ASTM E1558-1999(2004) Standard Guide for Electrolytic Polishing of Metallographic Specimens《金相试样电解抛光标准指南》.pdf
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1、Designation: E 1558 99 (Reapproved 2004)Standard Guide forElectrolytic Polishing of Metallographic Specimens1This standard is issued under the fixed designation E 1558; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st 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 guide deals with electrolytic polishing as a meansof preparation of specimens for metallographic purposes.Procedur
3、es are described for polishing a variety of metals.NOTE 1References (1-133)2on electrolytic polishing will provide thereader with specific information beyond the scope of this guide.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theres
4、ponsibility 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. Specific safetyprecautions are described in Section 5 and 6.3.1.2. Referenced Documents2.1 ASTM Standards:3E 7 Terminology Relating
5、to MetallographyE 407 Test Methods for Microetching Metals and Alloys3. Terminology3.1 DefinitionsAll terms used in this guide are eitherdefined in Terminology E 7 or are discussed in 3.2.3.2 Definitions of Terms Specific to This Standard:3.2.1 electrolytic polish (electropolish)A method of pol-ishi
6、ng metals and alloys in which material is removed from thesurface by making the metal the anode in an electrolytic bath.4. Significance and Use4.1 Advantages of Electrolytic Polishing:4.1.1 For some metals, a high quality surface finish can beproduced that is equivalent to, or better than, that whic
7、h can beobtained by mechanical methods.4.1.2 Once procedures have been established, satisfactoryresults can be obtained rapidly with reproducibility.4.1.3 There can be a marked saving of time if manyspecimens of the same material are polished sequentially.4.1.4 Electropolishing a selected area on th
8、e surface of arelatively large metal part can be accomplished nondestruc-tively, that is, without the need for sectioning to remove apiece.4.1.5 Soft, single-phase metals, which may be difficult topolish by mechanical methods, may be successfully electropol-ished.4.1.6 The true microstructure of a s
9、pecimen can be obtainedbecause artifacts (such as disturbed metal, scratches, andmechanical twins) produced on the surface, even by carefulgrinding and mechanical polishing operations, can be removed.These features are important in low-load hardness testing,X-ray diffraction studies, and in electron
10、 microscopy, wherehigher resolution puts a premium on undistorted metal sur-faces.4.1.7 After electropolishing is completed, etching can oftenbe accomplished by reducing the voltage (generally to aboutone-tenth that required for polishing) for a short time before itis turned off.NOTE 2Not all electr
11、opolishing solutions produce good etchingresults.4.2 Disadvantages of Electrolytic Polishing:4.2.1 Many of the chemical mixtures used in electropolish-ing are poisonous or dangerous if not properly handled (seeSection 5). These hazards are similar to those involved in themixing and handling of etcha
12、nts, see Test Methods E 407.4.2.2 In multi-phase alloys, the polishing rate of each phasemay be different. The result may be a non-planar surface.4.2.3 Electropolished surfaces may be slightly undulatedrather than perfectly planar and, therefore, may not be suitablefor examination at all magnificati
13、ons.4.2.4 The rate of polishing in areas adjacent to variousinhomogeneities, such as nonmetallic inclusions and voids, isusually greater than that in the surrounding matrix and tends toexaggerate the size of the inclusions and voids.4.2.5 Dimples, pits, and waviness limit applications involv-ing sur
14、face phenomena, coatings, interfaces, and cracks. Edgestend to be attacked preferentially, resulting in edge rounding.4.2.6 Artifacts may be produced by electropolishing.1This guide is under the jurisdiction of ASTM Committee E04 on Metallographyand is the direct responsibility of Subcommittee E04.0
15、1 on Specimen Preparation.Current edition approved June 1, 2004. Published July 2004. Originally approvedin 1993. Last previous edition approved in 1999 as E 1558 99.2The boldface numbers in parentheses refer to the references at the end of thisstandard.3For referenced ASTM standards, visit the ASTM
16、 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 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United
17、 States.4.2.7 Specimen mounting materials may react with theelectrolyte.4.2.8 The electropolished surfaces of certain materials maybe passive and difficult to etch.4.2.9 Metal removal rates by electropolishing are usuallyquite low, typically about 1 m/min, and all of the priorinduced damage from cut
18、ting and grinding may not be re-moved if preparation is stopped after a 600-grit SiC grind andelectropolishing times are short.4.2.10 A large number of electrolytes may be needed topolish the variety of metals encountered by a given laboratory.Considerable time may be required to develop a procedure
19、 fora new alloy.5. General Safety Precautions5.1 Before using or mixing any chemicals, all product labelsand pertinent Material Safety Data Sheets (MSDS) should beread and understood concerning all of the hazards and safetyprecautions to be observed. Users should be aware of the typeof hazards invol
20、ved in the use of all chemicals used, includingthose hazards that are immediate, long-term, visible, invisible,and with or without odors.5.1.1 Consult the product labels and MSDS for recommen-dations concerning proper protective clothing.5.1.2 All chemicals are potentially dangerous. All personsusin
21、g any electrolyte should be thoroughly familiar with all ofthe chemicals involved and the proper procedure for handling,mixing, and disposing of each chemical, as well as anycombinations of those chemicals.5.1.3 Table 1 includes specific safety precautions for themixing or use of some electrolytes.
22、The user should take careto observe each of these specific precautions.TABLE 1 Electrolytes for ElectropolishingClass Use Formula Cell Voltage Time RemarksGroup I (Electrolytes Composed of Perchloric Acid and Alcohol With or Without Organic Additions)I-1 Al and Al alloys with less than ethanol (95 %
23、) 800 mL 30 to 80 15 to 60 s2 percent Si distilled water 140 mLperchloric acid (60 %) 60 mLsteelscarbon, alloy, stainless 35 to 65 15 to 60 sPb, Pb-Sn, Pb-Sn-Cd, Pb-Sn-Sb 12 to 35 15 to 60 sZn, Zn-Sn-Fe, Zn-Al-Cu 20 to 60 .Mg and high Mg alloys . . nickel cathodeI-2 stainless steel and aluminum etha
24、nol (95 %) 800 mL 35 to 80 15 to 60 sperchloric acid (60 %) 200 mLI-3 stainless steel ethanol (95 %) 940 mL 30 to 45 15 to 60 sperchloric acid (65 %) 60 mLI-4 steel, cast iron, Al, Al alloys, Ni,Sn, Ag, Be, Ti, Zr, U,heat-resisting alloysethanol (95 %)2-butoxy ethanolperchloric acid (30 %)700 mL100
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