1、Designation: E716 10Standard Practices forSampling and Sample Preparation of Aluminum andAluminum Alloys for Determination of ChemicalComposition by Spectrochemical Analysis1This standard is issued under the fixed designation E716; the number immediately following the designation indicates the year
2、oforiginal adoption 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.1. Scope1.1 These practices describe procedures for producing achill
3、cast disk sample from molten aluminum during theproduction process, and from molten metal produced bymelting pieces cut from products.1.2 These practices describe a procedure for obtainingqualitative results by direct analysis of product using sparkatomic emission spectroscopy.1.3 These practices de
4、scribe procedures for preparation ofsamples and products prior to analysis.1.4 The values stated in SI units are to be regarded asstandard. The values given in parentheses are mathematicalconversions to inch-pound units that are provided for informa-tion only and are not considered standard.1.5 This
5、 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 safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific precau-tionar
6、y statements are given in 6.1 and 7.2.2. Referenced Documents2.1 ASTM Standards:2E135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related MaterialsE401 Practice for Bonding Thin Spectrochemical Samplesand Standards to a Greater Mass of Material3E607 Test Method for Atomic Emiss
7、ion SpectrometricAnalysis Aluminum Alloys by the Point to Plane Tech-nique Nitrogen AtmosphereE1251 Test Method for Analysis of Aluminum and Alumi-num Alloys by Atomic Emission Spectrometry3. Terminology3.1 For definitions of terms used in this practice, refer toTerminology E135.4. Summary of Practi
8、ces4.1 Molten metal representative of the furnace melt ispoured or drawn by vacuum into a specified mold to producea chill-cast disk. The disk is machined to a specified depth thatrepresents the average composition and produces an acceptablesurface for analysis by spark atomic emission spectroscopy.
9、4.2 Pieces of solid aluminum fabricated, cast, or wroughtproducts are remelted and cast into molds or briquetted thenremelted and cast into molds.4.3 Product can be qualitatively analyzed directly withoutremelting after suitable surface preparation. Product withinsufficient mass for direct analysis
10、may be bonded to moremassive material prior to analysis.4.4 Special practices are included for the sampling andanalysis of aluminum-silicon alloys, containing greater than14 % silicon.5. Significance and Use5.1 The practice for taking a sample of molten metal duringproduction and producing a chill c
11、ast disk, used in conjunctionwith the following appropriate quantitative spark atomic emis-sion spectrochemical methods, Test Methods E607 and E1251,is suitable for use in manufacturing control or certifying, orboth, that the entire lot of alloy sampled meets establishedcomposition limits.5.2 The pr
12、actice for melting a piece of a product to producea chill cast disk analyzed in conjunction with the followingappropriate quantitative spark atomic emission spectrochemi-cal methods, Test Methods E607 and E1251, is suitable, if a1These practices are under the jurisdiction of ASTM Committee E01 onAna
13、lytical Chemistry for Metals, Ores, and Related Materials and are the directresponsibility of Subcommittee E01.04 on Aluminum and Magnesium.Current edition approved Sept. 1, 2010. Published December 2010. Originallyapproved in 1980. Last previous edition approved in 2002 as E716 94 (2002).DOI: 10.15
14、20/E0716-10.2For 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 ASTM website.3Withdrawn. The last approved version of this his
15、torical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.representative sample is taken, for determining if the piecesampled meets Aluminum Association composition limits.5.3 The practice for dire
16、ct analysis of product is suitable fordetermining an approximate composition of the piece analyzed6. Apparatus6.1 Ladle, capable of holding a minimum of 250 g (8.8 oz)of molten metal, with a handle of sufficient length to reach intoa furnace, trough, or crucible. The ladle should be lightlycoated wi
17、th a tightly adhering ladle wash that will serve in partto prevent contamination of the sample and also preventcontact of molten aluminum with metal oxides, that is, rust.(WarningTraces of moisture in the coating may causedangerous spattering.)NOTE 1A suitable ladle wash may be prepared as follows:
18、Mix 255 g(9 oz) of fine whiting (CaCO3) with 3.8 L (1 gal) of water and boil for20 min. Add 127 g (4.5 oz) of sodium silicate solution (40 B to 42 B)and boil for 30 min. Stir well before using.NOTE 2Molten aluminum in contact with rust may initiate a thermitereaction.6.2 Sample Molds shall be capabl
19、e of producing homog-enous chill-cast disks having smooth surfaces, free of surfacepockets and porosity. These chill cast disks should have aspectrochemical response similar to the reference materialsused in preparing the analytical curves and should at least havea spark to spark repeatability of no
20、 more than 2 % relative onmajor elements. They must be representative of the melt in theregion excited. Several types of molds have been foundacceptable:6.2.1 Type B,4center-pour mold, is shown in Fig. 1. Theadvantage of this mold is that the sample obtained may beexcited around the entire annular a
21、rea. This mold produces ahorizontally cast disk with the sprue over the center of oneside. The mold dimensions are such as to produce a diskapproximately 50 mm to 64 mm (1.97 in. to 2.5 in.) in diameterby 6 mm to 13 mm (0.24 in. to 0.50 in.) in thickness.Acircularcentral recess 10 mm to 20 mm (0.4 i
22、n. to 0.8 in.) in diameteron one side of the disk facilitates machining of that side inpreparation for excitation. It also promotes more uniformfreezing of the raised peripheral area, but the correspondingraised portion of the mold must not be so large as to restrict thethroat for the sprue. A sligh
23、t taper, 1 to 2, on the hingedportion of the mold facilitates opening when a disk has beencast. The mold material should be steel or cast iron and shouldweigh approximately 3.5 kg to 4.5 kg (8 lb to 10 lb).6.2.2 Vacuum Mold5is shown in Fig. 2.This mold producesdisks that are 38 mm (1.5 in.) in diame
24、ter and 13 mm (0.5 in.)thick and weigh approximately 40 g (1.4 oz). The mold con-sists of a solid copper base and a porous bronze wall in theform of a composite mold insert which is located in a steelmold body. A graphite coated cast iron tip is attached to themold body by a spring clamp assembly. T
25、he vacuum source istypically a rubber syringe bulb connected to the mold body.6.2.3 Other Types of MoldsOther molds of different types,materials, and dimensions may be substituted provided that theuniformity of the samples so obtained is sufficient for theintended use of the results. Furthermore suc
26、h samples shouldhave a sizeable area that represents the bulk composition of theentire sample and have a spectrochemical response similar tothe reference materials used for preparing the analytical curve.6.3 Lathe or Milling Machine, capable of machining asmooth flat surface and capable of repeating
27、 the selected depthof cut to within 60.013 mm (60.005 in.).6.4 Tool BitsDiamond tipped, alloy steel, or cementedcarbide bits are recommended. The best shape of the lathe toolvaries with the type and speed of the lathe. A tool bit designthat has been found satisfactory for most aluminum alloys isshow
28、n in Fig. 3.6.5 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.7. Materials7.1 Graphite Rods, of suitable diameter for stirring themolten aluminum.7.2 P
29、hosphorus, red, amorphous, or other suitable source ofphosphorus for grain refining of high silicon alloys during theremelt procedure. (WarningProvide adequate ventilationwhen phosphorus is added to molten metal.)4Type B molds, available from Machine and Welding Incorporated, 713 FortuneCrescent, Ki
30、ngston, ON Canada K7P2T4, have been found suitable for this purpose.5A portable Vacuum Sampler, available from Aluminum Company of America,Alcoa Center, PA 15069, has been found suitable for this purpose.6AJelrus Handy-Melt furnace and graphite crucible, available from Cole-ParmerInstrument Co., 742
31、5 North Oak Park Ave., Chicago, IL 60648, has been foundsuitable for this purpose.FIG. 1 Type B MoldE716 1028. Preparation of Samples8.1 Molten Metal:8.1.1 Chill-Cast Disk by Molds A or B:8.1.1.1 When a furnace or crucible of molten metal is to besampled, the temperature must be well above the point
32、 atwhich any solid phase could be present. Using the ladle or aseparate skimming tool, coated with a dry, tightly adheringmold wash (Note 1) and free of any remaining previous metal,push as much dross as possible away from the sampling area.Next, dip the ladle sideways into the clear area well below
33、 thesurface and stir momentarily. Then turn the ladle upright, andquickly withdraw. Two things are thus accomplished, namely,heating the ladle prevents metal freezing on the wall andobtaining metal well beneath the surface minimizes the dangerof inclusion of small particles of oxide.8.1.1.2 Unless t
34、he 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 an even rate of pourwhich allows the escape of air from the mold. Do not dump themetal into t
35、he 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 roughness.8.1.2 Chill Cast Disk Using Vacuum MoldSkim the drossfrom the molten metal as in 8
36、.1.1.1, using a skimming tool.Attach the cast iron mold tip to the mold body using the clamparm assembly. Squeez the rubber syringe bulb while immersingthe mold into the metal to prevent oxide skim from entering themold tip. Wait about five seconds to allow time for preheatingthe sampler. Release th
37、e rubber syringe bulb to apply vacuumthat will draw the metal into the sampler. Remove the mold tipfrom the metal, detach the mold tip from the mold body, andremove the disk. The surface of the disk must be free of anyshrinkage, inclusions, cracks, or roughness.8.1.3 Machine the disk to appropriate
38、depth for the particu-lar sampler dimensions. Typically a depth of between 14 % and22 % of the original thickness corresponds to the compositionon the phase diagram that best represents the average compo-sition of the whole disk and therefore the actual composition ofthe melt. It is advisable to det
39、ermine the most appropriatemachining depth for the particular disk thickness used and totarget and tightly control that specific depth. Machining todifferent depths may result in a different analysis and thereforecannot be accepted as valid.NOTE 3Aluminum samples shall not be prepared by sanding org
40、rinding. Sanding or grinding tends to smear the relatively soft aluminumphase over the harder constituent phases or cause hard grains to be tornfrom the sample and may cause biased results for spark atomic emissionspectrometry.8.1.3.1 The machined surface must be smooth and free ofscuffs, pits, or i
41、nclusions. The ideal surface is neither polishednor visibly grooved but should be a surface showing very finetool marks. More specifically, the ideal surface may be definedas approximately a 1.6 3 103-mm (63-in.) standard ma-chine finish. A surface much finer or much coarser may resultin an apparent
42、 analytical difference. Furthermore, it is impor-tant that both sample and reference material have the samemachine finish. Analysis can be made 360 around the disk inthe annular area adjacent to the edge, avoiding the center area.8.1.4 Other Accepted MoldsIf molds other than Type B orthe vacuum mold
43、 are used, the same instructions given in 8.1would apply. In addition, since a mold of different dimensionsmay result in a different freezing pattern, each new type ofmold must be evaluated in order to ascertain the proper depthof machining to represent the true composition of the melt.8.2 Remelting
44、 and Casting a Sample from Fabricated andCast Products:8.2.1 Chill-Cast Disk by Type B Mold, 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 th
45、e alloy. A clay, graphite, or other inertcrucible may be used and placed in a convenient laboratoryelectric furnace. Then cast a portion of the melt in one of theFIG. 2 Mold for Vacuum Cast SamplesFIG. 3 Tool BitE716 103molds as described in 8.1. If the sample is in the form ofturnings, thin sheet,
46、or other finely divided material, removegrease or any coatings with a suitable solvent and press into abriquet before melting and proceeding as in 8.1. Details ofbriquet size and formation are not critical to the success ofpreparing a melt. The largest briquet that can be successfullyformed and that
47、 will fit into the remelt crucible will obviouslyspeed up the remelt process. Carry out the melting and castingoperation as rapidly as possible, and use as large melt aspractical to minimize losses of volatile elements. Follow theprocedures in 8.1.1-8.1.3 for preheating each particular sam-pler type
48、.NOTE 4Analysis of samples can be used to determine compliancewith composition analysis for the piece sampled if a representative sampleis obtained. Direct analysis of samples obtained from fabricated and castaluminum product shall not be used for determining compliance withcomposition specification
49、s. Cast lot composition should be determinedusing samples taken during pouring of castings or ingots.NOTE 5Remelting is not satisfactory for the determination of volatileelements such as sodium, calcium, lithium, strontium, and some magne-sium may also be lost if the melt is overheated or kept molten for anexcessive time.8.2.2 Direct Analysis of Wrought or Cast ProductsPiecesof wrought or cast aluminum product can be analyzed directlyon the surface when the sample preparation procedures de-scribed in 8.1 cannot be followed, for example, when there isinsuffici
