BS EN ISO 15329-2006 Corrosion of metals and alloys - Anodic test for evaluation of intergranular corrosion susceptibility of heat-treatable aluminium alloys《金属和合金的腐蚀 可热处理的铝合金粒间腐蚀敏.pdf

1、BRITISH STANDARDBS EN ISO 15329:2008Corrosion of metals and alloys Anodic test for evaluation of intergranular corrosion susceptibility of heat-treatable aluminium alloysICS 77.060g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36

2、g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN ISO 15329:2008This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 June 2006 BSI 2008ISBN 978 0 580 60548 2National forewordThis British Standard is the UK im

3、plementation of EN ISO 15329:2008. It is identical with ISO 15329:2006. It supersedes BS ISO 15329:2006 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee ISE/NFE/8, Corrosion of metals and alloys.A list of organizations represented on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

4、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.Compliance with a British Standard cannot confer immunity from legal obligations.Amendments/corrigenda issued since publi

5、cationDate Comments29 August 2008 This corrigendum renumbers BS ISO 15329:2006 as BS EN ISO 15329:2008EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 15329April 2008ICS 77.060English VersionCorrosion of metals and alloys - Anodic test for evaluation ofintergranular corrosion susceptibility of

6、heat-treatable aluminiumalloys (ISO 15329:2006)Corrosion des mtaux et alliages - Essai anodique pourlvaluation de la sensibilit la corrosion intergranulairedes alliages daluminium aptes au traitement thermique(ISO 15329:2006)Korrosion von Metallen und Legierungen - AnodischePrfung fr Auswertung der

7、interkristallinenKorrosionsempfindlichkeit von aushrtbarenAluminiumlegierungen (ISO 15329:2006)This European Standard was approved by CEN on 21 March 2008.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the sta

8、tus of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the CEN Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A

9、version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, D

10、enmark, 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 STANDARDIZATIONCOMIT EUROPEN DE NORMALISAT

11、IONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2008 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN ISO 15329:2008: EiiForewordThe text of ISO 15329:2006 has been prepared by Technical Committ

12、ee ISO/TC 156 “Corrosion of metals and alloys” of the International Organization for Standardization (ISO) and has been taken over as EN ISO 15329:2008 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

13、iven the status of a national standard, either by publication of an identical text or by endorsement, at the latest by October 2008, and conflicting national standards shall be withdrawn at the latest by October 2008. Attention is drawn to the possibility that some of the elements of this document m

14、ay be 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: Austri

15、a, Belgium, Bulgaria, 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 the United Kingdom. Endorsement

16、 notice The text of ISO 15329:2006 has been approved by CEN as a EN ISO 15329:2008 without any modification. BS EN ISO 15329:2008iiiContents Page1 Scope 12 Normative references 13 Terms and definitions 14 Principle 15 Specimens 26 Surface preparation . 37 Procedure . 38 Metallographic examination 49

17、 Assessment of results 410 Test report 4Bibliography . 7BS EN ISO 15329:2008blank1Corrosion of metals and alloys Anodic test for evaluation of intergranular corrosion susceptibility of heat-treatable aluminium alloys1ScopeThis International Standard specifies an electrochemical method to determine s

18、usceptibility to intergranularcorrosion of solution-heat-treatable aluminium alloys, that is 2XXX, 6XXX, 7XXX and 8XXX alloys, withoutprotective coatings and in various ageing conditions.This International Standard is applicable to cast and wrought heat-treatable aluminium alloys in the form ofcasti

19、ngs, forgings, plates, sheets, extrusions, and semi-finished or finished parts, in order to carry out acomparative assessment of alloys of different grades and thickness depending on their chemical compositionand other factors, and also to check the thermal processing quality of the tested materials

20、. The test resultsprovide information to help to determine the intergranular corrosion resistance and thermal processing qualityof the tested materials (see Clauses 8 and 9).The test results cannot be regarded as absolute, because they are not applicable to all environments that canbe met in service

21、. They are best used in a relative manner, to compare the intergranular corrosion resistance ofvarious heats of solution-heat-treatable aluminium alloys.2 Normative referencesThe following referenced documents are indispensable for the application of this document. For datedreferences, only the edit

22、ion cited applies. For undated references, the latest edition of the referenced document(including any amendments) applies.ISO 3696:1987, Water for analytical laboratory use Specification and test methodsISO 8044:1999, Corrosion of metals and alloys Basic terms and definitionsISO 11846:1995, Corrosi

23、on of metals and alloys Determination of resistance to intergranular corrosion ofsolution heat-treatable aluminium alloys3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 8044 apply.4 PrincipleThe method is based on the principle that, if an aluminium a

24、lloy is susceptible to intergranular corrosion, thissusceptibility will show as a breakdown during the anodic polarization of the alloy when exposed to solutionscontaining chloride ions.The sensitivity of solution-heat-treatable aluminium alloys to intergranular corrosion depends on the alloycomposi

25、tion, method of manufacturing, solution heat treatment, quench treatment, and artificial precipitationhardening (ageing) treatment.BS EN ISO 15329:20082In the naturally aged condition, the sensitivity of solution-heat-treatable aluminium alloys to intergranularcorrosion is a function primarily of th

26、e rate of cooling during quenching over a critical temperature range.Regardless of the type of pitting initiation and development zones (along the grain boundaries or through thebody of a crystal), depassivation (disturbance of passive state of the metal) occurs at the attaining of pittinginitiation

27、 potential. The development of intergranular corrosion occurs more frequently at the potential which issomewhat more positive compared to the pitting-initiation potential.Historically, acceleration of intergranular corrosion tests have tended toward arbitrary, and possibly extremeconditions, includi

28、ng impressed electrical currents (galvanostatic) or impressed electrode potentials(potentiostatic). Such testing can be improved by selecting the electrochemical force, with consideration of therelative anodic characteristics of the material in relationship witha) the relative cathodic phases of the

29、 material, andb) the chemical composition of the test medium.This test method starts with the anodic polarization of a specimen to determine the subsequent impressedpotential. Like any other accelerated test, the test results must be correlated with the service performance of thematerials being test

30、ed.Metallographical examination is needed to determine the localised corrosion mode.The principle involves anodic polarization of specimens in aqueous sodium chloride solution up to the potentialat which the alloy shows intergranular corrosion susceptibility and to the exposure at this potential ( )

31、. (SeeFigure 1.)5Specimens5.1 Test specimensSampling should be carried out in order to provide representative specimens from the most typical areas of thematerial or the part being tested.When controlling solution heat treatment, test specimens are taken from that part of the semi-finished productwh

32、ere cooling rates during quenching are the lowest. In the case of small parts, which are quenched in baskets,the samples are taken from the central part of the basket. If quenching is performed on racks, samples aretaken from the upper and lower parts of the rack. If semi-finished products (such as

33、tubes, sheets, plates orpanels) are vertically quenched, the samples are taken from the lower and upper ends. If there are nodifferences in the cooling conditions, the samples are taken at random (see ISO 11846).Samples shall be taken from each solution-heat-treatment charge.The location of sampling

34、 and three-dimensional grain structure should be agreed upon between the user andsupplier.5.2 Dimensions, shapes, number of specimens and surface requirementsSpecimens can have arbitrary configuration and dimensions, but they should be similar for repetitive tests.Specimens with surface defects (met

35、allurgical or mechanical) should not be tested.Tests should be carried out on not less than three specimens having the same configuration, dimensions, andsurface preparation.EicBS EN ISO 15329:200836 Surface preparation6.1 Before testing, specimens should be mechanically ground and degreased with an

36、 organic solvent(hydrocarbon, with a boiling point between and ) using a clean soft brush or an ultrasonic cleaningdevice, carrying out the cleaning in a vessel full of solvent. After cleaning, the specimens should be rinsed witha fresh solvent, dried and stored in a desiccator for .6.2 Pre-treatmen

37、t may be carried out according to ISO 11846.7 Procedure7.1 Naturally aged alloys are tested after quenching. Artificially aged alloys may be tested by this methodat any time.7.2 Solutions are prepared using distilled or deionized water, with a conductivity not greater than (see ISO 3696), just befor

38、e testing. To prepare the solutions, analytical grades of chemicals are used.7.3 The ratio of the solution volume to the total specimen area should be not less than , and a freshsolution should be used for each test.7.4 The specimens are placed in the solution in such a way that they do not touch ea

39、ch other and the vesselwalls. The solution level should be not less than above the upper edge of the specimens and should bethe same for all specimens. It is not permissible to test specimens of different alloy systems in the samesolution.7.5 Tests are carried out in glass vessels, or in vessels mad

40、e from inert materials.7.6 Tests are carried out according to the following procedure:Tests are carried out in a thermostatically controlled, electrochemical cell (which includes test, auxiliary, andreference electrodes), at between and . The test solution is sodium chloride with a mass fraction of.

41、 A potentiostat is used to polarize the test electrode at controlled scan rates and at the potential.The test electrode is a specimen with a mechanically polished surface area not less than . The surfaceroughness .The auxiliary electrode is a platinum electrode, and the reference electrode is either

42、 calomel or silver/silverchloride.First, the anodic polarization curve is plotted for one specimen by scanning the potential from a cathodic valueof to the hydrogen electrode at a scan rate of to the pitting initiation potential, .The potential for pitting initiation is the potential after which the

43、 density of current is increased by at least oneorder of magnitude in the process of anodic polarization (see ISO 8044). Another specimen is then immersed inthe same cell, allowed to rest for , and the potential is moved to:Exposure at this potential is continued as follows: for copper-containing al

44、loys (range to Cu): ; for copper-free alloys (maximum Cu): .After the tests, the specimens are taken out of the cell, washed in distilled water, dried, and metallographicallyexamined.60C 120C1h24 h10S/cm50 ml/cm220 mm18C 25C0,1 % Eic1cm2Ra lessorequalslant 1mE = 2,00 V 50 mV/min Epi5 minEic= Epi+ 50

45、 mV0,25 % 6,5 % 10 min 1 min0,25 % 40 min 5 minBS EN ISO 15329:200848 Metallographic examinationEach tested specimen is examined at to magnification, and one or two zones with the most seriouscorrosion attack are marked. The sections for metallographic analysis are cut through these zones and arepre

46、pared for microscopic examination.9 Assessment of resultsInterpretation of the sensitivity of solution-heat-treatable aluminium alloys to intergranular corrosion is based onthe type (pitting or intergranular), depth, and relative extent of the attack.At first, the type of corrosion should be determi

47、ned according to the references (see Figure 2, A, B, C, D).References A and B represent pitting corrosion, i.e. the cases when intergranular corrosion susceptibility isabsent. References C and D represent intergranular corrosion. In this case, its rating should be classifiedaccording to Table 1 on t

48、he basis of maximal corrosion-damage depth.When used to judge the quality of solution heat treatment, the acceptable susceptibility to intergranularcorrosion is agreed upon by the supplier and the user.10 Test reportThe test report shall include the following information:a) a reference to this Inter

49、national Standard: ISO 15329;b) designation and composition of the alloy;c) type of semi-finished product or part;d) method of manufacturing of product or part;e) heat treatment;f) surface condition;g) specimen sizes;h) pitting potential;i) period of exposure;j) current at the pitting potential at the end of testing;k) type of corrosion;l) rating criteria of the alloy resistance to intergranular corrosion and rating number.Table 1 Intergranular corrosion ratings for aluminium alloys (see 2 in the Bibliography)Corrosion resistance RatingMa