1、Designation: E238 12Standard Test Method forPin-Type Bearing Test of Metallic Materials1This standard is issued under the fixed designation E238; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number i
2、n 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 a pin-type bearing test ofmetallic materials to determine bearing yield strength andbearing strength.NOTE 1The presenc
3、e of incidental lubricants on the bearing surfacesmay significantly lower the value of bearing yield strength obtained bythis method.1.2 UnitsThe values stated in inch-pound units are to beregarded as standard. The values given in parentheses aremathematical conversions to SI units that are provided
4、 forinformation only and are not considered standard.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 and health practices and determine the applica-bility o
5、f regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE83 Practice for Verification and Classification of Exten-someter SystemsB769 Test Method for Shear Testing
6、of Aluminum AlloysB831 Test Method for Shear Testing of Thin AluminumAlloy Products3. Terminology3.1 Definitions:3.1.1 bearing areathe product of the pin diameter andspecimen thickness.3.1.2 bearing stressthe force per unit of bearing area.3.1.3 bearing strainthe ratio of the bearing deformationof t
7、he bearing hole, in the direction of the applied force, to thepin diameter.3.1.4 bearing yield strengththe bearing stress at which amaterial exhibits a specified limiting deviation from the pro-portionality of bearing stress to bearing strain.3.1.5 bearing strengththe maximum bearing stress whicha m
8、aterial is capable of sustaining.3.1.6 edge distancethe distance from the edge of a bear-ing specimen to the center of the hole in the direction ofapplied force (Fig. 1).3.1.7 edge distance ratiothe ratio of the edge distance tothe pin diameter.3.1.8 For definitions of other terms see Terminology E6
9、.4. Significance and Use4.1 The data obtained from the bearing test are the bearingultimate and yield strength. The data provide a measure of theload-carrying capacity of a material edge loaded with aclose-fitting cylindrical pin through a hole located a specificdistance from the specimen edge.4.2 B
10、earing properties are useful in the comparison ofmaterials and design of structures under conditions where thepin is not restricted.5. Apparatus5.1 Testing MachinesMachines used for bearing testingshall conform to the requirements of Practices E4.5.2 Gripping DevicesVarious types of gripping devices
11、may be used to transmit the measured load applied by thetesting machine to the test specimens. Any grips considered toapply the load axially for tension testing, such as pin connec-tions or wedge grips, are satisfactory for use in bearing testing.5.3 PinThe bearing load is generally applied to thesp
12、ecimen through a close-fitting cylindrical pin. The pin shallbe harder and stronger than the material being tested. Restraintof movement of the specimen where it is in contact with the pinhas a considerable effect upon the hole deformation obtained asa function of the load applied. Close control of
13、surfaceconditions on both the specimen and pin is needed to assurereproducible results. The pins used should be uniform indiameter, hardness, and surface roughness. Pin materials,hardness, and surface roughness as shown in Table 1 arerecommended for testing the materials listed. The pin shouldbe che
14、cked carefully after each test to ensure that no metallicresidue adheres to it and that it is both straight and undeformed.If there is any question regarding its quality it should bereplaced.1This test method is under the jurisdiction of ASTM Committee E28 onMechanical Testing and is the direct resp
15、onsibility of Subcommittee E28.04 onUniaxial Testing.Current edition approved June 1, 2012. Published August 2012. Originallyapproved in 1964. Last previous edition approved in 2008 as E238 84 (2008).DOI: 10.1520/E0238-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontac
16、t ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West C
17、onshohocken, PA 19428-2959, United States.5.4 Pin SupportThe jig supporting the pin should positionthe pin concentric with the hole in the specimen. It should notrestrain the thickening of the specimen as the load from the pindeforms the hole. Bending of the pin should be kept to aminimum by having
18、the jig support the pin close to thespecimen. Fig. 2 and Fig. 3 show examples of the types of jigthat have been used and are considered satisfactory.5.5 ExtensometersExtensometers used for measuring thebearing deformation shall comply with the requirements forClass B-2 or better as described in Prac
19、tice E83. The bearingdeformation measurement shall be made in a manner to obtainthe axial bearing deformation with a minimum of otherdeformations being included such as the bending of the pin andtensile strain in the specimen. Fig. 2 shows an adaptation of aTemplin extensometer system to record bear
20、ing deformation.Fig. 3 illustrates a mechanism that can be used to transfer thebearing deformation so it can be measured with the sameextensometers used for tension testing. A method of measuringbearing deformation featuring two linear differential transform-ers is shown in Fig. 4.6. Test Specimens6
21、.1 Specimen GeometryThe specimen shall be a flat sheettype, with the full thickness of the product being used ifpossible. If the specimen is too thick in relation to the pindiameter, the pin is likely to bend considerably or break beforethe bearing strength is obtained. If a specimen is too thin,buc
22、kling may occur. A ratio of pin diameter to specimenthickness of from 2 to 4 has been used to avoid both conditions.The hole should have approximately the same diameter as forthe intended use. For example, if the bearing test results arebeing used to obtain data for a riveted part, a hole316 in. or1
23、4in. (5 or 6 mm) in diameter would be suitable, while for abolted assembly, a larger hole might be desirable. A differencein test results may be obtained with holes of different diam-eters. The width of the specimen shall be 4 to 8 times the holediameter. A wider specimen encourages the intended she
24、ar-outFIG. 1 Bearing Test SpecimenTABLE 1 Characteristics of Pin for Various Materials TestedMaterial Tested MaterialRockwellHardnessSurface Roughness, in. (m) (avg)Aluminum alloys hardened steel C60 to 64 4 to 8 (0.1 to 0.2 m)Beryllium alloys hardened steel C60 to 64 4 to 8 (0.1 to 0.2 m)Copper all
25、oys hardened steel C60 to 64 4 to 8 (0.1 to 0.2 m)Magnesium alloys hardened steel C60 to 64 4 to 8 (0.1 to 0.2 m)Zinc alloys hardened steel C60 to 64 4 to 8 (0.1 to 0.2 m)FIG. 2 Bearing Test Fixture Used on Aluminum SheetE238 122failure mode. The edge distance ratio shall be specified and theedge di
26、stance held within a tolerance of 62 %. Edge distanceratios of 1.50 and 2.00 are commonly used (see Fig. 1).Aclosefit between the specimen and pin is required, since a loose fitwill tend to give lower results. The diameter of the hole shallnot exceed the pin diameter by more than 0.001 in. (0.02 mm)
27、.The free length between the point of loading and the test pinhole shall be greater than 1.5 times the specimen width. Thetotal length of the test specimen is not critical and may dependon the method used to grip the specimen. Fig. 1 shows abearing test specimen commonly used.6.1.1 Specimen orientat
28、ionThe measured bearing proper-ties can depend on the specimen orientation and the directionin which the load is applied relative to the grain flow in thespecimen. The specimen orientation and the loading directionshall be identified by the following system.6.1.2 The reference grain directions for r
29、ectangular shapedproducts are indicated in Fig. 5. These are suitable for sheet,plate, extrusions, forgings, and other shapes of nonsymmetricalgrain flow.6.1.3 The two-letter specimen orientation codes are alsoshown in Fig. 5 to describe the specimen orientation andloading directions. The first lett
30、er designates the normal to theexpected shear plane. The second letter designates the directionof force application. The most commonly used specimenorientations are T-L and L-T for thin products. This orientationFIG. 3 Schematic Drawing of Bearing Deformation Transfer DeviceFIG. 4 Autographic Measur
31、ement of Bearing DeformationE238 123code is identical to that used for cylindrical and flat shearspecimens in Test Methods B769 and B831.6.2 Specimen PreparationA flat specimen with a holenormal to the face shall be used. A smooth, round hole with aminimum of cold work on the surface must be obtaine
32、d. Thefinished hole is generally bored, reamed, or ground as a finaloperation to obtain the desired degree of roundness. Any burron the periphery of the hole is indicative of a cold-workedsurface on the hole and should be avoided. Removal of the burrwill not eliminate the cold work.7. Procedure7.1 M
33、easurement of SpecimensMeasure the actual thick-ness of the specimen and the pin diameter, preferably readingto at least the nearest 0.5 % of the dimension measured, and inany case to at least the nearest 0.001 in. (0.02 mm). Calculatethe stress on the basis of the measured dimensions. Measurethe ed
34、ge distance to the nearest 0.01 in. (0.2 mm).7.2 CleaningClean the specimen, pin, and adjacent areasof the jig of all foreign matter and contamination, especiallylubricants, prior to assembly. Keep in that condition until thetest is completed. It has been found that oil from human fingerstouching th
35、e pin significantly lowers the results of the test. Ahandle on the pin has been found to help in keeping fingersfrom touching the test area of the pin. Recommended methodsof cleaning are given in the Appendix X1.3The cleanersrecommended for the materials given in the Appendix X1 aregenerally satisfa
36、ctory for cleaning the pin and fixtures, too.7.3 TestingLoad the specimen and obtain simultaneousreadings of the load and bearing deformation. Any convenientmethod of load application and system of strain recording maybe used.Autographic strain recording equipment can be readilyadapted to measure be
37、aring deformation (see Figs. 1-6).7.4 Conduct the tests at a controlled rate of straining orloading. The recommended rate for metallic materials is 0.05bearing strain per minute. If a testing speed other than a strainrate of 0.05/min is used, report this fact.8. Determination of Bearing Yield Streng
38、th8.1 Determine the bearing yield strength from a graph of thebearing load versus bearing deformation. Fig. 6 is an illustra-tion of such a graph. Calculate the yield strength from the loadat an offset from the initial straight-line portion of the graphequal to 2 % of the pin diameter. Calculate the
39、 stress bydividing the load by the bearing area.9. Determination of Bearing Strength9.1 Calculate the bearing strength by dividing the maximumload carried by the specimen by the bearing area.10. Report10.1 The report shall include the following:10.1.1 Material tested and direction of test,10.1.2 Hol
40、e diameter, width, and thickness of specimen.10.1.3 Edge distance ratio,10.1.4 Temperature of testing (if other than at room tem-perature),10.1.5 Bearing yield strength,10.1.6 Bearing strength,10.1.7 Description of fracture,10.1.8 Cleaning procedure, and3Stickley, G. W., and Moore, A. A. , “Effects
41、of Lubrication and Pin Surface onBearing Strengths of Aluminum and Magnesium Alloys,” MTRSA, MaterialsResearch bearing test; bearing yield strength;metallic materials; pin-typeAPPENDIX(Nonmandatory Information)X1. RECOMMENDED METHODS OF CLEANINGX1.1 Recommended methods of cleaning the bearing testsp
42、ecimen, pin, and support assembly to get uniform test resultsare given in this Appendix. They are not intended to beexclusive but have been found adequate for the materialsindicated.X1.1.1 Aluminum AlloysUltrasonic cleaning in a suitablesolvent such as acetone.X1.1.2 Magnesium AlloysChemical cleanin
43、g with acleaner such as one consisting of 60 g of NaOH plus 10 g ofNa3PO412H2O/L of water at 180 to 200F.SUMMARY OF CHANGESCommittee E28 has identified the location of selected changes to this standard since the last issue(E23884(2008) that may impact the use of this standard.(1) Minor revisions to
44、improve clarity(2) Inclusion of a specimen orientation code in 6.1.1-6.1.3and Fig. 5.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 advised that determination of th
45、e 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, either reapproved or withdrawn. You
46、r 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
47、 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. Individual reprints (single or mult
48、iple 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 secured from the ASTM website (www.astm.org/COPYRIGHT/).E238 125
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