DIN EN ISO 21227-4-2008 Paints and varnishes - Evaluation of defects on coated surfaces using optical imaging - Part 4 Evaluation of filiform corrosion (ISO 21227-4 2008) English v.pdf

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1、June 2008DEUTSCHE NORM English price group 8No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 87.040!$ONK“1444340www.din

2、.deDDIN EN ISO 21227-4Paints and varnishes Evaluation of defects on coated surfaces using optical imaging Part 4: Evaluation of filiform corrosion (ISO 21227-4:2008)English version of DIN EN ISO 21227-4:2008-06Beschichtungsstoffe Beurteilung von Beschichtungsschden mittels digitaler Bildverarbeitung

3、 Teil 4: Beurteilung von Filiformkorrosion (ISO 21227-4:2008)Englische Fassung DIN EN ISO 21227-4:2008-06www.beuth.deDocument comprises 13 pagesDIN EN ISO 21227-4:2008-06 2 National foreword This standard falls in the domain of Technical Committee CEN/TC 139 “Paints and varnishes” (Secretariat: DIN,

4、 Germany). It is identical with International Standard ISO 21227-4 which was prepared by Technical Committee ISO/TC 35/SC 9 “General test methods for paints and varnishes” (Secretariat: BSI, United Kingdom). The responsible German body involved in its preparation was the Normenausschuss Beschichtung

5、sstoffe und Beschichtungen (Coatings and Coating Materials Standards Committee), Technical Committee NA 002-00-07 AA Allgemeine Prfverfahren fr Beschichtungsstoffe und Beschichtungen. DIN EN ISO 21227 consists of the following parts, under the general title Paints and varnishes Evaluation of defects

6、 on coated surfaces using optical imaging: Part 1: General guidance Part 2: Evaluation procedure for multi-impact stone-chipping test Part 3: Evaluation of delamination and corrosion around a scribe Part 4: Evaluation of filiform corrosion The DIN Standards corresponding to the International Standar

7、ds referred to in the EN are as follows: ISO 4623-1 DIN EN ISO 4623-1 ISO 4623-2 DIN EN ISO 4623-2 ISO 4628-10 DIN EN ISO 4628-10 ISO 21227-1 DIN EN ISO 21227-1 National Annex NA (informative) Bibliography DIN EN ISO 4623-1, Paints and varnishes Determination of resistance to filiform corrosion Part

8、 1: Steel substrate DIN EN ISO 4623-2, Paints and varnishes Determination of resistance to filiform corrosion Part 2: Aluminium substrates DIN EN ISO 4628-10, Paints and varnishes Evaluation of degradation of coatings Designation of quantity and size of defects, and of intensity of uniform changes i

9、n appearance Part 10: Assessment of degree of filiform corrosion DIN EN ISO 21227-1, Paints and varnishes Evaluation of defects on coated surfaces using optical imaging Part 1: General guidance EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 21227-4 March 2008 ICS 87.040 English Version Pai

10、nts and varnishes - Evaluation of defects on coated surfaces using optical imaging - Part 4: Evaluation of filiform corrosion (ISO 21227-4:2008) Peintures et vernis - valuation par imagerie optique des dfauts des surfaces revtues - Partie 4: valuation de la corrosion filiforme (ISO 21227-4:2008) Bes

11、chichtungsstoffe - Beurteilung von Beschichtungsschden mittels digitaler Bildverarbeitung - Teil 4: Beurteilung von Filiformkorrosion (ISO 21227-4:2008) This European Standard was approved by CEN on 21 February 2008. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which sti

12、pulate 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 Management Centre or to any CEN member. This European Standar

13、d 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 Management Centre has the same status as the official versions. CEN members are the national stand

14、ards bodies of Austria, 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 United King

15、dom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2008 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 21227-4:2008:

16、 E2 EN ISO 21227-4:2008 (E) - :DIN EN ISO 21227-4:2008-06 Contents Page Foreword .3 Introduction.4 1 Scope5 2 Normative references5 3 Terms and definitions .5 4 Principle .6 5 Requirements.6 6 Calibration6 7 Procedure.6 8 Image evaluation .7 9 Precision 8 10 Test report8 Annex A (informative) Extend

17、ed evaluation.10 Bibliography11 Foreword 3 This document (EN ISO 21227-4:2008) has been prepared by Technical Committee ISO/TC 35 “Paints and varnishes“ in collaboration with Technical Committee CEN/TC 139 “Paints and varnishes” the secretariat of which is held by DIN. This European Standard shall b

18、e given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by September 2008, and conflicting national standards shall be withdrawn at the latest by September 2008. Attention is drawn to the possibility that some of the elements of this doc

19、ument may 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:

20、 Austria, 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. Endo

21、rsement notice The text of ISO 21227-4:2008 has been approved by CEN as a EN ISO 21227-4:2008 without any modification. DIN EN ISO 21227-4:2008-06 EN ISO 21227-4:2008 (E) Introduction Conventional ISO test methods used for evaluating surface defects and appearance changes often utilize pictorial sta

22、ndards which depict particular types of surface deterioration and require human visual evaluation. The technology described in the various parts of this International Standard can yield more objective, accurate, quantitative and reproducible results when compared to the human visual evaluation techn

23、iques. 4 EN ISO 21227-4:2008 (E) DIN EN ISO 21227-4:2008-06 1 Scope This part of ISO 21227 describes a method for evaluating filiform corrosion by means of digital optical imaging. The filiform corrosion can be produced in accordance with ISO 4623-1, ISO 4623-2 or EN 3665. 2 Normative references The

24、 following referenced 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. ISO 4623-1, Paints and varnishes Determination of re

25、sistance to filiform corrosion Part 1: Steel substrates ISO 4623-2, Paints and varnishes Determination of resistance to filiform corrosion Part 2: Aluminium substrates ISO 21227-1, Paints and varnishes Evaluation of defects on coated surfaces using optical imaging Part 1: General guidance EN 3665, A

26、erospace series Test methods for paints and varnishes Filiform corrosion resistance test on aluminium alloys 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 21227-1 and the following apply. 3.1 filiform corrosion type of corrosion proceeding under a

27、coat of paint, varnish or related product, in the form of filaments, generally starting from bare edges or from local damage to the coating NOTE 1 Usually, the filaments are irregular in length and direction of growth, but they may also be nearly parallel and of approximately equal length. NOTE 2 Fi

28、liform corrosion can also occur under other protective coatings. ISO 4623-1 5 EN ISO 21227-4:2008 (E) DIN EN ISO 21227-4:2008-06 4 Principle A grey-scale or colour image is produced from the original image of the surface showing filiform corrosion. In the simplest case, this image is converted into

29、a binary image (thresholding). The damaged area and the maximum filament length are measured, and the mean width of the filiform corrosion is calculated. 5 Requirements 5.1 General The requirements laid down in ISO 21227-1 also apply for this part of ISO 21227. 5.2 Illumination The illumination shal

30、l be such that the damaged area can be clearly distinguished from the undamaged area. Bright-field or dark-field illumination can be used. NOTE 1 In the case of glossy specimens, directional illumination is suitable. For matt specimens, dark-field illumination is recommended. NOTE 2 When detecting f

31、iliform corrosion without previously removing the coating, directional reflection illumination can be of advantage because of the low contrast. After stripping the coating, filiform corrosion can be readily recognized when using diffuse reflection illumination, provided the contrast is sufficiently

32、high. 5.3 Resolution The minimum resolution shall be 6 pixels per millimetre. NOTE Different resolutions, in particular in the case of damage involving a large number of filaments, can lead to different values for the damaged area. 6 Calibration By calibrating the scale in both the x and y direction

33、s (e.g. with an object micrometer or a photographic picture graduated in millimetres), the digitized image can be measured with sufficient accuracy. 7 Procedure Prepare the test panels in accordance with ISO 4623-1, ISO 4623-2 or EN 3665. Using the previously calibrated digital optical-imaging syste

34、m, take a picture of the test panel area containing the scribe and the adjacent damaged area. After suitable threshold setting and damage detection, the digital image provides a value for the damaged area including the area of the scribe. The length of the scribe in the area assessed shall also be d

35、etermined and indicated in the test report. If the damaged areas at the ends of the scribe differ from the remaining damaged area, these areas are not assessed. If the test panel contains several scribes (e.g. two intersecting scribes), these can be considered as sections of a single scribe, and the

36、 relevant areas and scribe lengths can be added to one another. The area of intersection is not assessed. In the case of scribes perpendicular to each other, indicate the result for both scribes separately, as the scribe running perpendicular to the direction of rolling will show considerably more a

37、nd longer filiform corrosion than that running parallel to it. If the scribe width is not known, it shall be measured. If it cannot be measured, the same value (preferably zero) shall be used for all assessments intended to be comparative, and this value shall be quoted in the test report. 6 EN ISO

38、21227-4:2008 (E) DIN EN ISO 21227-4:2008-06 8 Image evaluation In contrast to the manual assessment of filiform corrosion, digital optical imaging can determine directly the size of an area of any shape (see Figure 1). The assessment will thus be more accurate and more reproducible. a) Original imag

39、e b) Binary image Key w width of scribe l scribe length evaluated Llmaximum filament length on left-hand side of scribe Lrmaximum filament length on right-hand side of scribe Figure 1 Images showing parameters required for assessment 7 EN ISO 21227-4:2008 (E) DIN EN ISO 21227-4:2008-06 Assuming the

40、scribe width w is known, calculate the area A of the scribe using Equation (1): A wl= (1) Calculate the mean width of the filiform corrosion fA, in millimetres, using Equation (2): 1A12AAfl= (2) where A is the area of the scribe, in square millimetres; A1is the area of the filiform corrosion, includ

41、ing the scribe area, in square millimetres; l is the scribe length evaluated, in millimetres. In the case of corrosion involving filaments of irregular length, an extended evaluation in accordance with Annex A is recommended in addition to the above. 9 Precision Information on the precision of this

42、method is currently not available. 10 Test report The test report shall contain at least the following information: a) all information necessary for identification of the coating tested (manufacturer, trade name, batch number, etc.); b) a reference to this part of ISO 21227 (ISO 21227-4:2008); c) th

43、e type of illumination used (light source, arrangement of lamps); d) the image acquisition set-up used, including details of the 1) original image, 2) optical components used, 3) resolution, 4) image size, 5) grey level/colour depth, 6) gamma correction; e) details of the image processing and image

44、analysis, including all processing procedures (filters) used; f) the scribe length evaluated; g) the result of the assessment, as indicated in Clause 8; 8 EN ISO 21227-4:2008 (E) DIN EN ISO 21227-4:2008-06 h) any deviations from the procedure specified; i) any unusual features (anomalies) observed d

45、uring the test; j) the date of the test; k) the name of the person who carried out the test. 9 EN ISO 21227-4:2008 (E) DIN EN ISO 21227-4:2008-06 Annex A (informative) Extended evaluation In the case of irregular corrosion, the degree of corrosion can be characterized more closely by reporting the f

46、ollowing additional parameters: a) The so-called g-value, which is a measure of the irregularity of the corrosion and is given by Equation (A.1): ()1lrA AgL Ll=+(A.1) where A is the area of the scribe, in square millimetres; A1is the area of filiform corrosion, including the scribe area, in square m

47、illimetres; Llis the maximum length of the filaments on the left-hand side of the scribe, in millimetres; Lris the maximum length of the filaments on the right-hand side of the scribe, in millimetres; l is the scribe length, in millimetres. A large g-value is obtained when there are many uniform fil

48、aments (as in the case of infiltration of a protective coating by water), the maximum value being 1. A low g-value is obtained when there is a high degree of irregularity, the minimum value being 0. b) The maximum filament length on each side of the scribe (see Figure 1). c) The most frequent filame

49、nt length (see ISO 4628-10). 10 EN ISO 21227-4:2008 (E) DIN EN ISO 21227-4:2008-06 Bibliography 1 ISO 4628-10, Paints and varnishes Evaluation of degradation of coatings Designation of quantity and size of defects, and of intensity of uniform changes in appearance Part 10: Assessment of degree of filiform corrosion 11 EN ISO 21227-4:2008 (E) DIN EN ISO 21227-4:2008-06