1、Designation: B331 10B331 16Standard Test Method forCompressibility of Metal Powders in Uniaxial Compaction1This standard is issued under the fixed designation B331; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. 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 laboratory test method covers the determination of the compressibility of metal powders and metal powder mixturesas me
3、asured by the extent to which a sample test portion can be densified under controlled conditions in a specified die.1.2 With the exception of density values, the values for density and mass, for which the g/cmuse of gram per cubic centermetre(g/cm3 unit ) and gram (g) units is the longstanding indus
4、try standard,practice, the values stated in inch-pound units are to beregarded as the standard. The values showngiven in parenthesisparentheses are mathematical conversions to SI units that arepresentedprovided for information only and are not to be considered as standard.1.3 This standard does not
5、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 and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B
6、215 Practices for Sampling Metal PowdersB243 Terminology of Powder MetallurgyB925 Practices for Production and Preparation of Powder Metallurgy (PM) Test SpecimensB962 Test Methods for Density of Compacted or Sintered Powder Metallurgy (PM) Products Using Archimedes PrincipleE456 Terminology Relatin
7、g to Quality and Statistics3. Terminology3.1 DefinitionsFor definitions of terms used in this test method refer to Terminology B243. Additional descriptive PMinformation is available in the Related Material section of Vol 02.05 of the Annual Book of ASTM Standards.4. Summary of Test Method4.1 A test
8、 sampleportion of metal powder is uniaxially compressed in a specific die under controlled conditions.4.2 The green density of the resulting compact is determined.4.3 The compressibility of the powder is defined as the green density of the test compact at the compacting pressure that wasused.5. Sign
9、ificance and Use5.1 The compressibility value obtained by this test is a measure of a material characteristic of the powder.5.2 The test method is useful in research and development projects, as a quality control test in the evaluation and manufacturingcontrol of metal powder production, and as an a
10、cceptance test for shipment of metal powder lots.5.3 In PM production operations, the test is helpful in determining pressing and tooling requirements for high density parts.1 This test method is under the jurisdiction ofASTM Committee B09 on Metal Powders and Metal Powder Productsand is the direct
11、responsibility of Subcommittee B09.02on Base Metal Powders.Current edition approved Oct. 1, 2010April 1, 2016. Published November 2010April 2016. Originally approved in 1958. Last previous edition approved in 20022010 asB331 - 95B331(2002). DOI:10.1520/B0331-10. 10. DOI:10.1520/B0331-16.2 For refere
12、ncedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standardsstandards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to pr
13、ovide 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 accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof th
14、e 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 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.4 Results may be affected by test conditions
15、such as the type, amount, and method of lubrication, dwell time duringcompaction, and die material. The compressibility values may not necessarily agree with results obtained under productionconditions.6. Apparatus6.1 Compacting ToolingA cemented carbide die or alternatively, hardened tool steel die
16、 and two hardened steel punchescapable of producing the compressibility test specimen. The designs shown in Practice B925 for a cylindrical test specimen anda transverse rupture test specimen are examples of acceptable tooling.6.2 Powder Compacting PressA compression testing machine or powder compac
17、ting press, capable of applying an adequateload with an accuracy of at least 61.0 %. 61.0 % at a rate of approximately 30 tsi/min (400 MPa/min).6.3 BalanceA laboratory balance readable to 0.001 g with a minimum capacity of 100 g to be used to determine the masssuitable for weighing at least 100 g of
18、 the compacted test specimen to the nearest 0.01 g.6.4 MicrometerStandard outside micrometers or other suitable measuring instruments for determining the dimensions of thegreen compressibility compacts to the nearest 0.0002 in. (0.005 mm).7. Gross Metal Powder Sample7.1 The gross powder sample is a
19、quantity of powder of sufficient mass to be split into the required number of powder testsamples.portions. It shall be taken from the lot of powder that is to be tested in accordance with PracticePractices B215.8. Preparation8.1 This test method contains procedures to be followed for either lubricat
20、ed or unlubricated metal powders. Lubrication isgenerally necessary to assist in the compaction and ejection of the compressibility compact.8.1.1 An alternative way of testing powder not containing a lubricant is to use an otherwise unlubricated die after thoroughlymixing into the powder a sufficien
21、t amount of a suitable lubricant.8.2 Lubricated Powders:8.2.1 Powder mixtures containing a lubricant shall be tested in the as-received condition.8.3 Unlubricated Powders:8.3.1 The needed lubrication may be supplied either by lubricating the walls of the die or by mixing a powdered lubricant intothe
22、 metal powder to be tested.8.3.1.1 Die-wall lubrication consists of coating the walls of the die with a thin film of lubricant prior to each compaction stepfollowing the die-wall lubrication procedure in Practices B925.8.3.1.2 Admixed lubrication consists of thoroughly mixing a small percentage of a
23、 powdered lubricant into the gross sample.8.4 Compressibility test results may vary in accordance with the method of lubrication, type, and amount of lubricant.8.5 Compressibility test results may vary depending on the rate at which the compacting pressure is applied.8.6 The parties concerned shall
24、agree on the method of lubrication and the details of the procedure.9. Procedure9.1 Testing Methods:9.1.1 The test for compressibility of metal powder may be conducted in any of three ways:9.1.1.1 Method 1Compressibility defined as the green density obtained at a selected compacting pressure.9.1.1.2
25、 Method 2Compressibility as a graph relating density as a function of at least four compacting pressures.9.1.1.3 Method 3Compressibility defined as the compacting pressure required to attain a target green density.9.2 Test Specimens for Powder Compressibility:9.2.1 Either of two compressibility test
26、 specimens may be selected to determine compressibility.9.2.1.1 Cylindrical Compressibility Test SpecimenAshort cylindrical compact 1.000 in. in diameter by 0.28060.010 in. thick(25.4 in diameter by 7.11 6 0.25 mm thick), as shown in Practice B925 as Cylindrical Powder Compressibility Test Specimen.
27、9.2.1.2 Rectangular Compressibility Test SpecimenA short rectangular compact 1.250 in. long by 0.500 in. wide by 0.250 60.010 in. thick. (31.8 by 12.7 by 6.35 6 0.25 mm), similar to that which is shown in Practices B925 as Transverse Rupture StrengthTest SpecimenThin.9.2.2 Release the pressure as so
28、on as the maximum pressure is attained, because pressure dwells of as little as 10 s can increaseiron powder compressibility by 0.3 %.9.3 Powder Test Sample:9.3.1 The thickness of the compressibility test specimen is critical as the area of die wall contact has a strong effect on the greendensity an
29、d the thicknesses specified have been determined to give equivalent results between the two powder compressibility testspecimens.B331 1629.3.2 The powder test sampleportion shall be a powder charge of sufficient mass to produce either a cylindrical test specimen0.280 6 0.010 in. (7.11 6 0.25 mm) thi
30、ck or a rectangular test specimen 0.250 6 0.010 in. (6.35 6 0.25 mm) thick.9.3.3 For a powder whose compressibility is not known, it may be necessary to adjust the mass of the powder charge based uponthe thickness obtained in an initial test.9.4 Compacting:9.4.1 Compact and identify three (3) duplic
31、ate compressibility test specimens of the shape that has been selected following thecompacting procedure listed in Practice B925.9.4.2 Be careful to release the load as soon as the maximum pressure is reached as a pressure dwell of as little as 10 s mayincrease compressibility by as much as 0.3 %.9.
32、4.3 Note the load used, then calculate and record the compacting pressure based on the pressing area of the selectedcompressibility test specimen.9.4.4 The compressibility compacts may be lightly sanded on fine emery paper to remove any flash.9.5 Measurements:9.5.1 Determine the mass of each green c
33、ompressibility test specimen to the nearest 0.01 g.9.5.2 Measure the dimensions of each green compressibility test specimen to the nearest 0.0002 in. (0.005 mm).10. Calculations10.1 Calculate the green density of each powder compressibility test specimen as follows:10.1.1 For the Cylindrical Test Sp
34、ecimen:Green Density,DG50.0783MD23T (1)Green Density, DG 5 0.0777 3 M!D2 3 T! (1)where:DG = green density of the cylindrical compressibility test specimen, g/cm3.0.0777 = combined conversion factor, in.3 to cm3 and pi for the area calculation.M = mass of the green compressibility test specimen, g.D2
35、 = diameter of the compact, squared, in.2.T = thickness of the compact, in.where:DG = green density of the cylindrical compressibility test specimen, g/cm 3.0.078 = combined conversion factor, in.3 to cm3 and pi for the area calculation.M = mass of the green compressibility test specimen, g.D2 = dia
36、meter of the compact, squared, in.2.T = thickness of the compact, in.10.1.2 For the Rectangular Test Specimens:Green Density,DG50.0613ML 3W 3T (2)Green Density, DG 5 0.0610 3 M!L 3 W 3 T! (2)where:DG = green density of the rectangular compressibility test specimen, g/cm3.0.0610 = conversion factor,
37、in.3, to cm3.M = mass of the green compressibility test specimen, g.L = length of the compact, in.W = width of the compact, in.T = thickness of the compact, in.where:DG = green density of the rectangular compressibility test specimen, g/cm 3.0.061 = conversion factor, in.3, to cm3.M = mass of the gr
38、een compressibility test specimen, g.L = length of the compact, in.W = width of the compact, in.T = thickness of the compact, in.10.2 The density of the green powder compressibility test specimen may also be determined by the water displacement methodof Test Method B962.B331 16311. Report11.1 Method
39、 1Report the compressibility in g/cm3 as the arithmetic average of three density measurements, calculated to thenearest 0.01 g/cm3, at a given compacting pressure. (for example 6.00 g/cm3 at 30 tsi (400 MPa).11.2 Method 2Display the compressibility as a graph of green density as a function of compac
40、ting pressure using at least four(4) determinations.11.3 Method 3Alternatively, report the compressibility in tsi to the nearest 0.5 tsi (10 MPa), as the compacting pressurerequired to reach the specified green density. (for example, 30.0 tsi (400 MPa) for a green density of 6.50 g/cm3)11.4 Report t
41、he compact type, thickness, and method of lubrication and the die material.11.4.1 For lubricated powder tested as-received, report the type and percentage of lubricant, if known.11.4.2 For unlubricated powder tested using die-wall lubrication, report the type and amount of lubricant as the mass perc
42、entdissolved in the solvent.11.4.3 For unlubricated powder tested after a powder lubricant has been admixed, report the type and percentage of the powderlubricant as well as details of the mixing procedure.12. Precision and Bias312.1 The following precision values were developed from data contained
43、in research report RR: RR:B09-1002 B09-1002collected using Method 1 of this test standard.12.1.1 Precision:12.1.1.1 The within-laboratory repeatability limit, r, as defined by Terminology E456, is estimated to be 0.025 g/cm3. Duplicateresults from the same laboratory should not be considered differe
44、nt at the 95 % confidence level unless they differ by more than0.025 g/cm3.12.1.1.2 The between-laboratories reproducibility limit, R, as defined by Terminology E456 is estimated to be 0.07 g/cm3.Duplicate results from different laboratories should not be considered different at the 95 % confidence
45、level unless they differ bymore than 0.07 g/cm3.12.1.2 Bias:12.1.2.1 No information can be presented on the bias of the procedures in this test method for measuring metal powdercompressibility because no material having an accepted reference value is available.12.1.3 Measurement Uncertainty:12.1.3.1
46、 The precision of this test method shall be considered by those performing the test when reporting metal powdercompressibility results.13. Keywords13.1 compressibility; metal powderSUMMARY OF CHANGESCommittee B09 has identified the location of selected changes to this standard since the last issue(B
47、331 - 95B331(2002) 10) that may impact the use of this standard. (October (ApprovedApril 1, 2010)2016.)(1) SubsectionChanged 1.2 rewritten.sample to test portion on section 1.1.(2) SubectionUpdated 2.1:Addedsection 1.2 B925to illustrate tooling and compacts and SI reference; and Terminology E456.mee
48、tB09 policy guide.(3) SubsectionReplaced sample 6: Deleted old references to tooling and made referral to with portion in section 4.1.B925.(4) SubsectionAdded 6.3: Rewrote description of ma after type in section 5.4.(5) Subsection 8.5: Added reference to rate of pressure paction in section 6.2.(6) S
49、ubsectionRemoved 9.1: Made reference to compact redundant language in B925.section 6.3 and added description to massbeing determined.(7) SectionReplaced 9 has been completely rewritten and have used the term “Powder Compressibility Test Specimen” to describethe compact resulting from the test procedure.samples with portions in section 7.1.(8) SubsectionsDeleted 10.1.1 andsection 9.2.2 10.1.2: Changed the symbol for density from Greek rho to D and corrected formula(2), which lacked a division sign after the first M.as it is rep
