1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 12111:2011Metallic materials Fatiguetesting Strain-controlledthermomechanical fatiguetesting methodBS ISO 12111:2011 BRITISH STANDARDNational forewordThis British Standard
2、 is the UK implementation of ISO 12111:2011.The UK participation in its preparation was entrusted to TechnicalCommittee ISE/101/6, Fatigue testing of metals and metal matrixcomposites.A list of organizations represented on this committee can beobtained on request to its secretary.This publication do
3、es not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2011ISBN 978 0 580 53934 3ICS 77.040.10Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of
4、 theStandards Policy and Strategy Committee on 31 October 2011.Amendments issued since publicationDate Text affectedBS ISO 12111:2011Reference numberISO 12111:2011(E)ISO 2011INTERNATIONAL STANDARD ISO12111First edition2011-08-15Metallic materials Fatigue testing Strain-controlled thermomechanical fa
5、tigue testing method Matriaux mtalliques Essais de fatigue Mthode dessai de fatigue thermo-mcanique avec dformation contrle BS ISO 12111:2011ISO 12111:2011(E) COPYRIGHT PROTECTED DOCUMENT ISO 2011 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utili
6、zed in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO 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 +
7、 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2011 All rights reservedBS ISO 12111:2011ISO 12111:2011(E) ISO 2011 All rights reserved iiiContents Page Foreword .v Introductionvi 1 Scope1 2 Normative references1 3 Terms and definitions .1 4 Symbols3 5 Appara
8、tus.4 5.1 Testing machine 4 5.2 Strain measuring system5 5.3 Heating system 5 5.4 Instrumentation for test monitoring 5 5.5 Checking and verification of the apparatus6 6 Specimens6 6.1 Geometry6 6.2 Preparation of specimens.9 6.3 Machining procedure 10 6.4 Sampling and marking10 6.5 Surface conditio
9、n of the specimen11 6.6 Dimensional check 11 6.7 Storage and handling of specimens11 7 Procedure.12 7.1 Laboratory environment .12 7.2 Specimen mounting 12 7.3 Temperature control12 7.4 Temperature gradients12 7.5 Mechanical strain control .13 7.6 Thermal strain compensation 13 7.7 Temperature/mecha
10、nical strain phasing 15 7.8 Command waveforms .16 7.9 Start of test.16 7.10 Monitoring the test 17 7.11 Failure criteria17 7.12 Failure.18 7.13 Test interruption sequence 18 8 Expression of results18 8.1 Preliminary data.18 8.2 Reduction of recorded data18 8.3 Analysis of results.18 9 Test report19
11、9.1 Aim of the study 19 9.2 Material .19 9.3 Specimen19 9.4 Test equipment details19 9.5 Description of test methodology .19 9.6 Test termination technique including definition of failure19 9.7 Deviations from specified test tolerances or recommended procedures .19 9.8 Test conditions 20 9.9 Present
12、ation of results20 BS ISO 12111:2011ISO 12111:2011(E) iv ISO 2011 All rights reservedAnnex A (informative) Representative diagrams .21 Annex B (informative) Modulus of elasticity determination24 Bibliography 25 BS ISO 12111:2011ISO 12111:2011(E) ISO 2011 All rights reserved vForeword ISO (the Intern
13、ational 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 technical committee has b
14、een 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 electrotechnical sta
15、ndardization. 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 Standards adopted by the technical committees are circulated to the member bodies f
16、or 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 of patent rights. ISO shall not be held responsible for identifying any or a
17、ll such patent rights. ISO 12111 was prepared by Technical Committee ISO/TC 164, Mechanical testing of metals, Subcommittee SC 5, Fatigue testing. BS ISO 12111:2011ISO 12111:2011(E) vi ISO 2011 All rights reservedIntroduction The fatigue lives of structural components subjected to simultaneously occ
18、urring thermal and mechanical loadings are often of critical interest and concern to design engineers. A common approach to investigating the behaviours of materials subjected to combined thermal and mechanical loadings is to idealize the conditions of a critical material element on a uniaxial labor
19、atory test specimen. The test condition is one where cyclic, theoretically uniform, within the test section, temperature and strain fields are externally imposed, simultaneously varied and controlled. Such a test is designated as “thermomechanical fatigue”, commonly abbreviated as TMF. In order to e
20、nsure reliability and consistency of results from different laboratories, it is necessary to generate and collect all data using test methodologies that comply with an established standard. This International Standard addresses both the generation and presentation of TMF data. BS ISO 12111:2011INTER
21、NATIONAL STANDARD ISO 12111:2011(E) ISO 2011 All rights reserved 1Metallic materials Fatigue testing Strain-controlled thermomechanical fatigue testing method 1 Scope This International Standard is applicable to the TMF testing of uniaxially loaded metallic specimens under strain control. Specificat
22、ions allow for any constant cyclic amplitude of mechanical strain and temperature with any constant cyclic mechanical strain ratio and any constant cyclic temperature-mechanical strain phasing. NOTE A list and sketch of the most common cyclic types is shown in Annex A. The range of cycles considered
23、 corresponds to that which is generally considered as the low-cycle fatigue domain, that is, Nf 105. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the lat
24、est edition of the referenced document (including any amendments) applies. ISO 7500-1:2004, Metallic materials Verification of static uniaxial testing machines Part 1: Tension/compression testing machines Verification and calibration of the force-measuring system ISO 9513, Metallic materials Calibra
25、tion of extensometer systems used in uniaxial testing ISO 12106, Metallic materials Fatigue testing Axial-strain-controlled method ISO 23718, Metallic materials Mechanical testing Vocabulary 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 23718 and I
26、SO 12106 and the following apply. 3.1 stress Fi/Ao, where Fiis the instantaneous force and Aois the original cross-sectional area at room temperature 3.2 original gauge length Lolength on the specimen between extensometer measurement points at room temperature and zero strain NOTE This definition av
27、oids the complexity of a continually varying gauge length due to thermal expansion and contraction. BS ISO 12111:2011ISO 12111:2011(E) 2 ISO 2011 All rights reserved3.3 gauge length L instantaneous length on the specimen between extensometer measurement points 3.4 strain L/Lo, where L is the change
28、in length and Lois the gauge length measured at room temperature 3.5 total strain totalgebraic sum of the mechanical and thermal strains: tot= m+ th3.6 thermal strain thstrain corresponding to the free expansion induced by a change in temperature 3.7 mechanical strain mstrain that is independent of
29、temperature and is associated with the applied force on the specimen 3.8 elastic strain strain component resulting when the stress is divided by the temperature-dependent Youngs modulus 3.9 inelastic strain strain component resulting when the elastic strain is subtracted from the mechanical strain 3
30、.10 cycle smallest segment of the strain-temperature-time pattern that is repeated periodically 3.11 maximum greatest algebraic value of a variable within one cycle 3.12 minimum least algebraic value of a variable within one cycle 3.13 mean one-half of the algebraic sum of the maximum and minimum va
31、lues of a variable 3.14 range algebraic difference between the maximum and minimum values of a variable 3.15 amplitude half the range of a variable BS ISO 12111:2011ISO 12111:2011(E) ISO 2011 All rights reserved 33.16 fatigue life number of applied cycles, Nf, to achieve a defined failure criterion
32、EXAMPLE An example of this is found in 7.11. 3.17 hysteresis loop closed curve of the stress-mechanical strain response during one cycle 3.18 mechanical strain ratio Rminimum mechanical strain divided by the maximum mechanical strain 3.19 phase angle angle between temperature and mechanical strain,
33、defined with respect to the temperature as reference variable NOTE The phase angle is expressed in degrees. A positive phase angle (0 2 are specified: diameter of cylindrical gauge length: d 5 mm; gauge length: Lo d; transition radius (from parallel section to grip end): r 2d; diameter of grip end:
34、D d; length of reduced section or distance between grips for a constant cross section specimen: Lc0), the mechanical strain may be gradually ramped to its minimum absolute value such that this value is reached at the appropriate temperature in the thermal cycle. At this point, the properly phased TM
35、F cycle is immediately commenced. For large total strain amplitude tests, the mechanical strain may be increased to its final amplitude over multiple cycles to prevent overshoot. Such a gradual increase may also be required for materials that exhibit a serrated yielding phenomenon. 7.10 Monitoring t
36、he test The control variables of specimen temperature and total strain must be monitored during the course of the test. The mechanical strain shall be maintained to the criteria set forth in 7.5, and the specimen temperature condition shall be maintained to the criteria set forth in 7.3. 7.11 Failur
37、e criteria 7.11.1 Specimen separation The specimen is considered to have failed when there is total separation or fracture of the specimen into two parts at some location within the uniform gauge section. All failure locations should be recorded. 7.11.2 Tensile force drop With this method, the speci
38、men is considered to have failed when there is a specified (typically between 5 and 50 %) force drop from the stabilized peak tensile force or from the projected straight line locus of peak tensile stress versus cycles in the case of continuously softening materials. 7.11.3 Specimen cracking A surfa
39、ce replication technique can be used for determining failure of the specimen. In this method, the fatigue test must be interrupted (see 7.13) at predetermined cyclic intervals to replicate the surface of the specimen, e.g. with acetyl cellulose film. The film is subsequently examined for surface con
40、nected cracks and failure is defined when the largest crack observed has grown to a specified length (typically between 0,1 mm and 1,0 mm). BS ISO 12111:2011ISO 12111:2011(E) 18 ISO 2011 All rights reserved7.12 Failure The test is terminated when the conditions for the selected end of test criterion
41、 are fulfilled. The specimen-heating device should be switched off as soon as the test terminates in order to limit the corrosion/oxidation of the specimen and cracked surfaces with a view to carrying out post mortem examinations. If the failure criterion is other than specimen separation, every eff
42、ort should be taken to ensure that the specimen is not over-loaded during test termination. It is recommended that post mortem examinations (metallographic and fractographic analysis) be conducted on the failed specimens. These will provide insight into various failure mechanics and also serve to ma
43、ke known any unusual phenomena that might stand to invalidate the test results. 7.13 Test interruption sequence If a test is interrupted, then care shall be taken to ensure that upon restart there is no significant overshoot in temperature, axial force or mechanical strain. An example of a suitable
44、technique is given below. Prior to interrupting a strain-controlled TMF test, record the maximum and minimum forces of the final 3 cycles. After the test has been discontinued, record several free thermal cycles (at zero force control) prior to cooling the specimen to room temperature and note the m
45、aximum and minimum strain values. The thermal strain range should not have changed but may have shifted due to gauge section changes. Prior to removing the extensometer, a room temperature strain value should be recorded and the extensometers position marked on the specimen. After specimen replicati
46、on and its careful re-mounting, the extensometer should be placed at the markings and manually adjusted to the same strain value as when removed. Thermal cycling should then be initiated and the thermal strains should match the post shutdown strains previously recorded. Adjust the extensometer until
47、 the thermal strains are matched. Upon restart, the forces recorded prior to shut down shall be matched. Some small amount of extensometer tare may be used to aid in matching the previous force level. 8 Expression of results 8.1 Preliminary data The elastic modulus, measured as a function of tempera
48、ture, E(T) (see Annex B), may be plotted for each specimen. The thermal strain as a function of temperature, shall be plotted and tabulated for each specimen. 8.2 Reduction of recorded data As a minimum, plots of stress, mechanical strain, and temperature as a function of time, mechanical strain as
49、a function of stress and temperature shall be generated for representative cycles. 8.3 Analysis of results 8.3.1 Determination of TMF life The failure criterion shall be defined in detail and maintained constant for the test series. 8.3.2 Strain-life relationship As a minimum, a plot of the cyclic life as a function of applied mechanical strain range shall be generated. BS ISO 12111:2011ISO 12111:2011(E) ISO 2011 All rights reserved 199 Test report 9.1 Aim of the study
