ASTM E716-2016 8109 Standard Practices for Sampling and Sample Preparation of Aluminum and Aluminum Alloys for Determination of Chemical Composition by Spark Atomic Emission Spectr.pdf

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1、Designation: E716 16Standard Practices forSampling and Sample Preparation of Aluminum andAluminum Alloys for Determination of ChemicalComposition by Spark Atomic Emission Spectrometry1This standard is issued under the fixed designation E716; the number immediately following the designation indicates

2、 the year 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. Scope*1.1 These practices describe procedures for produc

3、ing achill 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 spectrometry.1.3 These p

4、ractices describe 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 standa

5、rd.1.5 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 safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific pr

6、ecau-tionary statements are given in 6.1 and 7.2.2. Referenced Documents2.1 ASTM Standards:2B985 Practice for Sampling Aluminum Ingots, Billets, Cast-ings and Finished or Semi-Finished Wrought AluminumProducts for Compositional AnalysisE135 Terminology Relating to Analytical Chemistry forMetals, Ore

7、s, and Related MaterialsE401 Practice for Bonding Thin Spectrochemical Samplesand Standards to a Greater Mass of Material (Withdrawn1995)3E607 Test Method for Atomic Emission SpectrometricAnalysis Aluminum Alloys by the Point to Plane Tech-nique Nitrogen Atmosphere (Withdrawn 2011)3E1251 Test Method

8、 for Analysis of Aluminum and Alumi-num Alloys by Spark Atomic Emission Spectrometry3. Terminology3.1 For definitions of terms used in this practice, refer toTerminology E135.4. Summary of Practices4.1 Molten metal representative of the furnace melt ispoured or drawn by vacuum into a specified mold

9、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 spectrometry.4.2 Pieces of solid aluminum fabricated, cast, or wroughtproducts are remelted and cast into molds or bri

10、quetted thenremelted and cast into molds.4.3 Product can be qualitatively analyzed directly withoutremelting after suitable surface preparation. Product withinsufficient mass for direct analysis may be bonded to moremassive material prior to analysis.4.4 Special practices are included for the sampli

11、ng 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 cast disk, used in conjunctionwith the following appropriate quantitative spark atomic emis-sion spectroch

12、emical 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.1These practices are under the jurisdiction of ASTM Committee E01 onAnalytical Chemistry for Metals, Ores, and Rela

13、ted Materials and are the directresponsibility of Subcommittee E01.04 on Aluminum and Magnesium.Current edition approved June 1, 2016. Published June 2016. Originallyapproved in 1980. Last previous edition approved in 2010 as E716 10. DOI:10.1520/E0716-16.2For referenced ASTM standards, visit the AS

14、TM 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.3The last approved version of this historical standard is referenced onwww.astm.org.*A Summary of Changes

15、 section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 The practice for melting a piece of a product to producea chill cast disk analyzed in conjunction with the followingappropriate quantitati

16、ve spark atomic emission spectrochemi-cal methods, Test Methods E607 and E1251, is suitable, if arepresentative sample is taken, for determining if the piecesampled meets Aluminum Association composition limits.5.3 The practice for direct analysis of product is suitable fordetermining an approximate

17、 composition of the piece ana-lyzed.6. 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 with a tightly adhering ladle wash that will serve in partto pre

18、vent 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: Mix 255 g(9 oz) of fine whiting (CaCO3) with 3.8 L (1 gal) of

19、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 capable of producing homog-enous chill-cast disks having smooth surf

20、aces, 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 more than 2 % relative onmajor elements. They must be represe

21、ntative of the melt in theregion excited. Several types of molds have been foundacceptable:6.2.1 Type B Mold4center-pour mold, is shown in Fig. 1.This mold produces a horizontally cast disk with the sprue overthe center of one side. The mold dimensions are such as toproduce a disk approximately 50 m

22、m to 64 mm (1.97 in. to2.5 in.) in diameter by 6 mm to 13 mm (0.24 in. to 0.50 in.) inthickness. A circular central recess 10 mm to 20 mm (0.4 in. to0.8 in.) in diameter on one side of the disk facilitates machin-ing of that side in preparation for excitation. It also promotesmore uniform freezing o

23、f the raised peripheral area, but thecorresponding raised portion of the mold must not be so largeas to restrict the throat for the sprue.Aslight taper, 1 to 2, onthe hinged portion of the mold facilitates opening when a diskhas been cast. The mold material should be steel or cast ironand should wei

24、gh approximately 3.5 kg to 4.5 kg (8 lb to10 lb).Aspecial Type B mold is recommended for hypereuteticaluminum-silicon alloys. It produces the thinner samples13 mm (0.24 in.) thick.NOTE 3About sample molds: Previously two relatively simple typesof massive iron or steel sample molds were considered su

25、itable, Type Aand Type B. Type A molds produced vertical chill cast samples with thesprue and riser on the edge of the sample, as opposed to the Type B whichproduces a horizontal chill cast sample with the sprue and riser on the backof the sample. The Type A sampler was later found to not produce ar

26、epeatable sparking surface, even in the restricted sparking areas. TheType A mold was removed from the list of recommended conventionalmolds. Because many people are familiar with the terms “Type A” and“Type B” molds, reference to “Type B” mold remains in the text of thisstandard even though referen

27、ce to the “Type A” no longer appears.6.2.2 Scissor Mold5is shown in Fig. 2. This mold producesdisks that are 60 mm (2.4 in.) in diameter and 13 mm (0.5 in.)thick and weigh approximately 100 g (3.5 oz). The moldconsists of two halves weighing about 3 kg (6.6 lbs). Thehalves are connected by a pivot b

28、olt which allows the halves tofunction as scissors. When the upper half with the sprue hole ismoved to cover the sample cavity in the lower half, moltenmetal is poured into the riser cup, through the sprue hole intothe sample cavity.After the metal has frozen, the user holds thesteel spring heat dis

29、sipater surrounding one handle and strikesthe other handle on the ground causing the upper half to pivotaway and shear off the riser at the sprue. The sample and thesprue can then be easily removed.6.2.3 Vacuum Mold is shown in Fig. 3. This mold producesdisks that are 38 mm (1.5 in.) in diameter and

30、 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 the4Type B molds, available from Danton Machine a

31、nd Welding Incorporated, 713Fortune Crescent, Kingston, ON Canada K7P 2T4, have been found suitable for thispurpose.5A scissor mold available from Herschal Products, 3778 Timberlake Dr.,Richfield, OH 44286 has been found suitable for this purpose.FIG. 1 Type B MoldE716 162mold body by a spring clamp

32、 assembly. The vacuum source istypically a rubber syringe bulb connected to the mold body.NOTE 4This sampler is made by Alcoa and is recommended inprevious issues of this standard. This device is no longer commerciallyavailable from Alcoa, but the description remains in this standard becauseit is st

33、ill used within the aluminum industry.6.2.4 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 such samples shouldhave a spectrochemical r

34、esponse similar to the referencematerials used for preparing the analytical curve.6.3 Lathe or Milling Machine, capable of machining asmooth flat surface and capable of repeating the selected depthof cut to within 60.013 mm (60.005 in.).6.4 Tool BitsDiamond tipped, or alloy steel, or cementedcarbide

35、 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 isshown in Fig. 4.6.5 An Electric Melting Furnace, using a clay or graphitecrucible with a minimum capacity of 100 g (3.5 oz)

36、 of moltenaluminum and capable of maintaining temperatures for meltingaluminum alloys.7. Materials7.1 Graphite Rods,6for stirring the molten aluminum.7.2 Asource of phosphorus, for grain refining of high siliconalloys before spectrometric analysis. Grain refining of theprimary silicon is important f

37、or an accurate analysis of silicon.NOTE 5Previous versions of these standard practices specified theaddition of red phosphorus to the sample ladle of molten hypereutecticAl-Si aluminum alloy. The requirement of the addition of red phosphoruswas based on the assumption that the larger quantity of mol

38、ten aluminumalloy (which was sampled by the ladle) had not previously been grainrefined with phosphorus. Red phosphorus is no longer available without aspecial license. The recommended replacement grain refining additive is acopper-8 % phosphorus alloy. The entire molten bath should be refinedbefore

39、 the sample ladle removes the smaller amount of molten metal forthe sample. If the sample must be taken prior to grain refinement of themain bath, either a small amount of copper-8 % phosphorus alloy shouldbe added to the ladle, with the expectation that the copper concentrationof the spectrometric

40、analysis will be wrong, or a phosphorus chemicalcompound without an interfering element should be added. This othercompound will be hazardous and must be handled carefully by anexperienced chemist. A suitable compound is phosphorus penta-chloride(PCl5). In either case, the phosphorus recovery after

41、the alloying additionwill be low, in a range of 15 % to 40 %.8. Preparation of Samples8.1 Molten Metal:8.1.1 When molten metal is to be sampled, the temperaturemust be well above the point at which any solid phase could bepresent. Using the ladle or a separate skimming tool, coatedwith a dry, tightl

42、y adhering mold wash (Note 1) and free of anyremaining previous metal, push as much dross as possibleaway from the sampling area. Next, dip the ladle sideways intothe clear area well below the surface and stir momentarily.Then turn the ladle upright, and quickly withdraw. Two things6Graphite stirrin

43、g rods are available from Budget Casting Supply LLC, 20811Upper Hillview Dr., Sonora, CA 95370FIG. 2 Scissor MoldFIG. 3 Mold for Vacuum Cast SamplesFIG. 4 Tool BitE716 163are thus accomplished, namely, heating the ladle preventsmetal freezing on the wall and obtaining metal well beneath thesurface m

44、inimizes the danger of inclusion of small particles ofoxide.8.1.2 Unless the mold is already hot, cast a preliminary diskinto the clean mold in order to preheat it and discard this disk.Remove excess metal from the ladle, dip into the molten metalas before, and fill the mold with an even rate of pou

45、r whichallows the escape of air from the mold. Do not dump the metalinto the mold. Avoid overfilling the sprue, otherwise the moldmay 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.8.1.3 C

46、hill Cast Disk Using Vacuum MoldSkim the drossfrom the molten metal as in 8.1.1, using a skimming tool.Attach the cast iron mold tip to the mold body using the clamparm assembly. Squeeze the rubber syringe bulb while immers-ing the mold into the metal to prevent oxide skin from enteringthe mold tip.

47、 Wait about five seconds to allow time forpreheating the sampler. Release the rubber syringe bulb toapply vacuum that will draw the metal into the sampler.Remove the mold tip from the metal, detach the mold tip fromthe mold body, and remove the disk. The surface of the diskmust be free of any shrink

48、age, inclusions, cracks, or roughness.8.1.4 Machine the disk to appropriate 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

49、disk and therefore the actual composition ofthe melt. It is advisable to determine 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 6Aluminum samples shall not be prepared by sanding orgrinding. 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 sp