1、BSI Standards PublicationBS EN ISO 7441:2015Corrosion of metals and alloys Determination of bimetalliccorrosion in atmosphericexposure corrosion testsBS EN ISO 7441:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN ISO 7441:2015.It supersedes BS EN ISO 7441:1
2、995 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee ISE/NFE/8, Corrosion of metals and alloys.A list of organizations represented on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 beobtained on request to its secretary.This publication does not purport to include all the necessary
3、provisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2015. Published by BSI StandardsLimited 2015ISBN 978 0 580 70422 2ICS 77.060Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was publishe
4、d under the authority of theStandards Policy and Strategy Committee on 31 January 2015.Amendments issued since publicationDate Text affectedEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 7441 January 2015 ICS 77.060 Supersedes EN ISO 7441:1995English Version Corrosion of metals and alloys
5、- Determination of bimetallic corrosion in atmospheric exposure corrosion tests (ISO 7441:2015) Corrosion des mtaux et alliages - Dtermination de la corrosion bimtallique par des essais dexposition de corrosion atmosphrique (ISO 7441:2015) Korrosion von Metallen und Legierungen - Bestimmung der Kont
6、aktkorrosion durch Freibewitterungsversuche (ISO 7441:2015) This European Standard was approved by CEN on 15 November 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 wit
7、hout 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, German). A version in any other
8、 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, Croatia, Cyprus, Czech Republic, D
9、enmark, 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 United Kingdom. EUROPEAN COMMIT
10、TEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2015 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 7441:2015 EBS EN ISO 74
11、41:2015EN ISO 7441:2015 (E) 3 Foreword This document (EN ISO 7441:2015) 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 Euro
12、pean Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by July 2015, and conflicting national standards shall be withdrawn at the latest by July 2015. Attention is drawn to the possibility that some of the elements
13、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 document supersedes EN ISO 7441:1995. According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following co
14、untries are bound to implement this European Standard: 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, Malta, Netherlands, Norway,
15、Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 7441:2015 has been approved by CEN as EN ISO 7441:2015 without any modification. BS EN ISO 7441:2015ISO 7441:2015(E)Contents PageForeword ivIntroduction v1 Sco
16、pe . 12 Normative references 13 Terms and definitions . 14 Overview and comparison of methods 25 Preparation of specimens . 35.1 Types of specimens . 35.1.1 General 35.1.2 Rectangular plates 35.1.3 Wire on bolt 85.2 Number and marking of specimens 96 Exposure of specimens . 97 Evaluation of specimen
17、s 107.1 General 107.2 Evaluation based on mass loss . 107.3 Other evaluation methods applicable for rectangular plates 107.3.1 Evaluation based on visual examination 107.3.2 Evaluation based on mechanical properties .117.4 Calculation of bimetallic effect . 118 Test report 12Bibliography .14 ISO 201
18、5 All rights reserved iiiBS EN ISO 7441:2015ISO 7441:2015(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 through ISO technical committ
19、ees. 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 collaborates closely with the Int
20、ernational Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the di
21、fferent types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directivesAttention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall no
22、t be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received. www.iso.org/patentsAny trade name used in this document is informati
23、on given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the fo
24、llowing URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 156, Corrosion of metals and alloys.This second edition cancels and replaces the first edition (ISO 7441:1984), which has been technically revised.iv ISO 2015 All rights reservedBS EN ISO 7441:2015
25、ISO 7441:2015(E)IntroductionBimetallic corrosion occurs when a metal in electrical contact with a more noble metal corrodes at a higher rate than it would in the same environment but without this contact.Bimetallic corrosion in the atmosphere, in contrast to that in electrolytes, is characterized by
26、 a large potential drop between the anode and the cathode. Therefore, bimetallic corrosion is usually limited to a distance within about 0,5 cm from the point of contact1.The determination of bimetallic corrosion in atmospheric exposure tests can be made with several methods, each with its own advan
27、tages. Three standardized tests are compared and described in this International Standard: rectangular plates; washers; wire on bolt.The standard starts with an overview and comparison of the three methods, with the purpose of aiding the selection of an appropriate test method. Test procedures for t
28、he rectangular plate and washer test are included in this standard since no independent standard describes these methods while those who wish to use the wire on bolt test need to consult ASTM G116 for a complete description of the method.The standard describes how to derive the bimetallic effect, wh
29、ich is a relative measure of the bimetallic corrosion of a metal compared to the corrosion of the same metal but without the bimetallic effect. A high galvanic effect does not necessarily mean that the bimetallic corrosion rate is high. Therefore, valuable complementary information is the classifica
30、tion of the corrosivity of the test site according to ISO 92232. ISO 2015 All rights reserved vBS EN ISO 7441:2015BS EN ISO 7441:2015Corrosion of metals and alloys Determination of bimetallic corrosion in atmospheric exposure corrosion tests1 ScopeThis International Standard specifies and compares m
31、ethods for the determination of bimetallic corrosion of metals and coated metals in atmospheric exposure corrosion tests.NOTE In the text of this International Standard, the term “metal” is used for both metals and alloys, and the term “coated metal” for metals and alloys with metallic and non-metal
32、lic inorganic coatings.The methods are intended for the determination of the amount and type of corrosion effect, arising in natural atmospheres, caused by contact with different metals.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document an
33、d 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.ISO 1456, Metallic and other inorganic coatings Electrodeposited coatings of nickel, nickel plus chr
34、omium, copper plus nickel and of copper plus nickel plus chromiumISO 2081, Metallic and other inorganic coatings Electroplated coatings of zinc with supplementary treatments on iron or steelISO 7599, Anodizing of aluminium and its alloys General specifications for anodic oxidation coatings on alumin
35、iumISO 6892-1, Metallic materials Tensile testing Part 1: Method of test at room temperatureISO 8044, Corrosion of metals and alloys Basic terms and definitionsISO 8407, Corrosion of metals and alloys Removal of corrosion products from corrosion test specimensISO 8565, Metals and alloys Atmospheric
36、corrosion testing General requirementsISO 15510, Stainless steels Chemical compositionASTM G116, Standard Practice for Conducting Wire-on-Bolt Test for Atmospheric Galvanic Corrosion3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 8044 and the followin
37、g apply.3.1test specimensspecimens that are exposed for evaluation of bimetallic corrosion caused by contact with different materialsINTERNATIONAL STANDARD ISO 7441:2015(E) ISO 2015 All rights reserved 1BS EN ISO 7441:2015ISO 7441:2015(E)3.2reference specimensspecimens prepared, exposed and evaluate
38、d in the same configuration and design as the test specimens but not subject to bimetallic corrosion, for example by being in contact with an inert non-conductive material or the same material, instead of the different material3.3standard specimensspecimens used to determine the corrosivity of the t
39、est environment in absence of bimetallic corrosion3.4control specimensspecimens prepared and evaluated in the same way as test specimens but, instead of being exposed in the test environment, stored under controlled conditions which prevent corrosion4 Overview and comparison of methodsThe determinat
40、ion of bimetallic corrosion in atmospheric exposure tests can be made with several methods. Three of these methods are compared and described in this International Standard: rectangular plates; washers; wire on bolt.An overview and comparison of methods are shown in Table 1. Each configuration has i
41、ts own advantages and the selection of method shall be based on the needs of the test programme. The main advantage with rectangular plate test is the possibility of evaluating the mechanical properties. The washer test is the only method where it is not necessary to know in advance which material i
42、s the anode. The short exposure time is the main advantage of the wire on bolt test.Table 1 Comparison of rectangular plates, washers and wire on bolt for conducting test assessing bimetallic corrosion in the atmosphereEffect Rectangular plates Washers Wire on boltSensitivity (exposure time) 1 year
43、1 year 90 daysaMaterial limitation None None Wire anodeAnode/cathode Necessary to know in advance which material is the anodeNot necessary to know in advance which material is the anodeNecessary to know in advance which material is the anodeEvaluation method(s) Mass lossMechanical propertiesMass los
44、s Mass lossMechanical Can be difficult to maintain electrical contact between pan-els throughout the exposure test.Can be difficult to main-tain electrical contact between panels through-out the exposure test.Can be difficult to main-tain enough wire tension without causing wire fractureCrevice corr
45、osion Crevice corrosion can be a problemCrevice corrosion can be a problemLower risk that crevice corrosion will be a prob-lemaA shorter duration of exposure is permissible under certain conditions, see Clause 6.2 ISO 2015 All rights reservedBS EN ISO 7441:2015ISO 7441:2015(E)5 Preparation of specim
46、ens5.1 Types of specimens5.1.1 GeneralWhen determining the risk of bimetallic corrosion, depending on the particular test, the specimens will not only suffer from increased corrosion due to bimetallic effects. For example, in the wire on bolt test the wire tension may influence the outcome of the te
47、st depending on the particular application. Therefore, several types of specimens (test specimens, reference specimens, standard specimens and control specimens) as defined in Clause 3 are needed depending on the purpose of the test programme.NOTE Comparison of effects of test and reference specimen
48、s gives the relative risk of bimetallic corrosion but reference specimens are generally not suitable for evaluation of the absolute corrosion attack when there is no risk of bimetallic corrosion due to the particular design of the specimens. For evaluation of the absolute attack standard specimens a
49、re more suitable. Flat or irregularly shaped specimens can be used, as described in ISO 8565, depending on the intended use of the tested material. For example, hanging wires can be used as standard specimens for the wire on bolt test but flat panels can also be used if they are easily obtained and more closely resembles the shape of the intended use.Control specimens shall be used if evaluation of mechanical properties is part of the test programme.Unless otherwise stated, the material, dimensions, direction of cutting, m
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