ASTM_D_6905_-_20.pdf

Designation:D690520Standard Practice forImpact Flexibility of Organic Coatings1This standard is issued under the fixed designation D6905;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.1.Scope*1.1 This practice covers a procedure for determining theability of a coating film and its substrate to resist shattering,cracking,or chipping when the film and substrate are distendedbeyond their original form by impact.1.2 This practice does not measure impact resistance butuses rapid impact to improve Test Methods D522,a testmethod for flexibility.Since the impact of the coating is almostinstantaneous,all of the problems associated with time vari-ables in the mandrel tests are eliminated.1.3 This practice is similar in content but not technicallyequivalent to Test Method D2794.1.4 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D522 Test Methods for Mandrel Bend Test of AttachedOrganic CoatingsD609 Practice for Preparation of Cold-Rolled Steel Panelsfor Testing Paint,Varnish,Conversion Coatings,andRelated Coating ProductsD823 Practices for Producing Films of Uniform Thicknessof Paint,Coatings and Related Products on Test PanelsD2240 Test Method for Rubber PropertyDurometer Hard-nessD2794 Test Method for Resistance of Organic Coatings tothe Effects of Rapid Deformation(Impact)D7091 Practice for Nondestructive Measurement of DryFilm Thickness of Nonmagnetic Coatings Applied toFerrous Metals and Nonmagnetic,Nonconductive Coat-ings Applied to Non-Ferrous Metals3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 impact flexibility,nof a coating,the percent areaincrease required to produce cracking in the deformed coating.4.Summary of Practice4.1 The organic coating under test is applied to suitable thinmetal panels(see Practice D609).After the coating has cured,a standard weight/indenter is dropped from a measured dis-tance so as to strike the substrate which deforms the coatingand the substrate.The percent elongation is the highest area ofdistensibility in which there is no film breaks that the film canstand.5.Significance and Use5.1 Coatings attached to substrates are subjected to damag-ing impacts during the manufacture of articles and their use inservice.This impact resistance practice has been found to beuseful in predicting the performance of organic coatings fortheir ability to resist cracking caused by impacts.6.Apparatus6.1 Impact Flexibility Tester3,assembly illustrated in Figs.1and 2.The instrument contains a 1.63 kg(3.6 lb)weight/indenter,a rubber pad and an aluminum pad,Fig.3.The round1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.23 on Physical Properties of Applied Paint Films.Current edition approved Dec.1,2020.Published December 2020.Originallyapproved in 2003.Last previous edition approved in 2012 as D6905 03(2012).DOI:10.1520/D6905-20.2For 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.3The sole source of supply of the apparatus known to the committee at this timeis the IM-172-GE Impact Tester,available from the Paul N.Gardner Company,Inc.,316 N.E.First Street,Pompano Beach,FL 33060.If you are aware of alternativesuppliers,please provide this information to ASTM International Headquarters.Your comments will receive careful consideration at a meeting of the responsibletechnical committee,1which you may attend.*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 StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Tr