1、Designation: E 768 99 (Reapproved 2005)Standard Guide forPreparing and Evaluating Specimens for AutomaticInclusion Assessment of Steel1This standard is issued under the fixed designation E 768; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、 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.1. Scope1.1 This guide2covers two preparation methods for steelmetallographic specimens that will be analy
3、zed for nonmetallicinclusions with automatic image analysis (AIA) equipment.The two methods of preparation are offered as acceptedmethods used to retain nonmetallic inclusions in steel. Thisguide does not limit the user to these methods.1.2 A procedure to test the suitability of the preparedspecimen
4、 for AIA inclusion work, using differential interfer-ence contrast (DIC), is presented.2. Referenced Documents2.1 ASTM Standards:3E3 Practice for Preparation of Metallographic SpecimensE7 Terminology Relating to MetallographyE45 Test Methods for Determining the Inclusion Contentof SteelE 883 Guide f
5、or Reflected-Light PhotomicrographyE 1122 Practice for Obtaining JK Inclusion Ratings UsingAutomatic Image AnalysisE 1245 Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic ImageAnalysis2.2 ASTM Adjuncts:4ADJE0768 Differential Interference Contrast Magn
6、ification100X and 500X (6 micrographs)3. Terminology3.1 Definitions:3.1.1 For definitions used in this practice, refer to Termi-nology E7.3.1.2 differential interference contrast microscopya com-prehensive definition appears in Guide E 883, paragraph 11.8.3.2 Definitions of Terms Specific to This St
7、andard:3.2.1 rigid grinding diska non-fabric support surface,such as a composite of metal/ceramic or metal/polymer,charged with an abrasive (usually 6 to 15-m diamond par-ticles), and used as the fine grinding operation in a metallo-graphic preparation procedure.4. Significance and Use4.1 Inclusion
8、ratings done either manually using Test Meth-ods E45or automatically using Practice E 1122 or E 1245 areinfluenced by the quality of specimen preparation. This guideprovides examples of proven specimen preparation methodsthat retain inclusions in polished steel specimens.4.2 This guide provides a pr
9、ocedure to determine if theprepared specimens are of suitable quality for subsequentrating of inclusions. None of these methods should be con-strued as defining or establishing specific procedures or limitsof acceptability for any steel grade.5. Preparation Methods5.1 Background:5.1.1 The inclusions
10、 in the plane of polish must be fullypreserved and clearly visible. Preparation should not produceexcessive relief around the perimeter of the inclusions thatwould exaggerate the size and number of inclusions on theplane of polish. In many cases, the preparation of specimensfor inclusion rating is m
11、ore readily performed after thespecimens have been hardened by a suitable heat treatmentprocedure (austenize, quench to fully martensitic structure,temper at a relatively low temperature).5.1.2 Cleanliness is an important consideration in all stagesof specimen preparation.5.1.2.1 Heat-treated specim
12、ens should be wire brushed orshot blasted or have the surface ground to remove adherentscale.5.1.2.2 After completing the grinding steps and beforeperforming the polishing steps, the specimens and specimenholders must be cleaned to prevent contamination of the next1This guide is under the jurisdicti
13、on ofASTM Committee E04 on Metallographyand is the direct responsibility of Subcommittee E04.01 on Sampling SpecimenPreparation, and Photography.Current edition approved My 1, 2005. Published May 2005. Originally approvedin 1999. Last previous edition approved in 2004 as E 76899(2004).2Supporting da
14、ta have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: E041002.3For 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 t
15、he standards Document Summary page onthe ASTM website.4A colored plate, consisting of six micrographs that illustrate the use of DIC indetermining a properly prepared sample (at 100x and 500x), is available fromASTM Headquarters. Order Adjuct: ADJE0768.1Copyright ASTM International, 100 Barr Harbor
16、Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.preparation step. Cleaning the specimens and specimen holdersbetween each grinding step can eliminate contamination ofcoarse abrasives to the following finer preparation step.5.1.2.3 After the preparation is complete, swab the surfa
17、cecarefully with cotton and a water/soap solution containing acorrosion inhibitor such as a machine coolant or ethyl alcoholsolution to remove any films or other debris that wouldinterfere with the inclusion rating.5.1.2.4 It is advisable to perform the inclusion analysis assoon as possible after pr
18、eparation to minimize staining or otherproblems that can affect the analysis.5.1.3 The two methods that follow have been found to bereliable procedures for retaining inclusions in steel and achiev-ing the desired results when evaluated by DIC. There are othermethods that will result in a quality spe
19、cimen as revealed byDIC. Each laboratory should develop preparation proceduresfor their materials so that the prepared surfaces meet therequirements presented in 6 of this guide.5.1.4 As described in Prractice E3, the specimens may besectioned and mounted to ease handling during preparation. Itis ad
20、visable to use a mounting medium that is hard enough topreserve edges and maintain flatness.5.1.5 Abrasive grit size designations in this guide areexpressed in the American National Standards Institute (ANSI)or Coated Abrasives Manufacturers Institute (CAMI) systemunits with the corresponding Federa
21、tion of European AbrasiveProcedure (FEPA) numbers in parentheses. Table 1 provides acorrelation between these two systems and the approximatemedian particle diameter for a given grit size in micrometres.5.1.6 Most preparation systems apply pressure on the speci-mens being processed. The best pressur
22、e to be used for eachpreparation step should be determined experimentally. Conver-sions between applied force and pressure are discussed in theAppendix X1.NOTE 1Care must be taken to protect the polished specimen surfacefrom scratches or contaminants when using a specimen leveling device.5.2 Silicon
23、 Carbide Procedure:5.2.1 A summary of the silicon carbide procedure can befound in Table 2.5.2.2 When using a semi-automatic polishing equipment,grinding and polishing should be performed using approxi-mately 18 kPa pressure per specimen. (For a specimen holdercontaining six 32-mm mounts, a force of
24、 approximately 87 Nmust be applied (see X1.4.2).5.2.2.1 Low pressures are recommended to ensure theretention of an assortment of inclusion types found in a varietyof steel grades. The relatively low pressures suggested in thisprocedure will not necessarily result in a satisfactory polish foretching
25、and the further evaluation of the specimens generalmicrostructure. The pressures used in the following rigid diskprocedure are more likely to result in a surface more satisfac-tory for revealing general microstructures.5.2.3 Grind the specimens on ANSI 80 grit (P80 FEPA)silicon carbide paper to ensu
26、re all sectioning artifacts anddeformation damage have been removed and the entire speci-men surface is co-planar to the grinding surface.NOTE 2If the sectioning method resulted in a smooth face and littledeformation damage, and if after securing the specimens in a fixture forpolishing, the entire s
27、urface of interest is co-planar to the grinding surface,then finer grit papers, such as ANSI 180 to 240 (P180 to P240 FEPA) canbe used for the initial grinding step.5.2.3.1 An adequate flow of water should remove all loos-ened abrasive and grinding debris from the paper during thegrinding procedure.
28、 The flow of water should ensure thespecimen is kept cool during grinding.5.2.4 Continue grinding through the sequence of siliconcarbide papers listed in Table 2. It may be necessary to cleanthe samples between every grinding step to prevent contami-nation of the next preparation step.5.2.5 After co
29、mpleting the entire grinding operation, cleanthe specimens thoroughly, using ethyl alcohol and cotton, thenrinse and dry. Ultrasonic cleaning can be used.5.2.5.1 The use of a soap and water solution in an ultrasoniccleaner can attack non-metallic inclusions in some carbon andlow alloy steels, leadin
30、g to an exaggeration in the inclusionsapparent size. Adding an inhibitor (such as that used as amachining coolant) may reduce this size exaggeration.5.2.6 Polish the specimens using 3-m diamond abrasive ona low nap cloth, such as woven wool, for 50 s. Clean and drythe specimens as described in 5.2.5
31、.5.2.7 Polish the specimens using a 1-m diamond abrasiveon a high nap cloth for 50 s. Clean and dry the specimens asdescribed in 5.2.5.5.2.8 A final manual polishing step may be added, using0.25-m diamond abrasive on a low nap cloth for 10 to 20 s,using relatively high pressure. Clean and dry the sp
32、ecimens asdescribed in 5.2.5.5.2.8.1 Ultrasonic cleaning is not recommended after thefinal manual or automatic polishing step. Ultrasonic cleaningcan cause cavitation damage, ultimately distorting the inclu-sion sizes.NOTE 3Depending on the material, it may be advisable to avoid waterafter polishing
33、.TABLE 1 Comparison of ANSI (CAMI) versus FEPA versusMedian Diameter of Grit Size in MicrometersANSIA(CAMI)BFEPACApproximate MedianDiameter(m)60 P60 25080 P80 180100 P100 150120 P120 125150 P150 90180 P180 75220 P220 63240 P240 58.5P280 52.2280 P320 46.2320 P360 40.5P400 35.0360 P500 30.2400 P600 25
34、.8P800 21.8500 P1000 18.3600 P1200 15.3800 P2400 8.41200 P4000D3.0AANSI - American National Standards InstituteBCAMI - Coated Abrasives Manufacturers InstituteCFEPA - Federation of European Abrasive ProducersDNot a FEPA designationE 768 99 (2005)25.3 Rigid Grinding Disk Procedure:5.3.1 Asummary of t
35、he rigid grinding disk procedure can befound in Table 3.5.3.2 Semi-automatic grinding equipment is required, withspecimens contained in a circular fixture for the entire proce-dure. For 5.3.2-5.3.5, a pressure of 42 kPa should be appliedper specimen. (For a specimen holder containing six 32-mmcircul
36、ar mounts, a force of approximately 203 N must beapplied (see X1.4.3).5.3.3 Grind for at least 15 s after achieving a co-planarcondition, using a 150-grit alumina grinding stone at 1450 rpmor 80-grit (P80 FEPA) alumina/zirconia grinding paper at 300rpm.5.3.3.1 An adequate flow of water should remove
37、 all loos-ened abrasive and grinding debris from the paper during thegrinding procedure. The flow of water should ensure thespecimen is kept cool during grinding.5.3.3.2 It may be necessary to clean the samples betweenevery grinding step to prevent contamination of the nextpreparation step.5.3.4 Fin
38、ish grind using 9-m diamond on a rigid grindingdisk for3mat150rpm, using an alcohol/glycol lubricant.Clean the specimens and fixture thoroughly (ultrasonic clean-ing is helpful) with alcohol and cotton, then dry with forced air.5.3.4.1 The use of a soap and water solution in an ultrasoniccleaner can
39、 attack non-metallic inclusions in some carbon andlow alloy steels, leading to an exaggeration in the inclusionsapparent size. Adding an inhibitor (such as that used as amachining coolant) may reduce this size exaggeration.5.3.5 Rough polish using 3-m diamond on a napless cloth(silk or non-woven che
40、motextile) or a low nap cloth (wovenwool) for 4 min at 150 rpm using alcohol/glycol lubricant.Clean as in 5.3.4.5.3.6 Final polish using 1-m diamond on a high nap clothfor 2 min at 150 rpm, using alcohol/glycol lubricant. Clean asin 5.3.4.5.3.6.1 Ultrasonic cleaning is not recommended after thefinal
41、 polishing step. Ultrasonic cleaning can cause cavitationdamage, ultimately distorting the inclusion sizes.TABLE 2 Preparation Method I Silicon Carbide Abrasive Paper GrindingSurface Coolent/LubricantAbrasive Size/TypeANSIAFEPABTime(seconds)ForceCnewtons lbsSurfaceSpeedRPMRelative RotationPlanar Gri
42、ndingPaper Water 80 P80 grit SIC 60 14 2 300 ComplementaryDFine GrindingPaper Water 120 P120 grit SIC 14 2 300 ComplementaryPaper Water 240 P240 grit SIC 60 14 2 300 ComplementaryPaper Water 320 P500 grit SIC 60 14 2 300 ComplimentaryPaper Water 400 P600 grit SIC 60 14 2 300 ComplementaryPaper Water
43、 600 P1200 grit SIC 60 14 2 300 ComplimentaryPaper Water 800P2400 grit SIC 60 14 2 300 ComplementaryRough PolishingNAP free cloth Extending fluid 3 m diamond 50 14 2 150 ComplementaryFinal PolishingLow nap cloth Extending fluid 1 m diamond 50 14 2 150 ComplementaryOptional Polishing (manual)Low nap
44、cloth Extending fluid 1 m diamond 50 relatively high NA NAEAAmerican National Standards Institute (ANSI) designation of grit size.BFederation of European Producers of Abrasives (FEPA) designation of grit size.CForce per 3-mm (1.25-in.) diameter specimen.DComplementary rotation, surface and specimens
45、 spin in same direction.ESince this optional step is completed manually, these two categories are not applicable.TABLE 3 Preparation Method II - Rigid Grinding Disk ProcedureSurface Coolant/LubricantAbrasive Size/Type ANSIAFEPABTime - seconds ForceCnewtons lbsSurface SpeedRPMRelative RotationPlanar
46、GrindingAlumina/zirconia paper Water 80 P80 grit 15 34 8 300 ComplementaryDOrAlumina grinding stone Water 150 P150 grit 15 34 8 1450 ComplementaryFine GrindingRigid grinding disk Alcohol/glycol 9 m diamond 180 34 8 150 ComplementaryRough PolishingNapless or stiff napped cloth Alcohol/glycol 3 m diam
47、ond 240 34 8 150 ComplementaryFinal PolishingSoft short napped cloth Alcohol/glycol 1 m diamond 120 34 8 150 ComplementaryOptional PolishingPorous Synthetic Cloth Water Alkaline Colloidal Silica orAcidic Colloidal AluminaE90 100 23 150 ComplementaryAAmerican National Standards Institute (ANSI) desig
48、nation of grit size.BFederation of European Producers of Abrasives (FEPA) designation of grit size.CForce per 32-mm (1.25-in.) diameter specimen.DComplementary rotation surface, and specimens spin in same direction.EWater is substituted for the colloidal oxide during the last 20 s.E 768 99 (2005)35.
49、3.7 An optional oxide-polishing step, using a poroussynthetic cloth with either alkaline colloidal silica or acidiccolloidal alumina, may be used if necessary to eliminate finescratches. The conditions are 90 s at 150 rpm, 100 N, withwater substituted for the colloidal oxide during the last 20 s.Clean as in 5.3.4.6. DIC Evaluation Method46.1 A microscope equipped with DIC illumination at mag-nifications of about 100x and 500x should be used whiledeveloping the preparation procedure to verify the true surf
