ASTM_D_2803_-_09_2015.pdf

Designation:D280309(Reapproved 2015)Standard Guide for TestingFiliform Corrosion Resistance of Organic Coatings onMetal1This standard is issued under the fixed designation D2803;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This guide covers three procedures for determining thesusceptibility of organic-coated metal substrates to formationof filiform corrosion.1.2 This guide is limited to the determination of whetherfiliform corrosion will occur between the organic coating andsubstrate.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety problems,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE1Procedure B of this standard is equivalent to ISO 4623.2.Referenced Documents2.1 ASTM Standards:2B117 Practice for Operating Salt Spray(Fog)ApparatusD609 Practice for Preparation of Cold-Rolled Steel Panelsfor Testing Paint,Varnish,Conversion Coatings,andRelated Coating ProductsD823 Practices for Producing Films of Uniform Thicknessof Paint,Varnish,and Related Products on Test PanelsD1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD1654 Test Method for Evaluation of Painted or CoatedSpecimens Subjected to Corrosive EnvironmentsD1730 PracticesforPreparationof AluminumandAluminum-Alloy Surfaces for PaintingD7091 Practice for Nondestructive Measurement of DryFilm Thickness of Nonmagnetic Coatings Applied toFerrous Metals and Nonmagnetic,Nonconductive Coat-ings Applied to Non-Ferrous MetalsE104 Practice for Maintaining Constant Relative Humidityby Means of Aqueous Solutions2.2 International Standard:3ISO 46231 Paints and VarnishesDetermination of resis-tance to filiform corrosionPart 1:On steelISO 46232 Paints and VarnishesDetermination of resis-tance to filiform corrosionPart 2:On aluminumISO 462810 Paints and VarnishesEvaluation of degrada-tion of coatingsDesignation of quantity and size ofdefects and of intensity of changesPart 10:Assessment offiliform corrosion3.Terminology3.1 Definitions:3.1.1 filiform corrosion,na special type of corrosion thatoccurs under coatings on metal substrates that is characterizedby a definite threadlike structure and directional growth.3.1.1.1 DiscussionFiliform corrosion usually occurs be-tween 20 and 35C(70 and 95F),with a correspondingrelative humidity range of 60 to 95%;above 95%humidity,blistering rather than filiform corrosion may occur.4.Summary of Method4.1 Coated metal specimens are scribed and placed in acorrosive atmosphere to initiate corrosion.The specimens arethen exposed to controlled temperature and humidity condi-tions known to be conducive to filiform corrosion.4.2 In Procedure A,panels are subjected to a preliminaryexposure in the salt spray cabinet to initiate corrosion,rinsed,and placed in a humidity cabinet.In Procedure B,based on ISO4623,panels are either exposed to salt spray or dipped in a saltsolution but not rinsed before placing in the humidity cabinetoperated at a higher temperature than in Procedure A.In1This guide is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.27 on Accelerated Testing.Current edition approved June 1,2015.Published June 2015.Originallyapproved in 1969.Last previous addition approved in 2009 as D2803 09.DOI:10.1520/D2803-09R15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 Procedure C,specimens are exposed as in Procedure A exceptthe humidity cabinet is operated at a higher temperature.4.3 The procedures contained in this guide differ signifi-cantly in method of initiation,and or temperature,or both,andhumidity of exposure and therefore may not yield comparableresults.5.Significance and Use5.1 Some organic coatings applied to metal substrates ex-hibit filiform corrosion when there is a break in the coating filmand the relative humidity is in the 70 to 95%range.5.2 This guide can be used t