ASTM_B_571_-_97_2013.pdf

Designation:B57197(Reapproved 2013)Standard Practice forQualitative Adhesion Testing of Metallic Coatings1This standard is issued under the fixed designation B571;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 practice covers simple,qualitative tests for evalu-ating the adhesion of metallic coatings on various substances.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Significance and Use2.1 These tests are useful for production control and foracceptance testing of products.2.2 Interpreting the results of qualitative methods for deter-mining the adhesion of metallic coatings is often a controver-sial subject.If more than one test is used,failure to pass anyone test is considered unsatisfactory.In many instances,theend use of the coated article or its method of fabrication willsuggest the technique that best represents functional require-ments.For example,an article that is to be subsequentlyformed would suggest a draw or a bend test;an article that isto be soldered or otherwise exposed to heat would suggest aheat-quench test.If a part requires baking or heat treating afterplating,adhesion tests should be carried out after such post-treatment as well.2.3 Several of the tests are limited to specific types ofcoatings,thickness ranges,ductilities,or compositions of thesubstrate.These limitations are noted generally in the testdescriptions and are summarized in Table 1 for certain metalliccoatings.2.4“Perfect”adhesion exists if the bonding between thecoating and the substrate is greater than the cohesive strengthof either.Such adhesion is usually obtained if good electro-plating practices are followed.2.5 For many purposes,the adhesion test has the objectiveof detecting any adhesion less than“perfect.”For such a test,one uses any means available to attempt to separate the coatingfrom the substrate.This may be prying,hammering,bending,beating,heating,sawing,grinding,pulling,scribing,chiseling,or a combination of such treatments.If the coating peels,flakes,or lifts from the substrate,the adhesion is less thanperfect.2.6 If evaluation of adhesion is required,it may be desirableto use one or more of the following tests.These tests havevarying degrees of severity;and one might serve to distinguishbetween satisfactory and unsatisfactory adhesion in a specificapplication.The choice for each situation must be determined.2.7 When this guideline is used for acceptance inspection,the method or methods to be used must be specified.Becausethe results of tests in cases of marginal adhesion are subject tointerpretation,agreement shall be reached on what is accept-able.2.8 If the size and shape of the item to be tested precludesuse of the designated test,equivalent test panels may beappropriate.If permitted,test panels shall be of the samematerial and have the same surface finish as the item to betested and shall be processed through the same preplating,electroplating,and postplating cycle with the parts they repre-sent.3.Bend Tests3.1 Bend the part with the coated surface away over amandrel until its two legs are parallel.The mandrel diametershould be four times the thickness of the sample.Examine thedeformed area visually under low magnification,for example,4,for peeling or flaking of the coating from the substrate,which is evidence of poor adhesion.If the coating fractures orblisters,a sharp blade may be used to attempt to lift off thecoating.With hard or brittle coatings,cracking usually occursin the bend area.Such cracks may or may not propagate intothe substrate.In either case,cracks are not indicative of pooradhesion unless the coating can be peeled back with a sharpinstrument.1This practice is under the jurisdiction of ASTM Committee B08 on Metallicand Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 onTest Methods.Current edition approved Dec.1,2013.Published December 2013.Originallyapproved in 1979.Last previous edition approved in 2008 as B571 97(2008)1.DOI:10.1520/B0571-97R13.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.2 Bend the part repeatedly,back and forth,through anangle of 180 until failure of the basis metal occurs.Examinethe region at low magnification,for example,10,for separa-tion or peeling of the coating.Prying with a s