1、BSI Standards PublicationBS ISO 7539-10:2013Corrosion of metals and alloys Stress corrosion testingPart 10: Reverse U-bend methodBS EN ISO 7539-10:2014BS EN ISO 7539-10:2014 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN ISO 7539-10:2014. It is identical to ISO
2、 7539-10:2013. It supersedes BS ISO 7539-10:2013, which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee ISE/NFE/8, Corrosion of metals and alloys.A list of organizations represented on this committee can be obtained on request to its secretary.This publicat
3、ion does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2015. Published by BSI Standards Limited 2015ISBN 978 0 580 84183 5ICS 77.060Compliance with a British Standard cannot confer immunity from
4、 legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 March 2013.Amendments/corrigenda issued since publicationDate Text affected31 January 2015 This corrigendum renumbers BS ISO 7539-10:2013 as BS EN ISO 7539-10:2014EUROPEAN
5、STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 7539-10 December 2014 ICS 77.060 English Version Corrosion of metals and alloys - Stress corrosion testing - Part 10: Reverse U-bend method (ISO 7539-10:2013) Corrosion des mtaux et alliages - Essais de corrosion souscontrainte - Partie 10: Mthode dess
6、ai par cintrage en U invers (ISO 7539-10:2013) Korrosion der Metalle und Legierungen - Prfung der Spannungsrisskorrosion - Teil 10: Vorbereitung und Anwendung von reversierten Bgelproben (ISO 7539-10:2013) This European Standard was approved by CEN on 16 December 2014. CEN members are bound to compl
7、y 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
8、Management 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 sam
9、e 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,
10、 Malta, 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 CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 201
11、4 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 7539-10:2014 EBS EN ISO 7539-10:2014EN ISO 7539-10:2014 (E) 3 Foreword The text of ISO 7539-10:2013 has been prepared by Technical Committee ISO/TC 156 “Corrosion of metals and
12、alloys” of the International Organization for Standardization (ISO) and has been taken over as EN ISO 7539-10:2014 by 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 standar
13、d, either by publication of an identical text or by endorsement, at the latest by June 2015, and conflicting national standards shall be withdrawn at the latest by June 2015. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and
14、/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czec
15、h Republic, Denmark, Estonia, Finland, Former Yugoslav 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
16、. Endorsement notice The text of ISO 7539-10:2013 has been approved by CEN as EN ISO 7539-10:2014 without any modification. BS EN ISO 7539-10:2014EN ISO 7539-10:2014 (E)BS ISO 7539-10:2013ISO 7539-10:2013(E) ISO 2013 All rights reserved iiiContents PageForeword iv1 Scope . 12 Normative reference . 1
17、3 Terms and definitions . 14 Principle 15 Specimens 25.1 General . 25.2 Tubing and piping 25.3 Other products 36 Experimental procedure 37 Post-exposure evaluation 38 Test report . 4Annex A (informative) Preparation of non-pre-strained half tube RUB specimen 5Annex B (informative) RUB specimens with
18、 a gauge section 7BS ISO 7539-10:2013ISO 7539-10:2013(E) ISO 2013 All rights reserved iiiContents PageForeword iv1 Scope . 12 Normative reference .3 Terms and definitions .4 Principle 5 Specimens 25.1 General . 25.2 Tubing and piping 25.3 Other products 36 Experimental procedure 7 Post-exposure eval
19、uation 8 Test report . 4Annex A (informative) Preparation of non-pre-strained half tube RUB specimen 5B RUB specimens with a gauge section 7BS EN ISO 7539-10:2014This page deliberately left blankINTERNATIONAL STANDARD ISO 7539-10:2013(E)Corrosion of metals and alloys Stress corrosion testing Part 10
20、: Reverse U-bend methodWARNING null This International Standard may involve hazardous materials, operations, and equipment. It is the responsibility of whoever uses this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitation
21、s prior to use.1 ScopeThis part of ISO 7539 covers procedures for designing, preparing and using reversed U-bend (RUB) test specimens for investigating the susceptibility of the metal to stress corrosion cracking. The term “metal” as used in this standard includes alloys.2 Normative referenceThe fol
22、lowing 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. Members of IEC
23、 and ISO maintain registers of currently valid International Standards.ISO 7539-1, Corrosion of metals and alloys Stress corrosion testing Part 1: General guidance on testing proceduresISO 8407, Corrosion of metals and alloys Removal of corrosion products from corrosion test specimens3 Terms and def
24、initionsFor the purposes of this document, the terms and definitions given in ISO 7539-1 apply.4 PrincipleThe RUB test is a particularly severe test for assessing susceptibility to stress corrosion cracking. The test is intended primarily for application to metals with high corrosion resistance, suc
25、h as Ni-based alloys, with the advantage compared to methods such as the conventional U-bend test of having significantly less stress relaxation. It is used primarily as a screening test for tubing, piping, plate, bar and other products including welded materials. It may also be used as an acceptanc
26、e test for performance in service subject to agreement between the parties.The principle of the test is to introduce very severe stresses in a high corrosion resistance metal, with minimum relaxation, in order to enhance the likelihood of inducing stress corrosion cracking.The test consists of expos
27、ing to the corroding medium a piece of metal of semicircular section bent back on itself (i.e. reversed bent) into a U-shape and held in a manner which ensures that there are initial tensile stresses in excess of the yield strength over a large proportion of the inner surface. The test is accelerate
28、d by the presence of complex bi-axial stresses that may or may not exist in service. In the act of forming specimens, varying amounts of cold work may be introduced and this deformation may influence the stress corrosion cracking tendency as compared to that of the material in the original condition
29、.The test is normally performed in the laboratory by exposing the specimens to simulated service conditions. ISO 2013 All rights reserved 1BS EN ISO 7539-10:2014A further objective of the test is to compare and evaluate the influence of different material parameters.The principal advantages of the t
30、est are its simplicity and its ability to provide rapid screening: if conventional U-bend or C-ring specimens are used for screening tests in high temperature solution as 573 K or higher, marked stress relaxation occurs and a long testing time is needed for the evaluation. However, the stress relaxa
31、tion in RUB specimens is smaller than that in conventional U-bend and C-ring specimens, due to the bi-axial stresses in RUB specimens. Therefore, screening tests can be done within a relatively short time through the use of RUB specimens.A disadvantage is that the stress state is complicated and is
32、difficult to quantify with accuracy. If an accurate stress state is desired an alternative method should be used.Wide variations in test results may be obtained for a given metal and environment even when testing nominally identical specimens and the replication of tests is frequently necessary.If s
33、pecimens are prepared from tubing of different dimensions or are subjected to different stressing procedures test results may be even more variable.5 Specimens5.1 GeneralRUB specimens are prepared from pieces of production tubing, piping, and other hollow cylindrical products cut into half longitudi
34、nally or from plate, bar or other products formed into a semicircular shape along the axial direction. In this case, forming of the specimen should be followed by a heat treatment to relieve residual stresses before undertaking the reversed U-bending process.5.2 Tubing and pipingA variety of tube di
35、mensions and specimen sizes can be employed. The tube is cut to selected specimen lengths and then sectioned axially to produce specimens with a semi-circular section.The tubing shall retain its original surface finish.During bending, deformation of the tube half may be constrained by the forming ji
36、g to force it to maintain its semicircular cross-section or its sides may be allowed to deform freely in which case it may tend to flatten at the apex. Both methods may be used. The latter procedure results in lower stresses, but has the advantage of avoiding cracking at the edges. The former type s
37、pecimen is named as “Half tube RUB specimen”, and the latter type specimen is named as “RUB specimen with a gauge section”, in this standard.When testing RUB specimens with a gauge section (in which the stresses generated during reverse bending are lower because of reduced constraint), pre-straining
38、 can be used to achieve the desired stress level.Examples of preparation of half tube RUB specimens are shown in Annex A. Examples of preparation of non-pre-strained and pre-strained RUB specimens with a gauge section are shown in Annex B.Final heat treatment shall be performed before bending (and p
39、re-straining if this is adopted).Either single-stage or two-stage stressing may be performed. In single-stage stressing the specimen is not allowed to spring back after bending before final stressing. In two-stage stressing the specimen is allowed to spring back after bending before final re-stressi
40、ng.When stressing specimens with a loading bolt after forming, care should be taken to ensure that the deflection is restored beyond that pertaining at the end of the forming operation. The final distance between the specimen legs at the loading bolt shall be at least 1 mm less than that at the end
41、of the forming operation. The final separation of the legs should be the same for all specimens in a given series; overloading should be avoided. To obtain consistency a micrometer measuring device should be used.ISO 7539-10:2013(E) 2 ISO 2013 All rights reservedBS EN ISO 7539-10:2014ISO 7539-10:201
42、3(E)The bolting material should have a similar (or lower) coefficient of thermal expansion to that of the specimen. In addition, the use of double nuts to reduce the likelihood of loosening of the bolts is recommended.5.3 Other productsA variety of bar stock, plate and other forged or rolled materia
43、l or welded material can be employed. These materials shall be machined into a plate after final heat treatment and pressed into a semicircular shape between inner and outer formers. Specimen preparation from a plate is shown in Annexes A and B.When testing welds, consideration shall be given to the
44、 orientation of the weld relative to the longitudinal axis of the specimen and this shall be noted. Tests may be conducted on the weld metal itself or on sections containing the weld metal and heat- affected zone.Either single-stage or two-stage stressing may be performed. In single-stage stressing
45、the specimen is not allowed to spring back after bending before final stressing. In two-stage stressing the specimen is allowed to spring back after bending before final re-stressing.When stressing specimens with a loading bolt after forming, care shall be taken to ensure that the deflection is rest
46、ored beyond that pertaining at the end of the forming operation. The final distance between the specimen legs at the loading bolt shall be at least 1 mm less than that at the end of the forming operation. The final separation of the legs should be the same for all specimens in a given series; overlo
47、ading should be avoided. To obtain consistency a micrometer measuring device should be used.The bolting material should have a similar (or lower) coefficient of thermal expansion to that of the specimen. In addition, the use of double nuts to reduce the likelihood of loosening of the bolts is recomm
48、ended.6 Experimental procedureIf more than one metal is present in a system, electrical insulation of the specimen may be necessary to avoid galvanic effects, depending on the test environment. Where insulation is used, the insulating material shall not deform during the test. Ceramic insulating mat
49、erials are suitable provided that they are compatible with the test conditions.Specimens shall be degreased prior to testing and should be handled with care thereafter.Specimens shall be examined, after forming, for cracks that may have developed before exposure to the test environment. It may also be desirable to prepare additional specimens, which are stressed but not exposed to the test environment for use as controls for later comparison.Where it is necessary to mark the specimen for purposes of identification, the methods given in ISO 7539-1 shoul
