1、BSI Standards PublicationBS ISO 26843:2015Metallic materials Measurement of fracturetoughness at impact loadingrates using precracked Charpy-type test piecesBS ISO 26843:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 26843:2015.The UK participation in its
2、 preparation was entrusted to Technical Committee ISE/101/4, Toughness testing.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 contract. Users are responsible for its corr
3、ect application. The British Standards Institution 2015.Published by BSI Standards Limited 2015ISBN 978 0 580 89332 2 ICS 77.040.10 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Str
4、ategy Committee on 31 December 2015.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 26843:2015 ISO 2015Metallic materials Measurement of fracture toughness at impact loading rates using precracked Charpy-type test piecesMatriaux mtalliques Mesure de la tnacit dprouve
5、ttes type Charpy prfissures soumises un chargement dimpactINTERNATIONAL STANDARDISO26843First edition2015-12-15Reference numberISO 26843:2015(E)BS ISO 26843:2015ISO 26843:2015(E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2015, Published in SwitzerlandAll rights reserved. Unless
6、otherwise specified, no part of this publication 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 addr
7、ess below or ISOs member body in the country of 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 26843:2015ISO 26843:2015(E)Foreword ivIntroduction v1 Scope . 12 Normative refere
8、nces 13 Symbols 14 Principle 35 Test specimens 56 Testing machines 67 Test procedures and measurements 67.1 General . 67.2 Impact velocity 77.3 Time to fracture 77.4 Multiple specimen tests. 77.5 Single-specimen tests 77.6 Post-test crack length measurements . 88 Evaluation of fracture mechanics par
9、ameters 89 Test report . 99.1 Organization 99.2 Specimen, material, and test environment . 99.2.1 Specimen description 99.2.2 Specimen dimensions 99.2.3 Material description 99.2.4 Test environment .109.3 Fatigue precracking conditions . 109.4 Test data qualification . 109.4.1 Limitations . 109.4.2
10、Crack length measurements . 109.4.3 Fracture surface appearance 109.4.4 Resistance curves .109.4.5 Checklist for data qualification . 109.5 Test results. 11Annex A (normative) Test machines suitable for each test procedure 12Annex B (informative) Estimation of strain rate .13Annex C (normative) Dyna
11、mic evaluation of fracture toughness 14Annex D (normative) Determination of resistance curves at impact loading rates by multiple specimen methods 19Annex E (normative) Estimation of Jd-a R-curves using the normalization method .21Annex F (normative) Determination of characteristic fracture toughnes
12、s value J0,2Bd.24Annex G (normative) Validity criteria 25Annex H (normative) Determination of fracture toughness in terms of J-integral .27Annex I (informative) Example test reports 29Bibliography .34 ISO 2015 All rights reserved iiiContents PageBS ISO 26843:2015ISO 26843:2015(E)ForewordISO (the Int
13、ernational 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 ha
14、s 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 electrotechnical
15、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 drafted in acc
16、ordance 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 patent rights. Detai
17、ls 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 not constitute an end
18、orsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee respo
19、nsible for this document is ISO/TC 164, Mechanical testing of metals, Subcommittee SC 4, Toughness testing Fracture (F), Pendulum (P), Tear (T) .iv ISO 2015 All rights reservedBS ISO 26843:2015ISO 26843:2015(E)IntroductionThis International Standard is closely related to ISO 14556 and was derived fr
20、om a draft procedure prepared by the Working Party “European Standards on Instrumented Precracked Charpy Testing” of the European Structural Integrity Society (ESIS) Technical Subcommittee on Dynamic Testing at Intermediate Strain Rates (TC5). ISO 2015 All rights reserved vBS ISO 26843:2015BS ISO 26
21、843:2015Metallic materials Measurement of fracture toughness at impact loading rates using precracked Charpy-type test pieces1 ScopeThis International Standard specifies requirements for performing and evaluating instrumented precracked Charpy impact tests on metallic materials using a fracture mech
22、anics approach. Minimum requirements are given for measurement and recording equipment such that similar sensitivity and comparable measurements are achieved.Dynamic fracture mechanics properties determined using this International Standard are comparable with conventional large-scale fracture mecha
23、nics results when the corresponding validity criteria are met. Because of the small absolute size of the Charpy specimen, this is often not the case. Nevertheless, the values obtained can be used in research and development of materials, in quality control, and to establish the variation of properti
24、es with test temperature under impact loading rates.Fracture toughness properties determined through the use of this International Standard may differ from values measured at quasistatic loading rates. Indeed, an increase in loading rate causes a decrease in fracture toughness when tests are perform
25、ed in the brittle or ductile-to-brittle regimes; the opposite is observed (i.e. increase in fracture toughness) in the fully ductile regime. More information on the dependence of fracture toughness on loading (or strain) rate is given in Reference 1. In addition, it is generally acknowledged that fr
26、acture toughness also depends on test temperature. For these reasons, the user is required to report the actual test temperature and loading rate for each test performed.In case of cleavage fracture of ferritic steels in the ductile-to-brittle transition region, variability can be very large and can
27、not be adequately described by simple statistics. In this case, additional tests are required and the analysis is to be performed using a statistical procedure applicable to this type of test, see for example Reference 2.NOTE Modifications to the analytical procedures prescribed in Reference 2 might
28、 be necessary to account for the effect of elevated (impact) loading rates.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated refe
29、rences, the latest edition of the referenced document (including any amendments) applies.ISO 148-1, Metallic materials Charpy pendulum impact test Part 1: Test methodISO 148-2, Metallic materials Charpy pendulum impact test Part 2: Verification of testing machinesISO 12135, Metallic materials Unifie
30、d method of test for the determination of quasistatic fracture toughnessISO 14556, Steel Charpy V-notch pendulum impact test Instrumented test methodISO 26203-2, Metallic materials Tensile testing at high strain rates Part 2: Servo-hydraulic and other test systems3 SymbolsFor the purposes of this In
31、ternational Standard, the following symbols given in Table 1 apply.INTERNATIONAL STANDARD ISO 26843:2015(E) ISO 2015 All rights reserved 1BS ISO 26843:2015ISO 26843:2015(E)Table 1 Symbols and definitions used in this International StandardSymbol Definition UnitaNominal crack length (for the purposes
32、 of fatigue precracking, an assigned value less than a0)mmafFinal crack length (a0+ a) mmamLength of machined notch mma0Initial crack length mma Crack extension (a a0) mmamaxCrack extension limit for J-controlled crack extension mmasCrack extension corresponding to displacement s mmB Specimen thickn
33、ess mmBeSpecimen effective thickness as defined in Formula (E.7) mmBNSpecimen net thickness after side-grooving mmCMCompliance of the test machine m/NC0Specimen elastic compliance m/NCSSpecimen theoretical compliance m/NE Youngs modulus of elasticity GPad/dt Strain rate s1fgOutput frequency limit Hz
34、F Applied force NFcdApplied force at onset of unstable crack extension in Figure 1 NFfMaximum fatigue precracking force during the final precracking stage NFgyApplied force at onset of general yielding as defined in ISO 14556 NFmMaximum applied force as defined in ISO 14556 NFsApplied force correspo
35、nding to a displacement s NJdDynamic J-integral MJ/m2JcdDynamic equivalent of Jc(B)in ISO 12135 (with B = 10 mm) MJ/m2JgJ at upper limit of J-controlled crack extension MJ/m2Jd,maxLimit of Jd-R material behaviour defined by this test method MJ/m2JudDynamic equivalent of Ju(B)in ISO 12135 (with B = 1
36、0 mm) MJ/m2J0,2BdDynamic equivalent of J0,2BL(B)in ISO 12135 (with B = 10 mm) MJ/m2dJd/dt Rate of change of dynamic J-integral MJ/m2s1KdDynamic stress intensity factor MPa m0,5KJdDynamic stress intensity factor calculated from J-integral MPa m0,5KIdyn(t) Stress intensity factor time history from the
37、 impact response curve method MPa m0,5KIdDynamic plane strain fracture toughness MPa m0,5KJcdDynamic stress intensity factor calculated from J-integral at the onset of cleavage MPa m0,5dKd/dt Rate of change of dynamic stress intensity factor MPa m0,5s1KV Absorbed energy as defined in ISO 148-1 JKV0A
38、vailable potential energy corresponding to a reduced pendulum impact velocity v0JM Total mass of the moving striker of the pendulum kgn Strain hardening exponent of the Ramberg-Osgood material law N Number of available test specimens 2 ISO 2015 All rights reservedBS ISO 26843:2015ISO 26843:2015(E)Sy
39、mbol Definition UnitRfdDynamic flow stress, defined as the average of dynamic yield strength and dynamic tensile strengthMPaRmdDynamic tensile strength determined at the strain rate of the fracture toughness test MPaRpdDynamic yield (proof) strength determined at the strain rate of the fracture toug
40、h-ness testMPaRpYield (proof) strength measured at quasistatic strain rate MPas Specimen displacement (calculated according to ISO 14556) mmsplPlastic component of specimen displacement mmS Span between outer loading points mmT Temperature Ct Time stfTime to fracture stiTime at the onset of crack pr
41、opagation strSignal rise time stoTime at striker impact s Period of force oscillation sv0Initial striker impact velocity m s1v0sStriker impact velocity corresponding to the maximum available energy of the pendu-lumm s1W Specimen effective width mmWmEnergy at maximum force as defined in ISO 14556 JWp
42、Plastic component of the area under the force-displacement test record up to displace-ment sJWsTotal fracture energy under the force-displacement test record up to displacement s JWtCalculated energy from area under complete force-displacement test record up to F = 0,02 Fmas defined in ISO 14556JWoA
43、vailable impact energy J Poissons ratio 4 PrincipleThis International Standard prescribes impact bend tests which may be performed on fatigue precracked Charpy-type specimens to obtain dynamic fracture mechanics properties of metallic materials. This International Standard extends the procedure for
44、V-notch impact bend tests in accordance with ISO 148-1, and may be used for the evaluation of the master curve reference temperature in accordance with Reference 2 provided that the corresponding validity requirements are met. Instrumented testing machines are required together with ancillary instru
45、mentation and recording equipment in accordance with ISO 14556.Fracture toughness properties depend on material response reflected in the force-time diagrams described in Table 2 and Figure 1. The logical structure for fracture property determination and validation is shown in the flow chart of Figu
46、re 2.Table 1 (continued) ISO 2015 All rights reserved 3BS ISO 26843:2015ISO 26843:2015(E)Table 2 Fracture toughness properties to be determinedMaterial response/fracture behaviour Corresponding diagram type (see Figure 1)R-curve Characteristic pa-rametersLinear-elastic I Jcd, KJcd, KId(B, dKd/dt, dJ
47、d/dt)Elastic-plastic, unstable fracture with a 0,15 (W a0)III Jd-a J0,2Bd(dJd/dt)Elastic-plastic; no unstable fracture IV Jd-a J0,2Bd(dJd/dt)ForceFcdForceFcdForceFmFcdFgytfTimeType IIIForceTimetfType IVFmFgyTestterminationType IType IIFigure 1 Typical force-time diagrams (schematic)4 ISO 2015 All ri
48、ghts reservedBS ISO 26843:2015ISO 26843:2015(E)tf3,456crack initiation is defined as a sudden drop of at least 5 % of the force registered at the instrumented striker, for which a quasistatic evaluation may be performed in accordance with Annex H. If tf 3, then crack initiation is defined as a sudde
49、n drop of at least 20 % in the crack tip strain gauge signal and dynamic toughness is evaluated using the impact response curve method.C.2.5 The stress intensity factor - time history, KIdyn(t), constitutes the impact response curve.14Using the measured tf, the impact fracture toughness KIdis determined as:KK ttId Idynf=()(C.1)Impact response curves for three particular impact velocities v0= 2,0 ms1, 3,8 ms1, and 5,0 ms1and a/W = 0,5 are shown in Figure C.3. The c
