1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA
2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any
3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-22676-3 SANS 10275:2009Edition 2ISO 10275:2007Edition 2SOUTH AFRICAN NATIONAL STANDARD Metallic materials Sheet and strip Determination of
4、 tensile strain hardening exponent This national standard is the identical implementation of ISO 10275:2007 and is adopted with the permission of the International Organization for Standardization. Published by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0001Tel: +
5、27 12 428 7911 Fax: +27 12 344 1568 www.sabs.co.za SABS SANS 10275:2009 Edition 2 ISO 10275:2007 Edition 2 Table of changes Change No. Date Scope National foreword This South African standard was approved by National Committee SABS TC 164, Engineering materials Mechanical testing of metals, in accor
6、dance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This SANS document was published in October 2009. This SANS document supersedes SANS 10275:2003 (edition 1). Reference numberISO 10275:2007(E)ISO 2007INTERNATIONAL STANDARD ISO10275Second editi
7、on2007-06-01Metallic materials Sheet and strip Determination of tensile strain hardening exponent Matriaux mtalliques Tles et bandes Dtermination du coefficient dcrouissage en traction SANS 10275:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the
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12、O at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2007 All rights reservedSANS 10275:2009This s tandar
13、d may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 10275:2007(E) ISO 2007 All rights reserved iiiContents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Symbols and designations 1 4 Principle. 3 5 Test equipment . 3 6 Test piece
14、s 3 7 Procedure 3 8 Test report . 8 Annex A (informative) International comparison of symbols used in the determination of the tensile strain hardening exponent . 9 Bibliography . 10 SANS 10275:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SA
15、BS .ISO 10275:2007(E) iv ISO 2007 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. E
16、ach member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the Internati
17、onal Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standa
18、rds adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject
19、 of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 10275 was prepared by Technical Committee ISO/TC 164, Mechanical testing of metals, Subcommittee SC 2, Ductility testing. This second edition cancels and replaces the first edition (ISO 10275:1993
20、), which has been technically revised. SANS 10275:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 10275:2007(E) ISO 2007 All rights reserved vIntroduction In the former version of this International Standard, for the calculation of th
21、e true strain, the elastic strain did not need to be subtracted from the total strain if it was lower than 10 % of the total strain. In this new International Standard, the elastic strain is subtracted from the total strain for calculation of the true strain, which is now referred to as “true plasti
22、c strain”. SANS 10275:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .SANS 10275:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .INTERNATIONAL STANDARD ISO 10275:2007(E) ISO 20
23、07 All rights reserved 1Metallic materials Sheet and strip Determination of tensile strain hardening exponent 1 Scope This International Standard specifies a method for determining the tensile strain hardening exponent n of flat products (sheet and strip) made of metallic materials. The method is va
24、lid only for that part of the stress-strain curve in the plastic range where the curve is continuous and monotonic (see 7.4). In the case of materials with a serrated stress-strain curve in the work hardening range (materials which show the Portevin-Le Chatelier effect, e.g. AlMg-alloys) the automat
25、ic determination (linear regression of the logarithm true stress vs. the logarithm true plastic strain, see 7.7) should be used to give reproducible results. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only e
26、dition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 6892:1998, Metallic materials Tensile testing at ambient temperature ISO 7500-1:2004, Metallic materials Verification of static uniaxial testing machines Part 1: Tensio
27、n/compression testing machines Verification and calibration of the force-measuring system ISO 9513:1999, Metallic materials Calibration of extensometers used in uniaxial testing ISO 10113, Metallic materials Sheet and strip Determination of plastic strain ratio 3 Symbols and designations The symbols
28、 and corresponding designations used in determining the tensile strain hardening exponent are given in Table 1. SANS 10275:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 10275:2007(E) 2 ISO 2007 All rights reservedTable 1 Symbols and
29、 designations Symbol Designation Units LeExtensometer gauge length (Le) mm L Instantaneous extension of the measurement base mm L Instantaneous length of the extensometer gauge length L = Le+ L mm epSpecified plastic (engineering) strain at which the tensile strain hardening exponent should be deter
30、mined (single data point method) % ep epSpecified plastic (engineering) strain range at which the tensile strain hardening exponent should be determined (linear regression method, ep= lower limit of the plastic strain in percent, ep= upper limit of the plastic strain in percent) % SoOriginal cross-s
31、ectional area of the parallel length mm2S True cross-sectional area mm2F Instantaneous force applied to the test piece N R Stress MPa True stress MPa True plastic strain mESlope of the elastic part of the stress/percentage extension-curve MPa n Tensile strain hardening exponent C Strength coefficien
32、t MPa N Number of measurements made in determining the tensile strain hardening exponent r Plastic strain ratio RmTensile strength MPa AePercentage yield point extension % AgPercentage plastic extension at maximum force % A, B, x, y Variables used for the evaluation of n by the manual method NOTE 1
33、In the literature the readers may encounter other symbols. For an international comparison of symbols, see Annex A. NOTE 2 1 MPa = 1 N/mm2. 3.2 The tensile strain hardening exponent n is defined as the exponent of the true plastic strain in the mathematical equation relating the true stress to the t
34、rue plastic strain (during uniaxial application of a force). This equation can be taken as follows: nC = (1) 3.3 This equation can be transformed into a logarithmic one as follows: ln ln lnCn =+ (2) The strain hardening exponent in the logarithmic system of coordinates is defined as the slope of the
35、 corresponding straight line. SANS 10275:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 10275:2007(E) ISO 2007 All rights reserved 34 Principle A test piece is subjected to uniaxial tensile strain at a prescribed constant rate within
36、 the region of uniform plastic strain. The tensile strain hardening exponent n is calculated either by considering a portion of the stress-strain curve in the plastic region, or by considering the whole uniform plastic strain region. 5 Test equipment 5.1 Tensile testing machine, verified and calibra
37、ted in accordance with ISO 7500-1:2004 and of class 1 or better. The method of gripping the test piece shall conform to the requirements of ISO 6892. 5.2 Extensometer, of class 2 or better (class 1 in the event of determination of the plastic strain ratio r, see ISO 10113) in accordance with ISO 951
38、3:1999, for measuring changes in the gauge length. 5.3 Dimension-measuring equipment, capable of measuring the width and thickness of the parallel-sided section of the test piece to within the tolerances specified for these dimensions in ISO 6892. 6 Test pieces 6.1 Sampling to obtain test pieces sha
39、ll be in accordance with the requirements of the relevant product standard or, if not specified therein, by agreement. Machining tolerances, tolerances on shape, and the marking shall be as specified in ISO 6892. 6.2 In the event of the plastic strain ratio r and the tensile strain hardening exponen
40、t n being determined simultaneously, the conditions of ISO 10113 shall apply. 6.3 The thickness of the test piece shall be that of the full sheet, unless otherwise specified. 6.4 The surface of the test piece shall not be damaged (by scratches, etc.). 7 Procedure 7.1 In general, the test shall be ca
41、rried out at ambient temperature, i.e. between 10 C and 35 C. Tests carried out under controlled conditions, where required, shall be made at a temperature of (23 5)C. 7.2 The test piece shall be mounted in the tensile testing machine (see 5.1) so that the force can be applied axially in accordance
42、with ISO 6892. 7.3 In the plastic range, the strain rate of parallel length shall not exceed 0,008 s1, unless otherwise specified in the relevant standard. This rate shall be kept constant during the time interval over which the tensile strain hardening exponent is determined. If a proof strength or
43、 the yield strength is determined during the same tensile test, the strain rate for this determination shall be as defined in ISO 6892. 7.4 When n is determined over the whole uniform plastic strain range, the upper limit for these data points shall be immediately prior to the strain at which the ma
44、ximum force occurs. For materials with homogenous deformation behaviour (i.e. materials without upper and/or lower yield strength), the lower limit of the range over which n is determined shall not be lower than a point after which the final testing rate used for determining Rmhas been achieved (see
45、 Figure 1). For the materials exhibiting yield point phenomena (upper and/or lower yield strengths), the lower limit shall not be lower than the start of uniform work hardening and after which the final testing rate used for determining Rmhas been achieved (see Figures 2 and 3). SANS 10275:2009This
46、s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 10275:2007(E) 4 ISO 2007 All rights reservedThe lower limit and the upper limit shall be reported. Key X strain % Y stress 1 lower limit 2 upper limit Figure 1 Range for n220/Agor n2AgSANS 10275:
47、2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 10275:2007(E) ISO 2007 All rights reserved 5Key X strain % Y stress 1 lower limit 2 upper limit Figure 2 Range for n420/Agor n420SANS 10275:2009This s tandard may only be used and printe
48、d by approved subscription and freemailing clients of the SABS .ISO 10275:2007(E) 6 ISO 2007 All rights reservedKey X strain % Y stress 1 lower limit 2 upper limit Figure 3 Range for n420/Agor n4Ag7.5 From the values of the force and corresponding strain, calculate the true stress using the equation
49、 = (F/So) (Le+ L)/Le (3) Calculate the true plastic strain using the equation = ln(Le+ L)/Le F/(So mE) (4NOTE From the physical view, in Equation (4) the true cross-sectional area S according to Equation (5) should be used instead of the original cross-sectional area Soto calculate the true plastic strain . The code of practice has proved that the results obtained with Soor S are not significantly different. With respect to this and the lower comp
