BS ISO 12106-2017 Metallic materials Fatigue testing Axial-strain-controlled method《金属材料 疲劳试验 轴向应变控制法》.pdf

1、BS ISO 12106:2017Metallic materials Fatiguetesting Axial-strain-controlled methodBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS ISO 12106:2017 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 12106:2017.The UK participation i

2、n its preparation was entrusted to Technical Committee ISE/101/6, Fatigue testing of metals and metal matrix composites.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a con

3、tract. Users are responsible for its correct application. The British Standards Institution 2017.Published by BSI Standards Limited 2017ISBN 978 0 580 90261 1 ICS 77.040.10 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the

4、authority of the Standards Policy and Strategy Committee on 31 March 2017.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 12106:2017 ISO 2017Metallic materials Fatigue testing Axial-strain-controlled methodMatriaux mtalliques Essais de fatigue Mthode par dformation a

5、xiale contrleINTERNATIONAL STANDARDISO12106Second edition2017-03Reference numberISO 12106:2017(E)BS ISO 12106:2017ISO 12106:2017(E)ii ISO 2017 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2017, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no part of this publicatio

6、n may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of

7、 the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 12106:2017ISO 12106:2017(E)Foreword vIntroduction vi1 Scope . 12 Normative references 13 Terms and definitions . 14 Symbols 34.1

8、 Specimens . 34.2 Fatigue testing . 34.2.1 Symbols 34.2.2 Subscripts 54.3 Expression of results 55 Apparatus . 55.1 Test machine . 55.1.1 General 55.1.2 Force transducer 65.1.3 Gripping of specimen . 65.1.4 Alignment check . 65.2 Strain measurement . 75.3 Heating device and temperature measurement .

9、 85.4 Instrumentation for test monitoring . 85.4.1 Recording systems 85.4.2 Cycle counter . 95.5 Checking and verification 96 Specimens 96.1 Geometry 96.1.1 Round bars 96.1.2 Flat sheet products .106.2 Preparation of specimens . 146.2.1 General. 146.2.2 Machining procedure 146.2.3 Sampling and marki

10、ng .156.2.4 Surface condition of specimen 156.2.5 Dimensional check 166.2.6 Storage and handling 167 Procedure167.1 Laboratory environment . 167.2 Test machine control . 167.3 Mounting of the specimen 177.4 Cycle shape Strain rate or frequency of cycling 177.5 Start of test 187.5.1 Preliminary measu

11、rements . 187.5.2 Test commencement 197.6 Number of specimens 197.7 Data recording 197.7.1 Stress-strain hysteresis loops 197.7.2 Data acquisition .197.8 End of test . 207.9 Failure criteria 208 High-temperature strain-controlled creep-fatigue testing .229 Expression of results .239.1 Basic data (re

12、corded data (see 7.7) . 23 ISO 2017 All rights reserved iiiContents PageBS ISO 12106:2017ISO 12106:2017(E)9.2 Analysis of low-cycle fatigue results at Re= 1 239.2.1 Distinction between different types of strain values .239.2.2 Determination of fatigue life (see 7.9) .249.2.3 Stress-strain and strain

13、-fatigue life relationships 249.3 Analysis of creep-fatigue results . 2510 Test report 2510.1 General 2510.2 Purpose of the test 2610.3 Material 2610.4 Specimen . 2610.5 Test methods 2610.6 Test conditions . 2710.7 Presentation of results 2710.7.1 Presentation of single test results 2710.7.2 Present

14、ation of results of test series .2810.8 Values to be stored in a low-cycle fatigue database .29Annex A (informative) Measurement uncertainty 31Annex B (informative) Examples of graphical presentation of results 33Bibliography .37iv ISO 2017 All rights reservedBS ISO 12106:2017ISO 12106:2017(E)Forewo

15、rdISO (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. Each member body interested in a subject for which a technica

16、l 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 International Electrotechnical Commission (IEC) on all matters of ele

17、ctrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was

18、drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such pat

19、ent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www .iso .org/ patents).Any trade name used in this document is information given for the convenience of users and does n

20、ot constitute an endorsement.For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (T

21、BT) see the following URL: www .iso .org/ iso/ foreword .html.This document was prepared by Technical Committee ISO/TC 164, Mechanical testing of metals, Subcommittee SC 5, Fatigue testing.This second edition cancels and replaces the first edition (ISO 12106:2003), which has been technically revised

22、. ISO 2017 All rights reserved vBS ISO 12106:2017ISO 12106:2017(E)IntroductionMaterials and their microstructure may change when subjected to cyclic deformations and their mechanical properties can be significantly altered when compared with that resultant from monotonic deformations, for example, u

23、niaxial stress-strain response. The design of mechanical components subjected to fatigue loadings and cyclic deformations requires, in a number of industrial sectors (i.e. nuclear, aerospace, ground vehicles, medical devices, etc.), knowledge of the cyclic behaviour of the materials under reversed s

24、train control conditions, referred to as low-cycle fatigue, when cyclic plasticity is present.In order to ensure reliability and consistency of results from different laboratories, it is necessary to collect all data using test methodologies that comply with a number of key points.This document conc

25、erns both the generation of such strain-controlled fatigue data at room or elevated temperatures at fixed R-ratios (strain) and the presentation of results for fatigue properties, strain-life behaviour and cyclic stress-strain responses of metallic materials determined at an Re-ratio = 1. Since ther

26、e is a close relationship with strain-controlled, high-temperature testing, there is also a section devoted to creep-fatigue testing methodology.This document does not address safety or health concerns, should such issues exist, that may be associated with its use or application. The user of this do

27、cument has the sole responsibility to establish any appropriate safety and health concerns, as well as to determine the applicability of any national or local regulatory limitations regarding the use of this document.vi ISO 2017 All rights reservedBS ISO 12106:2017Metallic materials Fatigue testing

28、Axial-strain-controlled method1 ScopeThis document specifies a method of testing uniaxially deformed specimens under strain control at constant amplitude, uniform temperature and fixed strain ratios including at Re= 1 for the determination of fatigue properties. It can also be used as a guide for te

29、sting under other R-ratios, as well as elevated temperatures where creep deformation effects may be active.2 Normative referencesThe following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only t

30、he edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 7500-1, Metallic materials Calibration and verification of static uniaxial testing machines Part 1: Tension/compression testing machines Calibration and verification

31、 of the force-measuring systemISO 9513, Metallic materials Calibration of extensometer systems used in uniaxial testingISO 23788, Metallic materials Verification of the alignment of fatigue testing machines3 Terms and definitionsFor the purposes of this document, the following terms and definitions

32、apply.ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at h t t p :/ www .electropedia .org/ ISO Online browsing platform: available at h t t p :/ www .iso .org/ obp3.1engineering stressinstantaneous force divided by the

33、 initial cross-sectional area of the gauge lengthSFA= /O3.2true stressinstantaneous force divided by the instantaneous cross-sectional area of the gauge length =FA/Note 1 to entry: At strains to approximately 10 %, the true stress is approximated by the engineering stress, F/Ao. It is also important

34、 to note that at strains to approximately 10 %, it is the engineering strain that is actually measured by the extensometer and it is the controlled parameter in a test.3.3initial lengthgauge lengthLoinitial length between extensometer measurement points at test temperatureINTERNATIONAL STANDARD ISO

35、12106:2017(E) ISO 2017 All rights reserved 1BS ISO 12106:2017ISO 12106:2017(E)3.4parallel lengthLplength between transition radii of the test specimen3.5strainengineering straineLLLLL=Doiootrue total strain =dLLLLoiwhereLiis the instantaneous length of the gauge section;Lois the initial or gauge len

36、gth.Note 1 to entry: At true strain values to approximately 10 %, is approximated by the engineering strain e = L/L. It is also important to note that at strains to approximately 10%, it is the engineering strain that is the quantity measured by the extensometer and the controlled parameter in a str

37、ain-controlled fatigue test.3.6cyclesmallest segment of the strain-time function that is repeated periodically3.7maximumgreatest algebraic value of a variable within one cycle3.8minimumleast algebraic value of a variable within one cycle3.9meanone-half of the algebraic sum of the maximum and minimum

38、 values of a variable3.10rangealgebraic difference between the maximum and minimum values of a variable3.11amplitudehalf the range of a variable3.12fatigue lifeNfnumber of cycles that have to be applied to achieve a failureNote 1 to entry: Failure criteria are defined, for example, in 7.8. The failu

39、re criterion used shall be reported with the results and be consistent through a series of fatigue tests.2 ISO 2017 All rights reservedBS ISO 12106:2017ISO 12106:2017(E)3.13hysteresis loopclosed curve of the stress-strain response during one complete cycleNote 1 to entry: It is quite common that the

40、 beginning few hysteresis loops in a test sequence may not be completely “closed” due to cyclic softening, cyclic hardening, cyclic stress relaxation, stress “shakedown”, or ratchetting.4 SymbolsFor the purposes of this document, the symbols defined in 4.1 to 4.3 apply.4.1 SpecimensSee Table 1.Table

41、 1 Symbols and designations concerning specimensSpecimen Symbol Designation UnitLoInitial or gauge length mmLiInstantaneous gauge length mmAoInitial area of gauge section mm2A Instantaneous area of gauge section with AL = AoLomm2AfMinimum area at failure mm2rTransition radius (from parallel length i

42、nto the grip end of the test specimen)mmLzOverall length of specimen mmCylindricald Diameter of cylindrical gauge section mmD Diameter of grip end of specimen mmFlat-sheett Thickness mmW Width of grip end mmw Width of gauge section mm4.2 Fatigue testing4.2.1 SymbolsTable 2 Symbols and designations f

43、or variables and propertiesSymbol Definition UnitsE Modulus of Elasticitymean value of the slope of the initial linear portion of a stress-strain curveGigapascals (GPa)ETunloading modulus following a maximum stress (see Figure 1),Gigapascals (GPa)ECunloading modulus following a min-imum stress (see

44、Figure 1)Gigapascals (GPa)Nfnumber of cycles to failure ISO 2017 All rights reserved 3BS ISO 12106:2017ISO 12106:2017(E)Symbol Definition Unitstftime to failure; tf= TNfin which T is the period of the signal (duration of the wavelength)Seconds (s) true stress Megapascals (MPa)S engineering stress Me

45、gapascals (MPa)e engineering strainededt=strain rate Seconds to the power of minus one (s1)where t = time true strain range of a variableRzmean surface roughness Micrometres (m)Restrain ratio= (emin/emax)Figure 1 Stress-strain hysteresis loop at Re= 1NOTE For the purpose of defining plastic strain f

46、rom a stabilized stress-strain hysteresis loop, it is that non-recoverable strain at the mean stress established by (Smax+ Smin)/2 for the steady-state stress response in a controlled strain test. Frequently, it is the width of the hysteresis loop at zero stress crossing but it may not be in some me

47、tals.Table 2 (continued)4 ISO 2017 All rights reservedBS ISO 12106:2017ISO 12106:2017(E)4.2.2 SubscriptsTable 3 Subscripts and meaningSubscript Meaningt totalp plastice elastica amplitudem meanmin minimummax maximum4.3 Expression of resultsSee Table 4.Table 4 Symbols and designations concerning the

48、expression of fatigue properties for Re= 1 testsSymbol Designation UnityCyclic yield strengthaMPan Monotonic strain hardening exponent n Cyclic strain hardening exponent K Monotonic strength coefficient MPaK Cyclic strength coefficient MPafFatigue strength coefficient MPab Fatigue strength exponent

49、fFatigue ductility coefficient c Fatigue ductility exponent a0,2 % offset is typically used.5 Apparatus5.1 Test machine5.1.1 GeneralThe tests shall be conducted on a uniaxial tension-compression machine designed for smooth start-up with no backlash when passing through zero stress. The machine shall be capable of controlling strain and measuring force when applying the recommended waveform. It should be axially stiff and well aligned. The complete machine-loading system,