1、Designation: B939 09Standard 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 of rev
2、ision, 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 laboratoryprocedure for the determination of the radial
3、crushing strengthof materials using either a plain powder metallurgy (PM)bearing or a thin-walled hollow cylindrical test specimen. Thisis a destructive test that produces quantitative results.1.2 Limitations:1.2.1 The principle of this procedure is based on thematerial being tested having minimal d
4、uctility. The permanentdeflection of the cylinder during the test should not exceed10 % of the outside diameter.1.2.2 The radial crushing strength test results should be usedonly as a guide if the test specimen has a wall thickness that isgreater than one-third of the outside diameter. These test re
5、sultsshould 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, for which theg/cm3unit is the industry standard, the values stated ininch-pound units are to be considered the standard. The valuesin SI un
6、its, shown in parenthesis have been converted inaccordance with IEEE/ASTM Standard SI 10, may be approxi-mate and are only included for information.1.4 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 st
7、andard 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:2B243 Terminology of Powder MetallurgyB438 Specification for Bronze-Base Powder Metallurgy(PM) Bearings (Oil-Impregnated)B439
8、 Specification for Iron-Base Powder Metallurgy (PM)Bearings (Oil-Impregnated)B925 Practices for Production and Preparation of PowderMetallurgy (PM) Test SpecimensE456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Te
9、st Method2.2 IEEE/ASTM Standard:SI 10 American National Standard for Use of the Interna-tional System of Units (SI): The Modern Metric System2.3 MPIF Standard:3MPIF Standard 55 Determination of Radial Crush Strength(K) of Powder Metallurgy (PM) Test Specimens3. Terminology3.1 DefinitionsDefinitions
10、of powder metallurgy (PM)terms can be found in Terminology B243. Additional descrip-tive information is available in the related material section ofVol 02.05 of the Annual Book of ASTM Standards.4. Summary of Test Method4.1 Radial crushing strength is determined by subjecting aplain sleeve bearing o
11、r a thin-walled cylindrical test specimento a controlled compressive force applied perpendicular to itscentral axis under uniformly increasing load until fractureoccurs.4.2 The term radial crushing strength as used in this testmethod is the stress at fracture calculated from the breakingload and the
12、 dimensions of the test specimen.5. Significance and Use5.1 The radial crushing strength test is a destructive proce-dure used to determine a material strength characteristic of PMbearings and hollow cylindrical test specimens. These data canbe used to grade, classify, and evaluate the materials.5.2
13、 The PM bearing Specifications B438 and B439 requirethe use of this test method as an acceptance test for the strengthof oil-impregnated sintered bearings.1This test method is under the jurisdiction of ASTM Committee B09 on MetalPowders and Metal Powder Products and is the direct responsibility of S
14、ubcom-mittee B09.04 on Bearings.Current edition approved Nov. 1, 2009. Published January 2010. Originallyapproved in2005. Last previous edition approved in 2005 as B939 05. DOI:10.1520/B0939-09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at s
15、erviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Metal Powder Industries Federation (MPIF), 105 College Rd.East, Princeton, NJ 08540, http:/www.mpif.org.1*A Summary of Changes section appears at the e
16、nd of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.3 This test method may be used by powder producers andparts manufacturers as a lot acceptance test for metal powdersand lubricated powder mixtures intended for the
17、production ofporous parts.5.4 Companies in the PM industry use this test as amanufacturing control test because it is appropriate for pro-duction practices.5.5 Radial crushing strength is a property of the PMmaterial but is not a design value. However, experience hasshown that the radial crushing st
18、rength of a material isapproximately twice the ultimate tensile strength.6. Apparatus6.1 Measuring EquipmentMicrometers, calipers, and pluggages capable of measuring the inside and outside diametersand length of the test specimen to the nearest 0.001 in. (0.03mm).6.2 Compression Testing MachineA com
19、pression ma-chine capable of applying a controlled breaking force to the testspecimen with an accuracy of 1 % and readable to the nearest10 lbf (50 N).6.3 Loading PlatesTwo flat, hardened and ground steelplates of sufficient size to encompass the test specimen , can befastened to the press platens a
20、nd that will remain parallelwithin 0.002 in./in. (mm/mm) under load.7. Test Specimens7.1 The test specimen shall be a hollow right circularthin-walled cylinder.7.1.1 When PM bearings are to be tested, the test specimenshall be a plain sleeve bearing taken from a production lot oranother bearing that
21、 has been machined to a plain cylindricalshape.7.1.2 When metal powders are to be evaluated, the testspecimen shall be produced according to the procedure inPractices B925.8. Procedure8.1 Clean any surface oil from the specimen and measurethe outside diameter, inside diameter, and the length to then
22、earest 0.001 in. (0.03 mm).8.2 Wipe the loading plates clean and lay the test specimenin the central region of the lower plate.8.3 Bring the upper plate and test specimen into contact andslowly apply the diametrical load at a rate that does not exceed0.2 in./min (5 mm/min) (see Fig. 1).8.4 Using a s
23、cale on the compression testing machine thathas a precision of 1 % or better of the crushing load, record tothe nearest 10 lbf (50 N) the load at which the test specimenfractures or the first reading at which the applied load drops.9. Calculation9.1 Use the following equation to calculate the radial
24、crushing strength of the material in the specimen.Radial Crushing Strength, K 5PSD 1 d2DLSD 2 d2D25PD 2 t!Lt2(1)where:K = radial crushing strength, psi (MPa),P = breaking load, lbf (N),D = outside diameter, in. (mm),d = inside diameter, in. (mm),L = length, in. (mm), andt = wall thickness (D d)/2, i
25、n. (mm).10. Report10.1 The radial crushing strength, calculated as the averageof three determinations, shall be reported to the nearest 1000psi (10 MPa).10.2 The following information may also be included in thereport:10.2.1 Origin and processing of the test specimen,10.2.2 Chemical composition of t
26、he material,10.2.3 Density of the bearing or test specimen beforetesting, andFIG. 1 Diametrical Load Applied to the Upper Plate and TestSpecimenB939 09210.2.4 Details of any deviation from the test method and anyconditions or occurrences that may have affected the testresults.11. Precision and Bias1
27、1.1 PrecisionThe precision of this test method (Table 1)was determined by the Standards Committee of the MetalPowder Industries Federation for MPIF Standard 55 usingPractice E691.411.1.1 The within-laboratory repeatability interval, (r), asdefined by Terminology E456, is shown in Table 1. Duplicater
28、esults from the same laboratory should not be consideredsuspect at the 95% confidence level unless they differ by morethan r.11.1.2 The between-laboratory reproducibilty interval, (R),as defined in Technology E456, is shown in Table 1. Duplicateresults from different laboratories should not be consi
29、deredsuspect at the 95% confidence level unless they differ by morethan R.11.2 BiasNo information can be provided on the bias ofthe procedure in Test Method B939 for measuring the radialcrushing strength of PM bearings and structural materialsbecause no PM material having an acceptable reference val
30、ueis available.11.3 Measurement Uncertainty The precision of thistest method shall be considered by those performing the testwhen reporting the results.12. Keywords12.1 K; material strength; PM bearings; radial crushingstrengthSUMMARY OF CHANGESCommittee B09 has identified the location of selected c
31、hanges to this standard since the last issue (B93905)that may impact the use of this standard.(1) Title changed P/M to PM here and throughout thestandard.(2) Section 1.3 added this section on the use of the inch-pound system.(3) Section 2.1 deleted withdrawn standards and correctedtitle of B 438.(4)
32、 Section 11.1.2 added SI 10.(5) Rewrote and reorganized Section 11 on Precision and Bias.(6) Added Summary of Changes.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
33、 advised that determination of 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, ei
34、ther 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 atten
35、d. If you feel that your comments 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. In
36、dividual 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). Permission rights to photocopy the standard may also be secure
37、d from the ASTM website (www.astm.org/COPYRIGHT/).4The precision data is used herein with the permission of the Metal PowderIndustries Federation (MPIF), 105 College Rd. East, Princeton, NJ 08540, http:/www.mpif.org.TABLE 1 Precision DataMaterialMed GraphiteBronzeCTG-1001-K23Iron-CopperFC-1000-K20Co
38、pper-SteelFC-0208-50Dry 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 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 093
