1、Designation: B 598 09Standard Practice forDetermining Offset Yield Strength in Tension for CopperAlloys1This standard is issued under the fixed designation B 598; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev
2、ision. 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 Department of Defense.1. Scope*1.1 This practice establishes the requirements f
3、or determin-ing offset yield strength (0.01 %, 0.02 %, and 0.05 % offset) atroom temperature. It is intended for copper alloys in temperscommonly used for spring applications, and materials thickerthan 0.010 in. (0.25 mm).1.1.1 The primary application of this practice is intended forflat strip mater
4、ials that are used for springs; however, thispractice can be used for other product forms, such as wire, rod,and bar.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 forinformation
5、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 of regulatory lim
6、itations prior to use.2. Referenced Documents2.1 ASTM Standards:2B 950 Guide for Editorial Procedures and Form of ProductSpecifications for Copper and Copper AlloysE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical Test-ingE 8/E 8M Test Methods fo
7、r Tension Testing of MetallicMaterialsE74 Practice of Calibration of Force-Measuring Instru-ments for Verifying the Force Indication of Testing Ma-chinesE83 Practice for Verification and Classification of Exten-someter Systems3. Terminology3.1 For definitions of terms relating to mechanical testingr
8、efer to Terminology E6.4. Summary of Practice4.1 To determine the offset yield strength, it is necessary toacquire data (autographic or numerical) from which a stress-strain diagram may be drawn. The stress at which a specifieddeviation of strain from the linear portion of the stress-straincurve occ
9、urs is the yield strength at that particular offset.5. Significance and Use5.1 This practice may be used for approximating a limitingdesign stress at room temperature and, in some cases, forapproximating the range of elastic behavior. Elastic limit, orthe greatest stress that a material is capable o
10、f sustainingwithout any permanent strain remaining upon complete releaseof the stress, is a more technically accurate design parameter;however, the elastic limit is extremely difficult to measure inroutine testing. Caution should be used in applying such valuesto predict the behavior of flat or wire
11、 springs in bending,torsion or other stress modes, or at temperatures other than thatat which the determination is made.6. Apparatus6.1 Standard testing machine of adequate capacity, con-forming to the requirements of Practices E4and E74.6.2 Class B-1 or more accurate Extensometers, conformingto the
12、 requirements of Practice E83and suitable to the tensiontest specimen required for the application.6.3 Extensometer Calibrator, or similar device accurate to0.00002 in. (0.0005 mm).1This practice is under the jurisdiction of ASTM Committee B05 on Copper andCopper Alloys and is the direct responsibil
13、ity of Subcommittee B05.06 on Methodsof Test.Current edition approved April 1, 2009. Published May 2009. Originallyapproved in 1974. Last previous edition approved in 2004 as B 598 98 (2004).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serv
14、iceastm.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 Conshohocken, PA 19428-2959, Uni
15、ted States.7. Test Specimen7.1 Tension test specimens shall be selected from TestMethods E 8/E 8M as appropriate for the product form.8. Procedure8.1 Follow the accepted practices for preparation to performa tension test in accordance with Test Methods E 8/E 8M.Special care in the preparation of thi
16、n-gage samples, includingcontour and edge preparation should be used.8.2 Select the load range so that the yield strength fallswithin the upper half of the chart load range used. Choose astrain magnification so that the 0.0001, 0.0002 or 0.0005-in./in.(or mm/mm) increment of strain can be readily de
17、terminedfrom the chart.8.3 Apply a preload of nominally 10 % of the known oranticipated offset yield strength to the test specimen to align thegrips and to remove all slack and curvature from the specimen.8.4 Seat the extensometer firmly on the test specimen whilemaintaining the preload. Apply the l
18、oad uniformly until thedesired testing speed is attained. The rate of stress applicationshall not exceed 100 000 psi/min (11.5 MPa/s). Take care thatthe recording equipment is functioning correctly and indicatingthe load properly.8.5 Remove the extensometer when the curve indicatesadequate departure
19、 from linear behavior to reveal the desiredoffset, without stopping the test.8.6 Determine the offset yield strength from the stress-straindiagram as described in Test Methods E 8/E 8M.9. Calculation and Report9.1 Determine the load where the offset line intersects thestress-strain curve. This load
20、in pounds divided by the originalcross section area is the yield strength and is reported as yieldstrength (offset value).10. Precision and Bias10.1 PrecisionThe following parameters are reported toimpact upon the precision of this practice:10.1.1 Characteristics of the specimen such as orientation
21、ofgrains relative to the axial stress, grain size, residual stress,previous strain history, dimensions, and eccentricity.10.1.2 Testing conditions such as alignment of the speci-men, speed of testing, temperature, temperature variations,conditions of test equipment, ratio of error in load to the ran
22、gein load values, and ratio of error in extension measurement tothe range in extension values.10.1.3 Interpretation of data such as whether graphical ordigital data were taken, calibration of recording or data-loggingdevice, number of data pairs used to obtain slope of stress-strain curve.10.2 BiasA
23、 statement of bias of this practice requiresreference standard values for one or more materials based onmany measurements or round-robin test data. Such standardreference values or test data are presently not available.11. Keywords11.1 offset yield strength; tensile test; yield strengthSUMMARY OF CH
24、ANGESCommittee B05 has identified the location of selected changes to this standard since the last issue (B 598 98(2004) that may impact the use of this standard. (Approved April 1, 2009.)(1) The specification was revised in many sections to complywith the selected wording in Guide B 950.(2) Minor e
25、ditorial changes to sections 1.2, 2.1, (removed 2.2),3.1, 7.1, 8.1, 8.4, 8.6, and Keywords. No technical changeshave been made.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
26、expressly 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 re
27、vised, 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
28、may attend. 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. Individual 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).B598092
