ASTM B490-92 pdf free.Standard Practice for Micrometer Bend Test for Ductility of Electrodeposits.
An electrodeposit shall be prepared using a basis metalwith a smooth surface from which the electrodeposit can bereadily separated. A stainless steel or nickel electroplated steelpanel may be used for this purpose, prepared as in 6.2.A piece of cold-rolled steel, of any convenient size, suchas 100 by 150 mm, shall be properly cleaned, acid dipped, andelectroplated with approximately 7.5 um of nickel. Afterrinsing, the specimen shall be cleaned anodically for 15 s in ahot alkaline cleaner, rinsed, acid dipped in about 1 N sulfuricacid (about 27 mL of concentrated sulfuric acid added to about900 mL of cold water, mixed, and diluted with cold water to lL), and immediately placed in the electroplating solution of themetal to be tested.An electrodeposit 25 to 40 um thick shall beelectroplated on the prepared surface. The deposit shall beplated at an average current density and under conditions(agitation, temperature, etc.) approximating those used on partsplated in the solution being tested.The volume of the plating solution used to produce thetest specimen shall be sufficient so that the concentration of theadditives do not drop below 90 % of original additive concen-tration. Additions to the test solution shall not be made sincethey can alter the original composition.The ductility of nickel, with or without chromium, will varydepending upon plating conditions，contamination,and the additivesystem used.If electroplated with chromium, the foil may require heatingor aging to overcome temporary hydrogen embrittlement. A procedure toovercome hydrogen embrittlement is covered in 8.2 of Guide B 177.6.4 Proper preparation of the surface from which the foilmust be separated undamaged is critical.Buffed nickel orbuffed stainless steel, which may require anodic treatment, in ahot alkaline cleaner as defined in 6.2, can be used as the basismetal. Steel or nickel dipped in a chromating solution, such asused for chromating zinc，can be used as the basis metal.Copper or brass, masked on one side, can be used as the basismetal, and can be subsequently dissolved from the coating tobe tested. Because the dissolving step can embrittle the testdeposit, the test deposit must be aged as stipulated in Note 2.6.5 Cut off the edges of the panel with a power or handshear,or by any convenient method that permits ready sepa-ration of the foil from the basis metal. Using a pair of sharp scissors，cut two or more testspecimens, about 5 to 75 mm from the center of the foil. Measure the thickness of the test foil with the microme-ter at the point of bending. Bend the test foil in the shape of a“U”’ with the side of the foil that was against the basis metalfacing inward in the “U”. ASTM B490 pdf download.