1、BSI Standards PublicationBS ISO 22889:2013Metallic materials Methodof test for the determinationof resistance to stable crackextension using specimens oflow constraintBS ISO 22889:2013 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 22889:2013. Itsupersedes BS
2、ISO 22889:2007 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee ISE/101/4, Toughness testing.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessarypr
3、ovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2013. Published by BSI StandardsLimited 2013ISBN 978 0 580 77193 4ICS 77.040.10Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was publish
4、ed under the authority of theStandards Policy and Strategy Committee on 30 September 2013.Amendments issued since publicationDate Text affectedBS ISO 22889:2013 ISO 2013Metallic materials Method of test for the determination of resistance to stable crack extension using specimens of low constraintMa
5、triaux mtalliques Mthode dessai pour la dtermination de la rsistance la propagation stable de fissures au moyen dprouvettes faible taux de triaxialit des contraintesINTERNATIONAL STANDARDISO22889Second edition2013-10-01Reference numberISO 22889:2013(E)BS ISO 22889:2013ISO 22889:2013(E)ii ISO 2013 Al
6、l rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2013All rights reserved. Unless 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
7、 prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in Switzerla
8、ndBS ISO 22889:2013ISO 22889:2013(E) ISO 2013 All rights reserved iiiContents PageForeword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 24 Symbols 35 General requirements . 35.1 Introduction 35.2 Test specimens 45.3 Pre-test requirements . 65.4 Test apparatus . 65.5 T
9、est requirements 75.6 Post-test crack measurements 96 Determination of 5 a resistance curve and CTOA 116.1 General 116.2 Test procedure 116.3 R-curve plot . 116.4 Critical CTOA determination 127 Test report 137.1 General 137.2 Specimen, material and test environment . 137.3 Test data qualification .
10、 147.4 Qualification of the 5R-Curve .167.5 Qualification of c16Annex A (informative) Examples of test reports .27Annex B (informative) Apparatus for measurement of crack opening displacement, 5.32Annex C (informative) Determination of the crack tip opening angle, .34Annex D (informative) Determinat
11、ion of point values of fracture toughness 44Bibliography .47BS ISO 22889:2013ISO 22889:2013(E)ForewordISO (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
12、 out through ISO technical committees. Each 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
13、 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical 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 a
14、pproval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directivesAttention is drawn to the possibility that some of the elements of this document may be the subj
15、ect of patent rights. ISO shall not be held responsible for identifying any or all such patent 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. www.iso.org/patentsAny trade name
16、used in this document is information given for the convenience of users and does not constitute an endorsement.The committee responsible for this document is ISO/TC 164, Mechanical testing of metals, Subcommittee SC 4, Toughness testing Fracture (F), Pendulum (P), Tear (T).This second edition cancel
17、s and replaces the first edition (ISO 22889:2007), of which it constitutes a minor revision.The following changes have been made: in 5.2.2.3, the notch width is now limited to W/30; in 5.2.2.4.3, revised the zone of application for the limited precracking force and corrected the logic of the subclau
18、se for the compact specimen; in 5.2.2.4.4, revised the zone of application for the limited precracking force and corrected the logic of the subclause for the middle crack tension specimen; in 5.5.5, replaced the stress intensification rate with the stress intensity factor rate; in 5.6.1.3 a), revise
19、d the ratio a0/W from between “0,45 to 0,65” to “from 0,4 to 0,7” for compact specimens; in 5.6.1.3 d), revised the allowed distance between the fatigue crack and the notch at the start of the test from 0,025W to 1,3 mm or 0,013W, whichever is the larger; in 5.6.2, added a provision: “However, measu
20、ring positions in the thickness direction shall be based on the contracted thickness at the final crack tip location.”; in 6.4, added Formula (12) to define the minimum amount of crack extension, amin; in 6.4, added the statement: “Formulae (11) and (12) apply to both the compact and middle crack te
21、nsile specimen geometries.”; corrected notes 2 and 3 on Figure 2; corrected notes 2 and 3 on Figure 3; designated a new notch width as W/30 on Figure 4; revised the report in 7.3.5 to be consistent with the above changes.iv ISO 2013 All rights reservedBS ISO 22889:2013ISO 22889:2013(E)IntroductionIS
22、O 12135 uses compact and bend specimens to determine specific (point) values of fracture toughness at the onset of either stable or unstable crack extension, and to quantify resistance to stable crack extension. These specimen types have near-square remaining ligaments to provide conditions of high
23、constraint. If certain size requirements are met, then the values of the quantities KIc, 0,2BLand J0,2BLdetermined from these specimens are considered size insensitive, and regarded as lower-bound fracture toughness values. Although not explicitly stated, size insensitivity holds also for the crack
24、extension resistance curve (R-curve).In engineering practice, however, there are cases which are not covered by the method of test in ISO 12135, for example where the component thickness is much less than that required for size-insensitive properties as determined using ISO 12135, the thickness of t
25、he available material does not enable fabrication of specimens meeting the criteria for size insensitivity, and the loading conditions in the structural component are characterized by tension rather than bending.In these cases, constraint in the structural component may be lower than that of the spe
26、cimens specified by ISO 12135, thus leading to higher resistance to crack extension and higher load-carrying capability in the structural component than would have been forecast based on the test in ISO 12135. ISO 2013 All rights reserved vBS ISO 22889:2013BS ISO 22889:2013Metallic materials Method
27、of test for the determination of resistance to stable crack extension using specimens of low constraint1 ScopeThis International Standard specifies methods for determining the resistance to stable crack extension in terms of crack opening displacement, 5, and critical crack tip opening angle, c, for
28、 homogeneous metallic materials by the quasistatic loading of cracked specimens that exhibit low constraint to plastic deformation. Compact and middle-cracked tension specimens are notched, precracked by fatigue, and tested under slowly increasing displacement.This International Standard describes m
29、ethods covering tests on specimens not satisfying requirements for size-insensitive fracture properties; namely, compact specimens and middle-cracked tension specimens in relatively thin gauges.Methods are given for determining the crack extension resistance curve (R-curve). Point values of fracture
30、 toughness for compact specimens are determined according to ISO 12135. Methods for determining point values of fracture toughness for the middle-cracked tension specimen are given in Annex D.Crack extension resistance is determined using either the multiple-specimen or single-specimen method. The m
31、ultiple-specimen method requires that each of several nominally identical specimens be loaded to a specified level of displacement. The extent of ductile crack extension is marked and the specimens are then broken open to allow measurement of crack extension. Single-specimen methods based on either
32、unloading compliance or potential drop techniques can be used to measure crack extension, provided they meet specified accuracy requirements. Recommendations for single-specimen techniques are described in ISO 12135. Using either technique, the objective is to determine a sufficient number of data p
33、oints to adequately describe the crack extension resistance behaviour of a material.The measurement of 5is relatively simple and well established. The 5results are expressed in terms of a resistance curve, which has been shown to be unique within specified limits of crack extension. Beyond those lim
34、its, 5R-curves for compact specimens show a strong specimen dependency on specimen width, whereas the 5R-curves for middle-cracked tension specimens show a weak dependency.CTOA is more difficult to determine experimentally. The critical CTOA is expressed in terms of a constant value achieved after a
35、 certain amount of crack extension. The CTOA concept has been shown to apply to very large amounts of crack extension and can be applied beyond the current limits of 5applications.Both measures of crack extension resistance are suitable for structural assessment. The 5concept is well established and
36、 can be applied to structural integrity problems by means of simple crack driving force formulae from existing assessment procedures.The CTOA concept is generally more accurate. Its structural application requires numerical methods, i.e. finite element analysis.Investigations have shown a very close
37、 relation between the concept of constant CTOA and a unique R-curve for both compact and middle-cracked tension specimens up to maximum load. Further study is required to establish analytical or numerical relationships between the 5R-curve and the critical CTOA values.2 Normative referencesThe follo
38、wing 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 references, the latest edition of the referenced document (including any amendments) applies.INTERNATIONAL STA
39、NDARD ISO 22889:2013(E) ISO 2013 All rights reserved 1BS ISO 22889:2013ISO 22889:2013(E)ISO 3785, Metallic materials Designation of test specimen axes in relation to product textureISO 7500-1, Metallic materials Verification of static uniaxial testing machines Part 1: Tension/ compression testing ma
40、chines Verification and calibration of the force-measuring systemISO 9513, Metallic materials Calibration of extensometer systems used in uniaxial testingISO 12135:2002, Metallic materials Unified method of test for the determination of quasistatic fracture toughness3 Terms and definitionsFor the pu
41、rposes of this document, the following terms and definitions apply.3.1crack opening displacementCOD5relative displacement of the crack surfaces normal to the original (undeformed) crack plane at the tip of the fatigue precrack, as measured on the specimens side surface over an initial gauge length o
42、f 5 mm3.2crack tip opening angleCTOArelative angle of the crack surfaces measured (or calculated) at 1 mm from the current crack tip3.3stable crack extensionacrack extension that, in displacement control, occurs only when the applied displacement is increased3.4crack extension resistance curveR-curv
43、evariation in 5with stable crack extension a3.5critical crack tip opening anglecsteady-state value of crack tip opening angle at 1 mm from the current crack tipNote 1 to entry: This value is insensitive to the in-plane dimensions specified in this method; however, it may be thickness dependent.2 ISO
44、 2013 All rights reservedBS ISO 22889:2013ISO 22889:2013(E)4 SymbolsFor the purposes of this International Standard, the following symbols and units apply. For all parameters, the temperature is assumed to be the test temperature unless otherwise noted.Symbol Unit Designationa mm crack lengthafmm fi
45、nal crack length (a0+ af)ammm length of machined crack starter notcha0mm initial crack lengtha mm stable crack extensionaminmm crack extension beyond which cis nearly constantamaxmm crack extension limit for 5or ccontrolled crack extensionafmm final stable crack extensionB mm specimen thicknessE MPa
46、 Youngs modulus of elasticityF kN applied forceFfkN maximum fatigue precracking forceRp0,2MPa 0,2 % offset yield strength perpendicular to crack plane at the test tempera-tureRmMPa tensile strength perpendicular to crack plane at the test temperature degrees crack path deviationW mm width of compact
47、 specimen, half width of middle-cracked tension specimenW a mm uncracked ligament lengthW a0mm initial uncracked ligament lengthW afmm final uncracked ligament length degrees crack tip opening angle (CTOA)cdegrees critical crack tip opening angle (critical CTOA) Poissons ratio5mm crack opening displ
48、acement over a 5 mm gauge length at tip of fatigue pre-crackNOTE This is not a complete list of parameters. Only the main parameters are given here; other parameters are referred to and defined in the text.5 General requirements5.1 IntroductionThe resistance to stable crack extension of metallic mat
49、erials can be characterized in terms of either specific (single point) values (see Annex D) or a continuous curve relating fracture resistance to crack extension over a limited range of crack extension (see Clause 6). Any one of the fatigue-cracked test specimen configurations specified in this method may be used to measure or calculate any of these fracture resistance parameters. Tests are performed by applying slowly increasing displacement to the test specimen an
