SIST EN ISO 4945:2019

Steel - Determination of nitrogen - Spectrophotometric method (ISO 4945:2018)

This document specifies a spectrophotometric method for the determination of nitrogen in steel.
The method is applicable to the determination of nitrogen mass fraction between 0,000 6 % and 0,050 % in low alloy steels and between 0,010 % and 0,050 % in high alloy steels.
The method does not apply to samples containing silicon nitrides or having silicon contents higher than 0,6 %.

Stahl - Bestimmung des Stickstoffgehalts - Spektralphotometrisches Verfahren (ISO 4945:2018)

Acier - Détermination de l'azote - Méthode spectrophotométrique (ISO 4945:2018)

Le présent document spécifie une méthode spectrophotométrique de détermination de l'azote dans l'acier.
La méthode s'applique à la détermination des teneurs en azote comprises entre 0,000 6 % et 0,050 % dans les aciers faiblement alliés et entre 0,010 % et 0,050 % dans les aciers fortement alliés.
La méthode ne s'applique pas aux échantillons contenant des nitrures de silicium ou ayant une teneur en silicium supérieure à 0,6 %.

Jeklo - Določevanje dušika - Spektrometrična metoda (ISO 4945:2018)

Ta dokument določa spektrometrično metodo za določevanje dušika v jeklu. Metoda se uporablja za določevanje masnega deleža dušika med 0,0006 % in 0,050 % v malolegiranih jeklih ter med 0,010 % in 0,050 % v močnolegiranih jeklih.
Ta metoda se ne uporablja za vzorce, ki vsebujejo silicijev nitrid ali z vsebnostjo silicija več kot 0,6 %.

General Information

• Status: Published
• Public Enquiry End Date: 06-Mar-2018
• Publication Date: 09-Dec-2018
• ICS: 77.040.30 - Chemical analysis of metals
• ICS: 77.080.20 - Steels
• Technical Committee: IFEK - Ferrous metals
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 06-Dec-2018
• Due Date: 10-Feb-2019
• Completion Date: 10-Dec-2018
• Ref Project: EN ISO 4945:2018 - Steel - Determination of nitrogen - Spectrophotometric method (ISO 4945:2018)

Relations

• Replaces: SIST EN ISO 4945:2010 - Steel - Determination of nitrogen content - Spectrophotometric method (ISO 4945:1977)
• Effective Date: 05-Dec-2018
• Revised: SIST EN ISO 4945:2010 - Steel - Determination of nitrogen content - Spectrophotometric method (ISO 4945:1977)
• Effective Date: 10-Sep-2014

Overview

EN ISO 4945:2018 - titled Steel - Determination of nitrogen - Spectrophotometric method (ISO 4945:2018) - is a CEN-endorsed international standard that specifies a laboratory spectrophotometric procedure for determining nitrogen in steel. The method covers nitrogen mass fractions from 0,0006 % to 0,050 % for low-alloy steels and 0,010 % to 0,050 % for high-alloy steels. It is not applicable to materials containing silicon nitrides or to steels with silicon content above 0,6 %.

Key Topics and Requirements

• Analytical principle: Dissolution of a test portion in hydrochloric acid; fuming of the acid-insoluble residue with sulphuric acid (and potassium sulfate and copper(II) sulfate); alkaline steam distillation to liberate ammonia; trapping ammonia in dilute sulphuric acid; formation of a blue-coloured phenol-based complex (with sodium hypochlorite and sodium nitroprusside); spectrophotometric measurement at about 640 nm.
• Applicable range: 0,0006–0,050 % N (low-alloy steels); 0,010–0,050 % N (high-alloy steels).
• Limitations: Excludes samples containing silicon nitrides or Si > 0,6 %.
• Reagents and preparations: Defines required reagent grades and preparations (e.g., HCl 1+1, fuming H2SO4, NaOH solutions, sodium phenoxide, sodium nitroprusside, standard nitrogen solutions).
• Apparatus: Requires class A volumetric glassware, a spectrophotometer capable of 640 nm readings with 10 mm cells, and a suitable steam distillation setup (examples provided in Annex A).
• Calibration and quality control: Procedure includes blank tests, preparation of calibration solutions from a nitrogen stock/standard, plotting a calibration curve and reporting results. Precision and interlaboratory data are documented in informative annexes.

Applications

• Quality control in steel production: Monitoring nitrogen content to meet material specifications and performance requirements (e.g., mechanical properties, welding behavior).
• Metallurgical laboratories: Routine chemical analysis of low- and high-alloy steels where accurate low-level nitrogen determination is required.
• Third‑party testing and certification: Use in conformity assessment, inspection and verification of delivered steel products.
• Research and development: Studies where controlled nitrogen levels influence microstructure or alloys’ properties.

Who should use this standard

• Steel producers and mills, heat‑treatment shops, analytical laboratories, metallurgists, quality engineers, and standards bodies responsible for chemical analysis of metals.

Related standards

• ISO 14284 - Sampling and preparation of samples for determination of chemical composition
• ISO 3696 - Water for analytical laboratory use
• ISO 648 and ISO 1042 - Laboratory glassware (pipettes, volumetric flasks)
• EN ISO 4945:2018 is the CEN-adopted version of ISO 4945:2018

Keywords: EN ISO 4945:2018, ISO 4945, nitrogen determination, spectrophotometric method, nitrogen in steel, steel analysis, CEN standard.

Standards Content (Sample)

SLOVENSKI STANDARD
01-februar-2019
1DGRPHãþD
SIST EN ISO 4945:2010
-HNOR'RORþHYDQMHGXãLND6SHNWURPHWULþQDPHWRGD,62
Steel - Determination of nitrogen - Spectrophotometric method (ISO 4945:2018)
Stahl - Bestimmung des Stickstoffgehalts - Spektralphotometrisches Verfahren (ISO
4945:2018)
Acier - Détermination de l'azote - Méthode spectrophotométrique (ISO 4945:2018)
Ta slovenski standard je istoveten z: EN ISO 4945:2018
ICS:
77.040.30 Kemijska analiza kovin Chemical analysis of metals
77.080.20 Jekla Steels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 4945
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2018
EUROPÄISCHE NORM
ICS 77.080.20 Supersedes EN ISO 4945:2009
English Version
Steel - Determination of nitrogen - Spectrophotometric
method (ISO 4945:2018)
Acier - Détermination de l'azote - Méthode Stahl - Bestimmung des Stickstoffgehalts -
spectrophotométrique (ISO 4945:2018) Spektralphotometrisches Verfahren (ISO 4945:2018)
This European Standard was approved by CEN on 29 September 2018.

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-CENELEC 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-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 4945:2018 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 4945:2018) has been prepared by Technical Committee ISO/TC 17 "Steel" in
collaboration with Technical Committee ECISS/TC 102 “Methods of chemical analysis for iron and steel
” 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 May 2019, and conflicting national standards shall be
withdrawn at the latest by May 2019.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 4945:2009.
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,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 4945:2018 has been approved by CEN as EN ISO 4945:2018 without any modification.

INTERNATIONAL ISO
STANDARD 4945
Second edition
2018-10
Steel — Determination of nitrogen —
Spectrophotometric method
Acier — Détermination de l'azote — Méthode spectrophotométrique
Reference number
ISO 4945:2018(E)
©
ISO 2018
ISO 4945:2018(E)
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

ISO 4945:2018(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 2
6 Apparatus . 3
7 Sampling . 3
8 Procedure. 3
8.1 Test portion . 3
8.2 Blank test . 4
8.3 Determination . 4
8.3.1 Dissolution . 4
8.3.2 Treatment of insoluble residue . 4
8.3.3 Steam distillation (see Figure A.1, A.2 or A.3) . 4
8.3.4 Formation of the coloured complex . 5
8.3.5 Spectrophotometric measurements . 5
8.4 Establishment of the calibration curve . 5
8.4.1 Preparation of the calibration solutions . 5
8.4.2 Spectrophotometric measurements . 6
8.4.3 Plotting the calibration curve . 6
9 Expression of results . 6
9.1 Method of calculation . 6
9.2 Precision . 7
10 Test report . 7
Annex A (informative) Examples of distillation apparatus . 8
Annex B (informative) Additional information on the international interlaboratory test.11
Annex C (informative) Graphical representation of precision data .14
Bibliography .15
ISO 4945:2018(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO 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.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www. iso. org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www. iso.o rg/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www. iso
.org/iso/foreword. html.
This document was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 1, Methods of
determination of chemical composition.
This second edition cancels and replaces the first edition (ISO 4945:1977), which has been technically
revised. The following changes have been made:
— the scope and applicable range has been expanded as a result of the interlaboratory test;
— addition of copper(II) sulfate pentahydrate for the treatment of the insoluble residue.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www. iso. org/members. html.
iv © ISO 2018 – All rights reserved

INTERNATIONAL STANDARD ISO 4945:2018(E)
Steel — Determination of nitrogen —
Spectrophotometric method
1 Scope
This document specifies a spectrophotometric method for the determination of nitrogen in steel.
The method is applicable to the determination of nitrogen mass fraction between 0,000 6 % and
0,050 % in low alloy steels and between 0,010 % and 0,050 % in high alloy steels.
The method does not apply to samples containing silicon nitrides or having silicon contents higher
than 0,6 %.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 648, Laboratory glassware — Single-volume pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 14284, Steel and iron — Sampling and preparation of samples for the determination of chemical
composition
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
4 Principle
Dissolution of a test portion in hydrochloric acid.
Fuming of the acid-insoluble residue in sulphuric acid with potassium sulfate and copper(lI) sulfate.
Distillation of the solution made alkaline with sodium hydroxide, and collection of ammonia in a
receiver containing diluted sulphuric acid.
Formation of a blue-coloured complex between the ammonium ions and phenol in the presence of
sodium hypochlorite and disodium pentacyanonitrosylferrate(III) (sodium nitroprusside).
Spectrophotometric measurement of the complex at a wavelength of about 640 nm.
ISO 4945:2018(E)
5 Reagents
During the analysis, unless otherwise specified, use only reagents of recognized analytical grade and
only freshly prepared grade 2 water as specified in ISO 3696.
5.1 Hydrochloric acid solution, 1 + 1.
Add 500 ml of hydrochloric acid (ρ approximately 1,19 g/ml) to 500 ml of water and mix.
5.2 Sulphuric acid, ρ approximately 1,84 g/ml, free from nitrogen compounds.
It is preferable to prepare the acid by evaporating until the fume of sulphuric acid appears and to
continue fuming for 20 min to 30 min at the time of use.
5.3 Sulphuric acid solution, approximately 0,02 mol/l.
Add 30 ml of sulphuric acid (5.2) little by little into about 700 ml of water. After cooling, make up the
volume to 1 l with water, and mix. Dilute 40 ml of this solution to 1 l with water and mix.
5.4 Sodium hydroxide, 500 g/l solution.
Add cautiously, while stirring and cooling, about 900 ml of water into a polyethylene bottle containing
500 g of sodium hydroxide pellets. Cool, dilute to 1 l with water and mix.
5.5 Sodium hydroxide, 7,5 g/l solution.
Dilute 15 ml of sodium hydroxide (5.4) to 1 l with water and mix.
5.6 Potassium sulfate, K SO .
2 4
5.7 Copper(ll) sulfate pentahydrate, CuSO ·5H O.
4 2
5.8 Disodium hydrogenphosphate, 0,1 mol/l solution.
Dissolve 36 g of disodium hydrogenphosphate dodecahydrate (Na HPO ·12H O) in water, make up the
2 4 2
volume to 1 l with wat
...