1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN ISO 7539-1:2012Corrosion of metals and alloys Stress corrosion testingPart 1: General guidance on testing proceduresBS EN ISO 7539-1:2012 BRITISH STANDARDNational forewordT
2、his British Standard is the UK implementation of EN ISO 7539-1:2012.It supersedes BS EN ISO 7539-1:1995 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee ISE/NFE/8, Corrosion of metals and alloys.A list of organizations represented on this committee can b
3、eobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2013. Published by BSI StandardsLimited 2013 ISBN 978 0 580 71187 9 ICS 77.060 Compliance
4、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 January 2013. Amendments issued since publicationDate Text affectedEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO
5、 7539-1 December 2012 ICS 77.060 Supersedes EN ISO 7539-1:1995English Version Corrosion of metals and alloys - Stress corrosion testing - Part 1: General guidance on testing procedures (ISO 7539-1:2012) Corrosion des mtaux et alliages - Essais de corrosion sous contrainte - Partie 1: Lignes directri
6、ces gnrales relatives aux mthodes dessai (ISO 7539-1:2012) Korrosion der Metalle und Legierungen - Prfung der Spannungsrisskorrosion - Teil 1: Allgemeiner Leitfaden fr Prfverfahren (ISO/FDIS 7539-1:2012) This European Standard was approved by CEN on 18 December 2012. CEN members are bound to comply
7、with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the 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 Ma
8、nagement Centre or to any CEN member. This European Standard exists in three official versions (English, French, 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
9、status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, M
10、alta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2012 CEN All righ
11、ts of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 7539-1:2012: EBS EN ISO 7539-1:2012EN ISO 7539-1:2012 (E) 3 Foreword This document (EN ISO 7539-1:2012) has been prepared by Technical Committee ISO/TC 156 “Corrosion of metals and alloys“ in
12、 collaboration with Technical Committee CEN/TC 262 “Metallic and other inorganic coatings” the secretariat of which is held by BSI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by June 2013, and c
13、onflicting national standards shall be withdrawn at the latest by June 2013. Attention is drawn to the possibility that some of the elements of this document 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 docu
14、ment supersedes EN ISO 7539-1:1995. According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugosla
15、v Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 7539-1:2012 has
16、been approved by CEN as a EN ISO 7539-1:2012 without any modification. BS EN ISO 7539-1:2012ISO 7539-1:2012(E) ISO 2012 All rights reserved iiiContents PageForeword iv1 Scope . 12 Terms and definitions . 13 Background 24 Selection of test method . 35 Stressing systems . 45.1 General . 45.2 Constant
17、total strain tests 45.3 Constant load tests 55.4 Slow strain rate tests . 66 Environmental aspects . 76.1 General . 76.2 Temperature 76.3 Water chemistry 76.4 Flow rate . 96.5 Electrochemical aspects 97 Time dependent issues .107.1 General 107.2 Pitting and intergranular corrosion . 107.3 Hydrogen u
18、ptake 108 Specimen design and manufacture 118.1 General 118.2 Surface condition . 118.3 Area effects 138.4 Pre-cracked test pieces . 138.5 Welds 149 Stress corrosion test cells .1410 Initiation of stress corrosion tests 1511 Assessment and treatment of results 15Annex A (informative) Guide to select
19、ion of mechanical test method .18Bibliography .20BS EN ISO 7539-1:2012ISO 7539-1:2012(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 out t
20、hrough 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 colla
21、borates 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 Directives, Part 2.The main task of technical committees is to prepare International Stand
22、ards. 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 casting a vote.Attention is drawn to the possibility that some of the elements of t
23、his document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.ISO 7539-1 was prepared by Technical Committee ISO/TC 156, Corrosion of metals and alloys.This second edition cancels and replaces the first edition (ISO 7539-1:1987), wh
24、ich has been technically revised.ISO 7539 consists of the following parts, under the general title Corrosion of metals and alloys Stress 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 specimen
25、s Part 4: Preparation and use of uniaxially loaded tension specimens Part 5: Preparation and use of C-ring specimens Part 6: Preparation and use of pre-cracked specimens for tests under constant load or constant displacement Part 7: Method for slow strain rate testing Part 8: Preparation and use of
26、specimens to evaluate weldments Part 9: Preparation and use of pre-cracked specimens for tests under rising load or rising displacement Part 10: Reverse U-bend method Part 11: Guidelines for testing the resistance of metals and alloys to hydrogen embrittlement and hydrogen-assisted crackingiv ISO 20
27、12 All rights reservedBS EN ISO 7539-1:2012INTERNATIONAL STANDARD ISO 7539-1:2012(E)Corrosion of metals and alloys Stress corrosion testing Part 1: General guidance on testing procedures1 Scope1.1 This part of ISO 7539 describes the general considerations that apply when designing and conducting tes
28、ts to assess susceptibility of metals to stress corrosion.1.2 This part of ISO 7539 also gives some general guidance on the selection of test methods.NOTE 1 Particular methods of test are not treated in detail in this part of ISO 7539. These are described in the additional parts of ISO 7539.NOTE 2 T
29、his part of ISO 7539 is applicable to cathodic protection conditions.2 Terms and definitions2.1stress corrosionprocess involving conjoint corrosion and straining of the metal due to applied or residual stress2.2threshold stressstress corrosion stress above which stress corrosion cracks initiate and
30、grow, for the specified test conditions2.3threshold stress intensity factorKISCCstress corrosion cracking stress intensity factor above which stress corrosion crack propagation is sustainedNote 1 to entry: The threshold stress intensity factor is a concept of linear elastic fracture mechanics (LEFM)
31、 and is applicable when the plastic zone size is large compared with the microstructure and a high constraint to plastic deformation prevails; i.e. under plain strain-predominant conditions. For growing stress corrosion cracks, LEFM is not necessarily applicable in detail but is adopted as a pragmat
32、ic tool that is commonly used.Note 2 to entry: Stress corrosion cracks may initiate at a surface or a surface defect and grow in the “short crack” regime at stress levels below the apparent threshold stress intensity factor. However, LEFM is not applicable in the short crack regime and sustained pro
33、pagation of these cracks requires that the threshold stress intensity factor be exceeded.2.4test environmenteither a service environment, or an environment produced in the laboratory, to which the test specimen is exposed and which is maintained constant or varied in an agreed mannerNote 1 to entry:
34、 In the case of stress corrosion, the environment is often quite specific (see Clause 6). ISO 2012 All rights reserved 1BS EN ISO 7539-1:2012ISO 7539-1:2012(E)2.5start of testtime when the stress is applied or when the specimen is exposed to the test environment, whichever occurs later2.6crack initi
35、ation timeperiod from the start of a test to the time when a crack is detectable by the means employed2.7time to failureperiod elapsing between the start of a test and the occurrence of failure, the criterion of failure being the first appearance of cracking or the total separation of the test piece
36、, or some agreed intermediate condition2.8slow strain rate testtest for evaluating the susceptibility of a metal to stress corrosion cracking that most commonly involves pulling a tensile specimen to failure in a representative environment at a constant displacement rate, the displacement rate being
37、 chosen to generate nominal strain rates usually in the range 105s1to 108s1Note 1 to entry: Slow strain rate testing may also be applied to specimens in bend.2.9strain to failurestrain at which failure occurs in a slow strain rate test expressed usually as the plastic strain to failure See ISO 7539-
38、7.2.10average crack velocitymaximum depth of crack(s) due to stress corrosion, divided by the test time2.11orientationdirection of applied tensile stress of a test specimen with respect to some specified direction in the product from which it was prepared, e.g. the rolling direction in the plate3 Ba
39、ckground3.1 Although it is generally agreed that cracking is the usual result of stress corrosion, other manifestations such as intergranular corrosion or elongated fissures, which are enhanced by the presence of stress, have also to be recognized.As far as this part of ISO 7539 is concerned, all ph
40、enomena involving metal dissolution or the action of hydrogen introduced into the metal as the result of simultaneous effects of a corrosive environment and a tensile stress are included, except for embrittlement by liquid metal and exfoliation corrosion.3.2 There exists a wide diversity of methods
41、used for assessing the stress corrosion properties of metals. Each has its own particular advantage in certain situations.3.3 Stress corrosion cracking depends on both the exposure conditions and the mechanical and microstructural characteristics of the material and susceptibility or resistance to s
42、tress corrosion can only be defined in that context. Thus, for example, there is no intrinsic threshold stress intensity factor for a material.3.4 Ideally, in order to establish the risk of stress corrosion in a given application, it is necessary to carry out simulation testing under all likely serv
43、ice exposure conditions. In practice, this is difficult, if not impossible, and rarely achieved, but a number of “standard tests” have been found as a result of experience to provide reasonable guidance on likely service behaviour for given specific applications. However, these laboratory “standard
44、tests” are only appropriate to service conditions where experience 2 ISO 2012 All rights reservedBS EN ISO 7539-1:2012ISO 7539-1:2012(E)has shown an appropriate relationship, however empirical, to exist. The fact that a given alloy passes or does not pass a test previously found useful in relation t
45、o another alloy may or may not be significant and a test that discriminates correctly between alloys used for a given application will not necessarily provide safe guidance if the exposure conditions are different. The use of a standard test beyond the point for which there is experience therefore r
46、equires validation.3.5 In the following clauses, attention is drawn particularly to the fact that the stress corrosion process can be extremely sensitive to small changes in exposure or test conditions. The user of materials is responsible for selecting the conditions under which stress corrosion te
47、sts are performed and the fact that some tests are described in this part of ISO 7539 does not imply that these tests are the most appropriate ones for any given situation. The justification for describing these tests in a standard is that they are in widespread use and have been proven as valid for
48、 specific or common equipment-environment systems. However, the responsibility for interpretation of the test results remains with the user of materials and it is in no way diminished by the existence of this standard.3.6 In addition to specific parts of ISO 7539 to cover the most widely used method
49、s, it is considered that this more general document, concerned with the selection of test details and the interpretation of results, is required.4 Selection of test method4.1 Before embarking on a programme of stress corrosion testing, a decision has to be made regarding which type of test is appropriate. Such a decision depends largely upon the purpose of the test and the information required. While some tests attempt to reproduce service conditions as closely as possible and are of value to the plant engineer, others may be designed
