ASTM_D_2794_-_93_2019.pdf

Designation:D279493(Reapproved 2019)Standard Test Method forResistance of Organic Coatings to the Effects of RapidDeformation(Impact)1This standard is issued under the fixed designation D2794;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 test method covers a procedure for rapidly deform-ing by impact a coating film and its substrate and for evaluatingthe effect of such deformation.1.2 This test method should be restricted to testing in onlyone laboratory when numerical values are used because of thepoor reproducibility of the method.Interlaboratory agreementis improved when ranking is used in place of numerical values.1.3 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.4 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.1.5 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:2D609 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 PanelsD1186 Test Methods for Nondestructive Measurement ofDry Film Thickness of Nonmagnetic Coatings Applied toa Ferrous Base(Withdrawn 2006)33.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 impact resistance,of a coating,nthe number ofinch-pounds(kilogram-metres)required to produce cracking inthe deformed coating.4.Summary of Test Method4.1 The organic coatings under test are applied to suitablethin metal panels.After the coatings have cured,a standardweight is dropped a distance so as to strike an indenter thatdeforms the coating and the substrate.The indentation can beeither an intrusion or an extrusion.By gradually increasing thedistance the weight drops,the point at which failure usuallyoccurs can be determined.Films generally fail by cracking,which is made more visible by the use of a magnifier,by theapplication of a copper sulfate(CuSO4)solution on steel,or bythe use of a pin hole detector.5.Significance and Use5.1 Coatings attached to substrates are subjected to damag-ing impacts during the manufacture of articles and their use inservice.In its use over many years,this test method for impactresistance has been found to be useful in predicting theperformance of organic coatings for their ability to resistcracking caused by impacts.6.Apparatus6.1 Tester,consisting of a vertical tube to guide a cylindricalweight that is dropped on a punch resting on the test panel.6.1.1 Guide Tube,24 to 48 in.(0.6 to 1.2 m)long mountedvertically in a base plate.A slot is cut lengthwise on one sideof the tube to act as a guide for a cylindrical weight that fitsinside the tube.Graduations are marked in inch-pounds along1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.23 on Physical Properties of Applied Paint Films.Current edition approved Jan.1,2019.Published January 2019.Originallyapproved in 1969.Last previous edition approved in 2010 as D2794 93(2010).DOI:10.1520/D2794-93R19.2For 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 last approved version of this historical standard is referenced onwww.astm.org.Copyright 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 Trade Organization Technical Barriers to Trade(TBT)Committee.1 the slot.The base is constructed so that a thin flat panel can beinserted at 2 in.(50 mm)below the tube.6.1.2 Weight,metal cylinder,made