be of a size that the level of the water does not rise more than2.5 mm (0.10 in.) when the test specimen is lowered into the water.6.4 Test Specimen Support for Weighing in WaterTwotypical arrangements are shown in Fig. 1. The
20、 suspension wiremay be twisted around the test specimen or the test specimenmay be supported in a wire basket that is attached to thesuspension wire. For either arrangement, a single corrosionresistant wirefor example, austenitic stainless steel, copper,nichromeshall be used for the basket and suspe
21、nsion wire.For the maximum recommended diameter of suspension wireto be used for various mass ranges see Table 2.NOTE 6For the most precise density determinations, it is importantthat the mass and volume of all supporting wires immersed in water beminimized.6.5 ThermometerA thermometer with an accur
22、acy of0.2 C to measure the temperature of the water.7. Preparation of Test Specimens7.1 A complete part or a section of a part may be used forthe test specimen. For the highest precision, the test specimenshall have a minimum mass of 5.0 g. If less precision can beTABLE 1 Balance SensitivityMass, g
23、Balance Sensitivity, gless than 10 0.000110 to less than 100 0.001100 to less than 1000 0.011000 to less than 10 000 0.1FIG. 1 Methods for Holding the Test Specimen When Weighing in WaterTABLE 2 Maximum Recommended Wire DiameterMass, g Wire Diameter, mm (in.)less than 50 0.12 (0.005)50 to less than
24、200 0.25 (0.010)200 to less than 600 0.40 (0.015)600 and greater 0.50 (0.020)B311082tolerated, several test specimens may be used to reach theminimum mass, provided each test specimen has a mass of notless than 1.0 g.7.2 All test specimen surfaces shall be thoroughly cleanedof all adhering foreign m
25、aterials, such as, dirt, grease, oil,oxide scale, metal powders or assembly materials. For cutspecimens, care must be used to avoid rough surfaces to whichan air bubble can adhere. A100-grit sanding or abrasivegrinding is recommended to remove all rough surfaces.8. Procedure8.1 Weigh the test specim
26、en in air using an analyticalbalance. This is mass A. This and all subsequent weighingsshall be to 0.01% of the test specimen mass.It is important that the test specimen, analytical balance andsurrounding air be at a uniform temperature when the weighingis performed.NOTE 7For improved reproducibilit
27、y, the analytical balance should beperiodically calibrated with a standard mass that is approximately equal tothe test specimen mass.8.2 Support the container of water over the pan of thebalance using a suitable bridge as shown in Fig. 2. Thecontainer of water may also be supported below the balance
28、 forweighing larger specimens if the balance has a lower beamhook for this purpose. See Fig. 2b. If this arrangement is used,it is important to shield the suspension wire between thecontainer of water and the bottom of the balance from airdrafts.8.3 Suspend the test specimen support with the test sp
29、eci-men from the beam hook of the balance. The water shouldcover any wire twists and the specimen support basket by atleast 6 mm (14 in.) to minimize the effect of surface tensionforces on the weighing. Care should be taken to ensure that thetest specimen and specimen support hang freely from thebal
30、ance beam hook, are free of air bubbles where immersed inthe water and are at the same temperature as the water andbalance. Care should also be taken to ensure the surface of thewater is free of dust particles.8.4 Weigh the test specimen and specimen support im-mersed in water. This is mass B.8.5 Re
31、move the test specimen. Weigh the test specimensupport immersed in water at the same depth as before. This ismass C. Care should be taken to ensure that the suspensionsupport is free of air bubbles and that the suspension wire is notimmersed below its normal hanging depth as a change in depthwill ch
32、ange the measured mass.NOTE 8Some balances are capable of being tared. This automaticallyremoves the necessity of reweighing the specimen support every time. Inthis case, tare the specimen support alone, immersed in water to the samedepth as with the specimen, before weighing the specimen support an
33、dFIG. 2 Methods for Weighing in WaterB311083specimen immersed in water. The mass of the specimen support andspecimen immersed in water is mass F, which replaces mass B minusmass C.8.6 Measure the temperature of the water to the nearest0.5 C and record its density E, at that temperature, fromTable 3.
34、9. Calculation9.1 Calculate the density as follows:Density 5 D 5 Mass/Volume (1)D 5 A/A 2 B 2 C!#E(2)D 5 A 3 E!/A 2 B 1 C! 5 A 3 E!/A 2 F! (3)where:D = density of test specimen, g/cm3,A = mass of test specimen in air, g,B = apparent mass of test specimen and specimen supportin water, g,C = mass of s
35、pecimen support immersed in water, g,F = mass of test specimen in water with mass of specimensupport tared, g, andE = density of water in g/cm3.10. Report10.1 Report the density rounded to the nearest 0.01 g/cm3.11. Precision and Bias11.1 The following precision data were developed using theprocedur
36、es contained in Test Method B 311 86. The results ofthe interlaboratory study that was conducted are summarized ina Research Report4. An interlaboratory study is planned usingthe procedures in this revised test method.11.2 There is no estimate of bias because no material havingan accepted reference
37、value is available.12. Keywords12.1 cemented carbides; density; hard metals; metal injec-tion molded (MIM) parts; powder metallurgy (PM); powderforged (PF) parts; powder metallurgySUMMARY OF CHANGESCommittee B09 has identified the location of selected changes to this standard since the last issue(B
38、311 93(2002)1) that may impact the use of this standard.(1) Terminology section added (Section 3) and reference madeto B 243 in Section 2.1.(2) Deleted reference to “thermistor” thermometer in Section6.5.(3) Deleted NOTE 7 (duplicate weighings)(4) Included a reference to the Research Report on file
39、atASTM Headquarters (RR B09-1014).(5) New versions of Figures 1 and 2 have been included.ASTM 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 advised that determination o
40、f 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 reapproved or withdrawn.
41、 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 you feel that your comm
42、ents 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
43、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).4Supporting data have been filed at ASTM International Headquarters and maybe obtained by re
44、questing Research Report RR: B09-1014.TABLE 3 Density of Air-Free WaterATemperature (C) Density (g/cm3)18.0 0.998618.5 0.998519.0 0.998419.5 0.998320.0 0.998220.5 0.998121.0 0.998021.5 0.997922.0 0.997822.5 0.997623.0 0.997523.5 0.997424.0 0.997324.5 0.997225.0 0.997025.5 0.996926.0 0.996826.5 0.996627.0 0.996527.5 0.996428.0 0.996228.5 0.996129.0 0.995929.5 0.995830.0 0.9956AMetrological Handbook 145,“ Quality Assurance for Measurements,” NationalInstitute of Standards and Technology, 1990, p. 9.10.B311084
