1、Designation: B 489 85 (Reapproved 2003)Standard 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 ad
2、option 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.1. Scope1.1 This practice covers a test procedure for determining theductility of
3、 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 E 8 can be used if the coatings are tooductile and require mandrels too small to be practic
4、al.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. Reference
5、d Documents2.1 ASTM Standards:3B 177 Guide for Engineering Chromium ElectroplatingD 1193 Specification for Reagent WaterE 8 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 man
6、drel. 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
7、 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 S
8、hears 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, 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 thes
9、hape 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
10、.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 ofapprop
11、riate 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
12、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 mandrel in the vise. Bend the testspecimen, with the coating outward, over the mandrel so that asthe bend progresses the test specimen wil
13、l remain in contactwith the top of the mandrel. Continue bending with slow,steadily applied pressure until the two legs are parallel. If there1This practice is under the jurisdiction of ASTM Committee B08 on Metallicand Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 onTes
14、t Methods.Current edition approved Oct. 1, 2003. Published October 2003. Originallyapproved in 1968. Last previous edition approved in 1998 as B 489 85 (1998).2For a discussion and theory for this test see Mohrnheim, A. F., “the Bend Testfor Measuring the Strain Limit of Surfaces,” Plating, Vol 50,
15、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.1Copyright ASTM International, 100 Barr H
16、arbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.are no cracks visible 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
17、for the ductilitydetermination. If the coating is electrodeposited chromium, thespecimens may 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 to
18、the edges of the test specimen do not signify failure.7.1.2 At times, no single crack may develop 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
19、 of nickel, cracks may extend throughthe nickel to an intermediate copper layer or to the basis 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 t
20、he thickness. If the test is to be used toevaluate the electroplating or autocatalytic process 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 follo
21、ws:E 5 100 T/D 1 T!where:E = percent elongation,T = total thickness of the basis metal and deposit, 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 theduc
22、tility of metallic coatings. The largest source of error is inthe detection of crack initiation. The precision and bias for thispractice have not been statistically determined.10. Keywords10.1 autocatalytic deposits; ductility tests; electrodepositsAPPENDIX(Nonmandatory Information)X1. COPPER AND IR
23、ON DETECTIONSPOT TEST TECHNIQUEX1.1 ApparatusX1.1.1 Spot Test Plate.X1.1.2 Dropping Pipets (Medicine 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 mixt
24、ure by addingto 45 mL of glacial acetic acid 5 mL of wetting agent, such as1 % solution of sodium 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 Thio
25、cyanate SolutionAdd 8g of ASC reagent grade mercuric chloride and9gofASCreagent grade ammonium 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
26、.3 Copper Detection in the Presence of Nickel andChromiumX1.3.1 Using a dropping pipet, apply 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 th
27、e drop of reagent from the test part witha pipet to a cavity in the spot test plate. Wash the 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 thes
28、pot plate cavity.X1.3.4 Gently agitate the spot plate or stir the solution. 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 i
29、n contact with the surfacefor about 1 min.X1.4.3 Transfer the drop of HNO3with 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
30、 the spot or stir the solution. Theappearance of a blood red color indicates iron.B 489 85 (2003)2ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determ
31、ination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or w
32、ithdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that
33、your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee 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 (2003)3
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