ASTM B545-13 (R2021) pdf free download.Standard Specification for Electrodeposited Coatings of Tin.
1.1 This specification covers the requirements for electrode- posited (electroplated) coatings of tin applied to metallic articles. Tin coatings are used to provide a low contact- resistance surface, to protect against corrosion (see 1.2), to facilitate soldering. to provide anti-galling properties, and to he a stopolT coating in the nitriding of high-strength steels.
1.2 Some corrosion can be expected from tin coatings exposed outdoors. In normal indoor exposure, tin is protective on iron, steel, nickel, copper. and their alloys. Corrosion can be expected at discontinuities in the coating (such as pores) due to galvanic couples formed between the tin and the underlying metal through the discontinuities, especially in humid atmospheres. Porosity increases as the coating thickness decreases, so that minimum thicknesses must be specified for each application. Parts coated with tin can he assembled safely in contact with iron and steel, tin-coated aluminum, yellow chromated zinc, cadmium, and solder coatings. (See X5. 1 for oxidation and corrosion properties.)
1 .3 This specification applies to electroplated coatings of not less than 99 % tin (except where deliberately alloyed for special purposes, as stated in X6.3) obtained from any of the available tin electroplating processes (see 4.3).
1.4 This specification does not apply to hot-dipped tin or other non-electrodeposited coating; it also does not apply to mill products. For mill products. refer to Specifications A623 or A623M.
1 .5 The values stated in SI units are to he regarded as the standard. The values given in parentheses are for information only.
5. Ordering Information
5.1 in order to make the application of this specification complete, the purchaser must supply the following information to the seller in the purchase order and drawings:
5.1.1 Title, ASTM designation number, and year of issue of this specification:
5.1.2 Deposit by classification (4.1), including thickness or service class (4.2);
5. 1 .3 Composition and metallurgical condition of the substrate to be coated (6.1);
5.1.4 Additional underplating, if required (6.8);
5.1.5 Surface-appearance type (for example. matte, flowbrightened, or bright), if required (4.3 and 6.2);
5. 1 .6 Location of significant surfaces (3. 1 .3);
5.1.7 Hydrogen embrittlement relief, if required (Supplementary Requirement S2); and
5.1.8 Any other items needing agreement (for example,
6.5.2, 8.4 and 8.5).
6. Coating Requirements
6.1 Substrate—The metal substrate shall be subjected to such surface preparation, cleaning, and electroplating procedures as arc necessary to yield deposits with the desired quality.
NOTE 2—Careful preparation of metal surfaces is necessary in order to assure good adhesion and quality. For suitable methods, see Practices B 183, B242, B281, B320, B322, and B558. Also see 6.6.
6.2 Electroplating shall be applied after all basis metal heat treatments and mechanical operations have been completed.
6.3 Appearance—Tin coatings shall have the characteristic appearance, including surface texture (4.3), for the process used. The appearance shall be uniform throughout, insofar as the basis metal will permit. They shall be adherent and visually free of blisters, pits, peeled areas, cracks, nodules, and unplated areas. They shall not he stained or discolored. Flow-brightened coatings shall he free of dewetted areas and beads. All surfaces shall he substantially free of grease or oil used in the flow-brightening process.ASTM B545 pdf download.