1、Designation: E 1941 04Standard Test Method forDetermination of Carbon in Refractory and Reactive Metalsand Their Alloys1This standard is issued under the fixed designation E 1941; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、 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 applies to the determination of carbonin refractory and reactive metals and their alloys in
3、 concentra-tions from 0.004 to 0.100 % (see Note 1).NOTE 1Actual instrument range might vary from manufacturer tomanufacturer and according to sample size.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of
4、this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in Section 8.2. Referenced Documents2.1 ASTM Standards:2E 29 Practice for Using Significant Digits in Test Data to
5、Determine Conformance with Specifications.E 50 Practices for Apparatus, Reagents, and Safety Precau-tions for Chemical Analysis of MetalsE 55 Practice for Sampling Wrought Nonferrous Metals andAlloys for the Determination of Chemical CompositionE 1601 Practice for conducting an Interlaboratory Study
6、 toEvaluate the Performance of an Analytical MethodE 456 Terminology for Statistical MethodsE 1019 Test Methods for Determination of Carbon, Sulfur,Nitrogen, Oxygen, and Hydrogen in Steel and in Iron,Nickel, and Cobalt Alloys3. Summary of Test Method3.1 The metal specimen, contained in a single-use
7、ceramiccrucible, is ignited in an oxygen atmosphere in an inductionfurnace. The carbon in the specimen is oxidized to carbondioxide or carbon monoxide, or both, and is eventually carriedto the analyzer/detector. The amount of carbon present iselectronically processed and is displayed by the analyzer
8、readout.3.2 This test method is written for use with commerciallyavailable analyzers equipped to carry out the above operationsand calibrated using commercially available standards ofknown carbon content.4. Significance and Use4.1 This test method is intended to test for compliance withcompositional
9、 specifications. It is assumed that all who use thismethod will be trained analysts capable of performing commonlaboratory procedures skillfully and safely. It is expected thatthe work will be performed in a properly equipped laboratory.5. Interferences5.1 The elements ordinarily present in these al
10、loys do notinterfere. Halides that are present in some sponge type sampleswill cause low carbon recovery.6. Apparatus6.1 Combustion Furnace and Measurement Apparatus, au-tomatic carbon determinator, consisting of an induction fur-nace; a dust/debris removal trap; an analytical gas streampurification
11、 system; an infrared detection system; and anautomatic readout (see Note 2).NOTE 2Several models of commercial carbon determinators areavailable and presently in use in industry. Each has its own unique designcharacteristics and operational requirements. Consult the instrumentmanufacturers instructi
12、on manuals for operational details.6.2 Oxygen Tank and Regulator.6.3 Ceramic Crucibles and Lids, that meet or exceed theinstrument manufacturers specifications. Use lids with holesin them.6.4 Crucible Tongs, capable of handling recommended cru-cibles.6.5 Balance, capable of weighing to the nearest m
13、illigram.6.6 Muffle Furnace, capable of reaching and sustaining atemperature of at least 700C.1This test method is under the jurisdiction of ASTM Committee E01 onAnalytical Chemistry for Metals, Ores, and Related Materials and is the directresponsibility of Subcommittee E01.06 on Titanium, Zirconium
14、, Tungsten, Molyb-denum, Tantalum, Niobium, Hafnium, and Rhenium.Current edition approved May 1, 2004. Published June 2004. Originallyapproved in 1998. Last previous edition approved in 1998 as E 194198.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Ser
15、vice at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7. Reagents7.1 Acetone (A.R., or other suit
16、able, degreasing reagents).7.2 Copper Accelerator, (low carbon).7.3 Iron Chip Accelerator.7.4 Magnesium Perchlorate (Anhydrone)7.5 Oxygen, high purity (99.5 % minimum).7.6 Sodium Hydroxide on Clay Base (8-20 Mesh), com-monly known as Ascarite III.7.7 Reference Materials, commercially available RMs o
17、fknown carbon content.8. Hazards8.1 For hazards to be observed in the use of certain reagentsand equipment in this test method, refer to Practices E 50.8.2 Use care when handling hot crucibles and operatingfurnaces to avoid personal injury by either burn or electricalshock.9. Preparation of Apparatu
18、s9.1 Assemble the apparatus as recommended by the manu-facturer.9.2 Test the furnace and analyzer to ensure the absence ofgas leaks. Make the required electrical power connections.Prepare the apparatus for operation in accordance with themanufacturers instructions. Make a minimum of two determi-nati
19、ons as directed in 12.2 before attempting to calibrate thesystem or determine the blank.9.3 Crucible PreparationHeat crucibles in a muffle fur-nace at 700 to 800C for at least2horat900to1000C for atleast 1 h. Remove the crucibles from the muffle furnace andallow them to cool in a covered container (
20、see Note 3). Handleprepared crucibles only with clean crucible tongs.NOTE 3If crucibles or lids, or both, are not used within4hofremoving them from the muffle furnace, they should be reheated asdescribed in 9.3 and 9.4.9.4 Crucible Lid PreparationCrucible lids should bepreheated in a muffle furnace
21、at 700 to 800C for at least 1 hor at 900 to 1000C for at least 30 min. Remove the cruciblelids from the muffle furnace and allow them to cool in acovered container. Handle prepared lids only with cleancrucible tongs.10. Sample Preparation10.1 The sample selected shall be representative of themateria
22、l to be analyzed.10.2 Nibble, drill, or machine a clean sample in such amanner the particles are uniform in size and do not exceed adiagonal length of 10 mm.10.3 Wash in solvent to remove any oil or grease contami-nation. Decant the solvent and dry the sample on the low heatof an electric hot plate.
23、 Store the clean dried samples incovered glass beakers or vials.11. Calibration11.1 Calibration Reference MaterialsWhenever possible,select RMs with matrices similar to that of the unknowns: thecalibration RMs will consist of a commercial RMs of knowncarbon content (standard value should slightly ex
24、ceed that ofthe unknown), one scoop (approximately 1 g) of iron chipaccelerator and one scoop (approximately 1.5 g) of copperaccelerator in a prepared crucible, plus a prepared crucible lid.11.2 Crucible BlankThe crucible blank will consist of onescoop (approximately 1 g) of iron chip accelerator an
25、d onescoop (approximately 1.5 g) of copper accelerator in a preparedcrucible plus a prepared crucible lid.11.3 Calibration Procedure11.3.1 Prepare at least four 0.50 g specimens of a carbonRM as directed in Section 10 and 11.1. Also prepare fourcrucible blanks as described in 11.2.11.3.2 Follow the
26、calibration procedure as detailed in themanufacturers instruction manual. Calibrate with at least threeRMs and three crucible blanks.11.3.3 Analyze a fourth carbon RM and a fourth crucibleblank. The obtained value should be within the allowable limitsof the certificate value and the blank value shou
27、ld be within 5g of the adjusted zero.TABLE 1 Carbon in Refractory and Reactive Metals and Their AlloysMetal IdentityCarbonfound, ppmMinimumSD (SM,Practice E 1601)Repro-ducibilitySD (SR,Practice E 1601)Repro-ducibilityIndex (R,Practice E 1601)Rrel%Zirconium 3500701 24 3 6 17 71660b 346 7 15 42 12SRM
28、360a 151 6 10 27 18Titanium #1 654 8 32 90 14#2 72 3 9 27 37SRM 176 132 6 19 52 40Hafnium 420b 194 12 26 74 38Niobium 752 19 3 7 19 100SP5943 327 4 13 36 11Molybdenum 5657 22 4 7 20 905654 38 3 10 27 72Tungsten C-6 56 3 10 28 50C-3 111 3 9 24 21Tantalum A 119 3 7 20 17B37 82 60Nine laboratories cont
29、ributed results for all the samples included in this study.E194104212. Procedure12.1 Assemble the apparatus and condition it as directed inSection 9.12.2 Procedure for Operation:12.2.1 Make any pre-operational instrument checks as rec-ommended by the instrument manufacturer.12.2.2 Set the analyzer t
30、o the operate mode.12.2.3 Prepare a 0.50 g specimen as directed in Section 10and place it in a prepared crucible (see 9.3), add one scoop eachof iron chip and copper accelerator and cover with a preparedlid (see 9.4) (see Note 4).NOTE 4Users of simultaneous carbon-sulfur determinators should beaware
31、 that copper accelerator may have a negative affect on the sulfurresult.12.2.4 Place the crucible plus specimen on the inductionfurnace pedestal and close the furnace.12.2.5 Enter the specimen weight as recommended by themanufacturer. If specimen identification feature is provided bymanufacturer, en
32、ter identification.12.2.6 Start the analysis cycle, referring to the manufactur-ers recommended procedure.13. Calculation13.1 The carbon reading (result) will be direct if the blankand specimen weight have been correctly entered in theappropriate portion of the analyzer (see Note 5).NOTE 5If the ana
33、lyzer does not offer these functions, calculate thecarbon content by the following:carbon, ppm 5 A2B!/C (1)where:A = g of carbon in specimen,B = g, of carbon in blank, andC = specimen weight (in g).14. Precision and Bias14.1 PrecisionNine laboratories cooperated in testing 15samples representing 7 d
34、ifferent matrices. The data obtained ispresented in Table 1. The testing and statistical analysis wereperformed according to the provision of Practice E 1601.14.2 BiasNo information on the accuracy of this testmethod is available because no suitable certified referencematerials were available when t
35、he interlaboratory test wasperformed.15. Keywords15.1 carbon content; refractory metalsASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of
36、the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Y
37、our comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your commen
38、ts have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).E1941043
