EN 10178:2024

Steels - Determination of niobium - Spectrophotometric method

This document specifies a spectrophotometric method for the determination of niobium in steels.
The method is applicable to all grades of steels with niobium contents up to 1,3 % (by mass), with a lower limit of detection of 0,002 % (by mass).
The precision data of the present method are given in Annex A.

Stähle - Bestimmung von Niob - Photometrisches Verfahren

Dieses Dokument legt ein photometrisches Verfahren zur Bestimmung von Niob in Stählen fest.
Das Verfahren ist anwendbar für alle Stahlsorten mit Niobgehalten bis zu 1,3 % (Massenanteil), mit einer unteren Nachweisgrenze von 0,002 % (Massenanteil).
Die Präzisionsdaten dieses Verfahren sind in Anhang A wiedergegeben.

Aciers - Détermination du niobium - Méthode spectrophotométrique

Le présent document spécifie une méthode spectrophotométrique de détermination du niobium dans les aciers.
La méthode est applicable à tous les types d’acier pour des teneurs en niobium allant jusqu’à 1,3 % (en masse), avec une limite inférieure de détection de 0,002 % (en masse).
Les données de fidélité de la présente méthode figurent dans l'Annexe A.

Jekla - Določevanje niobija - Spektrofotometrična metoda

Ta dokument določa spektrofotometrično metodo za določevanje niobija v jeklu.
Metoda se uporablja za vse razrede jekla z vsebnostjo niobija do 1,3 % (glede na maso) in spodnjo mejo detekcije 0,002 % (glede na maso).

General Information

• Status: Published
• Publication Date: 18-Jun-2024
• ICS: 77.040.30 - Chemical analysis of metals
• Technical Committee: ECISS/TC 102 - Methods of chemical analysis for iron and steel
• Drafting Committee: CEN/TC 459/SC 2/WG 4 - Determination of oxygen in steel
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 19-Jun-2024
• Due Date: 27-Jan-2025
• Completion Date: 19-Jun-2024
• Ref Project: SIST EN 10178:2024 - Steels - Determination of niobium - Spectrophotometric method

Relations

• Replaces: EN 10178:1989 - Chemical analysis of ferrous materials - Determination of niobium in steels - Spectrophotometric method
• Effective Date: 19-Jan-2023

Overview

EN 10178:2024 - Steels: Determination of niobium - Spectrophotometric method (CEN) specifies a validated spectrophotometric procedure for measuring niobium (Nb) in steels. The method applies to all steel grades with niobium contents up to 1.3 % (m/m) and has a lower limit of detection of 0.002 % (m/m). Precision data for the method are provided in Annex A.

Key topics and requirements

• Principle: dissolution of a 1 g test portion in hydrochloric acid, oxidation with hydrogen peroxide, selective precipitation of Nb (with tantalum) using phenylarsonic acid and zirconium carrier, followed by colour development with 4-(2‑pyridylazo)-resorcinol (PAR) in a buffered sodium‑tartrate medium and spectrophotometric measurement at 550 nm.
• Range & sensitivity: applicable up to 1.3 % Nb; detection down to 0.002 % Nb.
• Reagents and materials: analytical‑grade reagents and grade 2 water (EN ISO 3696); specific reagents include PAR, zirconium nitrate, phenylarsonic acid, EDTA, tartaric/sodium acetate buffers and hydrogen peroxide.
• Apparatus: grade A volumetric glassware (EN ISO 648 / EN ISO 1042), pH meter, and a spectrophotometer capable of absorbance at 550 nm with 1 cm or 4 cm cells.
• Procedure essentials:
  • Typical test portion ~1.0 g; run a parallel blank test using high‑purity iron.
  • Choice of aliquot volume (25, 10 or 5 ml) and cell path length is based on expected Nb content (guidance provided in the standard).
  • Establish a calibration curve using prepared Nb standard solutions and correct readings by subtracting the zero member (blank).
• Reporting: results expressed as % (m/m) Nb, and the test report must identify the sample, method reference, results, any deviations and the responsible analyst.

Practical applications and users

• Laboratories performing chemical analysis of metals and quality control in steel production.
• Metallurgists and materials engineers verifying Nb additions for microstructure control (e.g., grain refinement, precipitation strengthening).
• Regulatory and conformity testing bodies requiring standardized, traceable niobium assays.
• Useful where mid‑range Nb levels (ppm to percent) must be quantified reliably for product specification or R&D.

Related standards and references

• Normative references cited: EN ISO 648, EN ISO 1042, EN ISO 14284, EN ISO 3696 (glassware, sampling, and water quality).
• Precision and interlaboratory performance data are given in Annex A of EN 10178:2024.

Keywords: EN 10178:2024, niobium determination, spectrophotometric method, niobium in steel, chemical analysis of metals, PAR reagent, spectrophotometry 550 nm.

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2024
Jekla - Določevanje niobija - Spektrofotometrična metoda
Steels - Determination of niobium - Spectrophotometric method
Stähle - Bestimmung von Niob - Photometrisches Verfahren
Aciers - Détermination du niobium - Méthode spectrophotométrique
Ta slovenski standard je istoveten z: EN 10178:2024
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 10178
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2024
EUROPÄISCHE NORM
ICS 77.040.30 Supersedes EN 10178:1989
English Version
Steels - Determination of niobium - Spectrophotometric
method
Aciers - Détermination du niobium - Méthode Stähle - Bestimmung von Niob - Photometrisches
spectrophotométrique Verfahren
This European Standard was approved by CEN on 29 April 2024.

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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye 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
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 10178:2024 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Principle . 4
5 Reagents . 4
6 Apparatus . 6
7 Sampling . 6
8 Procedure . 6
8.1 Test portion . 6
8.2 Blank test . 6
8.3 Determination . 6
8.3.1 Preparation of the test solution . 6
8.3.2 Separation of the niobium . 6
8.3.3 Development of the colour . 7
8.3.4 Spectrophotometric measurement . 7
8.4 Establishment of the calibration curve . 7
8.4.1 Preparation of the calibration solutions . 7
8.4.2 Spectrophotometric measurements . 8
8.4.3 Plotting the calibration curve . 8
9 Expression of results . 9
10 Test report . 9
Annex A (informative) Precision data . 11
Bibliography . 12

European foreword
This document (EN 10178:2024) has been prepared by Technical Committee CEN/TC 459/SC 2 “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 December 2024, and conflicting national standards shall
be withdrawn at the latest by December 2024.
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 10178:1989.
In comparison with the previous edition, the following technical modifications have been made:
— normative references: updated;
— Clause 3 Terms and definitions: added;
— reference 5.13: added;
— reference 5.18: title simplified;
— Clause 6: developed and subclauses 6.1 and 6.2, added;
— Clause 7: updated;
— former subclause 7.3.3: included in 8.3.2;
— Clause 10: updated;
— Bibliography: added.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the United
Kingdom.
1 Scope
This document specifies a spectrophotometric method for the determination of niobium in steels.
The method is applicable to all grades of steels with niobium contents up to 1,3 % (by mass), with a lower
limit of detection of 0,002 % (by mass).
The precision data of the present method are given in Annex A.
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.
EN ISO 648, Laboratory glassware — Single-volume pipettes (ISO 648)
EN ISO 1042, Laboratory glassware — One-mark volumetric flasks (ISO 1042)
EN ISO 14284, Steel and iron — Sampling and preparation of samples for the determination of chemical
composition (ISO 14284)
EN ISO 3696, Water for analytical laboratory use — Specification and test methods (ISO 3696)
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 https://www.electropedia.org/
4 Principle
Dissolution of a test portion with hydrochloric acid followed by oxidation with hydrogen peroxide.
Precipitation of niobium and tantalum with phenylarsonic acid using zirconium as a carrier.
Formation of a complex of niobium with 4-(2-pyridylazo)-resorcinol (PAR) in a buffered sodium tartrate
medium.
Spectrophotometric measurement of the coloured compound at a wavelength of 550 nm.
5 Reagents
5.1 General
During analysis, unless otherwise stated, use only reagents of recognized analytical grade and only
grade 2 water as specified in EN ISO 3696 or water of equivalent purity.
5.2 Iron, of high purity, free from niobium
5.3 Potassium hydrogen sulphate (KHSO )
5.4 Hydrochloric acid, ρ 1,19 g/ml approximately
5.5 Hydrochloric acid, solution 1 + 4
Carefully add 40 ml of hydrochloric acid (5.4) to 160 ml of water and mix.
5.6 Hydrochloric acid, solution 1 + 9
Carefully add 20 ml of hydrochloric acid (5.4)
...