EN ISO 7539-11-2014 en Corrosion of metals and alloys - Stress corrosion cracking - Part 11 Guidelines for testing the resistance of metals and alloys to hydrogen embrittlement and.pdf

1、BSI Standards PublicationBS ISO 7539-11:2013Corrosion of metals and alloys Stress corrosion crackingPart 11: Guidelines for testing theresistance of metals and alloys to hydrogenembrittlement and hydrogen-assistedcrackingBS EN ISO 7539-11:2014BS EN ISO 7539-11:2014 BRITISH STANDARDNational forewordT

2、his British Standard is the UK implementation of EN ISO 7539-11:2014. It is identical to ISO 7539-11:2013. It supersedes BS ISO 7539-11:2013 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee ISE/NFE/8, Corrosion of metals and alloys.A list of organizatio

3、ns 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 correct application. The British Standards Institution 2015. Published by BSI Standards Limited 2015ISBN

4、 978 0 580 84182 8ICS 77.060Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 July 2013.Amendments/corrigenda issued since publicationDate Text affected31 Janua

5、ry 2015 This corrigendum renumbers BS ISO 7539-11:2013 as BS EN ISO 7539-11:2014EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 7539-11 December 2014 ICS 77.060 English Version Corrosion of metals and alloys - Stress corrosion cracking - Part 11: Guidelines for testing the resistance of met

6、als and alloys to hydrogen embrittlement and hydrogen-assisted cracking (ISO 7539-11:2013) Corrosion des mtaux et alliages - Essai de corrosion sous contrainte - Partie 11: Lignes directrices pour les essais de rsistance des mtaux et alliages la fragilisation par lhydrogne et la fissuration assiste

7、sous hydrogne (ISO 7539-11:2013) Korrosion der Metalle und Legierungen - Prfung der Spannungsrisskorrosion - Teil 11: Leitfaden fr die Prfung der Resistenz von Metallen und Legierungen gegen Wasserstoffversprdung und wasserstoffverursachte Brche (ISO 7539-11:2013) This European Standard was approved

8、 by CEN on 16 December 2014. CEN members are bound to comply 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 s

9、tandards 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, German). A version in any other language made by translation under the responsibility of a CEN member into its own language an

10、d 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, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hunga

11、ry, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, 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-CENEL

12、EC Management Centre: Avenue Marnix 17, B-1000 Brussels 2014 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 7539-11:2014 EEN ISO 7539-11:2014 (E) 3 Foreword The text of ISO 7539-11:2013 has been prepared by Technical Committee

13、 ISO/TC 156 “Corrosion of metals and alloys” of the International Organization for Standardization (ISO) and has been taken over as EN ISO 7539-11:2014 by Technical Committee CEN/TC 262 “Metallic and other inorganic coatings” the secretariat of which is held by BSI. This European Standard shall be g

14、iven the status of a national standard, 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

15、the subject of patent rights. CEN and/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, Bel

16、gium, Bulgaria, Croatia, Cyprus, Czech 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, Switz

17、erland, Turkey and the United Kingdom. Endorsement notice The text of ISO 7539-11:2013 has been approved by CEN as EN ISO 7539-11:2014 without any modification. BS EN ISO 7539-11:2014EN ISO 7539-11:2014 (E)BS ISO 7539-11:2013ISO 7539-11:2013(E) ISO 2013 All rights reserved iiiContents PageForeword i

18、v1 Scope . 12 Normative references 13 Factors to be considered in hydrogen embrittlement and hydrogen-assisted cracking testing 13.1 Dynamic plastic straining 13.2 Test time and hydrogen uptake 23.3 Temperature 24 Selection of test method . 34.1 General . 34.2 Specimen type . 34.3 Test duration . 34

19、.4 Load form 84.5 Pre-charging and hydrogen effusivity 124.6 Testing of welds . 125 Post-test evaluation 13Bibliography .15BS ISO 7539-11:2013ISO 7539-11:2013(E) ISO 2013 All rights reserved iiiContents PageForeword iv1 Scope . 12 Normative references 3 Factors to be considered in hydrogen embrittle

20、ment and hydrogen-assisted cracking testing 13.1 Dynamic plastic straining 13.2 Test time and hydrogen uptake 23.3 Temperature 24 Selection of test method . 34.1 General . 34.2 Specimen type . 34.3 Test duration . 34.4 Load form 84.5 Pre-charging and hydrogen effusivity 124.6 Testing of welds . 125

21、Post-test evaluation 13Bibliography .15BS EN ISO 7539-11:2014ISO 7539-11:2013 (E)This page deliberately left blankINTERNATIONAL STANDARD BS EN ISO 7539-11:2014ISO 7539-11:2013 (E)Corrosion of metals and alloys Stress corrosion cracking Part 11: Guidelines for testing the resistance of metals and all

22、oys to hydrogen embrittlement and hydrogen-assisted cracking1 ScopeThis part of ISO 7539 gives guidance on the key features that should be accounted for in designing and conducting tests to evaluate the resistance of a metal or its alloy to hydrogen embrittlement and hydrogen-assisted cracking.NOTE

23、Particular methods of testing are not treated in detail in this document. These are described in other International Standards to which reference is given.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its app

24、lication. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 7539-7, Corrosion of metals and alloys Stress corrosion testing Part 7: Method for slow strain rate testingISO 17081, Method of

25、 measurement of hydrogen permeation and determination of hydrogen uptake and transport in metals by an electrochemical technique3 Factors to be considered in hydrogen embrittlement and hydrogen-assisted cracking testing3.1 Dynamic plastic straining3.1.1 Surface films such as passive oxide films, and

26、 sulphide films in the case of exposure of carbon steel to H2S environments, for example, can markedly reduce hydrogen uptake. Film rupture will enhance ingress locally, which means that dynamic plastic straining and the strain rate can be particularly important. In that context, there is then usual

27、ly no relationship between hydrogen uptake as measured in a permeation experiment and the cracking response since uptake is local at the film rupture sites. A possible exception is when there is a significant sub-surface region of susceptibility associated with residual stress or microchemistry as m

28、ight possibly be found in welds. Here, detailed characterization of the weld should be conducted prior to testing.3.1.2 Dynamic plastic straining may be induced under static load if there is significant creep, as in some duplex stainless steels.3.1.3 In testing of alloys that are actively corroding,

29、 there is often a correlation between cracking and the measured bulk hydrogen uptake. Dynamic plastic straining may have only a relatively minor role in hydrogen uptake in that case.3.1.4 In all alloys, dynamic plastic straining and the strain rate may be important in dislocation transport of hydrog

30、en. The mobility of hydrogen atoms and trapping at dislocations means that dislocations can ISO 2013 All rights reserved 1move hydrogen (though constrained by microstructural boundaries) and possibly deposit the hydrogen at susceptible sites, e.g. grain boundaries.3.2 Test time and hydrogen uptake3.

31、2.1 Hydrogen atoms are mobile and can diffuse to sites of potential susceptibility, which may be some distance from the primary source. A fundamental question is how long should a laboratory test be to ensure that hydrogen uptake is sufficient in reflecting behaviour in service, for which exposure t

32、imes are of the order of years. The critical issue is the location of cracking with respect to the primary source of hydrogen. If the latter is remote, then test times need to reflect this. Hence, hydrogen diffusivity and test time are important. In delayed hydrogen cracking, for example, analysis o

33、f the hydrogen distribution with time in response to concentration and stress gradients may be necessary to assess the likelihood of cracking in service.3.2.2 The location of cracking will be system-dependent. It may be associated with mid-thickness of a low-alloy carbon steel pipeline with centre-l

34、ine segregation. If using a pre-cracked specimen, it is self-evidently local to the crack tip. In a weld, it could be sub-surface.3.2.3 The primary source of hydrogen is most likely at a locally strained region if testing corrosion-resistant alloys in the passive state because film rupture sites pro

35、vide the main points of entry. In this case, test times may be relatively modest unless testing under conditions of pitting corrosion (or crevice corrosion). The local aggressive chemistry associated with pitting and crevice corrosion, together with the dissolution of protective films, will encourag

36、e hydrogen uptake. If the crack initiates from a pit, pit size may be a factor and, thus, there may be an effect of exposure time specific to that aspect. Failure may not be expected unless above the critical pitting/crevice temperature, though there could be an effect of stress on the value.3.2.4 F

37、or systems with no protective film, the primary source of hydrogen is a complex function of the solution chemistry and applied potential. If there is a species in the bulk solution that enhances hydrogen generation and absorption but is depleted in a crack, then the primary source is the external su

38、rface exposed to the bulk solution. Examples are acid solutions and solutions containing hydrogen sulphide. However, in H2S environments, the formation with exposure time of an iron sulphide film on the exposed external surface will progressively lead to a reduction in hydrogen entry and may change

39、the locality of the primary source to that of the crack tip.In less “aggressive” or gaseous environments, hydrogen uptake at the crack tip may be favoured. When using pre-cracked specimens with cathodic protection potentials at sacrificial anode values, the primary source of hydrogen is from the ext

40、ernal surface because of potential drop and chemistry changes in the crack.3.3 Temperature3.3.1 Embrittlement is often associated with hydrogen trapping. Increasing the temperature tends to decrease trap occupancy but this may be compensated by increased kinetics of hydrogen generation and solubilit

41、y in most materials. Diffusivity will also increase with temperature, and when comparing test results at different temperature, misconceptions about susceptibility can arise if the hydrogen uptake is not at steady-state and the different levels of hydrogen ingress are not accounted for. For unprotec

42、ted corrosion resistant alloys in the passive state cracking may occur only above a critical temperature associated with localized attack as noted in 3.2.3 Also, since the inherent ductility of metals tends to increase with increasing temperature, temperature will be expected to have a complex effec

43、t on embrittlement.3.3.2 Testing should reflect the range of temperatures expected in service. It is important to recognize that for cathodically protected alloys, the most severe temperature may be the lowest temperature because this encourages trapping (see Introduction).BS EN ISO 7539-11:2014ISO

44、7539-11:2013 (E) 2 ISO 2013 All rights reservedBS EN ISO 7539-11:2014ISO 7539-11:2013 (E) 3.3.3 The extent of information on the effect of temperature transients is limited. These can be important if the cooling rate is relatively rapid compared with the rate of hydrogen egress from the metal. For m

45、any alloys, the lattice hydrogen solubility increases with temperature and the trap occupancy decreases. The ductility also increases. Thus, at sufficiently elevated temperature, there may be significant hydrogen uptake but no cracking. However, problems can arise if the rate of cooling is fast rela

46、tive to diffusion. In certain steels, hydrogen may precipitate out of the lattice at interfaces as molecular hydrogen and raise the prospect of pressure-induced cracking. More generally, hydrogen atoms in the lattice will drop into trap sites. Combined with reduced ductility, cracking may ensue.4 Se

47、lection of test method4.1 GeneralA wide range of test methods have been developed that can be used to assess the resistance of materials to hydrogen embrittlement and hydrogen-assisted cracking. The Foreword lists a number of International Standards that are applicable to environment-assisted cracki

48、ng in general, including both stress corrosion and corrosion fatigue. The electrochemical method for hydrogen permeation (ISO 17081) gives guidance in measuring hydrogen uptake and diffusivity. Additional test methods related to hydrogen embrittlement and hydrogen-assisted cracking, mostly for syste

49、m-specific applications, are included in a complementary list in the Bibliography. In a number of applications, the loading and environmental exposure conditions are sufficiently straightforward and the purpose of the International Standard so constrained that additional guidelines in testing are not critical. However, for non-prescriptive test methods, the issues raised in Clause 3 need to be accounted for in defining the test.4.2 Specimen typeThe adoption of the specimen type in this respect depends on the design and maintenance philosophy in re