1、Designation: E 716 94 (Reapproved 2002)Standard Practices forSampling Aluminum and Aluminum Alloys forSpectrochemical Analysis1This standard is issued under the fixed designation E 716; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, 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 These practices describe the sampling of aluminum andaluminum-base alloys to obtain a chill-cast disk
3、suitable forquantitative optical emission spectrochemical analysis. Thedisk in the region to be excited is representative of the melt orproduct and gives a repeatability of results which approachesthat of the reference materials used.1.2 These practices describe procedures for representativesampling
4、 of molten metal, from fabricated or cast productswhich can be melted, and from other forms which cannot bemelted.1.3 This standard does not purport to address all of thesafety problems, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate s
5、afety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in 5.1 and 6.2.2. Referenced Documents2.1 ASTM Standards:E 101 Test Method for Spectrographic Analysis of Alumi-num and Aluminum Alloys by the Point-to-Pla
6、ne Tech-nique2E 227 Test Method for Optical Emission SpectrometricAnalysis of Aluminum and Aluminum Alloys by thePoint-to-Plane Technique2E 401 Practice for Bonding Thin Spectrochemical Samplesand Standards to a Greater Mass of Material3E 607 Test Method for Optical Emission SpectrometricAnalysis of
7、 Aluminum and Aluminum Alloys by thePoint-to-Plane Technique, Nitrogen Atmosphere3E 1251 Test Method for Optical Emission SpectrometricAnalysis of Aluminum and Aluminum Alloys by the ArgonAtmosphere, Point-to-Plane, Unipolar Self-Initiating Ca-pacitor Discharge33. Summary of Practices3.1 Molten meta
8、l representative of the furnace melt ispoured into a specified mold to produce a chill-cast disk. Thedisk is machined to a specified depth that represents theaverage composition and produces an acceptable surface forexcitation.3.2 Fabricated, cast, or wrought products are remelted andcast into molds
9、, briquetted and remelted, bonded to moremassive material, or excited directly without remelting.3.3 Special practices are included for the sampling andanalysis of aluminum-silicon alloys, containing greater than14 % silicon.4. Significance and Use4.1 These practices, used in conjunction with the fo
10、llowingappropriate quantitative optical emission spectrochemicalmethods, Test Methods E 101, E 227, E 607, and E 1251, aresuitable for use in manufacturing control, material or productacceptance, and research and development.5. Apparatus5.1 Ladle, capable of holding a minimum of 250 g (8.8 oz)of mol
11、ten metal, with a handle of sufficient length to reach intoa furnace, trough, or crucible. The ladle should be lightlycoated with a tightly adhering ladle wash that will notcontaminate the sample (Note 1).NOTE 1Caution: Traces of moisture in the coating may cause dan-gerous spattering.NOTE 2A suitab
12、le ladle wash may be prepared as follows: Mix 255 g(9 oz) of fine whiting (CaCO3) with 3.8 L (1 gal) of water and boil for 20min. Add 127 g (4.5 oz) of sodium silicate solution (40 to 42B) and boilfor 30 min. Stir well before using.45.2 Sample Molds, capable of producing homogenous chill-cast disks
13、having smooth surfaces, free of surface pockets andporosity. These castings should have a spectrochemical re-sponse similar to the reference materials used in preparing theanalytical curves and must have a repeatability from excitation-to-excitation of no more than 2 % relative on major elements.1Th
14、ese practices are under the jurisdiction of ASTM Committee E01 onAnalytical Chemistry for Metals, Ores, and Related Materials and are the directresponsibility of Subcommittee E01.04 on Aluminum and Magnesium.Current edition approved Jan. 15, 1994. Published March 1994. Originallypublished as E 716 8
15、0. Last previous edition E 716 85 (1989).2Annual Book of ASTM Standards, Vol 03.05.3Annual Book of ASTM Standards, Vol 03.06.4Other proprietary ladle washes such as Dycote, available from Foseco, Inc., P.O. Box 8728, Cleveland, OH 44135; and Zirconite, available from Titanium AlloyMfg. Co., 111 Broa
16、dway, New York, NY 10006, have been found suitable for thispurpose.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.They must be representative of the melt in the region excited.Several types of molds have been found acceptable:5.2.1
17、Type A, book mold, is shown in Fig. 1. The advantageof this mold is simplicity and low cost. This mold produces avertically cast disk with the sprue on its edge. The molddimensions are such as to produce a disk approximately 64 mm(2.5 in.) in diameter by 6 to 8 mm (0.24 to 0.32 in.) inthickness. A c
18、ircular central recess 15 to 25 mm (0.6 to 1.0 in.)in diameter on one side of the disk facilitates machining of thatside in preparation for excitation. It also promotes moreuniform freezing of the raised peripheral area. The moldmaterial should be steel or cast iron and should weighapproximately 2 t
19、o 3 kg (5 to 7 lb).5.2.2 Type B, center-pour mold, is shown in Fig. 2. Theadvantage of this mold is that the sample obtained may beexcited around the entire annular area. This mold produces ahorizontally cast disk with the sprue over the center on the backside. The mold dimensions are such as to pro
20、duce a diskapproximately 64 mm (2.5 in.) in diameter by 6 to 13 mm (0.24to 0.50 in.) in thickness. A circular central recess 10 to 20 mm(0.4 to 0.8 in.) in diameter on one side of the disk facilitatesmachining of that side in preparation for excitation. It alsopromotes more uniform freezing of the r
21、aised peripheral area,but the corresponding raised portion of the mold must not be solarge as to restrict the throat for the sprue. A slight taper, 1 to2 deg, on the hinged portion of the mold facilitates openingwhen a disk has been cast. The mold material should be steelor cast iron and should weig
22、h approximately 3.5 to 4.5 kg (8 to10 lb).NOTE 3Prepare the surface of the mold cavity to minimize theformation of gas pockets on the surface of the castings and to resist rustingof the mold cavity surface. To do this, blast the inner surface with a sharpgrit that cuts rather than peens. The resulti
23、ng finely roughened face isessential for obtaining a smooth and uniform surface on the cast disk.Next, degrease the mold, place in a cold furnace, and raise the temperatureto 400C (752F). At this temperature and throughout the remainder of theheating cycle, introduce steam into the furnace. Raise th
24、e temperature to540C (1004F) and maintain for 4 h. The resulting black oxide coating istenacious and of a dull black appearance.5.2.2.1 Special Type B Mold, which produces a disk 6 mm(0.24 in.) thick, is required for undiluted aluminum-siliconalloys containing greater than 14 % silicon.5.2.3 Vacuum
25、Mold5is shown in Fig. 4. This mold pro-duces disks that are 38 mm (1.5 in.) in diameter and 13 mm(0.5 in.) thick and weigh approximately 40 g (1.4 oz). Themold consists of a solid copper base and a porous bronze wallin the form of a composite mold insert which is located in asteel mold body. A graph
26、ite coated cast iron tip is attached tothe mold body by a spring clamp assembly. The vacuum sourcecan be either a small battery-operated vacuum pump or arubber syringe connected to the mold body.5.2.4 Other Types of MoldsOther molds of different types,materials, and dimensions may be substituted pro
27、vided that theuniformity of the samples so obtained is comparable to theuniformity of samples obtained from Type A or B molds, andfurthermore that such samples have a spectrochemical responsesimilar to the reference materials used for preparing theanalytical curve.5.3 Lathe, capable of machining a s
28、mooth flat surface andhaving automatic cross feed. A milling machine may also beused.5.4 Tool BitsEither alloy steel or cemented carbide isrecommended. The best shape of the tool varies with the typeand speed of the lathe, but in general, soft metals require lesstop and side rake than steel. For exa
29、mple, for pure aluminum,a top rake of 0 and a side rake of 0 to 6 should provesatisfactory. Also a side clearance of about 6 and a frontclearance of 15 should be satisfactory for all aluminum disksamples. The nose of the tool should be rounded. A tool bitdesign that has been found satisfactory for m
30、ost aluminumalloys is shown in Fig. 5.5.5 Portable Electric Melting Furnace,6equipped with agraphite crucible with a minimum capacity of 200 g (7.1 oz) ofmolten aluminum, and capable of maintaining temperatures formelting aluminum alloys.6. Materials6.1 Graphite Rods6.15 by 300-mm (0.242 by 12-in.)s
31、pectroscopic electrodes are satisfactory.6.2 Phosphorus, red, amorphous.NOTE 4Caution: Provide adequate ventilation when phosphorus isadded to molten metal.7. Preparation of Samples7.1 Molten Metal:7.1.1 Chill-Cast Disk by Molds A or B:7.1.1.1 When a furnace or crucible of molten metal is to besampl
32、ed, the temperature must be well above the point atwhich any solid phase could be present. Using the ladle or aseparate skimming tool, coated with a dry, tightly adheringmold wash (Note 2) and free of any remaining previous metal,push any dross away from the sampling area. Next, dip theladle sideway
33、s into the clear area well below the surface andstir momentarily. Then turn the ladle upright, and quicklywithdraw. Two things are thus accomplished, namely, heating5A portable Vacuum Sampler, available from Aluminum Company of America,Alcoa Center, PA 15069, has been found suitable for this purpose
34、.6A Jelrus Handy-Melt furnace and graphite crucible, available from Cole-ParmerInstrument Co., 7425 North Oak Park Ave., Chicago, IL 60648, has been foundsuitable for this purpose.FIG. 1 Type A Mold and SampleE 716 94 (2002)2the ladle prevents metal freezing on the wall and obtainingmetal well benea
35、th the surface minimizes the danger ofinclusion of small particles of oxide.7.1.1.2 Unless the mold is already hot, cast a preliminarydisk into the clean mold in order to preheat it and discard thisdisk. Remove excess metal from the ladle, dip into the moltenmetal as before, and fill the mold with a
36、n even rate of pourwhich allows the escape of air from the mold. Do not dump themetal into the mold. Avoid overfilling the sprue, otherwise themold may be difficult to open. Allow the metal to freeze quietlywithout jarring. The surface of the disk must be free of anyshrinkage, inclusions, cracks, or
37、 roughness. Cut off the sprueand machine the raised peripheral area surrounding the recessto a depth of 14 to 22 % of the original thickness. This depthis important because it corresponds to the composition on thephase diagram that best represents the average composition ofthe whole disk and therefo
38、re the actual composition of themelt. Any other depth may result in a different analysis andtherefore cannot be accepted as valid. It is advisable todetermine the most appropriate machining depth for theparticular disk thickness used. The machined surface must besmooth and free of scuffs, pits, or i
39、nclusions. The ideal surfaceis neither polished nor visibly grooved but should be a surfaceshowing very fine tool marks. More specifically, the idealsurface may be defined as approximately a 1.6 3 103-mm(63-in.) standard machine finish. A surface much finer ormuch coarser may result in an apparent a
40、nalytical difference.Furthermore, it is important that both sample and referencematerial have the same machine finish. Note that Type A disksmay be excited only in certain areas (7:30 to 10:30 oclock and1:30 to 4:30 oclock positions) while Type B disks may beexcited around the entire annular area. F
41、or both types, the outer5 mm (0.2 in.) to the edge and the inner region up toapproximately 12-mm (0.48-in.) radius should not be excited.Fig. 3 illustrates both types of samples and the areas suitablefor exciting are shaded.7.1.2 Chill Cast Disk Using Vacuum MoldSkim the drossFIG. 2 Type B Molds and
42、 SamplesNOTE 1Shaded areas acceptable for analysis.FIG. 3 Samples from Type A and B MoldsFIG. 4 Mold for Vacuum Cast SamplesFIG. 5 Tool BitE 716 94 (2002)3from the molten metal as in 7.1.1.1, using a skimming tool.Preheat the cast iron mold tip and attach it to the mold bodyusing the clamp arm assem
43、bly. Insert the mold tip into themolten metal and immediately apply the vacuum to draw themetal into the mold cavity. Remove the mold tip from themetal, detach the mold tip from the mold body, and remove thedisk. The disks are prepared for analysis by machining asmooth surface on the side opposite t
44、he sprue at a depth of 2.0mm (0.08 in.) below the original surface. Analysis can be made360 around the disk in the annular area adjacent to the edge,avoiding the center area.7.1.3 Other Accepted MoldsIf molds other than Types Aand B or the vacuum mold are used, the same instructionsgiven in 7.1 woul
45、d apply. In addition, since a mold of differentdimensions may result in a different freezing pattern, each newtype of mold must be evaluated in order to ascertain the properdepth of machining to represent the true composition of themelt.7.2 Fabricated and Cast Products:7.2.1 Chill-Cast Disk by Molds
46、 A, B, or the VacuumMoldWhen the metal to be analyzed is in wrought or castform and a destructive test is applicable, remelt a representa-tive portion of the metal at a temperature well above theliquidus line of the alloy. A clay-graphite or other inert cruciblemay be used and placed in a convenient
47、 laboratory electricfurnace. Then cast the melt in one of the molds as described in7.1. If the sample is in the form of turnings, thin sheet, or otherfinely divided material, remove grease or any coatings with asuitable solvent and press into a briquet before melting andproceeding as in 7.1. Details
48、 of briquet size and formation arenot critical to the success of preparing a melt. The largestbriquet that can be successfully formed and that will fit into theremelt crucible will obviously speed up the remelt process.Carry out the melting and casting operation as rapidly aspossible, and use as lar
49、ge melt as practical to minimize lossesof volatile elements.NOTE 5Remelting is not satisfactory for the determination of sodium,calcium, and lithium, and some magnesium may also be lost if the melt isoverheated or held for an excessive time.7.2.2 Direct Excitation Without Casting a SampleWhenthe sample preparation procedures described in 7.1 cannot befollowed, for example, where melting would cause loss of avolatile constituent, or where it is otherwise impractical,usually only approximate analyses can be made. (1) Thesample must be sufficiently massive
