1、Designation: E 2142 01Standard Test Methods forRating and Classifying Inclusions in Steel Using theScanning Electron Microscope1This standard is issued under the fixed designation E 2142; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, 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.1. Scope1.1 This test method covers procedures to obtain particlesize distribution, chemical classification, and
3、 E 45 ratings ofinclusions in steels using an automated scanning electronmicroscope (SEM) with X-ray analysis and automatic imageanalysis capabilities.1.2 There are three discrete methods described. Method 1 isthe SEM analog of E 1122, which uses image analysis and lightmicroscopy to produce automat
4、ed E 45 ratings. Method 2produces similar ratings based predominantly on sorting inclu-sions by chemistry into the traditional classes defined in E 45.Method 3 is recommended when explicit detail is needed onparticular inclusion types, not necessarily defined in E 45, suchas to verify the compositio
5、n of inclusions in inclusion-engineered steel. Method 3 reports stereological parameterssuch as volume or number fraction, rather than E 45 typeratings.1.3 This test method deals only with the recommended testmethods and nothing in it should be construed as defining orestablishing limits of acceptab
6、ility for any grade of steel orother alloy where the method is appropriate.1.4 The values stated in SI units are to be regarded as thestandard. Values in parentheses are conversions and are ap-proximate, and for information only.1.5 This standard does not purport to address all of thesafety concerns
7、, 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 to use.2. Referenced Documents2.1 ASTM Standards:E3 Practice for Preparation of Metallographi
8、c Specimens2E 7 Terminology Relating to Metallography2E45 Test Methods for Determining the Inclusion Contentof Steel2E 766 Practice for Calibrating the Magnification of a Scan-ning Electron Microscope2E 768 Practice for Preparing and Evaluating Specimens forAutomated Inclusion Analysis of Steel2E 11
9、22 Practice for Obtaining Inclusion Ratings UsingAutomatic Image Analysis2E 1245 Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic ImageAnalysis2E 1508 Guide for Quantitative Analysis by Energy Disper-sive Analysis22.2 Adjuncts:ANSI/IEEE STD 759 IEEE S
10、tandard Test Procedure forSemiconductor X-Ray Energy Spectrometers33. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, see Terminology E 7.3.2 Definitions of Terms Specific to This Standard:3.2.1 Analysis Rules3.2.1.1 acquisition analysis rulesinclude the criteria totermin
11、ate X-ray collection (counts or time, or both), the list ofelements to be analyzed, the number of fields or particles to beanalyzed, morphologies of particles from which spectra will becollected, etc. (see Appendix X1 for a more complete listing oftypical Acquisition Rules).3.2.1.2 post-acquisition
12、analysis rulesdefine ratios ofX-ray intensities or elemental compositions required to identifyan inclusion as belonging to a particular chemical classificationand, for Methods 1 and 2 herein, define the main inclusionclass (A, B, or C) to which each chemical classificationbelongs.3.2.2 chemical clas
13、sificationdefined compositional cat-egories in which inclusions are placed according to the analysisrules. Categories may be broad (e.g., sulfide, aluminate,silicate) or more precise (e.g., calcium sulfide, calcium silicate,anorthite, etc.).1These test methods are under the jurisdiction of ASTM Comm
14、ittee E04 onMetallography and are the direct responsibility of Subcommittee E04.11 on X-Rayand Electron Metallogrpahy jointly with E04.09 on Steel Inclusions.Current edition approved April 10, 2001. Published June 2001.2Annual Book of ASTM Standards, Vol 03.01.3This standard is available from The In
15、stitute of Electrical and ElectronicsEngineers, Inc., 345 East 47th Street, New York, NY 10017.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.3 critical aspect ratiothe aspect ratio of a singleinclusion that defines the boundary
16、 between “globular” and“elongated”.3.2.4 discontinuous stringertwo or more Type C or threeor more Type B inclusions aligned in a plane parallel to the hotworking axis and offset from the stringer centerline by no morethan 15 m (.0006 in), with a separation of 4 12 12B $2 9 9 15 15C $2 5 5 12 12D $2
17、8 8 13 13TABLE 2 Minimum Values for Inclusion Severity Rating Levelsfor Measurements in Micrometers (For expression in other units,see E 1122,Table2)Test Method E45Rating Limits (m at 13 or count)Severity A B C D0.5 37.0 17.2 17.8 11.0 127.0 76.8 75.6 21.5 261.0 184.2 176.0 42.0 436.1 342.7 320.5 92
18、.5 649.0 554.7 510.3 163.0 898.0 822.2 746.1 253.5 1181.0 1147.0 1029.0 364.0 1498.0 1530.0 1359.0 494.5 1898.0 1973.0 1737.0 815.0 2230.0 2476.0 2163.0 100E2142014features. Polishing must not alter the true appearance of theinclusions by excessive relief, pitting, and pull-out. Use ofautomatic grin
19、ding and polishing devices is recommended.9.3 Inclusion retention is generally easier to accomplish inspecimens that are hardened rather than in annealed condition.If inclusion retention is inadequate in annealed specimens, theyshould be subjected to a standard heat treatment cycle using arelatively
20、 low tempering temperature. After heat treatment, thespecimen must be descaled and the longitudinal plane must bereground below any decarburization. This recommendationonly applies to heat-treatable steel grades.9.4 Mounting of specimens is not required if unmountedspecimens can be properly polished
21、.9.5 Polishing practice should follow Practice E 768.10. Calibration and Standardization10.1 The SEM magnification should be calibrated accordingto E 766. It is important to calibrate the magnification of theSEM to obtain accurate E 45 ratings and to ensure that analysistime is minimized. The number
22、 of particles of a given sizeincreases strongly as size decreases; if particles below thedesired low size limit are included due to magnification error,the number of spectra collected, and therefore the total analysistime, will increase significantly.10.2 The EDX energy calibration should be done ac
23、cordingto section 8.1 of E 1508.10.3 The EDX energy resolution should be checked peri-odically. The energy resolution, defined as the Full Width atHalf Maximum (FWHM) height of the Mn Ka X-ray line, afterbackground has been subtracted, should be measured accord-ing to the practice suggested by the m
24、anufacturer, provided thatit is in accordance with the IEEE methodology.11. Procedure11.1 Prepare specimens following the standard protocol setforth in Practice E 768.At this time, a small piece of aluminumtape or other reference material may be placed on the edge ofthe sample. The tape may later be
25、 used as a target in order todetermine the proper setting of the electron probe current or tocheck its stability.11.2 Position the sample in the SEM at a working distancethat is suitable for both BSE and EDX.11.3 Set the beam accelerating voltage appropriately for theelemental range of interest, bea
26、ring in mind that excessivevoltage will give rise to an (unwanted) increase in matrixcontribution to the spectrum. Use of 1015 kV is typical,although slightly lower or higher voltages may be appropriatedepending on the particular application. Use the microscopemanufacturers procedures for saturating
27、 the filament, aligningthe column and setting other parameters to optimize imagequality.11.4 Calibrate the X-ray analyzer such that the collectedspectrum will include all the elements of interest; 010 keV isrecommended. If there are X rays of interest above 10 keV(such as Pb L lines), use 020 keV.11
28、.5 Set electron probe current by direct measurement usinga pico-ammeter and Faraday cup, if the optimum probe currenthas previously been determined. Alternatively, the current canbe set by moving the aluminum tape under the beam andrecording X-ray counts. Probe current (or “spot size”, which ispropo
29、rtional to probe current) is adjusted until approximately40 % dead time, if possible, is achieved. The steel matrix itselfmay be used as the basis of current setting in place of the tape,but this will likely result in the least consistent setting of thedescribed methods.11.6 Select the BSE imaging m
30、ode, which is used becausethe brightness of a feature in the BSE image is directly relatedto its average atomic number. The matrix, which consistsprimarily of iron, will be brighter than some inclusions (e.g.,MnS) and darker than other inclusions (e.g., Pb). Sinceinclusions are discriminated by the
31、BSE gray level, thethreshold(s) must be set appropriately using the procedurerecommended by the manufacturer.11.7 Select and store the region of the sample to beexamined following the stage control manufacturers recom-mended procedure. The region can be larger than but notsmaller than 160 mm2; if th
32、e sample region is larger, then thesoftware shall select a contiguous area of exactly 160 mm2wholly contained within the user-selected region to analyze. InMethod 3 of this Test Method, analysis can be based on thenumber of inclusions detected rather than sample area.11.8 As the beam rasters the sel
33、ected region, the softwarerecognizes features that fall within the previously defined rangeof gray-levels. Morphological and chemical parameters areimmediately calculated and stored or, alternatively, raw data isstored for off-line processing.11.8.1 In Test Method E45inclusions are examined usingfie
34、ld areas of 0.50 mm2and magnifications of 1003. Theinclusions can be examined and discriminated by type usingmagnifications other than 1003 and field areas other than 0.50mm2as long as the severity ratings (see Section 12) are basedon the required 0.50 mm2field area.11.9 Define the Analysis Rules:11
35、.9.1 The EDX acquisition should continue until sufficientstatistics are accumulated to classify the inclusion. For adiscussion on X-ray counting and chemical classificationstatistics, see Appendix X2 and standard text books.4Theminimum number of counts in a peak necessary for peakidentification must
36、 be entered.11.9.2 Define the relevant chemical classes and their analy-sis rules. In Method 2, for example, at least three chemicalclasses are defined: sulfides, aluminates, and silicates. Addi-tional classes may be defined, depending on the application.For example, a “calcium silicate” class may b
37、e defined andincluded as Type B, as such inclusions appear similar to andhave the same detrimental effects as traditional Type Binclusions. Each chemical class and the main inclusion class towhich it is assigned should be reported.11.9.3 Define the measure of intensity in the X-ray spectrumwhich mus
38、t be met in order to identify the particle as belongingto a certain classification. Each class should be defined in termsof one or more of the following: (1) peak intensity range, (2)peak to background ratio, (3) peak intensity ratios, (4) elemen-tal percentage as calculated by established methods,
39、or (5)4Goldstein, et al, Scanning Electron Microscopy and X-Ray Microanalysis, 2nded, Plenum Publishing Corporation, New York, NY, 1992, pp 493-505.E2142015other chemical measurement(s) that characterizes a specifictype of inclusion. This choice is either narrowed or made by thesystem or software ma
40、nufacturer.11.10 Set the relevant imaging parameters such as themagnification(s) to be used, the minimum and maximumparticle sizes to be recorded, and the critical aspect ratiodefining an elongated inclusion (see 11.14). Appendix X1provides a more complete list of analysis rules.11.10.1 For the sele
41、cted magnification, digital imaging reso-lution should be chosen such that there are an adequate numberof pixels in each inclusion for the computer program toaccurately make measurements. In order to detecta2mparticle, the step size of the electron probe, which is in fact thepixel size, must be at m
42、ost 2 m. If a 256 3 256 image isdisplayed on a 10 cm screen, the field of view is 512 m wide,and the magnification is 195.3 3 (magnification = 10/0.0512).However, to accurately measure the size ofa2mparticle towithin, say, 10%, a step size of 0.2 m would be dictated,corresponding to a magnification
43、of 19533 . Depending uponthe inclusion analysis software, such pixel size and magnifica-tion may be selected automatically, based on the minimuminclusion size of interest input by the user. In the examplegiven, a magnification of 195.33 could be used to search forinclusions; once detected, the magni
44、fication is automaticallyincreased to 19533 to measure the inclusion dimensions. Theinclusion analysis software must include this or an equivalentanalysis strategy to provide the required accuracy.11.11 Start the analysis, which will run unattended in acompletely automated system.11.12 Ratings simil
45、ar to E45 ratings will be determinedautomatically within Methods 1 and 2 of this Test Method.Inclusions will be classified according to type (or chemistry),morphology and thickness. Since ratings using light micros-copy may differ from those using the SEM, ratings resultingfrom application of this T
46、est Method shall be called E45-SEM1, if method 1 is used, and E45-SEM2, if method 2 isused.11.13 The acquired raw data should be saved, unaltered bythe application of any analysis software. The raw data can thenbe used at a later time for re-classification of the inclusionsbased on different criteri
47、a.11.14 A critical parameter in the morphological character-ization of an inclusion is the Aspect Ratio (AR), at or abovewhich an inclusion is considered elongated. In Practice E 1122,which relies on morphology to distinguish oxide types, arelatively high AR of 5 is used in order to more reliablydif
48、ferentiate silicates, which are generally highly elongated,from aluminates, which are less elongated. In this Test Method,the X-ray spectrum from the inclusion is directly obtained andwill serve to differentiate aluminates from silicates, reducingthe dependence on morphology. Therefore, a less strin
49、gent andmore intuitive test of elongation, namely that a particle has anAR $ 3, can be applied. For consistency with E 1122,however, Method 1, which is the SEM analog of E 1122, willretain the use of 5 as the critical AR. In Method 2, used for“chemistry-based” E45 ratings, and Method 3, used forcustom analyses, a critical AR of 3 is suggested. Inclusionanalysis software must allow the critical AR to be selectable asan Analysis Rule, with default settings as described above.11.15 In Method 3, the analysis will automatically terminatewhen a minimum number of inclusions h
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