1、Designation: B598 14B598 14aStandard Practice forDetermining Offset Yield Strength in Tension for CopperAlloys1This standard is issued under the fixed designation B598; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st revision. 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 U.S. Department of Defense.1. Scope*1.1 This practice establishes the req
3、uirements for determining offset yield strength (0.01 %, 0.02 %, and 0.05 % offset) at roomtemperature. It is intended for copper alloys in tempers commonly used for spring applications, and materials thicker than 0.010in. (0.25 mm).1.1.1 The primary application of this practice is intended for flat
4、 strip materials that are used for springs; however, this practicecan be used for other product forms, such as wire, rod, and bar.1.2 UnitsValues stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematicalconversions to SI units which are provided for
5、information only and are not considered standard.1.3 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 establish appropriate safety and health practices and determine the applicability of reg
6、ulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B846 Terminology for Copper and Copper AlloysE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE8/E8M Test Methods for Tension Testing of Metallic MaterialsE74 Prac
7、tice of Calibration of Force-Measuring Instruments for Verifying the Force Indication of Testing MachinesE83 Practice for Verification and Classification of Extensometer Systems3. Terminology3.1 For definitions of terms related to copper and copper alloys, refer to Terminology B846.3.2 For definitio
8、ns of terms related to mechanical testing, refer to Terminology E6.4. Summary of Practice4.1 To determine the offset yield strength, it is necessary to acquire data (autographic or numerical) from which a stress-straindiagram may be drawn. The stress at which a specified deviation of strain from the
9、 linear portion of the stress-strain curve occursis the yield strength at that particular offset.5. Significance and Use5.1 This practice may be used for approximating a limiting design stress at room temperature and, in some cases, forapproximating the range of elastic behavior. Elastic limit, or t
10、he greatest stress that a material is capable of sustaining without anypermanent strain remaining upon complete release of the stress, is a more technically accurate design parameter; however, the1 This practice is under the jurisdiction of ASTM Committee B05 on Copper and Copper Alloys and is the d
11、irect responsibility of Subcommittee B05.06 on Methods ofTest.Current edition approved April 1, 2014Sept. 1, 2014. Published May 2014September 2014. Originally approved in 1974. Last previous edition approved in 20092014 asB598 09.B598 14. DOI: 10.1520/B0598-14.10.1520/B0598-14A.2 For referencedASTM
12、 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.This document is not an ASTM standard and is intended only to provide the user of
13、 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 the standard as pub
14、lished 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 States1elastic limit is extremely difficult to measure in routine testi
15、ng. Caution should be used in applying such values to predict thebehavior of flat or wire springs in bending, torsion or other stress modes, or at temperatures other than that at which thedetermination is made.6. Apparatus6.1 Standard testing machine of adequate capacity, conforming to the requireme
16、nts of Practices E4 and E74.6.2 Class B-1 or more accurate Extensometers, conforming to the requirements of Practice E83 and suitable to the tension testspecimen required for the application.6.3 Extensometer Calibrator, or similar device accurate to 0.00002 in. (0.0005 mm).7. Test Specimen7.1 Tensio
17、n test specimens shall be selected from Test Methods E8/E8M as appropriate for the product form.8. Procedure8.1 Follow the accepted practices for preparation to perform a tension test in accordance with Test Methods E8/E8M. Specialcare in the preparation of thin-gage samples, including contour and e
18、dge preparation should be used.8.2 Select the load range so that the yield strength falls within the upper half of the chart load range used. Choose a strainmagnification so that the 0.0001, 0.0002 or 0.0005-in./in. (or mm/mm) increment of strain can be readily determined from thechart.8.3 Apply a p
19、reload of nominally 10 % of the known or anticipated offset yield strength to the test specimen to align the gripsand to remove all slack and curvature from the specimen.8.4 Seat the extensometer firmly on the test specimen while maintaining the preload.Apply the load uniformly until the desiredtest
20、ing speed is attained. The rate of stress application shall not exceed 100 000 psi/min (11.5 MPa/s). Take care that the recordingequipment is functioning correctly and indicating the load properly.8.5 Remove the extensometer when the curve indicates adequate departure from linear behavior to reveal
21、the desired offset,without stopping the test.8.6 Determine the offset yield strength from the stress-strain diagram as described in Test Methods E8/E8M.9. Calculation and Report9.1 Determine the load where the offset line intersects the stress-strain curve. This load in pounds divided by the origina
22、l crosssection area is the yield strength and is reported as yield strength (offset value).10. Precision and Bias10.1 PrecisionThe following parameters are reported to impact upon the precision of this practice:10.1.1 Characteristics of the specimen such as orientation of grains relative to the axia
23、l stress, grain size, residual stress,previous strain history, dimensions, and eccentricity.10.1.2 Testing conditions such as alignment of the specimen, speed of testing, temperature, temperature variations, conditionsof test equipment, ratio of error in load to the range in load values, and ratio o
24、f error in extension measurement to the range inextension values.10.1.3 Interpretation of data such as whether graphical or digital data were taken, calibration of recording or data-loggingdevice, number of data pairs used to obtain slope of stress-strain curve.10.2 BiasA statement of bias of this p
25、ractice requires reference standard values for one or more materials based on manymeasurements or round-robin test data. Such standard reference values or test data are presently not available.11. Keywords11.1 offset yield strength; tensile test; yield strengthB598 14a2SUMMARY OF CHANGESCommittee B0
26、5 has identified the principal changes to this standard practice that have been incorporated sincethe B598 14 issue as follows (Approved Sept. 1, 2014):(1) Removal of E74 from Sections 2.1 and 6.1.SUMMARY OF CHANGESCommittee B05 has identified the principal changes to this standard practice that hav
27、e been incorporated sincethe B598 09 issue as follows (Approved April 1, 2014):(1) Added Terminology B846 to the Terminology Section 3 and to the Referenced Documents Section 2.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item ment
28、ionedin this standard. Users of this standard are 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
29、and must be reviewed every five years andif not revised, 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
30、of theresponsible technical committee, which you 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 Bo
31、x 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). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 14a3
