DIN 50905-1-2009 Corrosion of metals - Corrosion testing - Part 1 General guidance《金属的腐蚀 腐蚀试验 第1部分 一般指南》.pdf

1、September 2009DEUTSCHE NORM Translation by DIN-Sprachendienst.In case of doubt, the German-language original should be consulted as the authoritative text.English price group 8No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Be

2、uth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 77.060!$s9“1568022www.din.deDDIN 50905-1Corrosion of metals Corrosion testing Part 1: General guidanceKorrosion der Metalle Korrosionsuntersuchungen Teil 1: GrundstzeSupersedesDIN 50905-1:198

3、7-01www.beuth.deDocument comprises pages12DIN 50905-1:2009-09 Contents Page Foreword. 3 Introduction 4 1 Scope . 4 2 Normative references . 4 3 Terms and definitions 5 4 General. 5 5 Materials 5 6 Corrosive medium 6 7 Procedure 6 8 Evaluation of results 8 8.1 Changes in mass 8 8.1.1 Loss in mass . 8

4、 8.1.2 Gain in mass 8 8.2 Surface changes . 9 8.3 Depth of attack 9 8.4 Changes in microstructure 9 8.5 Changes in mechanical properties . 9 8.6 Corrosion products 9 8.7 Changes in the corrosive medium 9 Annex A (informative) Overview of standards and other documents on corrosion testing and investi

5、gations 10 A.1 Main types of corrosion test 10 A.2 General corrosion tests . 10 A.3 Corrosion testing of ferrous materials . 10 A.4 Corrosion testing of aluminium 11 A.5 Corrosion testing of copper 11 A.6 Corrosion testing of nickel 11 A.7 Testing of non-organic coatings. 11 A.8 General aspects of t

6、esting corrosion . 12 2 DIN 50905-1:2009-09 Foreword This standard has been prepared by Working Committee NA 062-01-71 AA Korrosion und Korrosionsschutz of the Normenausschuss Materialprfung (NMP) (Materials Testing Standards Committee). Amendments This standard differs from DIN 50905-1:1987-01 as f

7、ollows: a) There is now an Introduction giving information taken from the scope of the previous edition. b) The scope has been modified. c) Clause 2 “Normative references” is now included. d) Clause 7 has been modified. e) Annex A has been extensively modified. f) The standard has been editorially r

8、evised. Previous editions DIN 4850: 1937-10 DIN 4851: 1937-10 DIN 4852: 1939x-08 DIN 50901: 1957-08 DIN 50905: 1952-11 DIN 50905-1: 1975-01, 1987-01 DIN 50906: 1958-10 3 DIN 50905-1:2009-09 Introduction There are many different types of corrosion test due to the wide variety of materials and corrosi

9、ve media involved; standardized rules for the performance of such tests are therefore necessary. The results of corrosion tests are only meaningful and reproducible if testing is carried out as specified in this standard. As a rule, significant information on the corrosion resistance of metallic mat

10、erials can only be obtained from tests which reproduce corrosion behaviour under service conditions. 1 Scope This standard lays down the most important principles for carrying out corrosion tests in which specimens are not subjected to additional mechanical stress. DIN 50905-2 deals with corrosion c

11、haracteristics under uniform corrosion attack, DIN 50905-3 with characteristics under non-uniform and localised attack, and DIN 50905-4 covers corrosion testing in liquids under laboratory conditions without mechanical stress. Annex A lists other standards and documents which cover corrosion testing

12、 where specimens are subjected to additional mechanical stress, tests involving the measurement of electrochemical parameters, the corrosion testing of inorganic coatings, and the determination of corrosion properties of individual metallic materials. 2 Normative references The following referenced

13、documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. DIN 50600, Testing of metallic materials Metallographic micrographs Pictur

14、e scales and formats DIN 50905-2, Corrosion of metals Corrosion testing Corrosion characteristics under uniform corrosion attack DIN 50905-3, Corrosion of metals Corrosion testing Corrosion characteristics under non-uniform and localized corrosion attack without mechanical stress DIN 50905-4, Corros

15、ion of metals Corrosion testing Corrosion testing in liquids under laboratory conditions without mechanical stress DIN 50919, Corrosion of metals Investigations of galvanic corrosion in electrolytic solutions DIN 50920-1, Corrosion of metals Corrosion testing in flowing liquids General DIN EN 10002-

16、1, Metallic materials Tensile testing Part 1: Method of testing at ambient temperature DIN EN ISO 7438, Metallic materials Bend test DIN EN ISO 8044, Corrosion of metals and alloys Basic terms and definitions DIN EN ISO 8565, Metals and alloys Atmospheric corrosion testing General requirements for f

17、ield tests 4 DIN 50905-1:2009-09 3 Terms and definitions For the purposes of this document the terms and definitions in DIN EN ISO 8044 apply. 4 General 4.1 Corrosion tests are frequently carried out for purposes of comparison. For example, when a material is to be selected, several materials will b

18、e compared by exposing them to the same test conditions. Often various corrosive media are also compared in terms of the corrosion resistance of a material in those media. It is also possible to include reference materials and/or media whose corrosion behaviour under service conditions is known in s

19、uch tests. 4.2 In corrosion tests the development of corrosion over time is to be observed and, where possible, quantified and documented. Ideally, the condition of test specimens is to be determined not only at the beginning and end of every test but also after at least two further periods of expos

20、ure. Corrosion tests shall be long enough so that once they are completed unambiguous results are obtained regarding the corrosion behaviour under test conditions of the material tested and of any reference material. If necessary, the test shall be prolonged beyond the original duration. 4.3 Individ

21、ual values are often not very meaningful due to the variation of measured results. The reliability of results increases with the number of specimens tested. In many cases two individual results will provide sufficient corroboration of the value of a test parameter. Each specimen shall be used for on

22、e measurement only. For long-term corrosion tests in which the variation of single results cannot be estimated beforehand it is recommended that a larger number of specimens be tested. 4.4 The exposure to corrosion shall simulate the relevant service conditions under which the materials and corrosiv

23、e medium are to be used. For instance, this applies to the shape, surface condition and microstructure of the material (see clause 5 for details) and to the concentration and temperature of the medium (see clause 6 for details). 4.5 In corrosion tests an attempt is often made to obtain useful result

24、s within as short a time as possible by intensifying the exposure to corrosion (accelerated corrosion testing, see DIN EN ISO 8044). However, accelerated testing, e.g. by increasing the temperature or concentration of a corrosive substance during the corrosion phase often produces results which are

25、not representative of behaviour under service conditions. Caution is therefore recommended when applying results which have been obtained in accelerated tests (see DIN EN ISO 8044). 4.6 Accelerated corrosion tests are used to quickly determine certain material characteristics relating to the corrosi

26、on behaviour of the material or to describe properties of corrosion protection coatings. Such accelerated tests are not intended to produce results that can be applied to behaviour under service conditions. 5 Materials 5.1 Test samples and specimens are to be clearly identified by marking. Where nec

27、essary, details shall be given regarding the chemical composition and any standard designation of the material; condition of the material (e.g. cast, hot rolled, cold rolled, forged, extruded, heat-treated); product form (e.g. sheet, wire, pipe, tube, bar, section); 5 DIN 50905-1:2009-09 position of

28、 the specimens in the sample (indicated in a sketch, where necessary); dimensions and mass of specimens; surface condition of the material (with or without rolling scale, pickled, ground, polished, chemically or electrolytically brightened or otherwise pretreated); mechanical properties of the mater

29、ial (characteristic strength, hardness, toughness); microstructure of the material (e.g. phases, grain size, texture and segregation); any coatings (type, structure, layer thicknesses). 5.2 The method of preparing specimens from the sample is to be stated. Specimens should be cut from the sample in

30、such a way that undue mechanical cold forming or heating at the cut edges is avoided. Any burrs shall be removed. In general a protective coating on cut edges is only necessary if it is expected that unprotected edges will adversely affect the behaviour of the material under test. 5.3 The specimen s

31、urface condition shall either be the same as in service or shall be modified to suit the particular objective of the test. Specimens shall generally be cleaned and degreased before the test. The cleaning and degreasing agents used shall be suitable for the relevant material and shall not influence t

32、he results of the test. The cleaning agent used shall be specified. 5.4 Test specimens shall be clearly marked, e.g. by means of indented numbers or letters, or by other means. Since the mechanical stress occurring during indentation can be conducive to local corrosion, in the case of particularly s

33、ensitive materials or under certain test conditions it is recommended that marking methods which do not involve cold forming be used, e.g. electromechanical marking or notching. Special heat treatment may be necessary subsequent to marking. 6 Corrosive medium 6.1 The source, composition and conditio

34、n of the corrosive medium shall be clearly described. 6.2 The description of the source of the corrosive medium shall state whether the substances are solutions, gases or solids occurring naturally, are derived from industrial processes, or are specially prepared. 6.3 Where possible, the quantitativ

35、e chemical composition of the corrosive medium shall be determined by means of analysis. Analysis shall also take into account small amounts of additives and impurities, including any dissolved gases present in liquid corrosive media, and the moisture content of gases or solids. 6.4 In the case of a

36、queous corrosive media the pH value, and where possible, the electric conductivity and redox potential shall be determined. 6.5 If the corrosive medium undergoes a substantial change during the course of the test, e.g. due to the nature of the corrosion reaction or as a result of evaporation, it sha

37、ll be renewed during the test, or the loss from evaporation shall be made up in order to keep the corrosion exposure constant. The test report shall state whether and at what intervals or to what extent the corrosive medium was renewed or the loss from evaporation was made up. 7 Procedure 7.1 The te

38、st procedure shall be clearly described. The stability of test conditions (e.g. duration of exposure, test atmosphere, test intervals in the case of cyclic corrosion exposures) shall be ensured throughout the entire test. 7.2 The quantity of corrosive medium used shall be proportional to the unit ar

39、ea of the specimen and should be at least 10 ml/cm2. 6 DIN 50905-1:2009-09 7.3 To minimize the influence of surface irregularities, the specimen surface area shall not be smaller than 25 cm if smaller areas are not required by a special test code or are expedient due to a specific test objective. Wh

40、en testing specimens taken from castings, it is recommended that the surface area be approximately double that specified above. 7.4 The specimen shape will depend on the test method and expected form of corrosion. If localized corrosion is expected, e.g. deep pitting, wide pitting or intercrystallin

41、e corrosion, specimens shall be of sufficient thickness for the depth of attack to be determined. If the mechanical properties are altered by corrosion, a specimen shape that is commonly used for mechanical testing should be selected to ensure that such changes can be determined in subsequent mechan

42、ical tests. 7.5 The arrangement of specimens in the corrosive medium can influence test results. In the case of flowing media, specimens shall be arranged relative to the flow direction as appropriate for the test objective (see DIN 50920-1). Details shall be given in the test report on flow charact

43、eristics and any movement induced in the medium, e.g. by stirring. Specimens shall generally be placed in the corrosive medium in such a way that the entire surface of the specimens is equally exposed to corrosion. In the case of liquid corrosive media, not only corrosion characteristics of fully im

44、mersed specimens may be of significance, but the effect on the three-phase boundary and the influence of condensate in the vapour zone may be significant as well. In this case testing shall also be carried out on partially immersed specimens and specimens located in the vapour zone (see DIN 50905-4)

45、. Specimens being tested simultaneously shall not be placed immediately next to each other but shall be placed at an adequate distance from each other in the test compartment or vessel. To avoid bimetallic corrosion, there shall be no metallic conductive connection between the specimens or between t

46、he specimens and a metal vessel (see DIN 50919). To suspend specimens a hole may be punched in the specimen, which then may be hung by means of a thin plastic thread or other nonconductive hanging device (e.g. glass hook). Test results may be influenced if the distance between the specimens and the

47、wall of the vessel is too small. 7.6 Only specimens of the same type of material shall be investigated at the same time in the same vessel, unless the objective of the test is to determine how materials influence each other. The vessel material shall not be attacked by the corrosive medium, and the

48、vessel shall be set up in such a way that the exposure to corrosion is not affected by external influences. In the case of corrosion tests in open vessels, the ambient air shall be free from components which might distort the test results. 7.7 Unless the effect on corrosion of temperature fluctuatio

49、ns is part of the test objective, the temperature of the corrosive medium shall be kept as constant as possible throughout the test. If the temperature changes during the corrosion test, details shall be given in the test report. 7.8 If, under service conditions, heat is transferred between the corrosive medium and the material as a result of a temperature gradient between them, this shall be taken into account when carrying out the test. 7.9 Before the loss in mass is determined, any corrosion products adhering to the specimens s