ASTM E7-03(2009)
(Terminology)Standard Terminology Relating to Metallography
Standard Terminology Relating to Metallography
SIGNIFICANCE AND USE
Standards of Committee E-4 consist of test methods, practices, and guides developed to ensure proper and uniform testing in the field of metallography. In order for one to properly use and interpret these standards, the terminology used in these standards must be understood.
The terms used in the field of metallography have precise definitions. The terminology and its proper usage must be completely understood in order to adequately communicate in this field. In this respect, this standard is also a general source of terminology relating to the field of metallography facilitating the transfer of information within the field.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E7 − 03(Reapproved 2009)
Standard Terminology Relating to
Metallography
This standard is issued under the fixed designation E7; the number immediately following the designation indicates the year of original
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (´) 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 Scope Automatic Image Analysis (Withdrawn 2006)
1.1 This standard covers the definition of terms, acronyms,
3. Significance and Use
and symbols used in ASTM documents related to the field of
3.1 Standards of Committee E-4 consist of test methods,
metallography and metallographic testing. Terms that are only
practices, and guides developed to ensure proper and uniform
relevant to a particular standard or that are adequately defined
testing in the field of metallography. In order for one to
in a general dictionary are not defined in this terminology
properly use and interpret these standards, the terminology
standard.
used in these standards must be understood.
1.2 This standard includes terminology used in metallo-
3.2 The terms used in the field of metallography have
graphic areas, such as, but not limited to: light microscopy,
precise definitions. The terminology and its proper usage must
microindentationhardnesstesting,specimenpreparation,x-ray
be completely understood in order to adequately communicate
and electron metallography, quantitative metallography,
in this field. In this respect, this standard is also a general
photomicrography, and determination of grain size and inclu-
source of terminology relating to the field of metallography
sion content.
facilitating the transfer of information within the field.
1.3 This standard may be of use to individuals utilizing
4. Terminology
standards of Committee E04 as well as by those in need of a
general reference source for terminology in the field of
absorption—the decrease in intensity which radiation under-
metallography.
goes during its passage through matter when the ratio of
transmitted or reflected luminous flux to incident is less than
2. Referenced Documents
1.
2.1 ASTM Standards:
absorption coefficient—specific factor characteristic of a
E80Recommended Practice for Dilatometric Analysis of
3 substance on which its absorption radiation depends. The
MetallicMaterials;ReplacedbyE228(Withdrawn1986)
rate of decrease of the natural logarithm of the intensity of a
E45Test Methods for Determining the Inclusion Content of
parallel beam per unit distance traversed in a substance. For
Steel
X-rays, the linear absorption coefficient is the natural loga-
E80Recommended Practice for Dilatometric Analysis of
3 rithm of the ratio of the incident intensity of an X-ray beam
MetallicMaterials;ReplacedbyE228(Withdrawn1986)
incident on unit thickness of an absorbing material to the
E92TestMethodforVickersHardnessofMetallicMaterials
3 intensity of the beam transmitted. If I is the incident inten-
e
(Withdrawn 2010)
sity of a beam of X-rays, Ithe transmitted intensity, and X
t
E112Test Methods for Determining Average Grain Size
the thickness of the absorbing material, then:
E1122Practice for Obtaining JK Inclusion Ratings Using
I 5 I exp 2µX (1)
~ !
t e
Here µ is the linear absorption coefficient. The mass absorp-
tion coefficient is given by µ/ρ where ρ is the density.
This terminology is under the jurisdiction of ASTM Committee E04 on
Metallography and are the direct responsibility of Subcommittee E04.02 on
absorption edge—an abrupt change in absorption coefficient
Terminology.
at a particular wavelength. The absorption coefficient is
Current edition approved Oct. 1, 2009. Published March 2010. Originally
approved in 1926. Last previous edition approved 2003 as E7–03. DOI: 10.1520/ always larger on the short wavelength side of the absorption
E0007-03R09.
edge.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
absorption limit—See absorption edge.
Standards volume information, refer to the standard’s Document Summary page on
accelerating potential—a relatively high voltage applied be-
the ASTM website.
tweenthecathodeandanodeofanelectronguntoaccelerate
The last approved version of this historical standard is referenced on
www.astm.org. electrons.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E7 − 03 (2009)
achromatic—literally, color-free.Alens or prism is said to be analyzer—an optical device, capable of producing plane
achromatic when corrected for two colors. The remaining polarized light, used for detecting the state of polarization.
color seen in an image formed by such a lens is said to be
angle of reflection: ( 1) reflection —the angle between the
secondary chromatic aberration. See apochromatic objec-
reflected beam and the normal to the reflecting surface.
tive
(2) diffraction—the angle between the diffracted beam and
achromatic objective—an objective that is corrected chro- the diffracting planes.
matically for two colors, and spherically for one, usually in
Angstrom unit (abbreviation)=A,Å , or A. U—a unit of
the yellow-green part of the spectrum.
−8
length equal to 10 cm. This is the standard unit of
measurement in X-ray crystallography.
achromatic objective lens—an objective lens with longitudi-
nal chromatic correction for green and blue, and spherical
angular aperture—See aperture, optical.
chromatic correction for green. Note—Lens should be used
anisotropic (replaces anisotropy)—having different values for
with a green filter.
a property, in different directions.
acid extraction—See extraction.
annealing-twin bands— See twin bands.
air-lock—an intermediate enclosed chamber of a vacuum or
anode aperture—See aperture.
pressure system through which an object may be passed
anvil—the base on which objects for hardness test are placed.
without materially changing the vacuum or pressure of the
system.
anvil effect—the effect caused by use of too high a load or
whentestingthehardnessoftoothinaspecimen,resultingin
alignment—a mechanical or electrical adjustment of the
a bulge or shiny spot on the under side of the specimen.
components of an optical device in such a way that the path
oftheradiatingbeamcoincideswiththeopticalaxisorother
aperture, electron:—
predeterminedpathinthesystem.Inelectronopticsthereare
anode aperture— the opening in the accelerating voltage
three general types:
anode shield of the electron gun through which the electrons
(1) magnetic alignment—an alignment of the electron
must pass to illuminate or irradiate the specimen.
optical axis of the electron microscope such that the image
condenser aperture—an opening in the condenser lens con-
rotatesaboutapointinthecenteroftheviewingscreenwhen
trolling the number of electrons entering the lens and the
the current flowing through a lens is varied.
angular aperture of the illuminating beam. The angular aper-
(2) mechanical alignment—a method of aligning the
ture can also be controlled by the condenser lens current.
geometrical axis of the electron microscope by relative
physical movement of the components, usually as a step physical objective aperture—a metal diaphragm, centrally
preceding either magnetic or voltage alignment. pierced with a small hole, used to limit the cone of electrons
(3) voltage alignment—a condition of alignment of an accepted by the objective lens. This improves image contrast
electron microscope such that the image expands or con- since highly scattered electrons are prevented from arriving at
the Gaussian image plane and therefore can not contribute to
tracts symmetrically about the center of the viewing screen
when the accelerating voltage is changed. background fog.
aperture, optical—the working diameter of a lens or a mirror.
allotriomorphic crystal—a crystal whose lattice structure is
normal, but whose outward shape is imperfect since it is
angular aperture— the angle between the most divergent
determinedtosomeextentbythesurroundings;thegrainsin
rays which can pass through a lens to form the image of an
a metallic aggregate are allotriomorphic crystals.
object.
alloy system—a complete series of compositions produced by
aperture diaphragm—a device to define the aperture.
mixing in all proportions any group of two, or more,
apochromatic objective—anobjectivewithlongitudinalchro-
components, at least one of which is a metal.
matic correction for red, green and blue, and spherical
alpha brass—a solid solution phase of one or more alloying
chromatic correction for green and blue. This is the best
elements in copper and having the same crystal lattice as
choice for high resolution or color photomicrography.
copper.
arcing—in electron diffraction, the production of segments of
alpha iron (Fe)—solid phase of pure iron which is stable at
circular patterns, indicating a departure from completely
temperatures below 910°C and possesses the body-centered
random orientation of the crystals of the specimen.
cubic lattice. It is ferro-magnetic below 768°C.
arrest—thatportionofacoolingcurveinwhichtemperatureis
amplifier—a negative lens, used in lieu of an eyepiece, to
invariant with time (for example, thermal or eutectic arrest).
project under magnification the image formed by an objec-
artifact—a false microstructural feature that is not an actual
tive.The amplifier is especially designed for flatness of field
characteristic of the specimen; it may be present as a result
and should be used with an apochromatic objective.
of improper or inadequate preparation, handling methods, or
ampliphan eyepiece— See amplifier. optical conditions for viewing.
E7 − 03 (2009)
ascending fork point—in a ternary phase diagram, the con- average coefficient of thermal expansion— general term.
figuration at the convergence of the three bivariant curves (See also average coefficient of cubical expansion and
uponeachofthefourphasesassociatedinClassIIunivariant average coefficient of linear expansion.)
equilibrium; for example, the union of two ascending liqui-
average grain diameter— See grain size.
dus surface valleys to form one ascending liquidus surface
axial ratio—the ratio of the length of one axis to that of
valley.
another (for example, c/a) or the continued ratio of three
aspect ratio—the length-to-width ratio of a microstructural axes (for example, a:b:c).
feature in a two-dimensional plane.
axis (crystal)—the edge of the unit cell of a space lattice.Any
oneaxisofanyonelatticeisdefined,inlengthanddirection,
asterism—a lengthening of diffraction spots usually in the
with respect to the other axes of that lattice.
radial direction.
Babo’s law—the vapor pressure over a liquid solvent is
astigmatism—a defect in a lens or optical system which
lowered approximately in proportion to the quantity of a
causes rays in one plane parallel to the optical axis to focus
nonvolatile solute dissolved in the liquid.
at a distance different from those in the plane at right angles
to it.
backing film—a film used as auxiliary support for the thin
replica or specimen-supporting film.
ASTM grain size number— See grain size.
athermal—not isothermal, with changing rather than constant
back reflection—the diffraction of X-rays at a Bragg angle
temperature conditions.
approaching 90°.
atomic replica—See replica. background blackening—a continuous, slowly varying
blackening of photographic film which has been exposed to
atomic scattering factor—the ratio of the amplitude of the
diffracted X-rays, on which the blackening due to diffracted
wave scattered by an atom to that scattered by a single
spots or lines is superimposed.
electron. Symbol=f.
bainite—upper, lower, intermediate— metastable micro-
austenite—a face-centered cubic solid solution of carbon or
structure or microstructures resulting from the transforma-
other elements in gamma iron.
tion of austenite at temperatures between those which
austenite grain size—the grain size which exists or existed in produce pearlite and martensite. These structures may be
austenite at a given temperature. See Test Methods E112.
formed on continuous (slow) cooling if the transformation
rate of austenite to pearlite is much slower than that of
autographic dilatometer—a dilatometer that automatically
austenite to bainite. Ordinarily, these structures may be
recordsinstantaneousandcontinuouschangesindimensions
formed isothermally at temperatures within the above range
and some other controlled variable such as temperature or
by quenching austenite to a desired temperature and holding
time.
for a period of time necessary for transformation to occur. If
the transformation temperature is just below that at which
autographic pyrometer— See pyrometer.
the finest pearlite is formed, the bainite (upper bainite) has a
automatic image analysis—the separation and quantitative
featheryappearance.Ifthetransformationtemperatureisjust
evaluation of an image into its elements with or without
above that at which martensite is produced, the bainite
operator interaction. It includes the enhancement, detection,
(lower bainite) is acicular, resembling slightly tempered
and quantification of the features contained in an image
martensite. At the higher resolution of the electron
through the use of optical, geometrical, and stereological
microscope, upper bainite is observed to consist of plates of
parameters and a computer program. Image analysis data
cementite in a matrix of ferrite.These discontinuous carbide
output can provide individual measurements on each sepa-
plates tend to have parallel orientation in the direction of the
rate feature (feature specific) or totals for all features of a
longerdimensionofthebainiteareas.Lowerbainiteconsists
particular type in the field (field specific).
of ferrite needles containing carbide platelets in parallel
array cross-striating each needle axis at an angle of about
automatic image analyzer—a device which can be pro-
60°. Intermediate bainite resembles upper bainite; however,
grammed to detect and measure features of interest in an
the carbides are smaller and more randomly oriented.
image. It may include accessories such as automatic focus
and an automatic traversing stage to permit unattended
balanced filters (X-rays)—a pair of filters used to eliminate
operation.
all but a narrow range of wavelengths. The filter materials
and thicknesses are chosen so that their absorption edges lie
average coefficient of cubical expansion—averagechangein
veryclosetogetherandsothattheyhavethesameabsorption
unit volume of a substance per unit change in temperature
except for wave
...
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