EN ISO 13520:2023

Determination of ferrite content in austenitic stainless steel castings (ISO 13520:2023)

Procedures are covered for estimating ferrite content in certain grades of austenitic iron-chromium-nickel alloy castings that have compositions balanced to create the formation of ferrite as a second phase in amounts controlled within specified limits. Methods are described for estimating ferrite content by chemical, magnetic and metallographic means.

Bestimmung des Ferritgehaltes in austenitischem nichtrostenden Stahlguss (ISO 13520:2023)

Es werden Verfahrensweisen zur Abschätzung von Ferritgehalten in bestimmten Sorten von Eisen-Chrom-Nickel-Gusslegierungen berücksichtigt, welche abgestimmte Zusammensetzungen zur Bildung von Ferrit, in kontrollierten Mengenanteilen und in festgelegten Grenzen, als Sekundärphase haben. Es werden Methoden zur Abschätzung der Ferritgehalte mittels chemischer, magnetischer und metallographischer Hilfsmittel beschrieben.

Détermination du taux de ferrite des pièces moulées en acier inoxydable austénitique (ISO 13520:2023)

Des modes opératoires sont donnés pour estimer le taux de ferrite de certaines nuances de pièces moulées en alliage austénitique de fer-chrome-nickel dont la composition est équilibrée pour provoquer la formation de ferrite en phase secondaire et en quantité maintenue dans des limites spécifiées. Les méthodes décrites permettent l'estimation du taux de ferrite par des procédés chimiques, magnétiques et métallographiques.

Določevanje feritov v avstenitnih ulitkih iz nerjavnega jekla (ISO 13520:2023)

Standard ISO 13520:2015 določa postopke za ocenjevanje vsebnosti ferita v določenih razredih ulitkov iz avstenitnih železo-kromo-nikljevih zlitin, katerih sestave so uravnotežene za ustvarjanje oblikovanja ferita kot druge faze v količinah, nadzorovanih znotraj določenih omejitev. Opisane so metode za vrednotenje vsebnosti ferita s kemičnimi, magnetnimi in metalografskimi sredstvi.

General Information

• Status: Published
• Publication Date: 04-Apr-2023
• ICS: 77.140.80 - Iron and steel castings
• Technical Committee: ECISS/TC 111 - Steel castings and forgings
• Drafting Committee: ECISS/TC 111 - Steel castings and forgings
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 05-Apr-2023
• Completion Date: 05-Apr-2023
• Ref Project: SIST EN ISO 13520:2023 - Determination of ferrite content in austenitic stainless steel castings (ISO 13520:2023)

Relations

• Replaces: EN ISO 13520:2019 - Determination of ferrite content in austenitic stainless steel castings (ISO 13520:2015)
• Effective Date: 13-Apr-2022

Overview

EN ISO 13520:2023 - Determination of ferrite content in austenitic stainless steel castings defines standardized procedures for estimating the ferrite content (volume percent) in austenitic iron‑chromium‑nickel alloy castings. The standard covers castings whose chemistry is intentionally balanced to form ferrite as a controlled second phase. It describes three accepted measurement routes - chemical, magnetic and metallographic - and provides guidance on sampling, ordering information, and interpretation of results to support quality control and specification compliance.

Key topics and technical requirements

• Scope and significance: Explains how ferrite fraction affects tensile/impact properties, weldability and corrosion resistance, and why controlled ferrite content is specified for many castings.
• Three methods of determination:
  • Chemical composition method - estimation from heat or product chemical analysis using chromium and nickel equivalents together with the Schoefer diagram to predict ferrite percentage. (ISO provides the required calculation approach and diagram references.)
  • Magnetic response method - non‑destructive magnetic measurements to estimate ferrite; notes sources of error such as other ferromagnetic phases, surface condition and instrument probe geometry.
  • Metallographic examination - point‑counting and quantitative metallography on prepared specimens; Annex A gives normative guidance for magnetic and metallographic procedures.
• Measurement uncertainty and limitations: Discusses precision issues for each method (segregation, thermal history, etching technique, grid size, chemical analysis accuracy) and the need to set realistic specification limits.
• Ordering and documentation: Specifies information to be included in purchase orders: product specification, alloy grade, required ferrite range (volume %), chosen test method and measurement locations.
• Normative and informative annexes: Includes Annex A (normative methods) and Annex B (notes on the Schoefer diagram).

Practical applications

• Process control during melting and casting to achieve target ferrite levels.
• Incoming inspection and acceptance testing of austenitic stainless steel castings.
• Failure or root‑cause analysis where ferrite fraction impacts mechanical behavior or corrosion performance.
• Weld procedure qualification and design checks where ferrite‑to‑austenite balance is critical.
• Contractual specifications between manufacturers and purchasers to define allowable ferrite ranges and test methods.

Who should use EN ISO 13520:2023

• Foundries and steelmakers (material production and melt control)
• Quality and inspection engineers (NDT and metallography)
• Materials and corrosion engineers (selection and design)
• Procurement and compliance teams (specifying acceptance criteria)
• Welding engineers and fabricators concerned with microstructural balance

Related standards

• ISO 4990 - Steel castings - General technical delivery requirements
• ISO 9042 - Manual point counting method for estimating volume fraction
• EN ISO 13520:2023 replaces EN ISO 13520:2019 and is published by CEN in collaboration with ISO/TC 17.

Keywords: EN ISO 13520:2023, ferrite content, austenitic stainless steel castings, ferrite determination, chemical method, magnetic method, metallographic method, Schoefer diagram, chromium equivalent, nickel equivalent.

Standards Content (Sample)

SLOVENSKI STANDARD
01-junij-2023
Določevanje feritov v avstenitnih ulitkih iz nerjavnega jekla (ISO 13520:2023)
Determination of ferrite content in austenitic stainless steel castings (ISO 13520:2023)
Bestimmung des Ferritgehaltes in austenitischem nichtrostenden Stahlguss (ISO
13520:2023)
Détermination du taux de ferrite des pièces moulées en acier inoxydable austénitique
(ISO 13520:2023)
Ta slovenski standard je istoveten z: EN ISO 13520:2023
ICS:
77.140.20 Visokokakovostna jekla Stainless steels
77.140.80 Železni in jekleni ulitki Iron and steel castings
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 13520
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2023
EUROPÄISCHE NORM
ICS 77.140.80 Supersedes EN ISO 13520:2019
English Version
Determination of ferrite content in austenitic stainless
steel castings (ISO 13520:2023)
Détermination du taux de ferrite des pièces moulées en Bestimmung des Ferritgehaltes in austenitischem
acier inoxydable austénitique (ISO 13520:2023) nichtrostenden Stahlguss (ISO 13520:2023)
This European Standard was approved by CEN on 10 March 2023.

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
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 13520:2023 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 13520:2023) has been prepared by Technical Committee ISO/TC 17 "Steel" in
collaboration with Technical Committee CEN/TC 459/SC 11 “Steel castings and forgings” the secretariat
of which is held by AFNOR.
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 October 2023, and conflicting national standards shall
be withdrawn at the latest by October 2023.
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 13520:2019.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
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, 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.
Endorsement notice
The text of ISO 13520:2023 has been approved by CEN as EN ISO 13520:2023 without any modification.

INTERNATIONAL ISO
STANDARD 13520
Third edition
2023-03
Determination of ferrite content in
austenitic stainless steel castings
Détermination du taux de ferrite des pièces moulées en acier
inoxydable austénitique
Reference number
ISO 13520:2023(E)
ISO 13520:2023(E)
© ISO 2023
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]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO 13520:2023(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Significance effects of ferrite content . 1
5 Methods of determination of ferrite content . 2
5.1 Chemical composition method . 2
5.2 Magnetic response method . 2
5.3 Metallographic examination . 2
6 Ordering information . 2
7 General caution . 2
8 Estimation of ferrite . 3
9 Acceptance standards .3
10 Certification . 3
Annex A (normative) Determination of ferrite content by magnetic or metallographic
means . 4
Annex B (informative) Notes to Schoefer diagram . 6
Bibliography .11
iii
ISO 13520:2023(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.org/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 11, Steel
castings, in collaboration with the European Committee for Standardization (CEN) Technical Committee
CEN/TC 459/SC 11, Steel castings and forgings, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 13520:2015), of which it constitutes a
minor revision. The changes are as follows:
— ASTM A799 and BNIF 345 where moved to the bibliography as they are not cited normatively;
— editorial revision.
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
INTERNATIONAL STANDARD ISO 13520:2023(E)
Determination of ferrite content in austenitic stainless
steel castings
1 Scope
Procedures are covered for estimating ferrite content in certain grades of austenitic iron-chromium-
nickel alloy castings that have compositions balanced to create the formation of ferrite as a second
phase in amounts controlled within specified limits. Methods are described for estimating ferrite
content by chemical, magnetic and metallographic means.
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 4990, Steel castings — General technical delivery requirements
ISO 9042, Steels — Manual point counting method for statistically estimating the volume fraction of a
constituent with a point grid
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology 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/
3.1
ferrite
ferromagnetic, body-centred cubic microstructural constituent of variable chemical composition in
iron-chromium-nickel alloys
Note 1 to entry: Ferrite includes both delta and alpha species.
3.2
ferrite content
proportion of total volume of an iron-chromium-nickel alloy present as the ferrite phase
3.3
ferrite percentage
ferrite content expressed as a volume percent
4 Significance effects of ferrite content
The tensile and impact properties, the weldability, and the corrosion resistance of iron-chromium-
nickel alloy castings may be influenced beneficially or detrimentally by the ratio of the amount of ferrite
to the amount of austenite in the microstructure. The ferrite content may be limited by purchase order
requirements or by the design construction codes governing the equipment in which castings will be
used. The quantity of ferrite in the structure is fundamentally a function of the chemical composition
of the alloy and its thermal history. Because of segregation, the chemical composition and, therefore,
ISO 13520:2023(E)
the ferrite content, may differ from point to point on a casting. Determination of the ferrite content by
any of the procedures described in Clause 5 is subject to varying degrees of imprecision which shall
be recognized in setting realistic limits on the range of ferrite content specified. Sources of error are
described in 5.1 to 5.3.
5 Methods of determination of ferrite c
...