EN ISO 10720:2007

SLOVENSKI STANDARD
01-junij-2007
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Steel and iron - Determination of nitrogen content - Thermal conductimetric method after
fusion in a current of inert gas (ISO 10720:1997)
Eisen und Stahl Bestimmung des Stickstoffgehaltes - Messung der Wärmeleitfähigkeit
nach Aufschmelzen in strömendem Inertgas (ISO 10720:1997)
Aciers et fontes - Dosage de l'azote - Méthode par conductibilité thermique apres fusion
dans un courant de gaz inerte (ISO 10720:1997)
Ta slovenski standard je istoveten z: EN ISO 10720:2007
ICS:
77.080.01 Železne kovine na splošno Ferrous metals in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 10720
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2007
ICS 77.080.01
English Version
Steel and iron - Determination of nitrogen content - Thermal
conductimetric method after fusion in a current of inert gas (ISO
10720:1997)
Aciers et fontes - Dosage de l'azote - Méthode par Eisen und Stahl Bestimmung des Stickstoffgehaltes -
conductibilité thermique après fusion dans un courant de Messung der Wärmeleitfähigkeit nach Aufschmelzen in
gaz inerte (ISO 10720:1997) strömendem Inertgas (ISO 10720:1997)
This European Standard was approved by CEN on 24 February 2007.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of 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.
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EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 10720:2007: E
worldwide for CEN national Members.

Foreword
The text of ISO 10720:1997 has been prepared by Technical Committee ISO/TC 17 “Steel” of the International
Organization for Standardization (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 or 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: 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.

Endorsement notice
The text of the International Standard ISO 10720:1997 has been approved by CEN as EN ISO 10720:2007
without any modification.
INTERNATIONAL Is0
STANDARD 10720
First edition
1997-08- 15
Steel and iron
- Determination of nitrogen
content - Thermal conductimetric method
after fusion in a current of inert gas
Aciers et fon tes - Dosage de I’azote -
Mkthode par conductibilitti
thermique apr& fusion sous un courant de gaz inerfe
Reference number
IS0 10720: 1997(E)
IS0 10720:1997(E)
Foreword
IS0 (the international Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
technical committees. Each member body interested in a subject for which
a technical committee has been established has the right to be
represented on that committee. International organizations, governmental
and non-governmental, in liaison with ISO, also take part in the work. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 10720 was prepared by Technical Committee
ISORC 17, Steel, Subcommittee SC 1, Methods of determination of
chemical composition.
Annexes A to C of this International Standard are for information only.
0 IS0 1997
All rights reserved. Unless otherwise specified, no part of this publication may be
reproduced or utilized in any form or by any means, electronic or mechanical, including
photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 l CH-1211 Geneve 20 l Switzerland
Internet central @ iso.ch
x.400 c=ch; a=400net; p=iso; o=isocs; s=central
Printed in Switzerland
ii
IS0 10720: 1997(E)
INTERNATIONAL STANDARD @ IS0
Steel and iron
- Determination of nitrogen content - Thermal
conductimetric method after fusion in a current of inert gas
1 Scope
This International Standard specifies 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 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 recent editions of the standards indicated below. Members of IEC and IS0 maintain
registers of currently valid International Standards.
IS0 385-l :I 984, Laboratory glassware - Burettes - Part 1: General requirements.
IS0 648:1977, Laboratory glassware - One-mark pipettes.
IS0 1042: ----I), Laboratory glassware - One-mark volumetric flasks.
IS0 3696:1987, Water for analytical laboratory use - Specification and test methods.
IS0 5725-l :I 994, Accuracy (trueness and precision) of measurement methods and results - Part I: General
principles and definitions.
IS0 5725-2:1994, Accuracy (trueness and precision) of measurement methods and results - Part 2: Basic method
for the determination of repeatability and reproducibility of a standard measurement method.
IS0 5725-3:1994, Accuracy (trueness and precision) of measurement methods and results - Part 3: Intermediate
measures of the precision of a standard measurement method.
- Sampling and preparation of samples for the determination of chemical
IS0 14284 :I 996, Steel and iron
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 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 IS0 3696.
1) To be published. (Revision of IS0 10427 983)

@ IS0
IS0 10720: 1997(E)
4.1 Water, prepare just before use.
4.2 Helium, high purity, total impurity content 0,000 5 % (m/m).
An oxidation reagent or catalyst [copper 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 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(CIO,),, particle size from I,2 mm to 2,O mm, or anhydrous calcium
sulfate, particle size from 0,60 mm to 0,85 mm.
4.6 Sodium hydroxide, on granulated support.
Particle size from 0,7 mm to I,2 mm.
Appropriate solvent, suitable for washing greasy or dirty test samples, e.g. acetone.
4.7
4.8 Potassium nitrate, standard solution.
After drying at between 100 “C and 105 OC for 2 h and allowing to cool in a desiccator, weigh, to the nearest 0,l 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 ml of each standard solution contains the mass of nitrogen indicated in table 1.
Table 1 - Standard solutions
Name of the Mass of potassium Corresponding
standard nitrate used concentration
solution
of nitrogen
mg/ml
cl
~~
12,5
4.8.1 9,022 8
4.8.2 7,218 2 IO,0
4.8.3 5,413 8
4.8.4 3,609 1
4.8.5 1,804 6 2,50
4.8.6 0,902 3 I,25
4.8.7 0,360 9 0,50
4.8.8 [4.8.5 x l/10] ') 0,25
4.8.9 [4.8.6 x l/IO] 0,125
4.8.10 [4.8.7 x l/IO] 0,050
1) e.g. .transfer 10,O ml of the standard solution (4.8.5) into a 100 ml one-mark volumetric flask,
dilute to the mark with water (4.1) and mix.
5 Apparatus
During the analysis, unless otherwise stated, use only ordinary laboratory apparatus.
@ IS0 IS0 10720: 1997(E)
All volumetric glassware shall be class A, in accordance with IS0 385-l) IS0 648 or IS0 1042 as appropriate.
The apparatus required for fusion of the test portion, separation and measurement of the nitrogen extracted may be
obtained commercially from a number of manufacturers. Follow the manufacturer’s instructions for the operation of
the instrument.
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 ul and 200 ~1, limit of error shall be less than 1 ~1.
5.3 Nickel capsule.
For example, about 6 mm in diameter; 8 mm in height; 0,2 g in mass and 0,23 ml in volume, or about 6 mm in
diameter; 125 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 % (mlm).
5.4 Crucible tongs, for handling the crucibles used.
5.5 Glass-wool filters.
6 Sampling
Carry out sampling in accordance with IS0 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 containers 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 introduction 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), or 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 of 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 to determine a high alloy test sample a high alloy certified reference material shall be used to know the
required heating power.
@ IS0
IS0 10720: 1997(E)
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, approximately ,0 g of the test sample for nitrogen conte nts up to 0,l % ( m/m)
approximately 0,50 g for nitrogen contents reater than 0,l % (m/m) (see note .
1)
cl
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 out the following blank tests in duplicate.
7.3.1 Sample with nitrogen contents up to 0,lO % (mlm)
7.3.1.1 Using the micropipette (5.2), transfer 200 ~1 of water (4.1) to a nickel capsule (5.3) and dry at 90 OC to
95 “C for 2 h. Treat the nickel capsule as specified in 7.4.1, and add the same quantity of 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 subtracting the of nitrogen in the pure iron used (4.3) from the mass of
bY
nitrogen in the blank tests.
The mean blank value (m,) is calculated from the two blank values (see note 2).
NOTE 2
It is essential that neither the m ean blank value nor the diffe rence between the two blank values exce IedlOpgof
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,lO % (ml@ and 0,50 % (m/m)
Using the micropipette (5.2), transfer 200 1.11 of water (4.1) to a degassed graphite crucible (5.1) and dry at 90 OC to
...