1、Designation: E 1245 03Standard 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 adoption or, in the
2、 case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis practice may be used to produce stereological measurements that describe the amou
3、nt, 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 obtaining stereo-logical
4、 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 this practiceto asse
5、ss 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 theseconstituents in a pr
6、eferred 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 attainment of statist
7、ically 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 measured values are stated in SI units, which are tobe regarded as standard. Equivalent inch-pound values are i
8、nparentheses and may be approximate.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 limi
9、tations prior to use.2. Referenced Documents2.1 ASTM Standards:E 3 Methods of Preparation of Metallographic Specimens2E 7 Terminology Relating to Metallography2E 45 Test Methods for Determining the Inclusion Contentof Steel2E 768 Practice for Preparing and Evaluating Specimens forAutomatic Inclusion
10、 Assessment of Steel23. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this practice, seeTerminology E 7.3.2 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 ar
11、ea (field area, mm2).HT= 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
12、length of thelines divided by the magnification), mm.n = the number of fields measured.NA= the number of inclusions or constituents of agiven type per unit area, mm2.1This practice is under the jurisdiction of ASTM Committee E04 on Metallog-raphy and is the direct responsibility of Subcommittee E04.
13、14 on QuantitativeMetallography.Current edition approved Jan. 10, 2003. Published April 2003. Originallyapproved in 1988. Last previous edition approved in 2000 as E 1245 00.2Annual Book of ASTM Standards, Vol 03.01.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken
14、, PA 19428-2959, United States.Ni= the number of inclusions or constituent par-ticles or the number of feature interceptions, inthe 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 pi
15、cture points.PPT= the total number of picture points in the fieldarea.s = the standard deviation.t = a multiplier related to the 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 measureme
16、nt.Xi= an individual measurement.l = the mean free path (m) of the inclusion orconstituent type perpendicular to the hot-working 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 % confi
17、dence interval.% RA = the relative accuracy, %.4. Summary of Practice4.1 The indigenous inclusions or second-phase constituentsin steels and other metals are viewed with a light microscopeor a scanning electron microscope using a suitably preparedmetallographic specimen. The image is detected using
18、atelevision-type scanner tube (solid-state or tube camera) anddisplayed on a high resolution video monitor. Inclusions aredetected 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
19、-nated picture point elements in the image.3These measure-ments are made on each field of view selected. Statisticalevaluation 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 i
20、ndigenous inclusionsor second-phase constituents of metals using basic stereologi-cal procedures performed by automatic image analyzers.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
21、 of exogenous inclu-sions, other methods involving complete inspection, for ex-ample, ultrasonics, must be used to locate their 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 exogenou
22、s matter for identi-fication and individual measurement. Direct size measurementrather than application of stereological methods is employed.5.3 Because the characteristics of the indigenous inclusionpopulation vary within a given lot of material due to theinfluence of compositional fluctuations, so
23、lidification condi-tions and processing, the lot must be sampled statistically toassess its inclusion content. The largest lot 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 f
24、or the lot size and characteristics.5.4 The practice is suitable for assessment of the indigenousinclusions in any steel (or other metal) product regardless of itssize or shape as long as enough different fields can be measuredto obtain reasonable statistical confidence in the data. Becausethe speci
25、fics of the manufacture of the product do influence themorphological characteristics of the inclusions, the reportshould state 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
26、same or similar types of steels, or othermetals, a standard sampling scheme should be adopted such asdescribed in Practice E 45.5.6 The test measurement procedures are based on thestatistically exact mathematical relationships of stereology4forplanar surfaces through a three-dimensional object exami
27、nedusing reflected light (see Note 1).5.7 The orientation of the sectioning plane relative to thehot-working axis of the product will influence test results. Ingeneral, a longitudinally oriented test specimen surface isemployed in order to assess the degree of elongation of themalleable (that is, de
28、formable) inclusions.5.8 Oxide inclusion measurements for cast metals, or forwrought sections that are not fully consolidated, may 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 inst
29、ances and suchmeasurements may be performed.5.9 Results of such measurements may be used to qualifymaterial for shipment according to agreed upon guidelinesbetween purchaser and manufacturer, for comparison of differ-ent manufacturing processes or process variations, or to pro-vide data for structur
30、e-property-behavior studies.6. Interferences6.1 Voids in the metal due to solidification, limited hotductility, or improper hot 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 de
31、tected as oxides and will bias the measurements ofthe indigenous oxides. Procedures for handling this situationare given in 12.5.9.6.3 Improper polishing techniques that leave excessivelylarge scratches on the surface, or create voids in or aroundinclusions, or remove part or all of the inclusions,
32、or dissolvewater-soluble inclusions, or create excessive relief will bias themeasurement results.3Vander Voort, G. F., “Image Analysis,” Vol 10, 9th ed., Metals Handbook:Materials Characterization, ASM, Metals Park, OH, 1986, pp. 309322.4Underwood, E. E., Quantitative Stereology, Addison-Wesley Publ
33、ishing Co.,Reading, MA, 1970.E12450326.4 Dust, pieces of tissue paper, oil or water stains, or otherforeign debris on the 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 obje
34、ctive causing detection of the mount or air (unmountedspecimen), measurements will be biased.6.6 Vibrations must be eliminated 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 s
35、ystem must be kept clean.7. Apparatus7.1 A reflected light microscope equipped with bright-fieldobjectives of suitable magnifications is used to image themicrostructure. The use of upright-type microscope allows foreasier stage control when selecting field areas; however, thespecimens will require l
36、eveling which can create artifacts, suchas scratches, dust remnants and staining, on the polishedsurface (see 12.2.1). 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.
37、 A scanning electron microscopealso may be used to image the structure.7.2 A programmable automatic stage to control movementin 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 fo
38、cus device may also be employed iffound to be reliable. Such devices may be unreliable whentesting steels or metals with 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
39、.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 relevantidentification/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 asstaini
40、ng may occur; very low humidity must also be avoided asstatic electricity may damage electronic components. Vibra-tions, 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 de
41、scribed in Practice E 45 (MicroscopicalMethods) or as defined by agreements between manufacturersand users.8.2 Characterization 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 b
42、ottom of the ingots (after discards are taken) will defineworst conditions of oxides and sulfides. Specimens taken frominterior billet locations will be more representative of the bulkof the material. Additionally, the inclusion content will varywith the ingot pouring sequence and sampling should te
43、st atleast the first, middle and last ingot teemed. The same trendsare observed in continuously cast steels. Sampling schemesmust be guided by sound engineering judgment, the specificprocessing parameters, and producer-purchaser agreements.9. Test Specimens9.1 In general, test specimen orientation w
44、ithin the test lot isthe same as described in Practice E 45 (Microscopical Meth-ods). The plane-of-polish should be parallel 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
45、desired or required.9.2 The surface to be polished should be large enough inarea to permit measurement of at least 100 fields at thenecessary magnification. Larger surface areas are beneficialwhenever the product form permits. A minimum polishedsurface area of 160 mm2(0.25 in.2) is preferred.9.3 Thi
46、n product forms can be sampled by placing a numberof longitudinally oriented pieces in the mount so that thesampling area is sufficient.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 pro
47、cedure to test thequality of the preparation using differential interference con-trast (DIC).10. Specimen Preparation10.1 Metallographic specimen preparation must be carefullycontrolled to produce acceptable quality surfaces for imageanalysis. Guidelines and recommended practices are given inMethods
48、 E 3, 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-polish by producingexcessive relief, pitting, cracking or pullout. Minor finescratches, such as from a 1-m diamond abrasive, do notusually interfere with inclusion de
49、tection 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-mens, they should be subjected to a standard heat treatment(hardening) cycle, appropriate for the grade. Because inclusionretention and cracking at carbides may be a prob
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