ASTM E1558-2009 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 09Standard 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 last revision. A num

2、ber 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 are described fo

3、r 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 thisstandard.1.3 This stan

4、dard 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 safetyprecautions

5、are described in Section 5 and 6.3.1.2. Referenced Documents2.1 ASTM Standards:3E7 Terminology Relating to MetallographyE 407 Practice for Microetching Metals and Alloys3. Terminology3.1 DefinitionsAll terms used in this guide are eitherdefined in Terminology E7or are discussed in 3.2.3.2 Definition

6、s 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:4.1.1 For some met

7、als, 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 time if manyspe

8、cimens of the same material are polished sequentially.4.1.4 Electropolishing a selected area on the 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 topolis

9、h by mechanical methods, may be successfully electropol-ished.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 be removed.Th

10、ese 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 (generally to abouto

11、ne-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 properly hand

12、led (seeSection 5). These hazards are similar to those involved in themixing and handling of etchants, 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 undulated

13、rather 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 toexaggerate the si

14、ze of the inclusions and voids.4.2.5 Dimples, pits, and waviness limit applications involv-ing surface 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 jurisdi

15、ction ofASTM Committee E04 on Metallographyand is the direct responsibility of Subcommittee E04.01 on Specimen Preparation.Current edition approved May 1, 2009. Published June 2009. Originallyapproved in 1993. Last previous edition approved in 2004 as E 1558 99(2004).2The boldface numbers in parenth

16、eses 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 ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copy

17、right ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United 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 elect

18、ropolishing 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 electrolytes may be needed topolish the variet

19、y 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 beread and understood concerning all

20、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 labels and MSDS for recommen-dation

21、s 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 well as anycombinations of those ch

22、emicals.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 or toxic vapors. In particular, not

23、e 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 user should take careto observe eac

24、h 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 electrolyte and it is imperative with th

25、ose 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 accidental explosion. Therefore, these el

26、ectrolytesmust 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 proper protective equipment (eyewea

27、r, 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 When using an electrolyte, always av

28、oid 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. Methanol should be used in a properly d

29、esignedchemical 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 according tothe manufacturers recommend

30、ations. 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 the electrolytes in the following li

31、sting 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 and may be unpredictable inuse. Man

32、y 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 oxidizable organic compounds and p

33、ower-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 then must be discarded in accordance w

34、ith 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 alkaline solutions that should be mixed

35、 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 mounted in bismuth or bismuth-contai

36、ningmetals 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 perchloricacid. Specimens mounted in organic mounting compounds

37、,such as Bakelite, must not be electropolished in electrolytescontaining perchloric acid as they may also react explosively.5.8 Specific Safety Precautions for Each Group of Electro-lytes:E1558092TABLE 1 Electrolytes for ElectropolishingClass Use Formula Cell Voltage Time RemarksGroup I (Electrolyte

38、s 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 s2 percent Si distilled water 140 mLperchloric acid (60 %) 60 mLsteelscarbon, alloy, stainless 35 to 6

39、5 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 15 to 60 sperchloric acid (60 %) 200 mLI-3 stainless steel ethanol (95 %) 940 mL 30 to 45 15 to 60 spe

40、rchloric 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 one of the best formulas foruniversal useI-5 steelsstainless, alloy,high-speed; Fe, Al, Zr, Pbethanol

41、 (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 mL35 to 60 15 to 60 s particularly good with Al-Si alloysI-7 Mo, Ti, Zr, U-Zr alloy methanol (absolute

42、)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)2-butoxy ethanolperchloric acid (65 %)590 mL350 mL60 mL30 3 s three-second cycles repeated atleast se

43、ven 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 (60 %)950 mL15 mL50 mL30 to 60 15 to 60 sI-11 steelscarbon, alloy, stainlessTi, high-temperature alloys

44、, 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 for Al-Cu and Al-Si alloys.Black film forms. Peel off after 11.5min and polish 1 min more.I-13 steel, Al

45、, Ni, Sn, Ti, Bestainless steelAl3Niethanol (95 %)butylcellosolvewaterperchloric acid700 mL100 mL137 mL62 mL20 20 s Mix ethanol and water, addperchloric acid carefully. Then, addbutylcellosolve before use.I-14 Ni, Ag, or Cu alloysCdethanol (95 %)butylcellosolveperchloric acid700 mL100 mL200 mL7080 1

46、5 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 (Electrolytes Composed of Perchloric Acid and Glacial Acetic Acid in Varying Proportions) Use in a wa

47、shdown/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 Zr, Ti, U, steelcarbon and alloy acetic acid (glacial)perchloric acid (60 %)900 mL100 mL12 to 70 0.5 to

48、 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 mL40 to 100 1 to 5 minII-5 3 percent Si-Fe acetic acid (glacial)perchloric acid (60 %)650 mL350 mL. 5 mi

49、n 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 mL50 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 cathodeE1558093TABLE 1 ContinuedClass Use Formula Cell Voltage Time RemarksIII-3 stainless, brass, Cu