1、Designation: B939 09B939 15Standard Test Method forRadial Crushing Strength, K, of Powder Metallurgy (PM)Bearings and Structural Materials1This standard is issued under the fixed designation B939; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、 of 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.1. Scope*1.1 This test method covers the equipment and laboratory procedure for the determination of the
3、 radial crushing strength ofmaterials using either a plain powder metallurgy (PM) bearing or a thin-walled hollow cylindrical test specimen. This is adestructive test that produces quantitative results.1.2 Limitations:1.2.1 The principle of this procedure is based on the material being tested having
4、 minimal ductility. The permanent deflectionof the cylinder during the test should not exceed 10 % of the outside diameter.1.2.2 The radial crushing strength test results should be used only as a guide if the test specimen has a wall thickness that isgreater than one-third of the outside diameter. T
5、hese test results should then only be used for comparison with data from the testspecimens of like materials and similar dimensions.1.3 With the exception of density values, the values for density and the mass used to determine density, for which the g/cmuseof the gram per cubic centimetre (g/cm3 un
6、it is ) and gram (g) units are the industry standard, the values stated in inch-pound unitsare to be considered theregarded as standard. The values in SI units, shown in parenthesis have been converted in accordance withIEEE/ASTM Standard SI 10, may be approximate and are only included for informati
7、on. given in parentheses are mathematicalconversions to SI units that are provided for information only and are not considered standard.1.4 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 this standard to e
8、stablish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B243 Terminology of Powder MetallurgyB438 Specification for Bronze-Base Powder Metallurgy (PM) Bearings (Oil-Impregnated)B439 Specificatio
9、n for Iron-Base Powder Metallurgy (PM) Bearings (Oil-Impregnated)B925 Practices for Production and Preparation of Powder Metallurgy (PM) Test SpecimensE456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method2
10、.2 IEEE/ASTM Standard:SI 10 American National Standard for Use of the International System of Units (SI): The Modern Metric System2.2 MPIF Standard:3MPIF Standard 55 Determination of Radial Crush Strength (K) of Powder Metallurgy (PM) Test Specimens3. Terminology3.1 DefinitionsDefinitions of powder
11、metallurgy (PM) terms can be found in Terminology B243. Additional descriptiveinformation is available in the related material section of Vol 02.05 of the Annual Book of ASTM Standards.1 This test method is under the jurisdiction ofASTM Committee B09 on Metal Powders and Metal Powder Products and is
12、 the direct responsibility of Subcommittee B09.04on Bearings.Current edition approved Nov. 1, 2009April 1, 2015. Published January 2010April 2015. Originally approved in2005. in 2005. Last previous edition approved in 20052009as B939 05.B939 09. DOI: 10.1520/B0939-09.10.1520/B0939-15.2 For reference
13、dASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from Metal Powder Industries Federation (MPIF), 105 College Rd.
14、East, Princeton, NJ 08540, http:/www.mpif.org.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 accurately
15、, 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 Harbor Drive
16、, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Summary of Test Method4.1 Radial crushing strength is determined by subjecting a plain sleeve bearing or a thin-walled cylindrical test specimen to acontrolled compressive force applied perpendicular to its central axis under uniforml
17、y increasing load until fracture occurs.4.2 The term radial“radial crushing strengthstrength,” as used in this test method is the stress at fracture calculated from thebreaking load and the dimensions of the test specimen.5. Significance and Use5.1 The radial crushing strength test is a destructive
18、procedure used to determine a material strength characteristic of PMbearings and hollow cylindrical test specimens. These data can be used to grade, classify, and evaluate the materials.5.2 The PM bearing Specifications B438 and B439 require the use of this test method as an acceptance test for the
19、strength ofoil-impregnated sintered bearings.5.3 This test method may be used by powder producers and parts manufacturers as a lot acceptance test for metal powders andlubricated powder mixtures intended for the production of porous parts.5.4 Companies in the PM industry use this test as a manufactu
20、ring control test because it is appropriate for production practices.5.5 Radial crushing strength is a property of the PM material but is not a design value. However, experience has shown thatthe radial crushing strength of a material is approximately twice the ultimate tensile strength.6. Apparatus
21、6.1 Measuring EquipmentMicrometers, calipers, and plug gages capable of measuring the inside and outside diameters andlength of the test specimen to the nearest 0.001 in. (0.03 mm).(0.03 mm).6.2 Compression Testing MachineAcompression machine readable to 0.1% of the full scale reading, and capable o
22、f applyinga controlled breaking force to the test specimen with an accuracy of 1 % and readable to the nearest 10 lbf (50 N).specimen. Usethe lowest range that can produce a measurable result.6.3 Loading PlatesTwo loading platesground, flat, hardened and ground steel plates of sufficient size to enc
23、ompass the testspecimen , can be fastened to the press platens and that will remain parallel within 0.002 in./in. (mm/mm) under load. of a hardnessgreater than the microindentation hardness of the material being tested and large enough to encompass the entire length of thespecimen.7. Test Specimens7
24、.1 The test specimen shall be a hollow right circular thin-walled cylinder.7.1.1 When PM bearings are to be tested, the test specimen shall be a plain sleeve bearing taken from a production lot or anotherbearing that has been machined to a plain cylindrical shape.7.1.2 When metal powders are to be e
25、valuated, the test specimen shall be produced according to the procedure in PracticesB925.8. Procedure8.1 Clean any surface oil from the specimen and measure the Measure the outside diameter, inside diameter, and the length ofthe test specimen to the nearest 0.001 in. (0.03(0.025 mm).8.2 The test sp
26、ecimen shall be round within 0.003 in./in. (0.08 mm/mm) of the outer diameter.8.3 Clean any surface oil or other contaminants from the test specimen and the flat surfaces of the loading plates.8.4 Wipe the loading plates clean and lay the Position the test specimen in the central region of the lower
27、 plate.loading platein the compression testing machine.8.5 Bring the upper plate and test specimen into contact into contact with the test specimen and slowly apply thediametricaldiametric load at a constant crosshead closure rate that does not exceed 0.2 in./min (5(5.0 mm/min) (see Fig. 1).8.6 Usin
28、gUse a scale on the compression testing machine that has a precision of 1 %0.1% or better of the crushing load, recordload and record, to the nearest 10 lbfprecision listed in Table 1(50 N) , the load at which the test specimen fractures or the firstreading at which the applied load drops.9. Calcula
29、tion9.1 Use the following equation to calculate the radial crushing strength of the material in the specimen.Radial Crushing Strength,K 5PS D1d2 DLS D 2d2 D2 5PD2t!Lt2 (1)B939 152where:K = radial crushing strength, psi (MPa),P = breaking load, lbf (N),D = outside diameter, in. (mm),d = inside diamet
30、er, in. (mm),L = length, in. (mm), andt = wall thickness (D d)/2, in. (mm).10. Report10.1 The radial crushing strength, calculated as the average of three at least three (3) but preferably five (5) determinations, shallbe reported to the nearest 1000 psi (10 MPa).10.1.1 Report whether the average is
31、 from three or five determinations.10.2 The following information may also be included in the report:10.2.1 Origin and processing of the test specimen,10.2.2 Chemical composition of the material,10.2.3 Density of the bearing or test specimen before testing, and10.2.4 Details of any deviation from th
32、e test method and any conditions or occurrences that may have affected the test results.FIG. 1 Diametrical Load Applied to the Upper Plate and Test SpecimenTABLE 1 Precision for the Measurement of the Crushing LoadInch-Pound(lbf)SI(N)(D-t)/Lt2 Record BreakLoad To: (D-t)/Lt2 Record BreakLoad To:100 1
33、 0.155 5B939 15311. Precision and Bias11.1 PrecisionThe precision of this test method (Table 12) was determined by the Standards Committee of the Metal PowderIndustries Federation for MPIF Standard 55 using Practice E691.411.1.1 The within-laboratory repeatability interval, (r),(r), as defined by Te
34、rminology E456, is shown in Table 2Table 1. .Duplicate results from the same laboratory should not be considered suspect at the 95% confidence level unless they differ by morethan r.11.1.2 The between-laboratory reproducibiltyreproducibility interval, (R),(R), as defined in TechnologyTerminology E45
35、6, isshown in Table 2Table 1. . Duplicate results from different laboratories should not be considered suspect at the 95% confidencelevel unless they differ by more than R.11.2 BiasNo information can be provided on the bias of the procedure in Test Method B939 for measuring the radial crushingstreng
36、th of PM bearings and structural materials because no PM material having an acceptable reference value is available.11.3 Measurement Uncertainty The precision of this test method shall be considered by those performing the test whenreporting the results.12. Keywords12.1 K; material strength; PM bear
37、ings; radial crushing strength4 The precision data is used herein with the permission of the Metal Powder Industries Federation (MPIF), 105 College Rd. East, Princeton, NJ 08540, http:/www.mpif.org.TABLE 12 Precision DataMaterialMed GraphiteBronzeCTG-1001-K23Iron-CopperFC-1000-K20Copper-SteelFC-0208
38、-50Dry Density (g/cm3) 6.56 5.96 6.76Sintered Density (g/cm3) 6.56 5.96 6.76Outside Diameter, D in. (mm) 1.00 (25.4) 1.00 (25.4) 2.00 (50.8)Inside Diameter, d in. (mm) 0.75 (19.1) 0.75 (19.1) 0.875 (22.2)Length, L in. (mm) 0.75 (19.1) 0.75 (19.1) 0.75 (19.1)Number of Participating Labs 9 9 10Radial
39、CrushingStrength, K psi (MPa) 31 000 (215) 58 000 (400) 114 000 (785)Repeatability, r psi (MPa) 2200 (15) 4900 (35) 6900 (50)Reproducibility, R psi (MPa) 3300 (25) 6600 (45) 6900 (50)B939 154SUMMARY OF CHANGESCommittee B09 has identified the location of selected changes to this standard since the la
40、st issue(B93905)(B93909) that may impact the use of this standard.(1) Title changed P/M to PM here and throughout the standard.(1) Section 1.3 added this section on the useChanged the statement on units in Section 1.3of the inch-pound system(2) SectionDeleted 2.1 deleted withdrawn standards and corr
41、ectedthe reference to SI 10 in Section 2.1title of B 438(3) Revised subsection 6.2 about the compression testing machine.(4) Section Revised subsection 2.26.3 added SI 10. on the loading plates.(5) Rewrote and reorganized Completely revised Section 118 on Precision and Bias.Procedure and incorporate
42、d a new table toindicate the precision for the measurement of the crushing load with respect to the dimensions of the test specimen.(6) Added SummaryChanged Section 10of Changes. , Report, and added a new subsection, 10.1.1.ASTM International takes no position respecting the validity of any patent r
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