1、Designation: B311 13B311 17Standard Test Method forDensity of Powder Metallurgy (PM) Materials ContainingLess Than Two Percent Porosity1This standard is issued under the fixed designation B311; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、 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.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope*1.1 This tes
3、t method covers the determination of density for powder metallurgy (PM) materials containing less than two percentporosity and for cemented carbides. This test method is based on the water displacement method.NOTE 1A test specimen that gains mass when immersed in water indicates the specimen contain
4、s surface-connected porosity. Unsealed surfaceporosity will absorb water and cause density values higher than the true value. This test method is not applicable if this problem occurs.1.2 With the exception of the values for density and the mass used to determine density, for which the use of the gr
5、am per cubiccentimetercentimetre (g/cm3) and gram (g) units is the long-standing industry practice, the values in SI units are to be regardedas standard.1.3 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 t
6、his standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles f
7、or the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2B243 Terminology of Powder MetallurgyE691 Practice for Conducting an Interlaboratory Study to Determi
8、ne the Precision of a Test MethodE456 Terminology Relating to Quality and Statistics3. Terminology3.1 Definitions of powder metallurgy (PM) terms can be found in Terminology B243. Additional descriptive material isavailable in the Related Material section of Vol. 02.05 of the Annual Book of ASTM Sta
9、ndards.4. Summary of Test Method4.1 Using an analytical balance, the test specimen is first weighed in air and then in water. The density is determined bycalculation using Archimedes principle.5. Significance and Use5.1 For PM materials containing less than two percent porosity, a density measuremen
10、t may be used to determine if the part hasbeen densified, either overall or in a critical region, to the degree required for the intended application. Density alone cannot beused for evaluating the degree of densification because chemical composition and heat treatment affect the pore-free density.1
11、 This test method is under the jurisdiction ofASTM Committee B09 on Metal Powders and Metal Powder Products and is the direct responsibility of Subcommittee B09.11on Near Full Density Powder Metallurgy Materials.Current edition approved April 1, 2013April 1, 2017. Published June 2013April 2017. Orig
12、inally approved in 1956. Last previous edition approved in 2008 as B311 08.DOI: 10.1520/B0311-13.10.1520/B0311-17.2 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
13、 standards Document Summary page on the ASTM website.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 version. Becauseit may not be technically possible to adequately depict all changes acc
14、urately, 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 section appears at the end of this standardCopyright ASTM International, 100 Barr Harbo
15、r Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 For cemented carbides, a density measurement is normally used to determine if there is any significant deviation incomposition of the carbide grade. For straight tungsten carbide-cobalt grades, the relationship is straightforw
16、ard. For complexcarbide grades (for example, grades containing tantalum carbide or titanium carbide, or both, in addition to tungstencarbide-cobalt), the situation is more complicated. If the measured density is beyond the specified limits, the composition is outsideof the specified limits. A measur
17、ed density within the specified limits does not ensure correct composition; compensation betweentwo or more constituents could result in the expected density with the wrong composition. Density alone cannot be used forevaluating a cemented carbide grade.6. Apparatus6.1 Analytical Balanceprecision si
18、ngle-pan analytical balance that will permit readings within 0.01% of the test specimenmass. The analytical balance shall be supported in a manner to eliminate mechanical vibrations and be shielded from air drafts.See Table 1.6.2 Weighing LiquidDistilled or deionized water to which 0.05 to 0.1 volum
19、e percent of a wetting agent has been added toreduce the effects of surface tension.NOTE 2Degassing the water by evacuation, boiling, or ultrasonic agitation helps to prevent air bubbles from collecting on the test specimen andspecimen support when immersed in water.6.3 Water ContainerA glass beaker
20、 or other suitable transparent container should be used to contain the water.NOTE 3A transparent container makes it easier to see air bubbles adhering to the test specimen and specimen support when immersed in water.NOTE 4For the most precise density determination, the water container should be of a
21、 size that the level of the water does not rise more than 2.5mm when the test specimen is lowered into the water.6.4 Test Specimen Support for Weighing in WaterTwo typical arrangements are shown in Fig. 1. The suspension wire may betwisted around the test specimen or the test specimen may be support
22、ed in a wire basket that is attached to the suspension wire.For either arrangement, a single corrosion resistant wirefor example, austenitic stainless steel, copper, nichromeshall be usedfor the basket and suspension wire. For the maximum recommended diameter of suspension wire to be used for variou
23、s massranges see Table 2.NOTE 5For the most precise density determinations, it is important that the mass and volume of all supporting wires immersed in water be minimized.6.5 ThermometerA thermometer with an accuracy of0.2 C to measure the temperature of the water.7. Preparation of Test Specimens7.
24、1 A complete part or a section of a part may be used for the test specimen. For the highest precision, the test specimen shallhave a minimum mass of 5.0 g. If less precision can be tolerated, several test specimens may be used to reach the minimum mass,provided each test specimen has a mass of not l
25、ess than 1.0 g.7.2 All test specimen surfaces shall be thoroughly cleaned of all adhering foreign materials, such as, dirt, grease, oil, oxide scale,metal powders or assembly materials. For cut specimens, care must be used to avoid rough surfaces to which an air bubble canadhere. A 100-grit sanding
26、or abrasive grinding is recommended to remove all rough surfaces.8. Procedure8.1 Weigh the test specimen in air using an analytical balance. This is mass A. This and all subsequent weighings shall be to0.01% of the test specimen mass.It is important that the test specimen, analytical balance and sur
27、rounding air be at a uniform temperature when the weighing isperformed.NOTE 6For improved reproducibility, the analytical balance should be periodically calibrated with a standard mass that is approximately equal to thetest specimen mass.8.2 Support the container of water over the pan of the balance
28、 using a suitable bridge as shown in Fig. 2. The container of watermay also be supported below the balance for weighing larger specimens if the balance has a lower beam hook for this purpose.See Fig. 2b. If this arrangement is used, it is important to shield the suspension wire between the container
29、 of water and the bottomof the balance from air drafts.TABLE 1 Balance SensitivityReadabilityMass, g Balance Sensitivity, gMass, g Balance Readable to, gless than 10 0.000110 to less than 100 0.001100 to less than 1000 0.011000 to less than 10 000 0.1B311 1728.3 Suspend the test specimen support wit
30、h the test specimen from the beam hook of the balance. The water should cover anywire twists and the specimen support basket by at least 6 mm to minimize the effect of surface tension forces on the weighing.Care should be taken to ensure that the test specimen and specimen support hang freely from t
31、he balance beam hook, are free ofair bubbles where immersed in the water and are at the same temperature as the water and balance. Care should also be taken toensure the surface of the water is free of dust particles.8.4 Weigh the test specimen and specimen support immersed in water. This is mass B.
32、8.5 Remove the test specimen. Weigh the test specimen support immersed in water at the same depth as before. This is massC. Care should be taken to ensure that the suspension support is free of air bubbles and that the suspension wire is not immersedbelow its normal hanging depth as a change in dept
33、h will change the measured mass.NOTE 7Some balances are capable of being tared. This automatically removes the necessity of reweighing the specimen support every time. In thiscase, tare the specimen support alone, immersed in water to the same depth as with the specimen, before weighing the specimen
34、 support and specimenimmersed in water. The mass of the specimen support and specimen 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 3.9. Calculation9.1 Calculate the
35、 density as follows:Density5D 5Mass/Volume (1)D 5A/A 2B 2C!#E (2)D 5A 3E!/A 2B1C! 5A 3E!/A 2F! (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 support in water, g,C = mass of specimen support immersed in water, g,F = ma
36、ss of test specimen in water with mass of specimen support 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 Interlaboratory Test ProgramAn interlaboratory study of the Density Test Method was run in 1990. Eleven
37、 testlaboratories tested eighteen different materials. The design of the study followed Practice E691 and a within-between analysis ofthe data are given in Research Report RR:B09-10143.11.2 Test ResultsThe precision information presented herein has been calculated for the results from eleven laborat
38、ories andfor duplicate results for each of eighteen materials tested.11.3 Precision:11.3.1 95% Repeatability Limit (within a laboratory)The within-laboratory repeatability limit, r, as defined by TerminologyE456, is estimated to be 0.025 g/cm3. At the 95% confidence level, duplicate density test res
39、ults from the same laboratory shouldnot be considered different unless they differ by more than r.3 Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:B09-1014. Contact ASTM CustomerService at serviceastm.org.TABLE 2 Maximum Recomm
40、ended Wire DiameterMass, g Wire Diameter, mmless than 50 0.1250 to less than 200 0.25200 to less than 600 0.40600 and greater 0.50B311 17311.3.2 95% Reproducibility Limit (between laboratories)The between laboratories reproducibility limit, R, as defined byTerminology E456, is estimated to be 0.03 g
41、/cm3 for test specimens with a mass of greater than 5 g. For test specimens with amass of from 1 to 5 g it is estimated to be 0.05 g/cm3. At the 95% confidence level, duplicate density test results from differentlaboratories should not be considered different unless they differ by more than R.11.4 B
42、iasNo information can be presented on the bias of the procedure in Test Method B311 for measuring Density becauseno material having an accepted reference value is available.11.5 Measurement UncertaintyThe precision of Test Method B311 shall be considered by those performing the test whenreporting De
43、nsity test results.FIG. 1 Methods for Holding the Test Specimen When Weighing in WaterB311 174FIG. 2 Methods for Weighing in WaterTABLE 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
44、.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.B31
45、1 17512. Keywords12.1 cemented carbides; density; hard metals; metal injection molded (MIM) parts; powder metallurgy (PM); powder forged(PF) parts; powder metallurgySUMMARY OF CHANGESCommittee B09 has identified the location of selected changes to this standard since the last issue(B311 08B311 13) t
46、hat may impact the use of this standard. (Approved April 1, 2013.)2017.)(1) Changed the wordingheading of the statement on units inright-hand column of Table 1 Section 1.2.from “Balance Sensitivity,g” to “Balance Readable to, g.”(2) Deleted reference to IEEE/ASTM SI 10 in Section 2.2.(3) Deleted ref
47、erence to ISO 3369 in Section 2.3.(4) Deleted the inch-pound units from Table 2.(5) Replaced the precision information that should have been in the 08 version of the standard and put it in the form required bythe B09 Policy Guide.(6) Added a bias statement.(7) Added a statement on measurement uncert
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49、s, 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.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 comments have not received a fair
