1、Designation: B 489 85 (Reapproved 2008)e1Standard Practice forBend Test for Ductility of Electrodeposited andAutocatalytically Deposited Metal Coatings on Metals1This standard is issued under the fixed designation B 489; the number immediately following the designation indicates the year oforiginal
2、adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEThe units statement in subsection 1.3 was corrected editorially in April
3、2008.1. 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 E8can
4、 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, associat
5、ed 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:3B 177 Guide for Engineering Chromium ElectroplatingD 1193 Spe
6、cification 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 ca
7、use 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
8、.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
9、round or chamferedges.5.5 Vise, to hold mandrels.5.6 Magnifier, 103.6. 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 co
10、nvenient 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
11、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 sam
12、e baths. The panel shall1This 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 April 1, 2008. Published April 2008. Originallyapproved in 1968. Last previous edit
13、ion approved in 2003 as B 489 85 (2003).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 Servi
14、ce at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.be sufficiently large to obtain several piece
15、s 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.7. Procedure7.1 Place the largest
16、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 visibl
17、e under a 103 magnifier, repeat the test,using new specimens, on progressively smaller-diameter man-drels, until cracks appear across or through the coating. Takethe preceding mandrel diameter as the value for the ductilitydetermination. If the coating is electrodeposited chromium, thespecimens may
18、require heating or aging to overcome tempo-rary hydrogen embrittlement. A procedure to overcome hydro-gen embrittlement is covered in Guide B 177.7.1.1 Small cracks not greater than 1.5 mm long, confined tothe edges of the test specimen do not signify failure.7.1.2 At times, no single crack may deve
19、lop over the convexsurface. If jagged cracks, or a series of shorter cracks develop(excluding edges), they signify failure.7.2 In multiple coatings, cracking may occur in the outercoatings only. In the case of nickel, cracks may extend throughthe nickel to an intermediate copper layer or to the basi
20、s metal.Methods for determining this are provided in the Appendix. Apositive test for copper or iron signifies failure.7.3 Except for very ductile coatings, the apparent ductility isan inverse function of the thickness. If the test is to be used toevaluate the electroplating or autocatalytic process
21、 by periodi-cally testing the ductility of coatings produced by the process,all specimens used must have approximately the same coatingand total thickness.8. Calculation8.1 Determine the elongation as follows:E 5 100 T/D 1 T!where:E = percent elongation,T = total thickness of the basis metal and dep
22、osit, andD = diameter of the mandrel.NOTE 1To calculate percent elongation, E, the dimensions of T and Dmust be identical.9. Precision and Bias9.1 This practice is a useful one for routine control of theductility of metallic coatings. The largest source of error is inthe detection of crack initiatio
23、n. The precision and bias for thispractice have not been statistically determined.10. Keywords10.1 autocatalytic deposits; ductility tests; electrodepositsAPPENDIX(Nonmandatory Information)X1. COPPER AND IRON DETECTIONSPOT TEST TECHNIQUEX1.1 ApparatusX1.1.1 Spot Test Plate.X1.1.2 Dropping Pipets (Me
24、dicine Droppers).X1.1.3 Wash Bottle.X1.1.4 Glass Stirring Rod.X1.2 ReagentsX1.2.1 The solutions shall be made with water conformingto Specification D 1193, Type IV.X1.2.2 Acetic Acid MixturePrepare the mixture by addingto 45 mL of glacial acetic acid 5 mL of wetting agent, such as1 % solution of sod
25、ium lauryl sulfate.X1.2.3 Hydrogen PeroxideUse 30 volume % solution.X1.2.4 Zinc Acetate SolutionPrepare the zinc acetatesolution by using 1 mass % of ASC reagent grade material.X1.2.5 Ammonium Mercuric Thiocyanate SolutionAdd 8g of ASC reagent grade mercuric chloride and9gofASCreagent grade ammonium
26、 thiocyanate to 100 mL of water.X1.2.6 Nitric Acid (1+4)Add 1 part of concentrated nitricacid (HNO3, sp gr 1.42) to 4 parts of water by volume.X1.2.7 Potassium Thiocyanate SolutionUse a 10 mass %solution.X1.3 Copper Detection in the Presence of Nickel andChromiumX1.3.1 Using a dropping pipet, apply
27、1 drop of the aceticacid mixture and 1 drop of hydrogen peroxide to the bent andcracked surface. Permit the solution to remain for about 1 to 2min, avoiding its contact with the cut edges.X1.3.2 Transfer the drop of reagent from the test part witha pipet to a cavity in the spot test plate. Wash the
28、test spot witha drop of water, and add the wash solution to the liquid in thespot plate.X1.3.3 Add 1 drop of zinc acetate solution and 1 drop ofammonium mercuric thiocyanate solution to the solution in thespot plate cavity.B 489 85 (2008)e12X1.3.4 Gently agitate the spot plate or stir the solution.
29、Aviolet colored precipitate indicates the presence of copper.X1.4 Iron Detection in the Presence of Chromium,Nickel, or CopperX1.4.1 Apply 1 drop of HNO3(1+4) to the bent surface to betested.X1.4.2 Allow the acid to remain in contact with the surfacefor about 1 min.X1.4.3 Transfer the drop of HNO3wi
30、th a dropping pipet toa cavity in the spot plate. At no time should the acid come incontact with the cut edges.X1.4.4 Add 1 drop of potassium thiocyanate solution to thesolution in the spot plate cavity.X1.4.5 Gently agitate the spot or stir the solution. Theappearance of a blood red color indicates
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34、ommittee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).B 489 85 (2008)e13
