1、Designation: B 311 93 (Reapproved 2002)e1Test Method forDensity Determination for Powder Metallurgy (P/M) MaterialsContaining Less Than Two Percent Porosity1This standard is issued under the fixed designation B 311; the number immediately following the designation indicates the year oforiginal adopt
2、ion or, in the case of revision, the year of last revision. A number in 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.e1N
3、OTEParagraphs 3.1, 4.1, 4.2, 5.4, and 6.1 were revised editorially in June 2002.1. Scope1.1 This test method covers the determination of density forpowder metallurgy (P/M) materials containing less than twopercent porosity and for cemented carbides. This test method isbased on the water displacement
4、 method.NOTE 1A test specimen that gains mass when immersed in waterindicates the specimen contains surface-connected 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 The values stat
5、ed in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.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 standard to establish appro-priate safety an
6、d health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ISO Standard:3369 Impermeable Sintered Metal Materials andHardmetalsDetermination of Density2NOTE 2The water density table in ISO 3369 differs from the tablecontained in this test me
7、thod.3. Summary of Test Method3.1 Using an analytical balance, the test specimen is firstweighed in air and then in water. The density is determined bycalculation.4. Significance and Use4.1 For P/M materials containing less than two percentporosity, a density measurement may be used to determine ift
8、he part has been densified, either overall or in a critical region,to the degree required for the intended application. Densityalone cannot be used for evaluating the degree of densificationbecause chemical composition and heat treatment affect thepore-free density.4.2 For cemented carbides, a densi
9、ty measurement is nor-mally used to determine if there is any significant deviation incomposition of the carbide grade. For straight tungstencarbide-cobalt grades, the relationship is straightforward. Forcomplex carbide grades (for example, grades containing tan-talum carbide or titanium carbide, or
10、 both, in addition totungsten carbide-cobalt), the situation is more complicated. Ifthe measured density is beyond the specified limits, thecomposition is outside of the specified limits. A measureddensity within the specified limits does not ensure correctcomposition; compensation between two or mo
11、re constituentscould result in the expected density with the wrong composi-tion. Density alone cannot be used for evaluating a cementedcarbide grade.5. Apparatus5.1 Analytical Balance, precision single-pan analytical bal-ance that will permit readings within 0.01 % of the testspecimen mass. The anal
12、ytical balance shall be supported in amanner to eliminate mechanical vibrations and be shieldedfrom air drafts.5.2 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 eva
13、cuation, boiling, or ultrasonicagitation helps to prevent air bubbles from collecting on the test specimenand specimen support when immersed in water.5.3 Water ContainerA glass beaker or other suitabletransparent container should be used to contain the water.NOTE 4A transparent container makes it ea
14、sier to see air bubblesadhering to the test specimen and specimen support when immersed inwater.NOTE 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 w
15、ater.1This test method is under the jurisdiction of ASTM Committee B09 on MetalPowders and Metal Powder Products and is the direct responsibility of Subcom-mittee B09.11 on Near Full Density Powder Metallurgy Materials.Current edition approved Dec. 15, 1993. Published April 1994. Originallypublished
16、 as B 311 56T. Last previous edition B 311 92.2Available from American National Standards Institute, 11 W. 42nd St., 13thFloor, New York, NY 10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.4 Test Specimen Support for Weighing
17、 in WaterTwotypical arrangements are shown in Fig. 1. The 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 ste
18、el, copper,nichromeshall be used for the basket and suspension wire.The maximum recommended diameter of suspension wire tobe used for various mass ranges is:Mass, g Wire Diameter, mm (in.)less than 50 0.12 (0.005)50 to less than 200 0.25 (0.010)200 to less than 600 0.40 (0.015)600 and greater 0.50 (
19、0.020)NOTE 6For the most precise density determinations, it is importantthat the mass and volume of all supporting wires immersed in water beminimized.5.5 ThermometerA thermistor thermometer should beused to measure the temperature of the water to the nearest0.5C.6. Preparation of Test Specimens6.1
20、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 betolerated, several test specimens may be used to reach theminimum mass, provided each test specimen has a mass of notless t
21、han 1.0 g.6.2 All test specimen surfaces shall be thoroughly cleanedof all adhering foreign materials, 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 abras
22、ivegrinding is recommended to remove all rough surfaces.7. Procedure7.1 Weigh the test specimen in air using an analyticalbalance. This is mass A. This and all subsequent weighingsshall be to 0.01% of the test specimen mass, for example:Mass, g Balance Sensitivity, gless than 10 0.000110 to less tha
23、n 100 0.001100 to less than 1000 0.011000 to less than 10 000 0.1It is important that the test specimen, analytical balance andsurrounding air be at a uniform temperature when the weighingis performed.NOTE 7For the most precise density determination, duplicate weigh-ings should be made for all mass
24、determinations. The analytical balanceshould be adjusted to zero prior to each weighing. Duplicate massdeterminations should be averaged before calculating the density.NOTE 8For improved reproducibility, the analytical balance should beperiodically calibrated with a standard mass that is approximate
25、ly equal tothe test specimen mass.7.2 Support the container of water over the pan of thebalance using an suitable bridge as shown in Fig. 2. Thecontainer of water may also be supported below the balance forweighing larger specimens if the balance has a lower beamhook for this purpose. See Fig. 2b. I
26、f this arrangement is used,it is important to shield the suspension wire between thecontainer of water and the bottom of the balance from airdrafts.7.3 Suspend the test specimen support with the test speci-men from the beam hook of the balance. The water shouldcover any wire twists and the specimen
27、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 thebalance beam hook, are free of air bubbles where immersed inthe water and are at the same temperature
28、 as the water andbalance. Care should also be taken to ensure the surface of thewater is free of dust particles.7.4 Weigh the test specimen and specimen support im-mersed in water. This is mass B.7.5 Remove the test specimen. Weigh the test specimensupport immersed in water at the same depth as befo
29、re. 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 change the measured mass.NOTE 9Some balances are capable of being tared. This automaticallyremoves t
30、he 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 andspecimen immersed in water. The mass of the specimen support andspecimen immersed in water is mas
31、s F, which replaces mass B minus massC.7.6 Measure the temperature of the water to the nearest0.5C and record its density E, at that temperature, from Table1.8. Calculation8.1 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)
32、a. Twisted wire arrangement b. Basket support arrangementFIG. 1 Methods for Holding the Test Specimen When Weighing inWaterB3112where: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 specimen suppor
33、t immersed in water, g,F = mass of test specimen in water with mass of specimensupport tared, g, andE = density of water in g/cm3.9. Report9.1 Report the density rounded to the nearest 0.01 g/cm3.10. Precision and Bias10.1 The following precision and bias data were developedusing the procedures cont
34、ained in Test Method B 311 86. Aninterlaboratory study is in-progress using the procedures in thisrevised test method.10.2 For test specimens over 5 g mass, the repeatabilityinterval, r, is 0.025 g/cm3. Duplicate results from the samelaboratory should not be considered suspect at the 95 %confidence
35、level unless they differ by more than r.10.3 For test specimens of over 5 g mass, the reproducibilityinterval, R, is 0.03 g/cm3. Test results from two differentlaboratories should not be considered suspect at the 95 %confidence level unless they differ by more than R.10.4 For test specimens of 1 to
36、5 g mass, the repeatabilityinterval, r, is 0.025 g/cm3.10.5 For test specimens of 1 to 5 g mass, the reproducibilityFIG. 2 Methods for Weighing in WaterTABLE 1 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
37、.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 Technol
38、ogy, 1990, p. 9.10.B3113interval, R, is 0.05 g/cm3.10.6 There is no estimate of bias because there is noaccepted reference material.11. Keywords11.1 cemented carbides; density; hard metals; metal injec-tion molded (MIM) parts; powder metallurgy (P/M); powderforged (P/F) parts; powder metallurgyASTM
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42、 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).B3114
