1、Designation: E1558 09 (Reapproved 2014)Standard Guide forElectrolytic Polishing of Metallographic Specimens1This standard is issued under the fixed designation E1558; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、 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 guide deals with electrolytic polishing as a meansof preparation of specimens for metallographic purposes.Procedures
3、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 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstanda
4、rd.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility 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 sa
5、fetyprecautions are described in Section 5 and 6.3.1.2. Referenced Documents2.1 ASTM Standards:3E7 Terminology Relating to MetallographyE407 Practice for Microetching Metals and Alloys3. Terminology3.1 DefinitionsAll terms used in this guide are eitherdefined in Terminology E7 or are discussed in 3.
6、2.3.2 Definitions of Terms Specific to This Standard:3.2.1 electrolytic polish (electropolish)A method of pol-ishing 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.
7、1.1 For some metals, a high quality surface finish can beproduced that is equivalent to, or better than, that which 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
8、 time if manyspecimens of the same material are polished sequentially.4.1.4 Electropolishing a selected area on the surface of arelatively large metal part can be accomplishednondestructively, that is, without the need for sectioning toremove a piece.4.1.5 Soft, single-phase metals, which may be dif
9、ficult topolish by mechanical methods, may be successfully electrop-olished.4.1.6 The true microstructure of a specimen can be obtainedbecause artifacts (such as disturbed metal, scratches, andmechanical twins) produced on the surface, even by carefulgrinding and mechanical polishing operations, can
10、 be removed.These features are important in low-load hardness testing,X-ray diffraction studies, and in electron 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 (gener
11、ally to aboutone-tenth that required for polishing) for a short time before itis turned off.NOTE 2Not all electropolishing 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
12、 properly handled (seeSection 5). These hazards are similar to those involved in themixing and handling of etchants, see Test Methods E407.4.2.2 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 sligh
13、tly undulatedrather than perfectly planar and, therefore, may not be suitablefor examination at all magnifications.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 toexag
14、gerate the size of the inclusions and voids.1This guide is under the jurisdiction ofASTM Committee E04 on Metallographyand is the direct responsibility of Subcommittee E04.01 on Specimen Preparation.Current edition approved Oct. 1, 2014. Published December 2014. Originallyapproved in 1993. Last prev
15、ious edition approved in 2009 as E1558 09. DOI:10.1520/E1558-09R14.2The boldface numbers in parentheses refer to the references at the end of thisstandard.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM
16、Standards 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 States14.2.5 Dimples, pits, and waviness limit applications involv-ing surface phenomena, coatings,
17、 interfaces, and cracks. Edgestend to be attacked preferentially, resulting in edge rounding.4.2.6 Artifacts may be produced by electropolishing.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
18、.4.2.9 Metal removal rates by electropolishing are usuallyquite low, typically about 1 m/min, and all of the priorinduced damage from cutting 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 electrolyte
19、s may be needed topolish the variety of metals encountered by a given laboratory.Considerable time may be required to develop a procedure fora new alloy.5. General Safety Precautions5.1 Before using or mixing any chemicals, all product labelsand pertinent Material Safety Data Sheets (MSDS) should be
20、read and understood concerning all of the hazards and safetyprecautions to be observed. Users should be aware of the typeof hazards involved 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
21、labels and MSDS for recommen-dations concerning proper protective clothing.5.1.2 All chemicals are potentially dangerous. All personsusing any electrolyte should be thoroughly familiar with all ofthe chemicals involved and the proper procedure for handling,mixing, and disposing of each chemical, as
22、well as anycombinations of those chemicals.5.1.3 When pouring, mixing, or etching, always use theproper protective equipment (glasses, gloves, apron, etc.) and itis strongly recommended to always work under a certified andtested fume hood. This is imperative with etchants that give offnoxious odors
23、or toxic vapors. In particular, note that solutionscontaining perchloric acid must be mixed and used in anexclusive hood equipped with a wash down feature to avoidaccumulation of explosive perchlorates.5.1.4 Table 1 includes specific safety precautions for themixing or use of some electrolytes. The
24、user should take careto observe each of these specific precautions.5.2 Some basic suggestions for the handling and disposal ofelectrolytes and their ingredients are as follows:5.2.1 As previously stated, it is good practice to alwayswork under a certified fume hood when mixing and utilizingany elect
25、rolyte and it is imperative with those electrolytes thatgive off noxious odors or toxic vapor. Additionally, theelectrolytes in Groups I and II must be treated with extracaution because dried perchlorates can accumulate in hoodductwork and on work surfaces creating the potential for apowerful accide
26、ntal explosion. Therefore, these electrolytesmust only be used in an exclusive hood equipped with a washdown feature. To avoid the accumulation of explosive, dryperchlorates, the hood should undergo a wash down cyclefollowing each use.5.2.2 When pouring, mixing, or using electrolytes, alwaysuse the
27、proper protective equipment (eyewear, gloves, apron,and so forth).5.2.3 Use proper devices (glass or plastic) for weighing,measuring, mixing, containing, and storage of solutions.5.2.4 When mixing electrolytes, always add reagents to thesolvent unless specific instructions indicate otherwise.5.2.5 W
28、hen using an electrolyte, always avoid direct physi-cal contact with the electrolyte and the specimen. Use tongs orsome other indirect method of handling specimens.5.2.6 Methanol is a cumulative poison hazard. Where etha-nol or methanol are listed as alternates, ethanol is the preferredsolvent. Meth
29、anol should be used in a properly designedchemical fume hood.5.2.7 All spills should be cleaned up and disposed ofproperly, no matter how small the spill.5.2.8 Properly dispose of all solutions that are not identifiedby composition and concentration.5.2.9 Store, handle, and dispose of chemicals acco
30、rding tothe manufacturers recommendations. Observe printed cau-tions on reagent containers.5.2.10 Information pertaining to the toxicity hazards andworking precautions of chemicals, solvents, acids, bases, andso forth, being used (such as MSDS) should be available forrapid consultation.5.3 Many of t
31、he electrolytes in the following listing can beexceedingly dangerous if carelessly handled. The pertinentsafety precautions for each class of electrolyte should be readbefore any electrolyte is mixed or used.5.4 Electrolytes containing perchloric acid and acetic anhy-dride are very dangerous to mix
32、and may be unpredictable inuse. Many industrial firms and research laboratories forbid theuse of such mixtures. Certain cities also have ordinancesprohibiting the use of such potentially explosive mixtures.These facts are considered sufficient reason for recommendingagainst their use.5.5 Mixtures of
33、 oxidizable organic compounds and power-ful oxidizing agents are always potentially dangerous. Aftersome use, any electrolyte will become heavily laden with ionsof the metals polished. These ions may interfere with furtherpolishing or catalyze the decomposition of the electrolyte. Theelectrolyte the
34、n must be discarded in accordance with appro-priate regulations.5.6 Most electrolytes (with few exceptions) should bemixed and stored in clean glass containers and never be incontact with foreign materials or organic compounds. Theexceptions are those electrolytes containing fluorides andstrong alka
35、line solutions that should be mixed and stored inpolyethylene or other appropriate material containers. Electro-lytes must never be allowed to become concentrated byevaporation. All electrolytes should be discarded appropriatelyas soon as they have exceeded their immediate usefulness.5.7 Specimens m
36、ounted in bismuth or bismuth-containingmetals must not be electropolished in perchloric acid solutionsbecause this mounting medium may react explosively with theelectrolyte. Likewise, bismuth or bismuth-containing alloysmust not be electropolished in solutions containing perchloricE1558 09 (2014)2TA
37、BLE 1 Electrolytes for ElectropolishingClass Use Formula Cell Voltage Time RemarksGroup I (Electrolytes Composed of Perchloric Acid and Alcohol With or Without Organic Additions) Use in a washdown/perchloric rated fume hood.I-1 Al and Al alloys with less than ethanol (95 %) 800 mL 30 to 80 15 to 60
38、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 ethanol (95 %) 800 mL 35 to 80
39、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 mL200 mL30 to 65 15 to 60 s
40、 one of the best formulas foruniversal useI-5 steelsstainless, alloy,high-speed; Fe, Al, Zr, Pbethanol (95 %)glycerinperchloric acid (30 %)700 mL100 mL200 mL15 to 50 15 to 60 s universal electrolyte comparable toI-4I-6 Al, Al-Si alloys ethanol (95 %)diethyl etherperchloric acid (30 %)760 mL190 mL50
41、mL35 to 60 15 to 60 s particularly good with Al-Si alloysI-7 Mo, Ti, Zr, U-Zr alloy methanol (absolute)2-butoxy ethanolperchloric acid (60 %)600 mL370 mL30 mL60to150 5to30sI-8 Al-Si alloys methanol (absolute)glycerinperchloric acid (65 %)840 mL125 mL35 mL50to100 5to60sI-9 vanadium methanol (absolute
42、)2-butoxy ethanolperchloric acid (65 %)590 mL350 mL60 mL30 3 s three-second cycles repeated atleast seven times to prevent heatinggermaniumtitaniumzirconium25 to 3558 to 6670 to 7530 to 60 s45 s15 spolish onlypolish and etch simultaneouslyI-10 aluminum methanol (absolute)nitric acidperchloric acid (
43、60 %)950 mL15 mL50 mL30 to 60 15 to 60 sI-11 steelscarbon, alloy, stainlessTi, high-temperature alloys, Pb,Momethanol (absolute)butylcellosolveperchloric acid600 mL360 mL60 mL3040 560 s good all purpose electropolishI-12 Al and Al alloys ethanol (95 %)perchloric acid1000 mL200 mL10 2 min not good fo
44、r Al-Cu and Al-Si alloys.Black film forms. Peel off after 11.5min and polish 1 min more.I-13 steel, Al, Ni, Sn, Ti, Bestainless steelAl3Niethanol (95 %)butylcellosolvewaterperchloric acid700 mL100 mL137 mL62 mL20 20 s Mix ethanol and water, addperchloric acid carefully. Then, addbutylcellosolve befo
45、re use.I-14 Ni, Ag, or Cu alloysCdethanol (95 %)butylcellosolveperchloric acid700 mL100 mL200 mL7080 15 sI-15 Mo and Mo alloys methanol (absolute)waterbutylcellosolveperchloric acid600 mL13 mL360 mL47 mL20 s Mix methanol and water, addperchloric acid carefully. Addbutylcellosolve before use.Group II
46、 (Electrolytes Composed of Perchloric Acid and Glacial Acetic Acid in Varying Proportions) Use in a washdown/perchloric rated fume hood.II-1 Cr, Ti, Zr, U,Fe, steelcarbon, alloy, stainlessacetic acid (glacial)perchloric acid (60 %)940 mL60 mL20 to 60 1 to 5 min good general-purpose electrolyteII-2 Z
47、r, Ti, U, steelcarbon and alloy acetic acid (glacial)perchloric acid (60 %)900 mL100 mL12 to 70 0.5 to 2 minII-3 U, Zr, Ti, Al, steelcarbon andalloyacetic acid (glacial)perchloric acid (60 %)800 mL200 mL40to100 1to15minII-4 Ni, Pb, Pb-Sb alloys acetic acid (glacial)perchloric acid (60 %)700 mL300 mL
48、40 to 100 1 to 5 minII-5 3 percent Si-Fe acetic acid (glacial)perchloric acid (60 %)650 mL350 mL. 5 min 0.06 A/cm2II-6 Cr acetic acid (glacial)perchloric acid1000 mL5mL3050 23 min can lower voltage to 25 V by adding515 % water.II-7 Hf, steelcarbon and alloy acetic acid (glacial)perchloric acid1000 m
49、L50 mL. . Used to polish Hf wires.Group III (Electrolytes Composed of Phosphoric Acid in Water or Organic Solvent)III-1 cobalt phosphoric acid (85 %) 1000 mL 1.2 3 to 5 minIII-2 pure copper distilled waterphosphoric acid (85 %)175 mL825 mL1.0 to 1.6 10 to 40 min copper cathodeIII-3 stainless, brass, Cu and Cualloys except Sn bronzewaterphosphoric acid (85 %)300 mL700 mL1.5 to 1.8 5 to 15 min copper cathodeE1558 09 (2014)3TABLE 1 ContinuedClass Use Formula Cell Voltage Time RemarksIII-4 alpha or alpha plus beta brass,Cu-Fe, Cu-Co, Co, Cdwaterphosphoric acid (85
