ASTM E7-17 Standard Terminology Relating to Metallography.pdf

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1、Designation: E7 17Standard Terminology Relating toMetallography1This standard is issued under the fixed designation E7; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the

2、year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This standard covers the definition of terms, acronyms,and symbols used in ASTM documen

3、ts related to the field ofmetallography and metallographic testing. Terms that are onlyrelevant to a particular standard or that are adequately definedin a general dictionary are not defined in this terminologystandard.1.2 This standard includes terminology used in metallo-graphic areas, such as, bu

4、t not limited to: light microscopy,microindentation hardness testing, specimen preparation, x-rayand electron metallography, quantitative metallography,photomicrography, and determination of grain size and inclu-sion content.1.3 This standard may be of use to individuals utilizingstandards of Commit

5、tee E04 as well as by those in need of ageneral reference source for terminology in the field ofmetallography.2. Referenced Documents2.1 ASTM Standards:2E45 Test Methods for Determining the Inclusion Content ofSteelE80 Recommended Practice for Dilatometric Analysis ofMetallic Materials; Replaced by

6、E 228 (Withdrawn 1986)3E112 Test Methods for Determining Average Grain SizeE1122 Practice for Obtaining JK Inclusion Ratings UsingAutomatic Image Analysis (Withdrawn 2006)33. Significance and Use3.1 Standards of Committee E04 consist of test methods,practices, and guides developed to ensure proper a

7、nd uniformtesting in the field of metallography. In order for one toproperly use and interpret these standards, the terminologyused in these standards must be understood.3.2 The terms used in the field of metallography haveprecise definitions. The terminology and its proper usage mustbe completely u

8、nderstood in order to adequately communicatein this field. In this respect, this standard is also a generalsource of terminology relating to the field of metallographyfacilitating the transfer of information within the field.4. Terminologyabsorptionthe decrease in intensity which radiation under-goe

9、s during its passage through matter when the ratio oftransmitted or reflected luminous flux to incident is less than1.absorption coefficientspecific factor characteristic of asubstance on which its absorption radiation depends. Therate of decrease of the natural logarithm of the intensity of aparall

10、el beam per unit distance traversed in a substance. ForX-rays, the linear absorption coefficient is the natural loga-rithm of the ratio of the incident intensity of an X-ray beamincident on unit thickness of an absorbing material to theintensity of the beam transmitted. If Ieis the incident inten-si

11、ty of a beam of X-rays, Itthe transmitted intensity, and Xthe thickness of the absorbing material, then:It5 Ieexp2X! (1)Here is the linear absorption coefficient. The mass absorp-tion coefficient is given by / where is the density.absorption edgean abrupt change in absorption coefficientat a particu

12、lar wavelength. The absorption coefficient isalways larger on the short wavelength side of the absorptionedge.absorption limitSee absorption edge.accelerating potentiala relatively high voltage applied be-tween the cathode and anode of an electron gun to accelerateelectrons.achromaticliterally, colo

13、r-free. A lens or prism is said to beachromatic when corrected for two colors. The remainingcolor seen in an image formed by such a lens is said to besecondary chromatic aberration. See apochromatic objec-tive1This terminology is under the jurisdiction of ASTM Committee E04 onMetallography and are t

14、he direct responsibility of Subcommittee E04.02 onTerminology.Current edition approved June 1, 2017. Published July 2017. Originally approvedin 1926. Last previous edition approved 2015 as E7 15. DOI: 10.1520/E0007-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact AS

15、TM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box

16、 C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by th

17、e World Trade Organization Technical Barriers to Trade (TBT) Committee.1achromatic objectivean objective that is corrected chro-matically for two colors, and spherically for one, usually inthe yellow-green part of the spectrum.achromatic objective lensan objective lens with longitudi-nal chromatic c

18、orrection for green and blue, and sphericalchromatic correction for green. NoteLens should be usedwith a green filter.acid extractionSee extraction.air-lockan intermediate enclosed chamber of a vacuum orpressure system through which an object may be passedwithout materially changing the vacuum or pr

19、essure of thesystem.alignmenta mechanical or electrical adjustment of thecomponents of an optical device in such a way that the pathof the radiating beam coincides with the optical axis or otherpredetermined path in the system. In electron optics there arethree general types:(1) magnetic alignmentan

20、 alignment of the electronoptical axis of the electron microscope such that the imagerotates about a point in the center of the viewing screen whenthe current flowing through a lens is varied.(2) mechanical alignmenta method of aligning thegeometrical axis of the electron microscope by relativephysi

21、cal movement of the components, usually as a steppreceding either magnetic or voltage alignment.(3) voltage alignmenta condition of alignment of anelectron microscope such that the image expands or con-tracts symmetrically about the center of the viewing screenwhen the accelerating voltage is change

22、d.allotriomorphic crystala crystal whose lattice structure isnormal, but whose outward shape is imperfect since it isdetermined to some extent by the surroundings; the grains ina metallic aggregate are allotriomorphic crystals.alloy systema complete series of compositions produced bymixing in all pr

23、oportions any group of two, or more,components, at least one of which is a metal.alpha brassa solid solution phase of one or more alloyingelements in copper and having the same crystal lattice ascopper.alpha iron (Fe)solid phase of pure iron which is stable attemperatures below 910C and possesses th

24、e body-centeredcubic lattice. It is ferro-magnetic below 768C.amplifiera negative lens, used in lieu of an eyepiece, toproject under magnification the image formed by an objec-tive. The amplifier is especially designed for flatness of fieldand should be used with an apochromatic objective.ampliphan

25、eyepiece See amplifier.analyzeran optical device, capable of producing planepolarized light, used for detecting the state of polarization.angle of reflection: ( 1) reflection the angle between thereflected beam and the normal to the reflecting surface.(2) diffractionthe angle between the diffracted

26、beam andthe diffracting planes.Angstrom unit (abbreviation) = A, , or A. Ua unit oflength equal to 108cm. This is the standard unit ofmeasurement in X-ray crystallography.angular apertureSee aperture, optical.anisotropic (replaces anisotropy)having different values fora property, in different direct

27、ions.annealing-twin bands See twin bands.anode apertureSee aperture.anvilthe base on which objects for hardness test are placed.anvil effectthe effect caused by use of too high a load orwhen testing the hardness of too thin a specimen, resulting ina bulge or shiny spot on the under side of the speci

28、men.aperture, electron:anode aperture the opening in the accelerating voltageanode shield of the electron gun through which the electronsmust pass to illuminate or irradiate the specimen.condenser aperturean opening in the condenser lens con-trolling the number of electrons entering the lens and the

29、angular aperture of the illuminating beam. The angular aper-ture can also be controlled by the condenser lens current.physical objective aperturea metal diaphragm, centrallypierced with a small hole, used to limit the cone of electronsaccepted by the objective lens. This improves image contrastsince

30、 highly scattered electrons are prevented from arriving atthe Gaussian image plane and therefore can not contribute tobackground fog.aperture, opticalthe working diameter of a lens or a mirror.angular aperture the angle between the most divergentrays which can pass through a lens to form the image o

31、f anobject.aperture diaphragma device to define the aperture.apochromatic objectivean objective with longitudinal chro-matic correction for red, green and blue, and sphericalchromatic correction for green and blue. This is the bestchoice for high resolution or color photomicrography.arcingin electro

32、n diffraction, the production of segments ofcircular patterns, indicating a departure from completelyrandom orientation of the crystals of the specimen.arrestthat portion of a cooling curve in which temperature isinvariant with time (for example, thermal or eutectic arrest).artifacta false microstru

33、ctural feature that is not an actualcharacteristic of the specimen; it may be present as a resultof improper or inadequate preparation, handling methods, oroptical conditions for viewing.ascending fork pointin a ternary phase diagram, the con-figuration at the convergence of the three bivariant curv

34、esupon each of the four phases associated in Class II univariantequilibrium; for example, the union of two ascending liqui-dus surface valleys to form one ascending liquidus surfacevalley.E7172aspect ratiothe length-to-width ratio of a microstructuralfeature in a two-dimensional plane.asterisma leng

35、thening of diffraction spots usually in theradial direction.astigmatisma defect in a lens or optical system whichcauses rays in one plane parallel to the optical axis to focusat a distance different from those in the plane at right anglesto it.ASTM grain size number See grain size.athermalnot isothe

36、rmal, with changing rather than constanttemperature conditions.atomic replicaSee replica.atomic scattering factorthe ratio of the amplitude of thewave scattered by an atom to that scattered by a singleelectron. Symbol = f.austenitea face-centered cubic solid solution of carbon orother elements in ga

37、mma iron.austenite grain sizethe grain size which exists or existed inaustenite at a given temperature. See Test Methods E112.autographic dilatometera dilatometer that automaticallyrecords instantaneous and continuous changes in dimensionsand some other controlled variable such as temperature ortime

38、.autographic pyrometer See pyrometer.automatic image analysisthe separation and quantitativeevaluation of an image into its elements with or withoutoperator interaction. It includes the enhancement, detection,and quantification of the features contained in an imagethrough the use of optical, geometr

39、ical, and stereologicalparameters and a computer program. Image analysis dataoutput can provide individual measurements on each sepa-rate feature (feature specific) or totals for all features of aparticular type in the field (field specific).automatic image analyzera device which can be pro-grammed

40、to detect and measure features of interest in animage. It may include accessories such as automatic focusand an automatic traversing stage to permit unattendedoperation.average coefficient of cubical expansion average change inunit volume of a substance per unit change in temperatureover a specified

41、 range of temperature.average coefficient of linear expansion average change inunit length of a body per unit change in temperature over aspecified range of temperature.average coefficient of thermal expansion general term.(See also average coefficient of cubical expansion andaverage coefficient of

42、linear expansion.)average grain diameter See grain size.axial ratiothe ratio of the length of one axis to that ofanother (for example, c/a) or the continued ratio of threeaxes (for example, a:b:c).axis (crystal)the edge of the unit cell of a space lattice. Anyone axis of any one lattice is defined,

43、in length and direction,with respect to the other axes of that lattice.Babos lawthe vapor pressure over a liquid solvent islowered approximately in proportion to the quantity of anonvolatile solute dissolved in the liquid.backing filma film used as auxiliary support for the thinreplica or specimen-s

44、upporting film.back reflectionthe diffraction of X-rays at a Bragg angleapproaching 90.bainiteupper, lower, intermediate metastable micro-structure or microstructures resulting from the transforma-tion of austenite at temperatures between those whichproduce pearlite and martensite. These structures

45、may beformed on continuous (slow) cooling if the transformationrate of austenite to pearlite is much slower than that ofaustenite to bainite. Ordinarily, these structures may beformed isothermally at temperatures within the above rangeby quenching austenite to a desired temperature and holdingfor a

46、period of time necessary for transformation to occur. Ifthe transformation temperature is just below that at whichthe finest pearlite is formed, the bainite (upper bainite) has afeathery appearance. If the transformation temperature is justabove that at which martensite is produced, the bainite(lowe

47、r bainite) is acicular, resembling slightly temperedmartensite. At the higher resolution of the electronmicroscope, upper bainite is observed to consist of plates ofcementite in a matrix of ferrite. These discontinuous carbideplates tend to have parallel orientation in the direction of thelonger dim

48、ension of the bainite areas. Lower bainite consistsof ferrite needles containing carbide platelets in parallelarray cross-striating each needle axis at an angle of about60. Intermediate bainite resembles upper bainite; however,the carbides are smaller and more randomly oriented.bandin electron diffr

49、action, a broad intensity maximum withsharp edges.banded structure (banding)alternate bands parallel withthe direction of working resulting from the elongation ofsegregated areas.barrel distortion See distortion.basal planethat plane of a hexagonal or tetragonal crystalwhich is perpendicular to the axis of highest symmetry. ItsMiller indices are (0001) or (001), respectively.bellows lengththe distance from the eyepiece to the photo-sensitive material or viewing screen in a photomicrographi