ASTM E3-95

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation:E3–95 An American National Standard
Standard Practice for
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Preparation of Metallographic Specimens
This standard is issued under the fixed designation E 3; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript
epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope 3. Significance and Use
1.1 The primary objective of metallographic examinations 3.1 Microstructures have a strong influence on the proper-
is to reveal the constituents and structure of metals and their ties and successful application of metals and alloys. Determi-
alloys by means of the light microscope. In special cases, the nation and control of microstructure requires the use of
objective of the examination may require the development of metallographic examination.
less detail than in other cases but, under nearly all conditions, 3.2 Many specifications contain a requirement regarding
the proper selection and preparation of the specimen is of microstructure; hence, a major use for metallographic exami-
major importance. Because of the diversity in available equip- nation is inspection to ensure that the requirement is met. Other
ment and the wide variety of problems encountered, the major uses for metallographic examination are in failure
following text presents for the guidance of the metallographer analysis, and in research and development.
only those practices which experience has shown are generally 3.3 Proper choice of specimen location and orientation will
satisfactory; it cannot and does not describe the variations in minimize the number of specimens required and simplify their
technique required to solve individual problems. interpretation. It is easy to take too few specimens for study,
but it is seldom that too many are studied.
NOTE 1—For a more extensive description of various metallographic
techniques, refer to Samuels, L. E., Metallographic Polishing by Mechani-
4. Selection of Metallographic Specimens
cal Methods, American Society for Metals (ASM) Metals Park, OH, 3rd
4.1 The selection of test specimens for metallographic
Ed., 1982; Petzow, G., Metallographic Etching, ASM, 1978; and Vander-
Voort, G., Metallography: Principles and Practice, McGraw Hill, NY, examination is extremely important because, if their interpre-
1984.
tation is to be of value, the specimens must be representative of
the material that is being studied. The intent or purpose of the
1.2 This standard does not purport to address all of the
metallographic examination will usually dictate the location of
safety concerns, if any, associated with its use. It is the
the specimens to be studied. With respect to purpose of study,
responsibility of the user of this standard to establish appro-
metallographic examination may be divided into three classi-
priate safety and health practices and determine the applica-
fications:
bility of regulatory limitations prior to use.
4.1.1 General Studies or Routine Work—Specimens from
2. Referenced Documents
locations that are most likely to reveal the maximum variations
within the material under study should be chosen. For example,
2.1 ASTM Standards:
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specimens should be taken from a casting in the zones wherein
E 7 Terminology Relating to Metallography
maximum segregation might be expected to occur as well as
E 45 Practice for Determining the Inclusion Content of
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specimens from sections where segregation should be at a
Steel
2
minimum. In the examination of strip or wire, test specimens
E 340 Test Method for Macroetching Metals and Alloys
2
should be taken from each end of the coils.
E 407 Test Methods for Microetching Metals and Alloys
4.1.2 Study of Failures—Test specimens should be taken as
E 1077 Test Method for Estimating the Depth of Decarbur-
2
closely as possible to the fracture or to the initiation of the
ization of Steel Specimens
failure. Before taking the metallographic specimens, study of
E 1268 Practice for Assessing the Degree of Banding or
2
the fracture surface should be complete, or, at the very least,
Orientation of Microstructures
the fracture surface should be documented. Specimens should
E 1558 Guide to Electrolytic Polishing of Metallographic
2
be taken in many cases from a sound area for a comparison of
Specimens
structures and properties.
4.1.3 Research Studies—The nature of the study will dictate
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This practice is under the jurisdiction of ASTM Committee E-4 on Metallog-
specimen location, orientation, etc. Sampling will usually be
raphy and is the direct responsibility of Subcommittee E04.01 on Sampling,
Specimen Preparation, and Photography.
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