1、Designation: E 1245 03 (Reapproved 2008)Standard Practice forDetermining the Inclusion or Second-Phase ConstituentContent of Metals by Automatic Image Analysis1This standard is issued under the fixed designation E 1245; the number immediately following the designation indicates the year oforiginal a
2、doption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis practice may be used to produce stereological measurements that
3、describe the amount, number,size, and spacing of the indigenous inclusions (sulfides and oxides) in steels. The method may also beapplied to assess inclusions in other metals or to assess any discrete second-phase constituent in anymaterial.1. Scope1.1 This practice describes a procedure for obtaini
4、ng stereo-logical measurements that describe basic characteristics of themorphology of indigenous inclusions in steels and other metalsusing automatic image analysis. The practice can be applied toprovide such data for any discrete second phase.NOTE 1Stereological measurement methods are used in thi
5、s practiceto assess the average characteristics of inclusions or other second-phaseparticles on a longitudinal plane-of-polish. This information, by itself,does not produce a three-dimensional description of these constituents inspace as deformation processes cause rotation and alignment of thesecon
6、stituents in a preferred manner. Development of such informationrequires measurements on three orthogonal planes and is beyond the scopeof this practice.1.2 This practice specifically addresses the problem ofproducing stereological data when the features of the constitu-ents to be measured make atta
7、inment of statistically reliabledata difficult.1.3 This practice deals only with the recommended testmethods and nothing in it should be construed as defining orestablishing limits of acceptability.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are inc
8、luded in thisstandard.1.5 This standard 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
9、to use.2. Referenced Documents2.1 ASTM Standards:2E3 Guide for Preparation of Metallographic SpecimensE7 Terminology Relating to MetallographyE45 Test Methods for Determining the Inclusion Contentof SteelE 768 Guide for Preparing and Evaluating Specimens forAutomatic Inclusion Assessment of Steel3.
10、Terminology3.1 Definitions:3.1.1 For definitions of terms used in this practice, seeTerminology E7.3.2 Symbols:A= the average area of inclusions or particles, m2.AA= the area fraction of the inclusion or constituent.Ai= the area of the detected feature.AT= the measurement area (field area, mm2).HT=
11、the total projected length in the hot-workingdirection of the inclusion or constituent in thefield, m.L= the average length in the hot-working directionof the inclusion or constituent, m.LT= the true length of scan lines, pixel lines, or gridlines (number of lines times the length of thelines divide
12、d by the magnification), mm.n = the number of fields measured.1This practice is under the jurisdiction of ASTM Committee E04 on Metallog-raphy and is the direct responsibility of Subcommittee E04.14 on QuantitativeMetallography.Current edition approved Oct. 1, 2008. Published January 2009. Originall
13、yapproved in 1988. Last previous edition approved in 2003 as E 1245 03.2For 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 AST
14、M website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NA= the number of inclusions or constituents of agiven type per unit area, mm2.Ni= the number of inclusions or constituent par-ticles or the number of feature interceptions, i
15、nthe field.NL= the number of interceptions of inclusions orconstituent particles per unit length (mm) ofscan lines, pixel lines, or grid lines.PPi= the number of detected picture points.PPT= the total number of picture points in the fieldarea.s = the standard deviation.t = a multiplier related to th
16、e number of fieldsexamined and used in conjunction with thestandard deviation of the measurements to de-termine the 95 % CIVV= the volume fraction.X= the mean of a measurement.Xi= an individual measurement.l = the mean free path (m) of the inclusion orconstituent type perpendicular to the hot-workin
17、g direction.(X = the sum of all of a particular measurement overn fields.(X2= the sum of all of the squares of a particularmeasurement over n fields.95 % CI = the 95 % confidence interval.% RA = the relative accuracy, %.4. Summary of Practice4.1 The indigenous inclusions or second-phase constituents
18、in steels and other metals are viewed with a light microscopeor a scanning electron microscope using a suitably preparedmetallographic specimen. The image is detected using atelevision-type scanner tube (solid-state or tube camera) anddisplayed on a high resolution video monitor. Inclusions aredetec
19、ted and discriminated based on their gray-level intensitydifferences compared to each other and the unetched matrix.Measurements are made based on the nature of the discrimi-nated picture point elements in the image.3These measure-ments are made on each field of view selected. Statisticalevaluation
20、of the measurement data is based on the field-to-field or feature-to-feature variability of the measurements.5. Significance and Use5.1 This practice is used to assess the indigenous inclusionsor second-phase constituents of metals using basic stereologi-cal procedures performed by automatic image a
21、nalyzers.5.2 This practice is not suitable for assessing the exogenousinclusions in steels and other metals. Because of the sporadic,unpredictable nature of the distribution of exogenous inclu-sions, other methods involving complete inspection, for ex-ample, ultrasonics, must be used to locate their
22、 presence. Theexact nature of the exogenous material can then be determinedby sectioning into the suspect region followed by serial,step-wise grinding to expose the exogenous matter for identi-fication and individual measurement. Direct size measurementrather than application of stereological method
23、s is employed.5.3 Because the characteristics of the indigenous inclusionpopulation vary within a given lot of material due to theinfluence of compositional fluctuations, solidification condi-tions and processing, the lot must be sampled statistically toassess its inclusion content. The largest lot
24、sampled is the heatlot but smaller lots, for example, the product of an ingot, withinthe heat may be sampled as a separate lot. The sampling of agiven lot must be adequate for the lot size and characteristics.5.4 The practice is suitable for assessment of the indigenousinclusions in any steel (or ot
25、her metal) product regardless of itssize or shape as long as enough different fields can be measuredto obtain reasonable statistical confidence in the data. Becausethe specifics of the manufacture of the product do influence themorphological characteristics of the inclusions, the reportshould state
26、the relevant manufacturing details, that is, dataregarding the deformation history of the product.5.5 To compare the inclusion measurement results fromdifferent lots of the same or similar types of steels, or othermetals, a standard sampling scheme should be adopted such asdescribed in Practice E45.
27、5.6 The test measurement procedures are based on thestatistically exact mathematical relationships of stereology4forplanar surfaces through a three-dimensional object examinedusing reflected light (see Note 1).5.7 The orientation of the sectioning plane relative to thehot-working axis of the product
28、 will influence test results. Ingeneral, a longitudinally oriented test specimen surface isemployed in order to assess the degree of elongation of themalleable (that is, deformable) inclusions.5.8 Oxide inclusion measurements for cast metals, or forwrought sections that are not fully consolidated, m
29、ay be biasedby partial or complete detection of fine porosity or mi-croshrinkage cavities and are not recommended. Sulfides canbe discriminated from such voids in most instances and suchmeasurements may be performed.5.9 Results of such measurements may be used to qualifymaterial for shipment accordi
30、ng to agreed upon guidelinesbetween purchaser and manufacturer, for comparison of differ-ent manufacturing processes or process variations, or to pro-vide data for structure-property-behavior studies.6. Interferences6.1 Voids in the metal due to solidification, limited hotductility, or improper hot
31、working practices may be detected asoxides because their gray level range is similar to that ofoxides.6.2 Exogenous inclusions, if present on the plane-of-polish,will be detected as oxides and will bias the measurements ofthe indigenous oxides. Procedures for handling this situationare given in 12.5
32、.9.6.3 Improper polishing techniques that leave excessivelylarge scratches on the surface, or create voids in or around3Vander Voort, G. F., “Image Analysis,” Vol 10, 9th ed., Metals Handbook:Materials Characterization, ASM, Metals Park, OH, 1986, pp. 309322.4Underwood, E. E., Quantitative Stereolog
33、y, Addison-Wesley Publishing Co.,Reading, MA, 1970.E 1245 03 (2008)2inclusions, or remove part or all of the inclusions, or dissolvewater-soluble inclusions, or create excessive relief will bias themeasurement results.6.4 Dust, pieces of tissue paper, oil or water stains, or otherforeign debris on t
34、he surface to be examined will bias themeasurement results.6.5 If the programming of the movement of the automaticstage is improper so that the specimen moves out from underthe objective causing detection of the mount or air (unmountedspecimen), measurements will be biased.6.6 Vibrations must be eli
35、minated if they cause motion inthe image.6.7 Dust in the microscope or camera system may producespurious indications that may be detected as inclusions. Con-sequently, the imaging system must be kept clean.7. Apparatus7.1 A reflected light microscope equipped with bright-fieldobjectives of suitable
36、magnifications is used to image themicrostructure. The use of upright-type microscope allows foreasier stage control when selecting field areas; however, thespecimens will require leveling which can create artifacts, suchas scratches, dust remnants and staining, on the polishedsurface (see 12.2.1).
37、The use of inverted microscopes usuallyresult in a more consistent focus between fields, thereby,requiring less focussing between fields and a more rapidcompletion of the procedure. A scanning electron microscopealso may be used to image the structure.7.2 A programmable automatic stage to control mo
38、vementin the x and y directions without operator attention is recom-mended (but not mandatory) to prevent bias in field selectionand to minimize operator fatigue.7.3 An automatic focus device may also be employed iffound to be reliable. Such devices may be unreliable whentesting steels or metals wit
39、h very low inclusion contents.7.4 An automatic image analyzer with a camera of adequatesensitivity is employed to detect the inclusions, performdiscrimination, and make measurements.7.5 A computer is used to store and analyze the measure-ment data.7.6 A printer is used to output the data and relevan
40、tidentification/background information in a convenient format.7.7 This equipment must be housed in a location relativelyfree of airborne dust. High humidity must be avoided asstaining may occur; very low humidity must also be avoided asstatic electricity may damage electronic components. Vibra-tions
41、, if excessive, must be isolated.8. Sampling8.1 In general, sampling procedures for heat lots or forproduct lots representing material from a portion of a heat lotare the same as described in Practice E45 (MicroscopicalMethods) or as defined by agreements between manufacturersand users.8.2 Character
42、ization of the inclusions in a given heat lot, ora subunit of the heat lot, improves as the number of specimenstested increases. Testing of billet samples from the extreme topand bottom of the ingots (after discards are taken) will defineworst conditions of oxides and sulfides. Specimens taken fromi
43、nterior billet locations will be more representative of the bulkof the material. Additionally, the inclusion content will varywith the ingot pouring sequence and sampling should test atleast the first, middle and last ingot teemed. The same trendsare observed in continuously cast steels. Sampling sc
44、hemesmust be guided by sound engineering judgment, the specificprocessing parameters, and producer-purchaser agreements.9. Test Specimens9.1 In general, test specimen orientation within the test lot isthe same as described in Practice E45(Microscopical Meth-ods). The plane-of-polish should be parall
45、el to the hot-workingaxis and, most commonly, taken at the quarter-thicknesslocation. Other test locations may also be sampled, for ex-ample, subsurface and center locations, as desired or required.9.2 The surface to be polished should be large enough inarea to permit measurement of at least 100 fie
46、lds at thenecessary magnification. Larger surface areas are beneficialwhenever the product form permits. A minimum polishedsurface area of 160 mm2is preferred.9.3 Thin product forms can be sampled by placing a numberof longitudinally oriented pieces in the mount so that thesampling area is sufficien
47、t.9.4 Practice E 768 lists two accepted methods for preparingsteel samples for the examination of inclusion content usingimage analysis. The standard also lists a procedure to test thequality of the preparation using differential interference con-trast (DIC).10. Specimen Preparation10.1 Metallograph
48、ic specimen preparation must be carefullycontrolled to produce acceptable quality surfaces for imageanalysis. Guidelines and recommended practices are given inMethods E3, and Practices E 45 and E 768.10.2 The polishing procedure must not alter the true appear-ance of the inclusions on the plane-of-p
49、olish by producingexcessive relief, pitting, cracking or pullout. Minor finescratches, such as from a 1-m diamond abrasive, do notusually interfere with inclusion detection but heavier scratchesare to be avoided. Proper cleaning of the specimen is necessary.Use of automatic grinding and polishing devices is recom-mended.10.3 Establishment of polishing practices should be guidedby Practice E 768.10.4 Inclusion retention is generally easier to accomplish ifspecimens are hardened. If inclusion retention is inadequatewith annealed, normalized, or low hardness as-rolled speci-m
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