1、BRITISH STANDARD BS EN ISO 10720:2007 Steel and Iron - Determination of nitrogen content - Thermal conductimetric method after fusion in a current of inert gas (ISO 10720:1997) ICS 77.080.01 BS EN ISO 10720:2007 This British Standard, having been prepared under the direction of the Engineering Secto
2、r Board, was published under the authority of the Standards Board and comes into effect on 15 December 1997 2009 BSI ISBN 978 0 580 68261 2 National foreword This British Standard is the UK implementation of EN ISO 10720:2007. It is identical with ISO 10720:1997. It supersedes BS 6200-3.22.4:1997 Th
3、e UK participation in its preparation was entrusted to Technical Committee ISE/18, Sampling and analysis of iron and steel. 30 June 2009 BS EN ISO 10720:2007 This corrigendum renumbers BS 6200-3.22.4.1997 as which is withdrawn.A list of organizations represented on this committee can be obtained on
4、request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Amendments/corrigenda issued since publication Date
5、CommentsEUROPEANSTANDARD NORMEEUROPENNE EUROPISCHENORM ENISO10720 March2007 ICS77.080.01 EnglishVersion SteelandironDeterminationofnitrogencontentThermal conductimetricmethodafterfusioninacurrentofinertgas(ISO 10720:1997) AciersetfontesDosagedelazoteMthodepar conductibilitthermiqueaprsfusiondansunco
6、urantde gazinerte(ISO10720:1997) EisenundStahlBestimmungdesStickstoffgehaltes MessungderWrmeleitfhigkeitnachAufschmelzenin strmendemInertgas(ISO10720:1997) ThisEuropeanStandardwasapprovedbyCENon24February2007. CENmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatetheconditions
7、forgivingthisEuropean Standardthestatusofanationalstandardwithoutanyalteration.Uptodatelistsandbibliographicalreferencesconcerningsuchnational standardsmaybeobtainedonapplicationtotheCENManagementCentreortoanyCENmember. ThisEuropeanStandardexistsinthreeofficialversions(English,French,German).Aversio
8、ninanyotherlanguagemadebytranslation undertheresponsibilityofaCENmemberintoitsownlanguageandnotifiedtotheCENManagementCentrehasthesamestatusasthe officialversions. CENmembersarethenationalstandardsbodiesofAustria,Belgium,Bulgaria,Cyprus,CzechRepublic,Denmark,Estonia,Finland, France,Germany,Greece,Hu
9、ngary,Iceland,Ireland,Italy,Latvia,Lithuania,Luxembourg,Malta,Netherlands,Norway,Poland,Portugal, Romania,Slovakia,Slovenia,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG ManagementCentre:ruedeStassart,36
10、B1050Brussels 2007CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforCENnationalMembers. Ref.No.ENISO10720:2007:EBS EN ISO 10720:2007 ii Foreword The text of ISO 10720:1997 has been prepared by Technical Committee ISO/TC 17 “Steel” of the International Organization for Standardiza
11、tion (ISO) and has been taken over as EN ISO 10720:2007 by Technical Committee ECISS/TC 20 “Methods of chemical analysis of ferrous products” the secretariat of which is held by SIS. This European Standard shall be given the status of a national standard, either by publication of an identical text o
12、r by endorsement, at the latest by September 2007, and conflicting national standards shall be withdrawn at the latest by September 2007. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard:
13、Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. Endorseme
14、nt notice The text of the International Standard ISO 10720:1997 has been approved by CEN as EN ISO 10720:2007 without any modification. BS EN ISO 10720:2007 iii Contents Page National foreword Inside front cover Foreword ii 1 Scope 1 2 Normative references 1 3 Principle 1 4 Reagents and materials 1
15、5 Apparatus 1 6 Sampling 2 7 Procedure 2 8 Expression of results 3 9 Test report 4 Annex A (informative) Features of commercial resistive electrode furnaces and nitrogen analysers 6 Annex B (informative) Additional information on the international cooperative tests 6 Annex C (informative) Graphical
16、representation of precision data 9 Figure C.1 Logarithmic relationship between nitrogen content and repeatability limit (r) or reproducibility limits (R and R w ) 9 Table 1 Standard solutions 2 Table 2 Calibration solutions, nitrogen contents up to 0,10 % (m/m) 4 Table 3 Calibration solutions, nitro
17、gen contents between 0,10 % (m/m) and 0,50 % (m/m) 4 Table 4 Results for repeatability and reproducibility limits 5 Table B.1 Test samples used in the interlaboratory tests 7 Table B.2 The results obtained in interlaboratory tests 8 (w N )BS EN ISO 10720:2007 1 1 Scope This International Standard sp
18、ecifies a thermal conductimetric method after fusion under inert gas for the determination of nitrogen in steel and iron. The method is applicable to nitrogen contents between 0,000 8 % (m/m) and 0,5 % (m/m). 2 Normative references The following standards contain provisions which, through reference
19、in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most
20、recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 385-1:1984, Laboratory glassware Burettes Part 1: General requirements. ISO 648:1977, Laboratory glassware One-mark pipettes. ISO 1042:, Laboratory glassware On
21、e-mark volumetric flasks 1) . ISO 3696:1987, Water for analytical laboratory use Specification and test methods. ISO 5725-1:1994, Accuracy (trueness and precision) of measurement methods and results Part 1: General principles and definitions. ISO 5725-2:1994, Accuracy (trueness and precision) of mea
22、surement methods and results Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method. ISO 5725-3:1994, Accuracy (trueness and precision) of measurement methods and results Part 3: Intermediate measures of the precision of a standard measuremen
23、t method. ISO 14284:1996, Steel and iron Sampling and preparation of samples for the determination of chemical composition. 3 Principle Fusion of a test portion in a single-use graphite crucible under helium gas at a high temperature (e.g. 2 200 C) Extraction of the nitrogen in the form of molecular
24、 nitrogen in the stream of helium. Separation from the other gaseous extracts and measurement by thermal conductimetric method. 4 Reagents and materials During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only grade 2 water as specified in ISO 3696. 4.1
25、 Water, prepare just before use. 4.2 Helium, high purity, total impurity content 0,000 5 % (m/m). An oxidation reagent or catalyst copper (II) oxide or platinum tube heated to a temperature above 450 C shall be used prior to a purifying unit, when the presence of organic contaminants is suspected in
26、 the helium. 4.3 Pure iron, of known low nitrogen contents less than 0,001 % (m/m). 4.4 Copper (II) oxide, on granulated support. 4.5 Anhydrous magnesium perchlorate, Mg(ClO 4 ) 2 , particle size from 1,2 mm to 2,0 mm, or anhydrous calcium sulfate, particle size from 0,60 mm to 0,85 mm. 4.6 Sodium h
27、ydroxide, on granulated support. Particle size from 0,7 mm to 1,2 mm. 4.7 Appropriate solvent, suitable for washing greasy or dirty test samples, e.g. acetone. 4.8 Potassium nitrate, standard solution. After drying at between 100 C and 105 C for 2 h and allowing to cool in a desiccator, weigh, to th
28、e nearest 0,1 mg, the masses of potassium nitrate purity 99,9 % (m/m) indicated in Table 1. Dissolve the potassium nitrate in about 50 ml of water (4.1), transfer quantitatively to a 100 ml one-mark volumetric flask, dilute to the mark with water (4.1) and mix. 1 m l o f e a c h s t a n d a r d s o
29、l u t i o n c o n t a i n s t h e m a s s o f nitrogen indicated inTable 1. 5 Apparatus During the analysis, unless otherwise stated, use only ordinary laboratory apparatus. All volumetric glassware shall be class A, in accordance with ISO 385-1, ISO 648 or ISO 1042 as appropriate. The apparatus req
30、uired for fusion of the test portion, separation and measurement of the nitrogen extracted may be obtained commercially from a number of manufacturers. Follow the manufacturers instructions for the operation of the instrument. 1) To be published. (Revision of ISO 1042:1983)BS EN ISO 10720:2007 2 Tab
31、le 1 Standard solutions Features of commercial instruments are given in Annex A. 5.1 Graphite crucible, single-use. Use high purity crucibles suitable for use with the apparatus. 5.2 Micropipette, 100 4l and 200 4l, limit of error shall be less than 1 4l. 5.3 Nickel capsule For example, about 6 mm i
32、n diameter; 8 mm in height; 0,2 g in mass and 0,23 ml in volume, or about 6 mm in diameter; 12,5 mm in height; 0,5 g in mass and 0,35 ml in volume. In any case, the nitrogen content shall be less than 0,000 2 % (m/m). 5.4 Crucible tongs, for handling the crucibles used. 5.5 Glass-wool filters 6 Samp
33、ling Carry out sampling in accordance with ISO 14284 or appropriate national standards for steel and iron. 7 Procedure WARNING The risks involved when using an apparatus for fusing the test portion are mainly risks of burns. It is therefore essential to use crucible tongs (5.4) and appropriate conta
34、iners for the used crucibles. 7.1 General instructions Keep the glass-wool filters (5.5) clean. Using a certified reference material, verify the effectiveness of the installed reagents (4.4, 4.5 and 4.6) and change them if necessary. In certain instruments, it is necessary to clean the sample introd
35、uction pipe in the furnace after each analysis in order to eliminate carbon deposits. If the electricity supply has been switched off for a long time, allow time for the instrument to stabilize as recommended by the manufacturer. After changing the filters (5.5) and/or reagents (4.4, 4.5 and 4.6), o
36、r when the apparatus has been inoperative for a period, stabilize the instrument by carrying out trial analyses, the results of which are to be disregarded, then proceed with calibration as indicated in 7.5 before analysing the sample. If the instrument used provides a direct reading in percentage o
37、f nitrogen, adjust the instrument reading for each calibration range as follows. Read the content of a certified reference material of high nitrogen content at various power settings. The required heating power for the determination of test samples is that at which the reading levels off. In order t
38、o determine a high alloy test sample a high alloy certified reference material shall be used to know the required heating power. 7.2 Test portion Degrease the test sample by washing in a suitable solvent (4.7). Evaporate the last traces of the washing liquid by heating. Weigh, to the nearest 1 mg, a
39、pproximately 1,0 g of the test sample for nitrogen contents up to 0,1 % (m/m) and approximately 0,50 g for nitrogen contents greater than 0,1 % (m/m) (see note 1). NOTE 1 The mass of the test portion may be dependent on the type of instrument used. 7.3 Blank test Prior to the determination, carry ou
40、t the following blank tests in duplicate. 7.3.1 Sample with nitrogen contents up to 0,10 % (m/m) 7.3.1.1 Using the micropipette (5.2), transfer 200 4l of water (4.1) to a nickel capsule (5.3) and dry at 90 C to 95 C for 2 h. Treat the nickel capsule as specified in 7.4.1, and add the same quantity o
41、f the pure iron (4.3) in place of the test portion. 7.3.1.2 Obtain the reading of the blank tests and convert it to micrograms of nitrogen by means of the calibration graph (see 7.5). The blank value is obtained by subtracting the mass of nitrogen in the pure iron used (4.3) from the mass of nitroge
42、n in the blank tests. Name of the standard solution Mass of potassium nitrate used g Corresponding concentration of nitrogen mg/ml 4.8.1 4.8.2 4.8.3 9,022 8 7,218 2 5,413 8 12,5 10,0 7,5 4.8.4 4.8.5 4.8.6 3,609 1 1,804 6 0,902 3 5,0 2,50 1,25 4.8.7 4.8.8 4.8.9 0,360 9 4.8.5 1/10 a 4.8.6 1/10 0,50 0,
43、25 0,125 4.8.10 4.8.7 1/10 0,050 a e.gtransfer 10,0 ml of the standard solution (4.8.5) into a 1 0 0 m l o n e - m a r k v o l u m e t r i c f l a s k , d i l u t e t o t h e m a r k w i t h water (4.1) and mix.BS EN ISO 10720:2007 3 The mean blank value (m 1 ) is calculated from the two blank value
44、s (see note 2). NOTE 2 It is essential that neither the mean blank value nor the difference between the two blank values exceed 10 4g of nitrogen. If these values are abnormally high, the source of contamination should be investigated and eliminated. 7.3.2 Sample with nitrogen contents between 0,10
45、% (m/m) and 0,50 % (m/m) Using the micropipette (5.2), transfer 200 4l of water (4.1) to a degassed graphite crucible (5.1) and dry at 90 C to 95 C for 2 h. Add the same quantity of the pure iron (4.3) instead of the test portion and proceed as specified in 7.3.1.2. 7.4 Determination 7.4.1 Sample wi
46、th nitrogen contents up to 0,10 % (m/m) 7.4.1.1 Place a graphite crucible (5.1) in the furnace (see Annex A) and then degas by heating at greater than 2 200 C. 7.4.1.2 Flatten a nickel capsule (5.3) by pressing, insert it and add the test portion (see 7.2) to the degassed graphite crucible. 7.4.1.3
47、Operate the furnace in accordance with the manufacturers instructions. At the end of the fusion and measuring cycle, remove and discard the crucible, and record the analyser reading. 7.4.2 Sample with nitrogen contents between 0,10 % (m/m) and 0,50 % (m/m) Place a graphite crucible (5.1) in the furn
48、ace (see Annex A) and then degas by heating at greater than 2 200 C. Add the test portion (see 7.2) to the degassed graphite crucible (5.1) and continue as specified in 7.4.1.3. 7.5 Establishment of the calibration graph 7.5.1 Preparation of the calibration series 7.5.1.1 Sample with nitrogen contents up to 0,10 % (m/m) Using the micropipette (5.2), transfer 200 4l of each of the potassium nitrate standard solutions (4.8) indicated in Table
