1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN ISO 7539-6:2011Corrosion of metals and alloys Stress corrosion testingPart 6: Preparation and use of precrackedspecimens for tests under constant load orconstant displaceme
2、nt (ISO 7539-6:2011)BS EN ISO 7539-6:2011 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN ISO7539-6:2011. It supersedes BS EN ISO 7539-6:2003 which iswithdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee ISE/NFE/8, Corrosion of me
3、tals and alloys.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2011ISBN 978 0 580 73608 7ICS 77.060Complianc
4、e with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 October 2011.Amendments issued since publicationDate Text affectedEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN IS
5、O 7539-6 October 2011 ICS 77.060 Supersedes EN ISO 7539-6:2003English Version Corrosion of metals and alloys - Stress corrosion testing - Part 6: Preparation and use of precracked specimens for tests under constant load or constant displacement (ISO 7539-6:2011) Corrosion des mtaux et alliages - Ess
6、ais de corrosion sous contrainte - Partie 6: Prparation et utilisation des prouvettes prfissures pour essais sous charge constante ou sous dplacement constant (ISO 7539-6:2011) Korrosion der Metalle und Legierungen - Prfung der Spannungsrisskorrosion - Teil 6: Vorbereitung und Anwendung von angeriss
7、enen Proben fr die Prfung unter konstanter Kraft oder konstanter Verformung (ISO 7539-6:2011) This European Standard was approved by CEN on 14 October 2011. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the
8、status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions (English, French
9、, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, C
10、roatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDA
11、RDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2011 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 7539-6:2011: EBS EN ISO 7539-6:2011EN ISO 7539-6:
12、2011 (E) 3 Foreword This document (EN ISO 7539-6:2011) has been prepared by Technical Committee ISO/TC 156 “Corrosion of metals and alloys“ in collaboration with Technical Committee CEN/TC 262 “Metallic and other inorganic coatings” the secretariat of which is held by BSI. This European Standard sha
13、ll be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by April 2012, and conflicting national standards shall be withdrawn at the latest by April 2012. Attention is drawn to the possibility that some of the elements of this documen
14、t may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN ISO 7539-6:2003. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are b
15、ound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain
16、, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of ISO 7539-6:2011 has been approved by CEN as a EN ISO 7539-6:2011 without any modification. BS EN ISO 7539-6:2011ISO 7539-6:2011(E) ISO 2011 All rights reserved iiiContents Page Foreword iv 1 Scope 1 2 Normative references 1
17、 3 Terms and definitions . 2 4 Principle . 4 5 Specimens 5 5.1 General . 5 5.2 Specimen design . 6 5.3 Stress intensity factor considerations 17 5.4 Specimen preparation . 22 5.5 Specimen identification 23 6 Initiation and propagation of fatigue cracks . 23 7 Procedure . 25 7.1 General . 25 7.2 Envi
18、ronmental considerations . 25 7.3 Environmental chamber 26 7.4 Environmental control and monitoring . 27 7.5 Determination of KISCCby crack arrest . 28 7.6 Determination of KISCCby crack initiation 31 7.7 Measurement of crack velocity 32 8 Test report 33 Annex A (normative) Use of notched specimens
19、for stress corrosion tests . 35 Annex B (normative) Determination of crack growth velocity . 38 BS EN ISO 7539-6:2011ISO 7539-6:2011(E) iv ISO 2011 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member
20、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 been established has the right to be represented on that committee. International organizations, governmental
21、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 standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directive
22、s, 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 for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies c
23、asting 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 all such patent rights. ISO 7539-6 was prepared by Technical Committee ISO/TC 156, Corrosion of metals and all
24、oys, in collaboration with the National Physical Laboratory (United Kingdom). This third edition cancels and replaces the second edition (ISO 7539-6:2003), of which it constitutes a minor revision. ISO 7539 consists of the following parts, under the general title Corrosion of metals and alloys Stres
25、s corrosion testing: Part 1: General guidance on testing procedures Part 2: Preparation and use of bent-beam specimens Part 3: Preparation and use of U-bend specimens Part 4: Preparation and use of uniaxially loaded tension specimens Part 5: Preparation and use of C-ring specimens Part 6: Preparatio
26、n and use of precracked specimens for tests under constant load or constant displacement Part 7: Method fo slow strain rate testing Part 8: Preparation and use of specimens to evaluate weldments Part 9: Preparation and use of pre-cracked specimens for tests under rising load or rising displacement T
27、he following parts are under preparation: Part 10: Testing of alloys using reverse U-bend test method Part 11: Guidelines for testing the resistance of metals and alloys to hydrogen embrittlement and hydrogen assisted cracking BS EN ISO 7539-6:2011INTERNATIONAL STANDARD ISO 7539-6:2011(E) ISO 2011 A
28、ll rights reserved 1Corrosion of metals and alloys Stress corrosion testing Part 6: Preparation and use of precracked specimens for tests under constant load or constant displacement 1 Scope 1.1 This part of ISO 7539 covers procedures for designing, preparing and using precracked specimens for inves
29、tigating susceptibility to stress corrosion. It gives recommendations for the design, preparation and use of precracked specimens for investigating susceptibility to stress corrosion. Recommendations concerning notched specimens are given in Annex A. The term “metal” as used in this part of ISO 7539
30、 includes alloys. 1.2 Because of the need to confine plasticity at the crack tip, precracked specimens are not suitable for the evaluation of thin products, such as sheet or wire, and are generally used for thicker products including plate bar and forgings. They can also be used for parts joined by
31、welding. 1.3 Precracked specimens can be loaded with equipment for application of a constant load or can incorporate a device to produce a constant displacement at the loading points. Tests conducted under increasing displacement or increasing load are dealt with in ISO 7539-9. 1.4 A particular adva
32、ntage of precracked specimens is that they allow data to be acquired from which critical defect sizes, above which stress corrosion cracking can occur, can be estimated for components of known geometry subjected to known stresses. They also enable rates of stress corrosion crack propagation to be de
33、termined. The latter data can be taken into account when monitoring parts containing defects during service. 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,
34、 the latest edition of the referenced document (including any amendments) applies. ISO 7539-1, Corrosion of metals and alloys Stress corrosion testing Part 1: General guidance on testing procedures ISO 11782-2:1998, Corrosion of metals and alloys Corrosion fatigue testing Part 2: Crack propagation t
35、esting using precracked specimens BS EN ISO 7539-6:2011ISO 7539-6:2011(E) 2 ISO 2011 All rights reserved3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 7539-1 and the following apply. 3.1 crack length a effective crack length measured from the crack
36、tip to either the mouth of the notch or the loading point axis, depending on the specimen geometry 3.2 specimen width W effective width of the specimen measured from the back face to either the face containing the notch or the loading plane, depending on the specimen geometry 3.3 specimen thickness
37、B side-to-side dimension of the specimen being tested 3.4 reduced thickness at side grooves Bnminimum side-to-side dimension between the notches in side-grooved specimens 3.5 specimen half-height H 50 % of the specimen height measured parallel to the direction of load application for compact tension
38、, double cantilever beam and modified wedge-opening-loaded test pieces 3.6 load P load which, when applied to the specimen, is considered positive if its direction is such as to cause the crack faces to move apart 3.7 deflection at loading point axis VLLcrack opening displacement produced at the loa
39、ding line during the application of load to a constant displacement specimen 3.8 deflection away from the loading line V0crack opening displacement produced at a location remote from the loading plane, e.g. at knife edges located at the notch mouth, during the application of load to a constant displ
40、acement specimen 3.9 modulus of elasticity E elastic modulus (i.e. stress/strain) in tension BS EN ISO 7539-6:2011ISO 7539-6:2011(E) ISO 2011 All rights reserved 33.10 stress intensity factor KIfunction of applied load, crack length and specimen geometry having dimensions of stress length which uniq
41、uely define the elastic-stress field intensification at the tip of a crack subjected to opening mode displacements (mode I) NOTE It has been found that stress intensity factors, calculated assuming that specimens respond purely elastically, correlate with the behaviour of real cracked bodies, provid
42、ed that the size of the zone of plasticity at the crack tip is small compared to the crack length and the length of the uncracked ligament. In this part of ISO 7539, mode I is assumed and the subscript I is implied everywhere. 3.11 initial stress intensity factor KIistress intensity applied at the c
43、ommencement of the stress corrosion test 3.12 plane strain fracture toughness KIccritical value of KIat which the first significant environmentally independent extension of the crack occurs under the influence of rising stress intensity under conditions of high resistance to plastic deformation 3.13
44、 provisional value of KIcKQKQ= KIcwhen the validity criteria for plane strain predominance are satisfied 3.14 threshold stress intensity factor for susceptibility to stress corrosion cracking KISCCstress intensity factor above which stress corrosion cracking will initiate and grow for the specified
45、test conditions under conditions of high resistance to plastic deformation, i.e. under plane strain predominant conditions 3.15 provisional value of KISCCKQSCCKQSCC= KISCCwhen the validity criteria for plane strain predominance are satisfied 3.16 maximum stress intensity factor Kmaxin fatigue highes
46、t algebraic value of the stress intensity factor in a cycle, corresponding to the maximum load 3.17 0,2 % proof stress Rp0,2stress which must be applied to produce a plastic strain of 0,2 % during a tensile test 3.18 applied stress stress resulting from the application of load to the specimen 3.19 s
47、tress intensity factor coefficient Y factor derived from the stress analysis for a particular specimen geometry which relates the stress intensity factor for a given crack length to the load and specimen dimensions BS EN ISO 7539-6:2011ISO 7539-6:2011(E) 4 ISO 2011 All rights reserved3.20 load ratio
48、 in fatigue loading R algebraic ratio of minimum to maximum load in a cycle: min minmax maxPKRPK 3.21 crack velocity instantaneous rate of stress corrosion crack propagation measured by a continuous crack monitoring technique 3.22 average crack velocity average rate of crack propagation calculated b
49、y dividing the change in crack length due to stress corrosion by the test duration 3.23 specimen orientation fracture plane of the specimen identified in terms of firstly the direction of stressing and secondly the direction of crack growth expressed with respect to three reference axes identified by the letters X, Y and Z NOTE Z is coincident with the main working force used during manufacture of the material (short-transverse axis); X is coincident with the direction of grain flow (longitudinal axis); Y i
