ASTM E1558-09(2021) PDF

SIGNIFICANCE AND USE 4.1 Advantages of Electrolytic Polishing: 4.1.1 For some metals, a high quality surface finish can be produced that is equivalent to, or better than, that which can be obtained by mechanical methods. 4.1.2 Once procedures have been established, satisfactory results can be obtained rapidly with reproducibility. 4.1.3 There can be a marked saving of time if many specimens of the same material are polished sequentially. 4.1.4 Electropolishing a selected area on the surface of a relatively large metal part can be accomplished nondestructively, that is, without the need for sectioning to remove a piece. 4.1.5 Soft, single-phase metals, which may be difficult to polish by mechanical methods, may be successfully electropolished. 4.1.6 The true microstructure of a specimen can be obtained because artifacts (such as disturbed metal, scratches, and mechanical twins) produced on the surface, even by careful grinding and mechanical polishing operations, can be removed. These features are important in low-load hardness testing, X-ray diffraction studies, and in electron microscopy, where higher resolution puts a premium on undistorted metal surfaces. 4.1.7 After electropolishing is completed, etching can often be accomplished by reducing the voltage (generally to about one-tenth that required for polishing) for a short time before it is turned off. Note 2: Not all electropolishing solutions produce good etching results. 4.2 Disadvantages of Electrolytic Polishing: 4.2.1 Many of the chemical mixtures used in electropolishing are poisonous or dangerous if not properly handled (see Section 5). These hazards are similar to those involved in the mixing and handling of etchants, see Test Methods E407. 4.2.2 In multi-phase alloys, the polishing rate of each phase may be different. The result may be a non-planar surface. 4.2.3 Electropolished surfaces may be slightly undulated rather than perfectly planar and, therefore, may not be suitable for exami... SCOPE 1.1 This guide deals with electrolytic polishing as a means of preparation of specimens for metallographic purposes. Procedures are described for polishing a variety of metals. Note 1: References (1-133)2 on electrolytic polishing will provide the reader with specific information beyond the scope of this guide. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific safety precautions are described in Section 5 and 6.3.1. 1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.