ASTM_B_537_-_70_2013.pdf

Designation:B53770(Reapproved 2013)Standard Practice forRating of Electroplated Panels Subjected toAtmospheric Exposure1This standard is issued under the fixed designation B537;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.Scope1.1 This practice covers a preferred method for evaluatingthe condition of electroplated test panels that have beenexposed to corrosive environments for test purposes.It is basedon experience in use of the method with standard 10-by 15-cm(4-by 6-in.)panels exposed on standard ASTM racks atoutdoor test sites in natural atmospheres.It has been used alsofor rating similar panels that have been subjected to acceleratedtests such as those covered by Practice B117,Method B287,Test Method B368,and Test Method B380.Any modificationsneeded to adapt the method to rating actual production parts arenot considered in this practice.1.2 This practice refers only to decorative-protective coat-ings that are cathodic to the substrate,typified by nickel/chromium or copper/nickel/chromium on steel or zinc diecastings.It is not intended for use with anodic sacrificialcoatings such as zinc and cadmium on steel.2.Referenced Documents2.1 ASTM Standards:2B117 Practice for Operating Salt Spray(Fog)ApparatusB287 Method of Acetic Acid-Salt Spray(Fog)Testing(Withdrawn 1987)3B368 Test Method for Copper-Accelerated Acetic Acid-SaltSpray(Fog)Testing(CASS Test)B380 Test Method for Corrosion Testing of DecorativeElectrodeposited Coatings by the Corrodkote Procedure2.2 ASTM Adjunct:4Dot charts(9 charts,812by 11 in.)(9 color photos,3 by 5in.)3.Basis of Procedure3.1 The rating method described in this recommendedpractice is based on the recognition that typical decorative-protective deposits such as nickel/chromium,with or without acopper undercoat,have two functions:(1)to protect thesubstrate from corrosion and thus prevent degradation ofappearance caused by basis metal corrosion products(forexample,rust and rust stain);and(2)to itself maintain asatisfactory appearance.Although these functions overlap,theycan be evaluated separately and it is frequently desirable to doso.Accordingly,this practice assigns separate ratings to(1)appearance as affected by corrosion of the substrate and(2)appearance as affected by deterioration of the coating itself.3.2 The rating number assigned to the ability of the coatingto protect the substrate from corrosion is called the“protec-tion”number or rating.3.3 The rating number assigned to the inspectors judgmentof the overall appearance of the panel,including all defectscaused by the exposure(Note 1),is called the“appearance”number or rating.NOTE1Panels that are not“perfect”even before being exposedshould normally be rejected(see Note 4).3.4 The result of inspecting a panel is recorded as twonumbers separated by a slash(/),the protection number beinggiven first.3.5 In addition to recording the numerical rating of a panel,the inspector should note the type(s)and severity of defect(s)contributing to the rating.This may be done by the use ofagreed symbols for the most common defects(Appendix X1)and abbreviations for degree or severity of these defects.1This practice is under the jurisdiction of ASTM Committee B08 on Metallicand Inorganic Coatingsand is the direct responsibility of Subcommittee B08.05 onDecorative Coatings.Current edition approved Dec.1,2013.Published December 2013.Originallyapproved in 1970.Last previous edition approved in 2007 as B537 70(2007).DOI:10.1520/B0537-70R13.2For 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.4Color reproductions of these photographs are available from ASTM Interna-tional Headquarters.Order Adjunct No.ADJB0537.Original adjunct produced in1987.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.Types of Defects4.1“Protection”defects include crater rusting(Note 2),pinhole rusting,rust stain,blisters(Note 3),and any otherdefects that involve basis metal corrosion.NOTE2“Rusting”or“rust”as used in this document includescorrosion products of the substrate and is not confined to iron or steel:thewhite corrosion products of zinc die castings and aluminum,for example,are included in this term.NOTE3Blisters on plated zinc die casting usually connote basis metalcorrosion;but the inspectors judgment may be required to decide whethera blister does or does not arise at the substrate-coating interface.4.2“Appearance”defects include,the addition to thosecaused by basis metal corrosion,all defects tha