DIN 50961-2012 Electroplated coatings - Zinc coatings on iron or steel - Terms testing and corrosion resistance《电镀层 钢铁材料的镀锌层 术语、试验和耐腐蚀》.pdf

1、April 2012 Translation by DIN-Sprachendienst.English price group 6No part of this translation 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 2

2、5.220.40!$F5“1913518www.din.deDDIN 50961Electroplated coatings Zinc coatings on iron or steel Terms, testing and corrosion resistance,English translation of DIN 50961:2012-04Galvanische berzge Zinkberzge auf Eisenwerkstoffen Begriffe, Korrosionsprfung und Korrosionsbestndigkeit,Englische bersetzung

3、von DIN 50961:2012-04Revtements lectrolytiques Revtements lectrolytiques de zinc sur fer ou acier Termes, essai et rsistance la corrosion,Traduction anglaise de DIN 50961:2012-04SupersedesDIN 50961:2000-09www.beuth.deDocument comprises pagesIn case of doubt, the German-language original shall be con

4、sidered authoritative.811.12 DIN 50961:2012-04 2 A comma is used as the decimal marker. Contents Page Foreword . 3 Introduction 4 1 Scope . 5 2 Normative references . 5 3 Terms and definitions 5 4 Surface condition of object to be coated . 6 5 Accelerated corrosion testing and evaluation . 6 6 Chrom

5、ating process . 8 7 Test report . 8 DIN 50961:2012-04 3 Foreword This document has been prepared by Working Group NA 062-01-76 AA Galvanische berzge of the Normenausschuss Materialprfung (Materials Testing Standards Committee) (NMP). Attention is drawn to the possibility that some elements of this d

6、ocument may be the subject of patent rights. DIN and/or DKE shall not be held responsible for identifying any or all such patent rights. Amendments This standard differs from DIN 50961:2000-09 as follows: a) the normative references have been updated; b) the definition of the term “electroplated coa

7、ting” has been changed to be in line with DIN EN 12508:2000-09; c) a note on chromating solutions and chromate coating types includes an indication to blue chromate coatings; d) a definition of the term “passivation of zinc coatings” has been added; e) Table 1 “Corrosion resistance of zinc plus chro

8、mate conversion coatings” has been reworked. Previous editions DIN 50941: 1968-01, 1978-05 DIN 50961: 1955-01, 1963x-03, 1976-04, 1987-06, 2000-09 DIN 50962: 1955-01, 1963-03, 1976-04 DIN 50961:2012-04 4 Introduction Metallic and other inorganic coatings Electroplated coatings of zinc with supplemen

9、tary treatments on iron or steel are standardized in DIN EN ISO 2081. This supplementary standard, DIN 50961, was developed because the testing of coatings in industrial atmospheres (formerly known as the “Kesternich test”) is not carried out in many European countries whereas in German industry it

10、is indispensable for the corrosion testing of zinc coatings. For this reason quality requirements also need to be specified for coating systems that are subjected to a DIN 50018 KFW 2,0 S test. Furthermore, zinc coatings that have not been subsequently treated are still occasionally found in practic

11、e, and so requirements are also required to be specified for such coatings. Finally, this standard gives additional information on the surface condition of the object to be coated and also on chromate conversion coating, which has not been included in DIN EN ISO 2081. DIN 50961:2012-04 5 1 Scope Thi

12、s standard is only to be used in conjunction with DIN EN ISO 2081, which specifies requirements to be met by electroplated coatings of zinc with supplementary treatments. This standard supplements the provisions of DIN EN ISO 2081 by specifying, for various service conditions, the minimum requiremen

13、ts regarding corrosion resistance when the coatings are tested using a DIN 50018 KFW 2,0 S test, as well as specifying recommended coating thicknesses. Requirements regarding corrosion resistance for zinc coatings which have not been subsequently treated are specified for coatings that are tested us

14、ing the DIN 50018 KFW 2,0 S test or the neutral salt spray test (NSS) as in DIN EN ISO 9227. Cr(VI) free passivated and sealed zinc and zinc alloy coatings are defined in DIN 50979. NOTE Users of this standard are to observe the statutory safety requirements and the valid national and European laws

15、and ordinances and regulations. 2 Normative references The 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) app

16、lies. DIN 50018, Sulfur dioxide corrosion testing in a saturated atmosphere DIN 50969-1, Prevention of hydrogen-induced brittle fracture of high-strength steel building elements Part 1: Advice on the prevention DIN 50979, Metallic coatings Electroplated zinc and zinc alloy coatings on iron or steel

17、with supplementary Cr(VI)-free treatment DIN EN 1403, Corrosion protection of metals Electrodeposited coatings Method of specifying general requirements DIN EN ISO 2064, Metallic and other inorganic coatings Definitions and conventions concerning the measurement of thickness) DIN EN ISO 2080:2009-08

18、, Metallic and other inorganic coatings Surface treatment, metallic and other inorganic coatings Vocabulary (ISO 2080:2008) DIN EN ISO 2081:2009-05, Metallic and other inorganic coatings Electroplated coatings of zinc with supplementary treatments on iron or steel (ISO 2081:2008) DIN EN ISO 9227, Co

19、rrosion tests in artificial atmospheres Salt spray tests DIN EN ISO 10289, Methods for corrosion testing of metallic and other inorganic coatings on metallic substrates Rating of test specimens and manufactured articles subjected to corrosion tests 3 Terms and definitions For the purposes of this do

20、cument, the terms and definitions in DIN EN 1403 and DIN EN ISO 2064 and the following apply. DIN 50961:2012-04 6 3.1 electrodeposited coating metal coating that is electrolytically deposited from a suitable electrolytic solution onto an object serving as a cathode, and which adheres to the object N

21、OTE See also DIN EN ISO 2080:2009-08, 2.5. 3.2 chromating solution usually an acidic solution that contains hexavalent chromium salts and may contain other salts that can be varied in order to affect the appearance and hardness of the film NOTE 1 For further information on chromating solutions see D

22、IN EN ISO 2081:2009-05, Annex A. NOTE 2 As a deviation from the clear chromate conversion coating (Code A in DIN EN ISO 2081), clear chromate conversion coatings with a special iridescent blue surface are also used in Germany. Coatings of this kind are still permitted and are required to be speciall

23、y agreed between the client and contractor. The requirements are identical with those for Code A from DIN EN ISO 2081 (except for their appearance). 3.3 passivation of zinc coatings production of Cr(VI) free conversion coatings in order to improve the corrosion resistance of the zinc coatings NOTE I

24、n DIN 50979, the new codes “An” (transparent), “Cn” (iridescent) und “Fn” (black) are defined, and the requirements for these coatings are specified. There are no generally recognized corrosion resistance values for “Fn”. 4 Surface condition of object to be coated The object to be coated shall be fr

25、ee of all material, finishing or surface defects which could impair corrosion protection and/or adversely affect the appearance of the coating. Defects in rolled products include cracks, pits, exogenous inclusions, and laminations. In cast pieces, such defects include sink marks, cold laps, cooling

26、cracks, toe cracks and shrinkage voids. It is recommended that the surface quality, and possibly the surfaces microgeometric structure, be agreed on between manufacturer and purchaser, since these can influence coating thickness, the measurement of the thickness, and corrosion behaviour. 5 Accelerat

27、ed corrosion testing and evaluation The results of accelerated corrosion tests do not necessarily provide an indication of the corrosion behaviour of the zinc-coated or chromated objects in service. However, a qualitative assessment of various coating systems is possible. The chromate coatings on th

28、e zinc coatings of the objects or test plates shall be conditioned at room temperature for at least 24 h prior to beginning the corrosion test. The evaluation of the specimens tested in accordance with Tables 1 and 2 is based on the extent of corrosion of the basis metal. The evaluation shall be acc

29、ording to DIN EN ISO 10289. A rating other than 10 may be agreed upon. The number and rating of specimens with a significant surface area smaller than 25 mm is to be agreed. Assessment shall be carried out at normal reading distance without a magnifier. DIN 50961:2012-04 7 Table 1 Corrosion resistan

30、ce of zinc plus chromate conversion coatings (Rating of 10 as in DIN EN ISO 10289) Coating designation (partial) Service condition No. of cycles in DIN 50018 KFW 2,0 S test Fe/Zn5/A Fe/Zn5/F Fe/Zn5/C Fe/Zn5/D 0 1 Fe/Zn8/A Fe/Zn8/F Fe/Zn8/C Fe/Zn8/D 1 2 Fe/Zn12/C Fe/Zn12/D Fe/Zn15/A Fe/Zn15/F 2 4 Fe/

31、Zn15/C Fe/Zn15/D Fe/Zn25/A Fe/Zn25/F 3 5 Fe/Zn25/C Fe/Zn25/D 4 10 DIN 50961:2012-04 8 Table 2 Corrosion resistance of untreated zinc coatings (Rating of 10 as in DIN EN ISO 10289) Zinc coating thickness No. of cycles in DIN 50018 KFW 2,0 S test Neutral salt spray test as in DIN EN ISO 9227 (NSS) m h

32、 5 1 24 8 2 48 12 3 96 25 7 192 6 Chromating process The fact that a small amount of zinc 0,2 m to 2 m, depending on the method used is always dissolved during the chromating process is to be taken into consideration when applying the chromate conversion coating, for otherwise the recommended minimum local thickness may not be obtained. Wet, freshly applied chromate conversion coatings are sensitive to abrasion. A resistance to abrasion is achieved only by fully dried coatings. 7 Test report The test report shall be drawn up according to DIN EN ISO 10289.