ASTM_B_489_-_85_2013.pdf

Designation:B48985(Reapproved 2013)Standard Practice forBend Test for Ductility of Electrodeposited andAutocatalytically Deposited Metal Coatings on Metals1This standard is issued under the fixed designation B489;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 test procedure for determining theductility of electrodeposited and autocatalytically depositedcoatings on sheet or strip basis metals.The purpose of the testis to determine the resistance of metal coatings to crackingduring distortion.21.2 Test Methods E8 can be used if the coatings are tooductile and require mandrels too small to be practical.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:3B177 Guide for Engineering Chromium ElectroplatingD1193 Specification for Reagent WaterE8 Test Methods for Tension Testing of Metallic Materials3.Summary of Practice3.1 The practice consists of bending a narrow strip of theelectroplated or coated article over a mandrel.An elongationmeasurement is obtained from the smallest diameter mandrelthat does not cause the coating to fracture.4.Significance and Use4.1 The routine measurement of the ductility of electrode-posited and autocatalytically deposited metal coatings can beuseful in process control,especially when the electroplatingprocess is used for decorative and engineering purposes.5.Apparatus5.1 Series of Mandrels,with diameters from 6 to 50 mm,in3-mm steps with lengths of 100 to 150 mm so they can be heldin a vise.5.2 Micrometer,to measure the thickness of the test speci-mens.5.3 Guillotine Shears or other device to cut the specimens tosize.5.4 File or Grinder to remove burrs and to round or chamferedges.5.5 Vise,to hold mandrels.5.6 Magnifier,10.6.Test Specimen6.1 Flat specimens,10 mm wide,and not less than 150 mmlong,shall be cut from the electroplated or coated article if theshape permits,no closer than 25 mm from the edges.Guillotineshears are preferred,but any convenient method may be used.Basis metal thickness and temper shall be suitable to permitbending around the smallest diameter mandrel,if necessary.Low-carbon AISI 1010 to 1025 steel strip or sheet,0.25 to 1.0mm thick is usually suitable.Basis metals that have lowductility can initiate cracks that can propagate through thecoatings.The procedure indicated in 6.2 shall then be followed.6.2 When the shape is such that a test specimen cannot beobtained from the part,a test panel may be prepared ofappropriate basis metal,such as low-carbon steel(see 6.1),with the same coating system in the same baths.The panel shallbe sufficiently large to obtain several pieces after trimming 25mm from the edges.The specimens shall be prepared inaccordance with 6.1.Brass or copper panels may be usedinstead of copper-electroplated zinc alloy panels.6.3 The long edges of the test pieces shall be rounded orchamfered by filing or grinding.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 1968.Last previous edition approved in 2008 as B489 85(2008)1.DOI:10.1520/B0489-85R13.2For a discussion and theory for this test see Mohrnheim,A.F.,“The Bend Testfor Measuring the Strain Limit of Surfaces,”Plating,Vol 50,1963,pp.1094 1099.3For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.Procedure7.1 Place the largest mandrel in the vise.Bend the testspecimen,with the coating outward,over the mandrel so that asthe bend progresses the test specimen will remain in contactwith the top of the mandrel.Continue bending with slow,steadily applied pressure until the two legs are parallel.If thereare no cracks visible under a 10 magnifier,repeat the test,using new specimens,on progressively smaller-diametermandrels,until cracks appear across or through the coating.Take the preceding mandrel diameter as the value for theductility determination.If the coating is electrodepositedchromium,the specimens may require heating or aging toovercome temporary h