Non-destructive testing - Standard test method for determining residual stresses by neutron diffraction (ISO 21432:2019)

This document describes the test method for determining residual stresses in polycrystalline materials
by neutron diffraction. It is applicable to both homogeneous and inhomogeneous materials including
those containing distinct phases.
The principles of the neutron diffraction technique are outlined. Suggestions are provided on:
— the selection of appropriate diffracting lattice planes on which measurements should be made for
different categories of materials,
— the specimen directions in which the measurements should be performed, and
— the volume of material examined in relation to the material grain size and the envisaged stress state.
Procedures are described for accurately positioning and aligning test pieces in a neutron beam and for
precisely defining the volume of material sampled for the individual measurements.
The precautions needed for calibrating neutron diffraction instruments are described. Techniques for
obtaining a stress-free reference are presented.
The methods of making individual measurements by neutron diffraction are described in detail.
Procedures for analysing the results and for determining their statistical relevance are presented.
Advice is provided on how to determine reliable estimates of residual stresses from the strain data and
on how to estimate the uncertainty in the results.

Zerstörungsfreie Prüfung - Standardprüfverfahren zur Bestimmung von Eigenspannungen durch Neutronenbeugung (ISO 21432:2019)

Dieses Dokument beschreibt das Messverfahren zur Bestimmung von Eigenspannungen in polykristallinen Werkstoffen durch Neutronenbeugung. Es ist sowohl bei homogenen als auch bei inhomogenen Werkstoffen anwendbar, einschließlich derjenigen Werkstoffe, die verschiedene Phasen enthalten.
Die Grundlagen des Verfahrens der Neutronenbeugung werden kurz dargestellt. Es werden Vorschläge bezüglich folgender Punkte bereitgestellt:
- die Auswahl geeigneter Beugungsgitterebenen, an denen Messungen für jeweils unterschiedliche Werkstoffkategorien erfolgen sollten;
- die Richtungen der Probe, in denen die Messungen durchgeführt werden sollten; und
- das untersuchte Werkstoffvolumen im Verhältnis zur Korngröße des Werkstoffs und den erwarteten Spannungszustand.
Es werden Verfahren zur genauen Positionierung und Ausrichtung von Proben in einem Neutronenstrahl sowie zur genauen Festlegung des für die einzelnen Messungen genutzten Werkstoffvolumens beschrieben.
Es erfolgt eine Beschreibung der für die Kalibrierung der zur Neutronenbeugung verwendeten Instrumente erforderlichen Vorkehrungen. Es werden Verfahren vorgestellt, mit denen eine spannungsfreie Referenzprobe hergestellt werden kann.
Die Verfahren zur Durchführung von Einzelmessungen mittels Neutronenbeugung werden ausführlich beschrieben. Es werden Vorgehensweisen zur Analyse der Ergebnisse und zur Bestimmung ihrer statistischen Relevanz vorgestellt. Es werden Hinweise gegeben, wie zuverlässige Schätzwerte von Eigenspannungen aus den Dehnungswerten bestimmt und wie die Unsicherheit der Ergebnisse bestimmt werden kann.
WARNUNG - Dieses Dokument erhebt nicht den Anspruch, dass die möglicherweise mit seiner Anwendung verbundenen Sicherheitsprobleme angesprochen werden. Es liegt in der Verantwortung des Anwenders dieses Dokumentes, geeignete Vorkehrungen für den Arbeits  und Gesundheitsschutz zu treffen und die Anwendbarkeit einschränkender Vorschriften vor der Anwendung zu bestimmen.

Essais non destructifs - Méthode normalisée de détermination des contraintes résiduelles par diffraction de neutrons (ISO 21432:2019)

AVERTISSEMENT — Le présent document n'a pas pour but de traiter des problèmes de sécurité qui sont, le cas échéant, liés à son utilisation. Il incombe à l'utilisateur du présent document de mettre en place des pratiques appropriées en matière d'hygiène et de sécurité, et de s'assurer de la conformité à la réglementation nationale en vigueur.

Neporušitvene preiskave - Standardizirana preskusna metoda za ugotavljanje zaostalih napetosti z uklonom nevtronskih žarkov (ISO 21432:2019)

General Information

Status
Published
Public Enquiry End Date
26-Jul-2020
Publication Date
09-Nov-2020
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Oct-2020
Due Date
06-Dec-2020
Completion Date
10-Nov-2020

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SLOVENSKI STANDARD
SIST EN ISO 21432:2020
01-december-2020
Nadomešča:
SIST-TS CEN ISO/TS 21432:2005
SIST-TS CEN ISO/TS 21432:2005/AC:2009
Neporušitvene preiskave - Standardizirana preskusna metoda za ugotavljanje
zaostalih napetosti z uklonom nevtronskih žarkov (ISO 21432:2019)

Non-destructive testing - Standard test method for determining residual stresses by

neutron diffraction (ISO 21432:2019)
Zerstörungsfreie Prüfung - Standardprüfverfahren zur Bestimmung von
Eigenspannungen durch Neutronenbeugung (ISO 21432:2019)
Essais non destructifs - Méthode normalisée de détermination des contraintes
résiduelles par diffraction de neutrons (ISO 21432:2019)
Ta slovenski standard je istoveten z: EN ISO 21432:2020
ICS:
19.100 Neporušitveno preskušanje Non-destructive testing
SIST EN ISO 21432:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 21432:2020
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SIST EN ISO 21432:2020
EN ISO 21432
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2020
EUROPÄISCHE NORM
ICS 19.100 Supersedes CEN ISO/TS 21432:2005
English Version
Non-destructive testing - Standard test method for
determining residual stresses by neutron diffraction (ISO
21432:2019)

Essais non destructifs - Méthode normalisée de Zerstörungsfreie Prüfung - Standardprüfverfahren zur

détermination des contraintes résiduelles par Bestimmung von Eigenspannungen durch

diffraction de neutrons (ISO 21432:2019) Neutronenbeugung (ISO 21432:2019)
This European Standard was approved by CEN on 31 August 2020.

This European Standard was corrected and reissued by the CEN-CENELEC Management Centre on 21 October 2020.

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, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATIO N
EUROPÄISCHES KOMITEE FÜR NORMUN G
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 21432:2020 E

worldwide for CEN national Members.
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SIST EN ISO 21432:2020
EN ISO 21432:2020 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 21432:2020
EN ISO 21432:2020 (E)
European foreword

The text of ISO 21432:2019 has been prepared by Technical Committee ISO/TC 135 "Non-destructive

testing” of the International Organization for Standardization (ISO) and has been taken over as

EN ISO 21432:2020 by Technical Committee CEN/TC 138 “Non-destructive testing” 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 March 2021, and conflicting national standards shall

be withdrawn at the latest by March 2021.

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 CEN ISO/TS 21432:2005.

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, Turkey and the

United Kingdom.
Endorsement notice

The text of ISO 21432:2019 has been approved by CEN as EN ISO 21432:2020 without any modification.

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SIST EN ISO 21432:2020
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SIST EN ISO 21432:2020
INTERNATIONAL ISO
STANDARD 21432
First edition
2019-12
Non-destructive testing — Standard
test method for determining residual
stresses by neutron diffraction
Essais non destructifs — Méthode normalisée de détermination des
contraintes résiduelles par diffraction de neutrons
Reference number
ISO 21432:2019(E)
ISO 2019
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SIST EN ISO 21432:2020
ISO 21432:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

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: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
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SIST EN ISO 21432:2020
ISO 21432:2019(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ..............................................................................................................................................................................................................................vii

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Symbols and abbreviated terms ........................................................................................................................................................... 5

4.1 Symbols and units ................................................................................................................................................................................ 5

4.2 Subscripts .................................................................................................................................................................................................... 7

4.3 Abbreviated terms ............................................................................................................................................................................... 7

5 Summary of method .......................................................................................................................................................................................... 7

5.1 General ........................................................................................................................................................................................................... 7

5.2 Outline of the principle — Bragg’s law .............................................................................................................................. 7

5.3 Neutron sources ..................................................................................................................................................................................... 7

5.4 Strain determination .......................................................................................................................................................................... 8

5.4.1 General...................................................................................................................................................................................... 8

5.4.2 Monochromatic instrument ................................................................................................................................... 8

5.4.3 TOF instrument ................................................................................................................................................................. 8

5.5 Neutron diffractometers ................................................................................................................................................................. 9

5.6 Stress determination ......................................................................................................................................................................... 9

6 Purpose, geometry and material ......................................................................................................................................................14

6.1 General ........................................................................................................................................................................................................14

6.2 Purpose of the measurement ..................................................................................................................................................14

6.3 Geometry ...................................................................................................................................................................................................14

6.4 Composition ...........................................................................................................................................................................................14

6.5 Thermal/mechanical history ...................................................................................................................................................15

6.6 Phases and crystal structures .................................................................................................................................................15

6.7 Homogeneity ......... .................................................................................................................................................................................15

6.8 Microstructure .....................................................................................................................................................................................15

6.9 Texture ........................................................................................................................................................................................................15

7 Preparations for measurements .......................................................................................................................................................15

7.1 General ........................................................................................................................................................................................................15

7.2 Alignment and calibration of the instrument ............................................................................................................15

7.3 Choice of diffraction conditions ............................................................................................................................................16

7.3.1 Monochromatic instruments ..............................................................................................................................16

7.3.2 TOF instruments ...........................................................................................................................................................18

7.4 Positioning procedures .................................................................................................................................................................19

7.5 Gauge volumes .....................................................................................................................................................................................19

7.6 Methods for establishing the macroscopically stress-free or reference lattice spacing .......20

8 Measurement and recording requirements ..........................................................................................................................22

8.1 General ........................................................................................................................................................................................................22

8.2 Recording requirements ..............................................................................................................................................................22

8.2.1 General...................................................................................................................................................................................22

8.2.2 General information — instrument ..............................................................................................................22

8.2.3 General information — specimen ..................................................................................................................23

8.2.4 Specific information required for each diffraction measurement .....................................23

8.3 Specimen co-ordinates ..................................................................................................................................................................24

8.4 Positioning of the specimen ......................................................................................................................................................24

8.5 Measurement directions ..............................................................................................................................................................24

8.6 Number and location of measuring positions ...........................................................................................................24

8.7 Gauge volume ........................................................................................................................................................................................25

8.8 Gauge volume centroid considerations ..........................................................................................................................25

© ISO 2019 – All rights reserved iii
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SIST EN ISO 21432:2020
ISO 21432:2019(E)

8.9 Temperature ...........................................................................................................................................................................................25

9 Calculation of stress .......................................................................................................................................................................................25

9.1 General ........................................................................................................................................................................................................25

9.2 Normal stress determinations ................................................................................................................................................25

9.3 Stress state determinations ......................................................................................................................................................26

9.3.1 General...................................................................................................................................................................................26

9.3.2 The sinψ method ........................................................................................................................................................26

9.4 Choice of elastic constants .........................................................................................................................................................27

9.5 Diffraction data analysis ..............................................................................................................................................................27

9.5.1 General...................................................................................................................................................................................27

9.5.2 Peak fitting function ...................................................................................................................................................27

9.5.3 Background function .................................................................................................................................................28

9.5.4 Peak to background ratio.......................................................................................................................................28

9.5.5 Distorted peak profiles ............................................................................................................................................28

10 Reliability ..................................................................................................................................................................................................................29

11 Reporting ...................................................................................................................................................................................................................30

11.1 General ........................................................................................................................................................................................................30

11.2 Strain or stress values ....................................................................................................................................................................30

11.2.1 General...................................................................................................................................................................................30

11.2.2 Stress-free or reference lattice spacing .....................................................................................................30

11.2.3 Conversion of strain to stress ............................................................................................................................30

11.2.4 Elastic constants .................. .................................................... ......................................................................................30

11.2.5 Positioning .........................................................................................................................................................................30

11.3 Neutron source and instrument ............................................................................................................................................30

11.4 General measurement procedures .....................................................................................................................................31

11.5 Specimens/materials properties ..........................................................................................................................................31

11.6 Original data ...........................................................................................................................................................................................31

11.7 Uncertainties and errors .............................................................................................................................................................31

Annex A (informative) Measurement and analysis methodologies ...................................................................................32

Annex B (informative) Determination of uncertainties in a measurand .....................................................................41

Bibliography .............................................................................................................................................................................................................................44

iv © ISO 2019 – All rights reserved
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SIST EN ISO 21432:2020
ISO 21432:2019(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 135, Non-destructive testing,

Subcommittee SC 5, Radiographic Testing.

This first edition cancels and replaces ISO/TS 21432:2005, which has been technically revised. It also

incorporates the Technical Corrigendum ISO/TS 21432:2005/Cor 1:2008. Furthermore this document

replaces ISO/TTA3: 2001.
The main changes compared to ISO/TS 21432 are as follows:

— Figures 1 and 5 were replaced with updated, more suitable versions. The keys for several figures

were updated in order to better reflect and explain the content of the figures.

— 5.4 was rearranged to emphasize the distinction between monochromatic instruments and time-of-

flight instruments.

— The former Clause 7 became Clause 6 and vice versa. The new order reflects better the real order of

steps taken in the preparation of a measurement.

— 7.6 was updated to provide additional details on the determination of the stress-free reference value.

— Clause 10 was slightly modified and the references to the ISO/IEC Guides relevant to uncertainty

determination were updated.
— 11.7 was added in order to include uncertainties and errors in the reporting.

— A.5.4 was revised and amended to provide more information on grain size effects and the possibilities

to mitigate these.

— A.9 was added to explain the calculation of stresses in the case of macroscopically anisotropic

material.
— The Bibliography was updated by including a few new references.
© ISO 2019 – All rights reserved v
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SIST EN ISO 21432:2020
ISO 21432:2019(E)

— Throughout the document minor revisions of the text were implemented in order to correct small

errors and to improve the clarity.

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.
vi © ISO 2019 – All rights reserved
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SIST EN ISO 21432:2020
ISO 21432:2019(E)
Introduction

Neutron diffraction is a non-destructive method that can be employed for determining residual

stresses in crystalline materials. It can also be used to determine internal stresses in samples subjected

to applied stresses. The procedure can be employed for determining stresses within the interior of

materials and adjacent to surfaces. It requires specimens or engineering components to be transported

to a neutron source. Elastic strains are derived from the measurements, which in turn are converted

into stresses. The purpose of this document is to provide an International Standard for reliably

determining stresses that are relevant to engineering applications.
© ISO 2019 – All rights reserved vii
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SIST EN ISO 21432:2020
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SIST EN ISO 21432:2020
INTERNATIONAL STANDARD ISO 21432:2019(E)
Non-destructive testing — Standard test method for
determining residual stresses by neutron diffraction

WARNING — This document does not purport to address the safety concerns, if any, associated

with its use. It is the responsibility of the user of this document to establish appropriate safety

and health practices and determine the applicability of regulatory limitations prior to use.

1 Scope

This document describes the test method for determining residual stresses in polycrystalline materials

by neutron diffraction. It is applicable to both homogeneous and inhomogeneous materials including

those containing distinct phases.

The principles of the neutron diffraction technique are outlined. Suggestions are provided on:

— the selection of appropriate diffracting lattice planes on which measurements should be made for

different categories of materials,
— the specimen directions in which the measurements should be performed, and

— the volume of material examined in relation to the material grain size and the envisaged stress state.

Procedures are described for accurately positioning and aligning test pieces in a neutron beam and for

precisely defining the volume of material sampled for the individual measurements.

The precautions needed for calibrating neutron diffraction instruments are described. Techniques for

obtaining a stress-free reference are presented.

The methods of making individual measurements by neutron diffraction are described in detail.

Procedures for analysing the results and for determining their statistical relevance are presented.

Advice is provided on how to determine reliable estimates of residual stresses from the strain data and

on how to estimate the uncertainty in the results.
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 13925-3:2015, Non-destructive testing — X-ray diffraction from polycrystalline and amorphous

materials — Part 3: Instruments
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at http:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
© ISO 2019 – All rights reserved 1
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SIST EN ISO 21432:2020
ISO 21432:2019(E)
3.1
neutron absorption
neutron capture by an atomic nucleus
Note 1 to entry: A table of nuclear
...

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