ASTM E1558-09(2021)

Standard Guide for Electrolytic Polishing of Metallographic Specimens

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.

General Information

• Status: Published
• Publication Date: 31-Aug-2021
• ICS: 49.025.05 - Ferrous alloys in general
• ICS: 49.025.15 - Non-ferrous alloys in general
• Technical Committee: E04 - Metallography
• Drafting Committee: E04.01 - Specimen Preparation

Standards Content (Sample)

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.
Designation: E1558 − 09 (Reapproved 2021)
Standard Guide for
1
Electrolytic Polishing of Metallographic Specimens
This standard is issued under the fixed designation E1558; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2.1 electrolytic polish (electropolish)—A method of pol-
ishingmetalsandalloysinwhichmaterialisremovedfromthe
1.1 This guide deals with electrolytic polishing as a means
surface by making the metal the anode in an electrolytic bath.
of preparation of specimens for metallographic purposes.
Procedures are described for polishing a variety of metals.
4. Significance and Use
2
NOTE 1—References (1-133) on electrolytic polishing will provide the
4.1 Advantages of Electrolytic Polishing:
reader with specific information beyond the scope of this guide.
4.1.1 For some metals, a high quality surface finish can be
1.2 The values stated in SI units are to be regarded as producedthatisequivalentto,orbetterthan,thatwhichcanbe
standard. No other units of measurement are included in this obtained by mechanical methods.
standard. 4.1.2 Once procedures have been established, satisfactory
results can be obtained rapidly with reproducibility.
1.3 This standard does not purport to address all of the
4.1.3 There can be a marked saving of time if many
safety concerns, if any, associated with its use. It is the
specimens of the same material are polished sequentially.
responsibility of the user of this standard to establish appro-
4.1.4 Electropolishing a selected area on the surface of a
priate safety, health, and environmental practices and deter-
relatively large metal part can be accomplished
mine the applicability of regulatory limitations prior to use.
nondestructively, that is, without the need for sectioning to
Specific safety precautions are described in Section 5 and
remove a piece.
6.3.1.
4.1.5 Soft, single-phase metals, which may be difficult to
1.4 This international standard was developed in accor-
polish by mechanical methods, may be successfully electrop-
dance with internationally recognized principles on standard-
olished.
ization established in the Decision on Principles for the
4.1.6 Thetruemicrostructureofaspecimencanbeobtained
Development of International Standards, Guides and Recom-
because artifacts (such as disturbed metal, scratches, and
mendations issued by the World Trade Organization Technical
mechanical twins) produced on the surface, even by careful
Barriers to Trade (TBT) Committee.
grindingandmechanicalpolishingoperations,canberemoved.
These features are important in low-load hardness testing,
2. Referenced Documents
X-ray diffraction studies, and in electron microscopy, where
3
2.1 ASTM Standards:
higher resolution puts a premium on undistorted metal sur-
E7Terminology Relating to Metallography
faces.
E407Practice for Microetching Metals and Alloys
4.1.7 After electropolishing is completed, etching can often
be accomplished by reducing the voltage (generally to about
3. Terminology
one-tenth that required for polishing) for a short time before it
3.1 Definitions—All terms used in this guide are either
is turned off.
defined in Terminology E7 or are discussed in 3.2.
NOTE 2—Not all electropolishing solutions produce good etching
3.2 Definitions of Terms Specific to This Standard:
results.
4.2 Disadvantages of Electrolytic Polishing:
1 4.2.1 Many of the chemical mixtures used in electropolish-
ThisguideisunderthejurisdictionofASTMCommitteeE04onMetallography
and is the direct responsibility of Subcommittee E04.01 on Specimen Preparation.
ing are poisonous or dangerous if not properly handled (see
Current edition approved Sept. 1, 2021. Published November 2021. Originally
Section 5). These hazards are similar to those involved in the
approved in 1993. Last previous edition approved in 2014 as E1558–09(2014).
mixing and handling of etchants, see Test Methods E407.
DOI: 10.1520/E1558-09R21.
2
4.2.2 In multi-phase alloys, the polishing rate of each phase
The boldface numbers in parentheses refer to the references at the end of this
standard.
may be different. The result may be a non-planar surface.
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
4.2.3 Electropolished surfaces may be slightly undulated
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
rather than perfectly planar and, therefore, may not be suitable
Standards volume information, refer to the standard’s Docume
...