CEN ISO/ASTM/TR 52906:2022

Additive manufacturing - Non-destructive testing - Intentionally seeding flaws in metallic parts (ISO/ASTM/TR 52906:2022)

This document is intended to serve as a best practice for the identification and “seeding” of nondestructively detectable flaw replicas of metal alloy PBF and DED processes. Three seeding categories are described:
a) process flaws through CAD design;
b) build parameter manipulation;
c) subtractive manufacturing.
These include flaws present within as-deposited materials, post heat-treated or HIP processed material, and those flaws made detectable because of post-processing operations. Geometrical aspects or measurement are not the subjects of this document.
WARNING — This document does not purport to address all of 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.

Additive Fertigung - Zerstörungsfreie Prüfung - Bewusstes Einbringen von Fehlern in Bauteile (ISO/ASTM/TR 52906:2022)

Dieses Dokument dient als Leitfaden für die Identifizierung und das „Einbringen“ von zerstörungsfrei nachweisbaren Nachbildungen von Fehlern bei PBF- und DED-Verfahren für Metalllegierungen. Es werden drei Kategorien zum Einbringen von Fehlern beschrieben:
a)   Prozessmängel durch CAD-Design;
b)   Manipulation der Bauparameter;
c)   subtraktive Fertigung.
Dazu gehören Fehler, die in den Werkstoffen nach der Ablagerung, nach der Wärmebehandlung oder nach der HIP-Bearbeitung zu finden sind, sowie Fehler, die aufgrund von Nachbearbeitungsvorgängen festgestellt werden. Geometrische Aspekte oder Messungen sind nicht Gegenstand dieses Dokuments.
WARNUNG — Dieses Dokument erhebt nicht den Anspruch, alle Sicherheitsprobleme zu behandeln, die im Zusammenhang mit ihrer Anwendung, wenn überhaupt, auftreten. Es liegt in der Verantwortung des Anwenders dieses Dokuments, entsprechende Maßnahmen zum Arbeits- und Gesundheitsschutz zu ergreifen sowie vor der Verwendung die Anwendbarkeit von gesetzlichen Einschränkungen festzustellen.

Fabrication additive - Essais non destructifs - Implantation intentionnelle de défauts dans les pièces métalliques (ISO/ASTM/TR 52906:2022)

Le présent document est destiné à servir de bonne pratique pour l'identification et «l'implantation» de répliques de défauts détectables de manière non destructive par les procédés PBF et DED en alliage métallique. Trois catégories d'implantation sont décrites:
a) les défauts du procédé par la conception CAO;
b) la manipulation des paramètres de fabrication;
c) la fabrication soustractive.
Cela comprend les défauts présents dans les matériaux tels que déposés, dans les matériaux traités par post-traitement thermique ou par HIP, et des défauts rendus détectables par les opérations de post-traitement. Les aspects géométriques ou les mesures ne font pas l'objet du présent document.
ATTENTION — Le présent document n'a pas pour but de traiter tous les problèmes de sécurité, le cas échéant, liés à son application. Il est de la responsabilité de l'utilisateur du présent document d'établir des pratiques de sécurité et d'hygiène appropriées, et de déterminer l'applicabilité des restrictions réglementaires avant utilisation.

Dodajalna izdelava - Neporušitveno preskušanje - Namerno vnašanje nepravilnosti v kovinske izdelke (ISO/ASTM TR 52906:2022)

Ta dokument je namenjen za uporabo kot primer najboljše prakse za ugotavljanje in »vnašanje« poustvarjenih nepravilnosti v procese laserskega pretaljevanja kovinskega prahu (PBF-LB) in laserskega navarjanja (DED) kovinskih zlitin, ki jih je mogoče zaznati z neporušitveno metodo. Opisane so tri kategorije vnašanja: 1. procesne nepravilnosti prek oblikovanja CAD; 2. manipuliranje s parametrom izdelave; 3. proizvodnja z odvzemom in 4) odlaganje/vstavljanje nepravilnosti po obdelavi. Slednje vključujejo nepravilnosti, prisotne v navarjenih materialih brez naknadne obdelave, v materialih z naknadno toplotno obdelavo ali obdelavo HIP, in nepravilnosti, zaznane zaradi postopkov naknadne obdelave. Ta dokument ne zajema geometrijskih vidikov merjenja.

General Information

• Status: Published
• Publication Date: 17-May-2022
• ICS: 25.030 - Additive manufacturing
• Technical Committee: CEN/TC 438 - Additive Manufacturing
• Drafting Committee: CEN/TC 438 - Additive Manufacturing
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 18-May-2022
• Completion Date: 18-May-2022
• Ref Project: SIST-TP CEN ISO/ASTM/TR 52906:2022 - Additive manufacturing - Non-destructive testing - Intentionally seeding flaws in metallic parts (ISO/ASTM TR 52906:2022)

Overview

CEN ISO/ASTM/TR 52906:2022 - Additive manufacturing - Non-destructive testing - Intentionally seeding flaws in metallic parts - is a technical report and best-practice guide for creating reproducible, nondestructively detectable flaw replicas in metal parts produced by powder-bed fusion (PBF) and directed energy deposition (DED). Endorsed by CEN and published jointly by ISO/ASTM, the document describes practical approaches to mimic real additive-manufacturing (AM) defects for NDT validation, training, and performance assessment.

Key topics

• Seeding categories: three primary approaches are defined:
  • CAD seeding (design-introduced flaws)
  • Build-parameter manipulation (process-induced flaws)
  • Subtractive (post-production) methods (mechanical, EDM, laser drilling)
• Applicable AM processes and heat sources: guidance covers PBF and DED workflows and considers laser beam (LB), electron beam (EB) and arc processes (AP).
• Flaw types discussed: pores/voids, entrapped unsintered powder, high-density inclusions, surface-connected flaws, and replicas introduced by machining or energy-based drilling.
• Material and post-processing contexts: seeding methods applicable to as-deposited, post-heat-treated, and HIP-processed materials; also covers flaws made detectable by post-processing.
• Limitations and exclusions: geometrical measurement and dimensional tolerancing are out of scope; intimate “kissing bonds” (very close-contact disbonds) currently have no proven controlled seeding method and are excluded.
• Safety and IP: the report warns users to establish appropriate safety practices and notes potential patent implications.

Applications

• NDT method development and validation: create controlled flaw replicas to verify performance of ultrasound, X-ray/CT, eddy-current and other NDT techniques for AM metallic parts.
• Calibration and qualification: develop reference artifacts for inspector qualification, procedure validation, and acceptance testing.
• Training and education: produce representative defects for operator training and image interpretation.
• R&D and process optimization: help AM process engineers study defect formation mechanisms by intentionally inducing known defects via CAD or parameter changes.
• Industry sectors: particularly relevant to aerospace, medical devices, automotive, and any safety-critical component manufacturers using AM and requiring robust NDT.

Who should use this standard

• NDT engineers and inspectors
• Additive manufacturing process engineers
• Quality managers and certification bodies
• Research laboratories and OEMs developing AM parts and inspection protocols

Related standards

• ISO/ASTM 52900 - AM terminology
• ISO/ASTM TR 52905 - complementary AM NDT guidance (referenced)
• ISO 17296-2 - AM process descriptions
• ASTM B243, ASTM E7, ASTM E1316 - metallurgy and NDT terminology referenced in the report

Keywords: additive manufacturing, non-destructive testing, NDT, flaw seeding, PBF, DED, metallic parts, CAD seeding, build parameter manipulation, seeded replicas.

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2022
Dodajalna izdelava - Neporušitveno preskušanje - Namerno vnašanje nepravilnosti
v kovinske izdelke (ISO/ASTM TR 52906:2022)
Additive manufacturing - Non-destructive testing - Intentionally seeding flaws in metallic
parts (ISO/ASTM TR 52906:2022)
Additive Fertigung - Zerstörungsfreie Prüfung und Bewertung - Bewusstes Einbringen
von Fehlern in Bauteilen (ISO/ASTM TR 52906:2022)
Fabrication additive - Essais non destructifs - Implantation intentionnelle de défauts dans
les pièces métalliques (ISO/ASTM TR 52906:2022)
Ta slovenski standard je istoveten z: CEN ISO/ASTM/TR 52906:2022
ICS:
19.100 Neporušitveno preskušanje Non-destructive testing
25.030 3D-tiskanje Additive manufacturing
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN ISO/ASTM/TR
TECHNICAL REPORT
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
May 2022
ICS
English Version
Additive manufacturing - Non-destructive testing -
Intentionally seeding flaws in metallic parts
(ISO/ASTM/TR 52906:2022)
Fabrication additive - Essais non destructifs - Additive Fertigung - Zerstörungsfreie Prüfung und
Implantation intentionnelle de défauts dans les pièces Bewertung - Bewusstes Einbringen von Fehlern in
métalliques (ISO/ASTM/TR 52906:2022) Bauteilen (ISO/ASTM/TR 52906:2022)

This Technical Report was approved by CEN on 28 April 2022. It has been drawn up by the Technical Committee CEN/TC 438.

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 NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN ISO/ASTM/TR 52906:2022 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (CEN ISO/ASTM/TR 52906:2022) has been prepared by Technical Committee ISO/TC
261 "Additive manufacturing" in collaboration with Technical Committee CEN/TC 438 “Additive
Manufacturing” the secretariat of which is held by AFNOR.
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.
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.
Endorsement notice
The text of ISO/ASTM TR 52906:2022 has been approved by CEN as CEN ISO/ASTM/TR 52906:2022
without any modification.
TECHNICAL ISO/ASTM TR
REPORT 52906
First edition
2022-05
Additive manufacturing — Non-
destructive testing — Intentionally
seeding flaws in metallic parts
Fabrication additive — Essais non destructifs — Implantation
intentionnelle de défauts dans les pièces métalliques
Reference number
ISO/ASTM TR 52906:2022(E)
© ISO/ASTM International 2022
ISO/ASTM TR 52906:2022(E)
© ISO/ASTM International 2022
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. In the United States, such requests should be sent to ASTM International.
ISO copyright office ASTM International
CP 401 • Ch. de Blandonnet 8 100 Barr Harbor Drive, PO Box C700
CH-1214 Vernier, Geneva West Conshohocken, PA 19428-2959, USA
Phone: [phone] Phone: [phone]
Fax: [phone]
Email: [e-mail] Email: [e-mail]
Website: www.iso.org Website: www.astm.org
Published in Switzerland
ii
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM TR 52906:2022(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 Typical AM flaws . 3
6 Procedure to produce replicas . 7
7 Seeding approaches .7
7.1 General . 7
7.2 CAD seeding . 8
7.3 AM process manipulation replicas . 10
7.3.1 General . 10
7.3.2 Entrapped unsintered powder. 11
7.3.3 Manual insertion of high-density inclusions . 11
7.4 Post-production mechanical introduction of replicas . 11
7.5 Significance and use for homogeneity .12
8 AM process manipulation for L-PBF and L-DED .14
8.1 General . 14
8.2 AM machine parameter manipulation . 14
8.3 Applicable flaw-seeding approaches as a function of desired flaw type .15
8.3.1 General .15
8.3.2 Porosity or voids (increased power density) . 15
8.3.3 Surface-connected flaws . 15
8.4 Applicable flaw-seeding approach as a function of AM process . 16
8.5 Applicable flaw-seeding approach as a function of AM material . 17
8.5.1 General . 17
8.5.2 High-density inclusions . 18
9 Applicable flaw-seeding approach as a function of post processing machining .18
9.1 General . 18
9.2 Mechanical machining . 18
9.3 Electrode discharge machining replicas . 18
9.4 Laser drilling replicas . 18
Bibliography .20
iii
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM TR 52906:2022(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 can 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 on 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 the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by ISO/TC 261, Additive manufacturing, in cooperation with ASTM
Committee F42, Additive Manufacturing Technologies, on the basis of a partnership agreement between
ISO and ASTM International with the aim to create a common set of ISO/ASTM standards on additive
manufacturing, and in collaboration with the European Committee for Standardization (CEN) Technical
Committee CEN/TC 438, Additive manufacturing, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
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/ASTM International 2022 – All rights reserved

ISO/ASTM TR 52906:2022(E)
Introduction
This document provides information for intentionally seeding flaws in additively manufactured parts
1)
and complements ISO/ASTM TR 52905 .
The different AM building descriptions can be found readily in published standards (see ISO 17296-2)
and scientific papers.
Jargon commonly used in the literature describing AM metal process defects includes “balling”,
“fireworks”, “smoke” and often are not specific to the morphology of the defect and often result from
widely differing mechanisms of formation.
When defining terms specific to AM metal flaws it may be useful to review some examples related to
welding technology.
This document is for the creation of seeded replicas supports the user’s understanding not only for the
characterization of actual flaws with respect to physical morphology but also for the materials and
mechanisms of formation, location, and orientation. In addition, the fundamentals of the processes
creating the replica (e.g. PBF or DED with regard to the heat sources electron beam (EB), laser beam
(LB) or AP (arc processes) also need to be considered). The intentional seeding to produce flaw replicas
can match the character of the actual flaw as closely as possible.
The reference photomicrographs or non-destructive testing images included in this document are in no
way to be construed as specifications. These reference photomicrographs and non-destructive testing
images are offered primarily to permit examples of “flaws” or replicate images thereof. They can be
used for comparison of reports. Flaw seeding will be discussed without context to a specific part,
location, or dimension. The material alloy will be provided as known. With some flaws the material
alloy may not be as important, for example, a pore may reside in any number of alloys. It can be noted
that there is currently no proven method for controlled and replicable seeding of intimate disbonds
(sometimes known as “kissing bonds”) – where two surfaces are in intimate or close contact, but with
compromised adhesion – in AM parts so this feature is, therefore, currently out of scope.
This document will not go into the fundamentals of each process but rather identify the parameters
within each process that can lead to the intentional seeding of AM structures.
1)  In preparation. Stage at the time of publication ISO/ASTM DTR 52905:2022.
v
© ISO/ASTM International 2022 – All rights reserved

TECHNICAL REPORT ISO/ASTM TR 52906:2022(E)
Additive manufacturing — Non-destructive testing —
Intentionally seeding flaws in metallic parts
1 Scope
This document is intended to serve as a best practice for the identification and “seeding” of
nondestructively detectable flaw replicas of metal alloy PBF and DED processes. Three seeding
categories are described:
a) process flaws through CAD design;
b) build parameter manipulation;
c) subtractive manufacturing.
These include flaws present within as-deposited materials, post heat-treated or HIP processed
material, and those flaws made detectable because of post-processing operations. Geometrical aspects
or measurement are not the subjects of this document.
WARNING — This document does not purport to address all of 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.
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/ASTM 52900, Standard Terminology for Additive Manufacturing — General Principles —Terminology
ASTM B243, Standard Terminology of Powder Metallurgy
ASTM E7, Standard Terminology Relating to Metallography
ASTM E1316, Standard Terminology for Nondestructive Examinations
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/ASTM 52900, ASTM E7,
ASTM B243, ASTM E1316 and the following apply.
NOTE Terms for AM metal technology flaws are logically divided between PBF and DED categories of
processes.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp
3.1
coupon
piece of material from which a specimen is prepared
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM TR 52906:2022(E)
3.2
flaw classification
classification approach that provides a high-level system based on a primary characteristic or a
combination of characteristics
Note 1 to entry: Flaw classification may include similar flaw types that were created differently.
3.3
inclusion
foreign material held mechanically
Note 1 to entry: Inclusions are typically oxides, nitrides, hydrides, carbides, or combinations thereof being
formed due to contamination of the chamber gas, or already be present in the metal powder.
3.4
keyhole
type of porosity characterised by a circular depression formed due to instability of the vapour cavity
during processing
3.5
pore
inherent or induced cavity within a powder particle or within an object not connected to an exterior
surface
3.6
porosity
presence of small voids in a part making it less than fully dense
3.7
replica
intentional manipulated condition (flaw) to serve as the “seed” in a coupon (3.1) representing a known
flaw type
3.8
seeding
act of intentionally creating flaws, through CAD or manipulation of designated processing parameters,
that results in the placement of the anticipated replica (3.7) or the act of intentionally creating a replica
(3.7) through the insertion of a foreign object
3.9
sintering
process of heating a powder metal compact to increase density and/or improve mechanical properties
via solid state diffusion
3.10
surface-connected flaw
flaw that is in the body of the material but its boundaries reach to the material’s surface
3.11
unsintered
powder unaffected or affected but not fully consolidated during the additive manufacturing printing
process
4 Abbreviated terms
AM Additive Manufacturing
BM Base Metal
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM TR 52906:2022(E)
CAD Computer-Aided Design/Computer-Aided Drafting/Computer-Aided Drawing
CNC Computer Numerical Control
DDC Ductility-Dip Cracking
DED Directed Energy Deposition
EB-DED Electron Beam Directed Energy Deposition
DR Digital Radiography (non-film)
EB-PBF Electron Beam Powder Bed Fusion
EDM Electrode Discharge Machining
GMA-DED Gas Metal Arc Directed Energy Deposition
HAZ Heat Affected Zone
HIP Hot Isostatic Pressing
LC Liquation Crack
L-DED Laser Directed Energy Deposition
L-PBF Laser Beam Powder Bed Fusion
MB Metal Base
NDE Non-destructive evaluation
NDT Non-destructive Testing
OEM Original Equipment Manufacturer
PBF Powder Bed Fusion
PSD Particle Size Distribution
RT Radiography Testing(film)
RQI Representative Quality Indicator
SC Solidification Crack
T Temperature melting point
m
WM Weld Metal
XCT X-ray Computed Tomography
5 Typical AM flaws
Typically, additive manufacturing flaws in materials fabricated using optimised parameters have small
spherical flaws. Builds with less developed parameters may have a keyhole or larger angular pores.
However, high value components are often screened for flaws at a level determined by fracture analysis
such as those described below. The ability to create replicas to support the NDT detection capability
of complex structures is unique to additive manufacturing and can be considered when standard
inspection techniques are not adequate to ensure inspection reliability.
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM TR 52906:2022(E)
The occurrence of unintentional flaws during the additive manufacturing build is a possibility. The flaw
classification has been laid out in ISO/ASTM TR 52905 both L-PBF and DED. These flaws are: layer-
defects (horizontal lack of fusion), cross-layer (vertical lack of fusion), unconsolidated powder, trapped
powder, inclusion, layer shift, porosity and void; moreover, incomplete fusion, hole and cracking. It is
important to highlight that some DED defects are similar to those produced during the welding process,
while for L-PBF some defects are unique.
In addition to flaws created to replicate naturally occurring anomalies, replicas may be generated
to serve as targets that can be used to understand x-ray, ultrasonic or other NDT capabilities (see
Figure 1). It is important that the fabricator of such replicas understands the physics of the NDT’s
method for which the flaws will be used. Capabilities demonstrations include detection in a specific
[5]
complex geometry such as a Representative Quality Indicator (RQI) according to ASTM E1817 , or
detection at a specific orientation relating to the radiation beam. This replica is “seeded” intentionally
around the needs of the demonstrations. Ultrasonic sensing may find applicability through the technical
[3]
approach of ASTM E127 . Additionally, some of these seeding methods are implemented and detection
capabilities of seven NDT methods are assessed in ISO/ASTM TR 52905.
It has been found that replica size, orientation, and location can be designed into the build model to
create shapes (spheres, cubes, and rectangular prisms), sizes (lengths and diameters), and depths. An
example is shown in Figure 1 where embedded defects were designed into the step wedge with CAD
software, and since they are embedded with no powder removal vent, they are filled with unmelted
powder (unconsolidated powder/trapped powder).
a)  CAD model showing the set of clusters and dimensions of the holes in the airfoil
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM TR 52906:2022(E)
b)  XCT scan displaying the visibility of the replicas seeded at different locations
and those that are not visible
Key
1 sets of holes containing 3 cluster
2 number of holes per cluster
3 holes dimensions per cluster
a
All 4 are visible.
b
⌀ 0,1 mm not visible.
Figure 1 — Example of RQI generic airfoil built on Ti-6Al-4V
With adjustments to the optimum build parameters, replicas can provide a desired off-nominal build
parameter. The shape of the replica can be planar, elliptical, rounded or another modelled configuration.
Two such off-nominal build parameters for seeding replicas are lowering laser power and increasing
the trace width to that which is greater than optimal.
Both of these types of replicas can be used to show the various NDT methods detection potentials. For
example, the computed tomography scans of the seeding replicas resulted in different yet detectable
material density changes created by each build parameter adjustment. The level of detail and different
views possible through computed tomography is shown in Figure 2 and Figure 3. The images in
both figures are not comparatives as those only illustrate differences in the detail when different
magnifications and methods are used.
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM TR 52906:2022(E)
a)  Computed tomography (XCT) slice image b)  Mi
...

SLOVENSKI STANDARD
01-september-2022
Aditivna proizvodnja - Neporušitveno preskušanje - Namerno vnešene
nepravilnosti v kovinskih delcih (ISO/ASTM TR 52906:2022)
Additive manufacturing - Non-destructive testing - Intentionally seeding flaws in metallic
parts (ISO/ASTM TR 52906:2022)
Additive Fertigung - Zerstörungsfreie Prüfung und Bewertung - Bewusstes Einbringen
von Fehlern in Bauteilen (ISO/ASTM TR 52906:2022)
Fabrication additive - Essais non destructifs - Implantation intentionnelle de défauts dans
les pièces métalliques (ISO/ASTM TR 52906:2022)
Ta slovenski standard je istoveten z: CEN ISO/ASTM/TR 52906:2022
ICS:
19.100 Neporušitveno preskušanje Non-destructive testing
25.030 3D-tiskanje Additive manufacturing
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN ISO/ASTM/TR
TECHNICAL REPORT
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
May 2022
ICS
English Version
Additive manufacturing - Non-destructive testing -
Intentionally seeding flaws in metallic parts
(ISO/ASTM/TR 52906:2022)
Fabrication additive - Essais non destructifs - Additive Fertigung - Zerstörungsfreie Prüfung und
Implantation intentionnelle de défauts dans les pièces Bewertung - Bewusstes Einbringen von Fehlern in
métalliques (ISO/ASTM/TR 52906:2022) Bauteilen (ISO/ASTM/TR 52906:2022)

This Technical Report was approved by CEN on 28 April 2022. It has been drawn up by the Technical Committee CEN/TC 438.

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 NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

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© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN ISO/ASTM/TR 52906:2022 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (CEN ISO/ASTM/TR 52906:2022) has been prepared by Technical Committee ISO/TC
261 "Additive manufacturing" in collaboration with Technical Committee CEN/TC 438 “Additive
Manufacturing” the secretariat of which is held by AFNOR.
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.
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.
Endorsement notice
The text of ISO/ASTM TR 52906:2022 has been approved by CEN as CEN ISO/ASTM/TR 52906:2022
without any modification.
TECHNICAL ISO/ASTM TR
REPORT 52906
First edition
2022-05
Additive manufacturing — Non-
destructive testing — Intentionally
seeding flaws in metallic parts
Fabrication additive — Essais non destructifs — Implantation
intentionnelle de défauts dans les pièces métalliques
Reference number
ISO/ASTM TR 52906:2022(E)
© ISO/ASTM International 2022
ISO/ASTM TR 52906:2022(E)
© ISO/ASTM International 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
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© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM TR 52906:2022(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 Typical AM flaws . 3
6 Procedure to produce replicas . 7
7 Seeding approaches .7
7.1 General . 7
7.2 CAD seeding . 8
7.3 AM process manipulation replicas . 10
7.3.1 General . 10
7.3.2 Entrapped unsintered powder. 11
7.3.3 Manual insertion of high-density inclusions . 11
7.4 Post-production mechanical introduction of replicas . 11
7.5 Significance and use for homogeneity .12
8 AM process manipulation for L-PBF and L-DED .14
8.1 General . 14
8.2 AM machine parameter manipulation . 14
8.3 Applicable flaw-seeding approaches as a function of desired flaw type .15
8.3.1 General .15
8.3.2 Porosity or voids (increased power density) . 15
8.3.3 Surface-connected flaws . 15
8.4 Applicable flaw-seeding approach as a function of AM process . 16
8.5 Applicable flaw-seeding approach as a function of AM material . 17
8.5.1 General . 17
8.5.2 High-density inclusions . 18
9 Applicable flaw-seeding approach as a function of post processing machining .18
9.1 General . 18
9.2 Mechanical machining . 18
9.3 Electrode discharge machining replicas . 18
9.4 Laser drilling replicas . 18
Bibliography .20
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ISO/ASTM TR 52906:2022(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 can 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 on 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 the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by ISO/TC 261, Additive manufacturing, in cooperation with ASTM
Committee F42, Additive Manufacturing Technologies, on the basis of a partnership agreement between
ISO and ASTM International with the aim to create a common set of ISO/ASTM standards on additive
manufacturing, and in collaboration with the European Committee for Standardization (CEN) Technical
Committee CEN/TC 438, Additive manufacturing, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
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.
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ISO/ASTM TR 52906:2022(E)
Introduction
This document provides information for intentionally seeding flaws in additively manufactured parts
1)
and complements ISO/ASTM TR 52905 .
The different AM building descriptions can be found readily in published standards (see ISO 17296-2)
and scientific papers.
Jargon commonly used in the literature describing AM metal process defects includes “balling”,
“fireworks”, “smoke” and often are not specific to the morphology of the defect and often result from
widely differing mechanisms of formation.
When defining terms specific to AM metal flaws it may be useful to review some examples related to
welding technology.
This document is for the creation of seeded replicas supports the user’s understanding not only for the
characterization of actual flaws with respect to physical morphology but also for the materials and
mechanisms of formation, location, and orientation. In addition, the fundamentals of the processes
creating the replica (e.g. PBF or DED with regard to the heat sources electron beam (EB), laser beam
(LB) or AP (arc processes) also need to be considered). The intentional seeding to produce flaw replicas
can match the character of the actual flaw as closely as possible.
The reference photomicrographs or non-destructive testing images included in this document are in no
way to be construed as specifications. These reference photomicrographs and non-destructive testing
images are offered primarily to permit examples of “flaws” or replicate images thereof. They can be
used for comparison of reports. Flaw seeding will be discussed without context to a specific part,
location, or dimension. The material alloy will be provided as known. With some flaws the material
alloy may not be as important, for example, a pore may reside in any number of alloys. It can be noted
that there is currently no proven method for controlled and replicable seeding of intimate disbonds
(sometimes known as “kissing bonds”) – where two surfaces are in intimate or close contact, but with
compromised adhesion – in AM parts so this feature is, therefore, currently out of scope.
This document will not go into the fundamentals of each process but rather identify the parameters
within each process that can lead to the intentional seeding of AM structures.
1)  In preparation. Stage at the time of publication ISO/ASTM DTR 52905:2022.
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© ISO/ASTM International 2022 – All rights reserved

TECHNICAL REPORT ISO/ASTM TR 52906:2022(E)
Additive manufacturing — Non-destructive testing —
Intentionally seeding flaws in metallic parts
1 Scope
This document is intended to serve as a best practice for the identification and “seeding” of
nondestructively detectable flaw replicas of metal alloy PBF and DED processes. Three seeding
categories are described:
a) process flaws through CAD design;
b) build parameter manipulation;
c) subtractive manufacturing.
These include flaws present within as-deposited materials, post heat-treated or HIP processed
material, and those flaws made detectable because of post-processing operations. Geometrical aspects
or measurement are not the subjects of this document.
WARNING — This document does not purport to address all of 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.
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/ASTM 52900, Standard Terminology for Additive Manufacturing — General Principles —Terminology
ASTM B243, Standard Terminology of Powder Metallurgy
ASTM E7, Standard Terminology Relating to Metallography
ASTM E1316, Standard Terminology for Nondestructive Examinations
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/ASTM 52900, ASTM E7,
ASTM B243, ASTM E1316 and the following apply.
NOTE Terms for AM metal technology flaws are logically divided between PBF and DED categories of
processes.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp
3.1
coupon
piece of material from which a specimen is prepared
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM TR 52906:2022(E)
3.2
flaw classification
classification approach that provides a high-level system based on a primary characteristic or a
combination of characteristics
Note 1 to entry: Flaw classification may include similar flaw types that were created differently.
3.3
inclusion
foreign material held mechanically
Note 1 to entry: Inclusions are typically oxides, nitrides, hydrides, carbides, or combinations thereof being
formed due to contamination of the chamber gas, or already be present in the metal powder.
3.4
keyhole
type of porosity characterised by a circular depression formed due to instability of the vapour cavity
during processing
3.5
pore
inherent or induced cavity within a powder particle or within an object not connected to an exterior
surface
3.6
porosity
presence of small voids in a part making it less than fully dense
3.7
replica
intentional manipulated condition (flaw) to serve as the “seed” in a coupon (3.1) representing a known
flaw type
3.8
seeding
act of intentionally creating flaws, through CAD or manipulation of designated processing parameters,
that results in the placement of the anticipated replica (3.7) or the act of intentionally creating a replica
(3.7) through the insertion of a foreign object
3.9
sintering
process of heating a powder metal compact to increase density and/or improve mechanical properties
via solid state diffusion
3.10
surface-connected flaw
flaw that is in the body of the material but its boundaries reach to the material’s surface
3.11
unsintered
powder unaffected or affected but not fully consolidated during the additive manufacturing printing
process
4 Abbreviated terms
AM Additive Manufacturing
BM Base Metal
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ISO/ASTM TR 52906:2022(E)
CAD Computer-Aided Design/Computer-Aided Drafting/Computer-Aided Drawing
CNC Computer Numerical Control
DDC Ductility-Dip Cracking
DED Directed Energy Deposition
EB-DED Electron Beam Directed Energy Deposition
DR Digital Radiography (non-film)
EB-PBF Electron Beam Powder Bed Fusion
EDM Electrode Discharge Machining
GMA-DED Gas Metal Arc Directed Energy Deposition
HAZ Heat Affected Zone
HIP Hot Isostatic Pressing
LC Liquation Crack
L-DED Laser Directed Energy Deposition
L-PBF Laser Beam Powder Bed Fusion
MB Metal Base
NDE Non-destructive evaluation
NDT Non-destructive Testing
OEM Original Equipment Manufacturer
PBF Powder Bed Fusion
PSD Particle Size Distribution
RT Radiography Testing(film)
RQI Representative Quality Indicator
SC Solidification Crack
T Temperature melting point
m
WM Weld Metal
XCT X-ray Computed Tomography
5 Typical AM flaws
Typically, additive manufacturing flaws in materials fabricated using optimised parameters have small
spherical flaws. Builds with less developed parameters may have a keyhole or larger angular pores.
However, high value components are often screened for flaws at a level determined by fracture analysis
such as those described below. The ability to create replicas to support the NDT detection capability
of complex structures is unique to additive manufacturing and can be considered when standard
inspection techniques are not adequate to ensure inspection reliability.
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM TR 52906:2022(E)
The occurrence of unintentional flaws during the additive manufacturing build is a possibility. The flaw
classification has been laid out in ISO/ASTM TR 52905 both L-PBF and DED. These flaws are: layer-
defects (horizontal lack of fusion), cross-layer (vertical lack of fusion), unconsolidated powder, trapped
powder, inclusion, layer shift, porosity and void; moreover, incomplete fusion, hole and cracking. It is
important to highlight that some DED defects are similar to those produced during the welding process,
while for L-PBF some defects are unique.
In addition to flaws created to replicate naturally occurring anomalies, replicas may be generated
to serve as targets that can be used to understand x-ray, ultrasonic or other NDT capabilities (see
Figure 1). It is important that the fabricator of such replicas understands the physics of the NDT’s
method for which the flaws will be used. Capabilities demonstrations include detection in a specific
[5]
complex geometry such as a Representative Quality Indicator (RQI) according to ASTM E1817 , or
detection at a specific orientation relating to the radiation beam. This replica is “seeded” intentionally
around the needs of the demonstrations. Ultrasonic sensing may find applicability through the technical
[3]
approach of ASTM E127 . Additionally, some of these seeding methods are implemented and detection
capabilities of seven NDT methods are assessed in ISO/ASTM TR 52905.
It has been found that replica size, orientation, and location can be designed into the build model to
create shapes (spheres, cubes, and rectangular prisms), sizes (lengths and diameters), and depths. An
example is shown in Figure 1 where embedded defects were designed into the step wedge with CAD
software, and since they are embedded with no powder removal vent, they are filled with unmelted
powder (unconsolidated powder/trapped powder).
a)  CAD model showing the set of clusters and dimensions of the holes in the airfoil
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM TR 52906:2022(E)
b)  XCT scan displaying the visibility of the replicas seeded at different locations
and those that are not visible
Key
1 sets of holes containing 3 cluster
2 number of holes per cluster
3 holes dimensions per cluster
a
All 4 are visible.
b
⌀ 0,1 mm not visible.
Figure 1 — Example of RQI generic airfoil built on Ti-6Al-4V
With adjustments to the optimum build parameters, replicas can provide a desired off-nominal build
parameter. The shape of the replica can be planar, elliptical, rounded or another modelled configuration.
Two such off-nominal build parameters for seeding replicas are lowering laser power and increasing
the trace width to that which is greater than optimal.
Both of these types of replicas can be used to show the various NDT methods detection potentials. For
example, the computed tomography scans of the seeding replicas resulted in different yet detectable
material density changes created by each build parameter adjustment. The level of detail and different
views possible through computed tomography is shown in Figure 2 and Figure 3. The images in
both figures are not comparatives as those only illustrate differences in the detail when different
magnifications and methods are used.
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ISO/ASTM TR 52906:2022(E)
a)  Computed tomography (XCT) slice image b)  M
...