1、Designation: B490 09 (Reapproved 2014)Standard Practice forMicrometer Bend Test for Ductility of Electrodeposits1This standard is issued under the fixed designation B490; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、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 describes a procedure for measuring theductility of electrodeposited foils.21.2 This practice is suitabl
3、e only for the evaluation ofelectrodeposits having low ductility.1.3 The obtained ductility values must only be consideredsemi-quantitative because this test has a significant operatordependence.1.4 This practice is best used for in-house process controlwhere measurements are always made by the same
4、 operator. Achange in ductility value can be used as an indication ofpossible changes in the electroplating solution.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport to address the safetypro
5、blems, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:3B456 Specification for Electrodeposited Co
6、atings of CopperPlus Nickel Plus Chromium and Nickel Plus Chromium3. Summary of Practice3.1 This practice consists of measuring the bend of a foilheld between the jaws of a micrometer; these are closed untilfracture or cracks appear.4. Significance and Use4.1 This practice is useful as one method of
7、 controllingsome electroplating solutions. It serves to indicate the presenceof contamination or some other adverse condition.4.2 Ductility measurements are of particular value whenelectroplated parts are to be subjected to moderate stress suchas that involved in bolting an electroplated bumper to a
8、nautomobile or when exposed to a wide range of fluctuatingtemperatures (thermal shock).5. Apparatus5.1 Micrometer, 25-mm with flat jaws to measure thethickness and to compress the foil.5.2 Tools such as a hand or power shear, grinding wheel, fileor hack saw, to initiate separation of the foil from t
9、he basismetal.5.3 Pair of Sharp Scissors to cut the test specimens.6. Test Specimens6.1 An electrodeposit shall be prepared using a basis metalwith a smooth surface from which the electrodeposit can bereadily separated. Proper preparation of the surface from whichthe foil must be separated undamaged
10、 is critical. The depositshall be electroplated at an average current density and underconditions (agitation, temperature, etc.) approximating thoseused on parts electroplated in the solution being tested. Thedeposit thickness shall be 25-30 m. The panels are prepared asin 6.2.6.2 The test panel mus
11、t be properly passivated beforeplating to allow for separation of the subsequent deposit.Stainless steel, brass or nickel dipped in a chromic acidsolution (see Note 1) for approximately 1 minute can be usedas the basis metal. The panel should be properly rinsed beforeplating. Entering the solution w
12、ith current on is recommendedto prevent activation of the basis metal. When testing nickeldeposits, other than rinsing, no post treatments shall be used.An alternative method is described in Note 2.NOTE 1For convenience, an ordinary hexavalent chromium electro-plating solution can be used for prepar
13、ing the basis metal.NOTE 2As an alternative basis metal, a piece of cold-rolled steel ofany convenient size, such as 100 by 150 mm, shall be properly cleaned,rinsed, acid dipped, rinsed and electroplated with approximately 7.5 m ofnickel. After rinsing, the specimen shall be cleaned anodically for1T
14、his 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 May 1, 2014. Published May 2014. Originallyapproved in 1968. Last previous edition approved in 2009 as B490 0
15、9. DOI:10.1520/B0490-09R14.2For a discussion of this test see Mohrnheim, A. F., “The Bend Test forMeasuring the Strain Limit of Surfaces,” Plating, Vol 50, 1963, pp. 10941099.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For
16、 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 States1approximately 15 seconds in a hot alkaline cleaner, rinsed, acid dipped
17、inapproximately 1 N sulfuric acid (approximately 27 mL of concentratedsulfuric acid added to approximately 900 mL of cold water, mixed, anddiluted with cold water to 1 L), rinsed, and immediately placed in theelectroplating solution of the metal to be tested.6.3 The panel size should be selected bas
18、ed upon thesolution volume to be used in order to maintain the additiveswithin 85% of their original concentrations. Additions to thetest solution shall not be made since they can alter the originalcomposition.6.4 Cut off the edges of the panel with a power or handshear, or by any convenient method
19、that permits ready sepa-ration of the foil from the basis metal.6.5 Using a pair of sharp scissors, cut three or more testspecimens from the center of the foil, at least 6 mm wide (butnot to exceed the width of the micrometer jaws) by at least 50mm in length.7. Procedure7.1 Measure the thickness of
20、the test foil with the microm-eter at the point of bending. Bend the test foil in the shape ofa “U” with the side of the foil that was against the basis metalfacing inward in the “U.” Place the bent foil between the jawsof the micrometer so that as the jaws are closed, the bendremains between the ja
21、ws and is in complete contact with themthroughout the procedure (See Note 3). Close the micrometerjaws slowly until the foil cracks (See Note 4). Use an averageof three or more foil tests. Record the micrometer reading as2R and the thickness of the foil as determined by the microm-eter as T.NOTE 3If
22、 any of the bent part of the foil is outside of the micrometerjaws the force may not be uniformly distributed, which could lead tomisleading results.NOTE 4With foils of a ductility of 70 % or greater it is helpful toexamine the foil at low magnification (10) while it is still in themicrometer.7.2 At
23、 times, no single crack may develop over the convexsurface. If jagged cracks or a series of shorter cracks develop(excluding edges), they signify failure. If no cracks develop,the maximum ductility values are obtained.8. Calculation8.1 Two standard formulas are used to compute ductility:Ductility, p
24、ercent 5 100T/2R 2 T! (1)Maximum value is 100%. (2)Ductility, ratio 5 T/2R (3)Maximum value is 0.5. (4)8.1.1 Either formula can be used but they give differentvalues for the same ductility. It is important that the formula beconsistently used for purpose of comparison. When reportingductility values
25、, the formula must be indicated.8.2 It should be understood that this value bears no simplerelation to the percentage elongation obtained through tensionor other tests. The ductility of this type of low-ductilityelectrodeposit varies with the thickness. Usually the greater thethickness, the lower is
26、 the percentage ductility for these foils.(Note 5).NOTE 5The foils used in this practice are 25 to 30 m thick. Foils inthis thickness range do not have the same properties as bulk metal. Forexample, a nickel electrodeposit 0.5 mm thick, prepared in purified brightnickel electroplating solutions for
27、which this test is being used, had lessthan 3 % elongation in a tension test, and could not be bent to a 90 anglewithout complete fracture. However, foils 25 to 30 m thick, electroplatedat the same time, had micrometer ductility values of at least 10% whenmeasured using this method. In order to comp
28、are results, foil thickness25-30 m should be used. See Specification B456 for minimum ductilityvalues for nickel electrodeposits.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard ar
29、e expressly advised that determination 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
30、revised, either reapproved or withdrawn. 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 yo
31、u may attend. If you feel that 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
32、 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).B490 09 (2014)2
