ISO/ASTM DTR 52905

Additive manufacturing of metals — Non-destructive testing and evaluation — Defect detection in parts

Fabrication additive de métaux — Essais et évaluation non destructifs — Détection de défauts dans les pièces

General Information

• Status: Not Published
• ICS: 25.030 - Additive manufacturing
• ICS: 77.040.20 - Non-destructive testing of metals
• Technical Committee: ISO/TC 261 - Additive manufacturing
• Drafting Committee: ISO/TC 261 - Additive manufacturing
• Current Stage: 5060 - Close of voting Proof returned by Secretariat
• Start Date: 27-Apr-2023
• Completion Date: 28-Apr-2023

Standards Content (Sample)

ISO/DTRTR 52905:20222023(E) Style Definition: Heading 1: Indent: Left: 0 pt, First

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ISO/TC 261
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Date: 2022-12-262023-xx
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Secretariat: DIN
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Additive manufacturing of metals — Non-destructive testing and evaluation —
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Defect detection in parts
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Fabrication additive de métaux — Essais et évaluation non destructifs — Détection de

défauts dans les pièces
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ISO/DTRTR 52905:20222023(E)
© ISO/ASTM 20222023
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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] Fax: [phone]
Email: [e-mail] Email: [e-mail]
Website: www.iso.orgwww.iso.org Website: www.astm.orgwww.astm.org
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ii © ISO 2022/ASTM International 2023 – All rights reserved
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ISO/DTRTR 52905:20222023(E)
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Contents ...
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Foreword ......................................................................................................................................................................... vi

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

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

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

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3 Terms and definitions .......................................................................................................................................... 2

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4 NDT potential for authentication and/or identification ......................................................................... 3

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5 List of abbreviated terms .................................................................................................................................... 3

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6 Typical flaws/defects in AM ............................................................................................................................... 4

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6.1 Flaw origins/causes ........................................................................................................................................ 4

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6.2 Flaw/defects classification .......................................................................................................................... 5

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6.3 Defect classification strategies for AM .................................................................................................. 13

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7 NDT standards review ................................................................................................................................ 14 ...

7.1 Post-process NDT standards .................................................................................................................... 14

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7.1.1 ISO review ....................................................................................................................................................... 14

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7.2 In-process NDT review ............................................................................................................................... 16

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8 Standard selection structure for AM ..................................................................................................... 19

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9 NDT techniques potential for AM only defects .................................................................................. 20

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10 AM artefacts .................................................................................................................................................... 27

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10.1 Design ............................................................................................................................................................... 27

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10.1.1 Star artefact .................................................................................................................................................... 27

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10.1.2 À la carte artefact ......................................................................................................................................... 34

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10.2 Manufacturing ............................................................................................................................................... 36

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10.2.1 Star artefact .................................................................................................................................................... 36

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10.2.2 À la carte artefact ......................................................................................................................................... 37

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11 NDT method trials and validation using star artefact ..................................................................... 38 ...

11.1 — Experimental trials ................................................................................................................................. 38

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11.1.1 X-ray Computed Tomography – XCT (MTC & GE & EWI) ................................................................ 39

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11.1.2 — Neutron Imaging — NI and Synchrotron radiation — SX (HZB & ESRF) ............................. 44

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11.1.3 — Thermography Testing — TT (University of Bath) ..................................................................... 53 ...

11.1.4 — Resonant Ultrasound Spectroscopy methods — RUS ................................................................. 60

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11.1.5 — Ultrasonic testing — UT and Phase Array UT — PAUT (EWI & NIST & LNE) ..................... 75

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11.1.6 — Residual stress — RS (ILL) ................................................................................................................... 81

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12 — Defect built validation star artefact (Cut-off MTC) ..................................................................... 86

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12.1 Summary of Procedure by XCT ................................................................................................................ 86

12.1.1 Apparatus ........................................................................................................................................................ 87

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12.1.2 Significance of Data/Interpretation of Results .................................................................................. 88

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12.2 Summary of Procedure by Metallography ........................................................................................... 91

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12.2.1 Apparatus ........................................................................................................................................................ 92 ...

12.2.2 Significance of Data/Interpretation of Results .................................................................................. 92

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12.3 Comments/Observations ........................................................................................................................... 94

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ISO/DTRTR 52905:20222023(E)

13 NDT trials for à la carte artefact .............................................................................................................. 95

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13.1 Summary of Procedure ............................................................................................................................... 95

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13.2 Apparatus ........................................................................................................................................................ 95

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13.3 Significance of Data/Interpretation of Results .................................................................................. 95

13.4 Comments/Observations ........................................................................................................................... 97

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14 Summary of the trials findings by material ........................................................................................ 97

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15 Main Conclusions ........................................................................................................................................ 104

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Annex A (informative) Causes and effects of defects in wire DED and PBF process ........................ 107

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Annex B (informative) Review of existing NDT standards for welding or casting for

application of post build AM flaws ....................................................................................................... 109

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Annex C (informative) Star artefacts using during the trials ................................................................... 114 Formatted: No underline, Font color: Auto

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Annex D (informative) Summary of star artefact manufacturing and NDT technologies for

trials ................................................................................................................................................................ 116

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Annex E (informative) XCT parameters and XCT set up used for inspection and validation ....... 118 Formatted: No underline, Font color: Auto

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E.1 Scan parameters for systems at EWI, MTC and GE ......................................................................... 118

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E.2 Scan set ups ................................................................................................................................................... 120

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E.2.1.1 MTC .................................................................................................................................................................. 120

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E.2.1.2 GE-UK .............................................................................................................................................................. 121

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E.3 Scan results ................................................................................................................................................... 122

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E.3.1.1 MTC .................................................................................................................................................................. 122

E.3.1.2 EWI ................................................................................................................................................................... 126

E.3.1.3 GE...................................................................................................................................................................... 127

E.3.1.4 MTC .................................................................................................................................................................. 129

E.3.1.5 EWI ................................................................................................................................................................... 129

E.3.1.6 GE...................................................................................................................................................................... 130

Annex F (informative) Parameters and set up for Neutron Image (NI) and Synchrotron (Sx)

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inspection ...................................................................................................................................................... 134

F.1 Scan parameters for CONRAD 2 and ID -19 ....................................................................................... 134

F.2 Ti6Al4V Samples ......................................................................................................................................... 135

F.3 Scan set up ..................................................................................................................................................... 136

Annex G (informative) Set up for PT and SHT thermography inspection ............................................ 138

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G.1 Settings for PT and SHT thermography methods ........................................................................... 138

G.2 PT and SHT thermography results ....................................................................................................... 140

Annex H (informative) Ultrasonic test .............................................................................................................. 141

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H.1 Scan parameters for CUT and PAUT-FMCV/TFM test .................................................................... 141

H.2 Results/Examples analysis ..................................................................................................................... 141

H.2.1 PAUT in Stainless Steel stars S1 and S2 design ................................................................................ 141

H.2.2 CUT in Aluminium star version S1 ....................................................................................................... 145

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ISO/DTRTR 52905:20222023(E)

H.2.3 PAUT in Aluminium stars S1 and S2 design ...................................................................................... 149

H.2.4 PAUT-FMC/TFM .......................................................................................................................................... 154

Annex I (informative) Residual stress characterisation of Ti6Al4V by Neutron diffraction ........ 158

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I.1 Scan parameters for SALSA ..................................................................................................................... 158

I.2 Scan set up ..................................................................................................................................................... 159

Bibliography ............................................................................................................................................................... 160

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ISO/DTRTR 52905:20222023(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national

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standards bodies (ISO member bodies). The work of preparing International Standards is normally

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carried out through ISO technical committees. Each member body interested in a subject for which a

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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

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the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all

matters of electrotechnical standardization.
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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

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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). 2 (see

www.iso.org/directives).
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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).www.iso.org/patents).

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Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.
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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’sISO's adherence to the

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World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see

www.iso.org/iso/foreword.html.www.iso.org/iso/foreword.html.
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The committee responsible for this document is ISO/TC 261, Additive manufacturing, in cooperation

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with ASTM Committee F42, Additive Manufacturing Technologiesmanufacturing technologies, on the

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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.additive manufacturing, 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).
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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/DTRTR 52905:20222023(E)
Introduction

In response to the urgent need for standards for Additive Manufacturing (AM), this document initially

indicates Non-Destructive Testing (NDT) methods with potential to detect defects and determine

residual strain distribution that are generated in AM processes. A number of these methods were

verified. The strategy adopted was to review existing NDT standards for matured manufacturing

processes which are similar to AM, namely casting and welding. This potentially reduces the number of

standards required to comprehensively cover the defects in AM. For identified AM unique defects, this

document proposes a two-level NDT approach: a star artefact as an Initial Quality Indicator (IQI) and à

la carte artefact where an example shows the specific steps to follow for the very specific unique AM

part to be built, paving the way for a structured and comprehensive framework.

Most metal inspection methods in NDT use ultrasound or X-rays, but these techniques cannot always

cope with the complicated shapes typically produced by AM. In most circumstances X-ray computed

tomography (CT) is a more suitable method, but it also has limitations and room for improvement or

adaptation to AM, on top of being a costly method both in time and money.

This document includes post-process non-destructive testing of additive manufacturing (AM) of

metallic parts with a comprehensive approach. It covers several sectors and a similar framework can be

applied to other materials (e.g. ceramics, polymers, etc.). In-process NDT and metrology standards are

referenced as they are being developed. This document presents current standards capability to detect

which of the Additive Manufacturing (AM) flaw types and which flaws require new standards, using a

standard selection tool. NDT methods with the highest potential will be tested.
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TECHNICAL REPORT ISO/DTRTR 52905:20222023(E)
Additive manufacturing — Non-Destructive Testing and
Evaluation — Standard Guideline for Defect Detection in Metallic
Parts
1 Scope

This document categorises Additive Manufacturingadditive manufacturing (AM) defects in DED and

PBF laser and electron category of processes, provides a review of relevant current NDT standards,

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details NDT methods that are specific to AM and complex 3D geometries and outlines existing

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non-destructive testing techniques that are applicable to some AM types of defects.

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This document is aimed at users and producers of AM processes and it applies, in particular, to the

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following:
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— Safetysafety critical AM applications;
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— Assuredassured confidence in AM;
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— Reversereverse engineered products manufactured by AM; Formatted: Pattern: Clear

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— Testtest bodies wishing to compare requested and actual geometries.
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2 Normative references
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There are no normative references in this document.
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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 Formatted: Pattern: Clear

undated references, the latest edition of the referenced document (including any amendments) applies.

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ISO 11484, Steel products — Employer's qualification system for non-destructive testing (NDT) personnel

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ISO/ASTM 52900, Additive manufacturing — General principles — Fundamentals and vocabulary

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ASTM E1316, Terminology for Nondestructive Testing
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EN 1330-2, Non-destructive testing — Terminology — Part 2: Terms common to the non-destructive

testing methods
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3 Terms and definitions
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stops: Not at 19.85 pt + 39.7 pt + 59.55 pt + 79.4 pt

For the purposes of this document, the terms and definitions given in ISO/ASTM 52900, ASTM E1316,

+ 99.25 pt + 119.05 pt + 138.9 pt + 158.75 pt +
EN 1330-2, ISO 11484, and the following apply.
178.6 pt + 198.45 pt

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

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— ISO Online browsing platform: available at https://www.iso.org/obphttps://www.iso.org/obp

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ISO/DTRTR 52905:20222023(E)

— IEC Electropedia: available at https://www.electropedia.org/https://www.electropedia.org/

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3.1
flaw type
identifiable features that defines a specific flaw

Note 1 to entry: defect term, this word is used when a flaw that does not meet specified acceptance criteria and is

rejectable.

Note 2 to entry: flawFlaw term, an imperfection or discontinuity that is not necessarily rejectable

3.2
lack of fusion
LOF

type of process-induced porosity, in which the powder or wire feedstock is not fully melted or fused

onto the previously deposited substrate

Note 1 to entry: In PBF, this type of flaw can be an empty cavity, or contain unmelted or partially fused powder,

referred to as unconsolidated powder.

Note 2 to entry: LOF typically occurs in the bulk, making its detection difficult.

Note 3 to entry: Like voids, LOF can occur on the build layer plane (layer/horizontal LOF) or across multiple build

layers (cross layer/vertical LOF).
3.3
unconsolidated powder

unmelted powder that due to process failure was not melted and became trapped internally

3.4
layer shift

see stop/start for PBF laser/E beam. In addition, in E beam when it is disturbed by a

magnetic field a layer or a number of layers are shifted away from the other build layers.

Note 1 to entry: see stop/start for PBF laser/E beam.
3.5
trapped powder

unmelted powder that is not intended for the part but is trapped within internal part cavities

3.6
porosity
presence of small voids in a part making it less than fully dense

Note 1 to entry: Porosity may be quantified as a ratio, expressed as a percentage of the volume of voids to the total

volume of the part.
[SOURCE: ISO/ASTM 52900:2019, 3.11.8]
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3.7
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keyhole

type of porosity characterised by a circular depression formed due to instability of the vapor cavity

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during processing
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ISO/DTRTR 52905:20222023(E)

Note 1 to entry: Keyhole porosity is created when the energy density is sufficiently high to cause a deep melt pool

resulting in hydrodynamic instability of the surrounding liquid metal and subsequent collapse, leaving a void at

the root of the keyhole.

Note 2 to entry: Like generic voids and gas porosity, keyhole porosity causes a part to be less than fully dense.

94 NDT potential for authentication and/or identification

Some of the NDT methods in this technical report have the additional potential to extract authentication

and/or identification apparatus or design embedded in the design of the AM part. Such a potential

clearly depends on the material(s), geometry and process elected to fabricate the part, however the

design information and AM data file can embed in its geometry or texture ad-hoc devices that

potentially could be extracted by NDT techniques. ISO/TC 292 Security and Resilience specifies and

maintains a number of standards supporting such devices within the ISO referential, and are fully

applicable to AM digital information. The specific requirements of design techniques, materials,

processes, NDT modalities and applications, however, still require careful evaluation, selection and

classification.
105 List of abbreviated terms
— AM Additive Manufacturingadditive manufacturing
Deleted Cells
— BAE British Aerospace and Engineering Systems
— EB-PBF Electron Beam Powder Bed Fusionelectron beam powder bed fusion
— ESFR European Synchrotron Research Facility
— EWI Edison Welding Institute
— FMC Full Matrix Capturefull matrix capture
— GE-PD General Electric Powder Divisiongeneral electric powder division
— HZB Helmholtz Zentrum Berlin
— ILL Institute Laue-Langevin
— IR Infraredinfrared
— IRT Infrared Thermographyinfrared thermography
— J & J Johnson & Johnson
— LNE Laboratoire National De Métrologie ET D'essais
— PBF-LB Laser Powder Bed Fusionlaser powder bed fusion
— DED-LB Laser Directed Energy Depositionlaser directed energy deposition
— MTC The Manufacturing Technology Centre
— ND Neutron Diffractionneutron diffraction
— NDE Nonnon-destructive evaluation
— NDT Nondestructive Testingnon-destructive testing
— NI Neutronneutron Imaging
— NIST National Institute of Standards and Technology
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ISO/DTRTR 52905:20222023(E)
— NLA No
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FINAL
TECHNICAL ISO/DTR
DRAFT
REPORT 52905
ISO/TC 261
Additive manufacturing of metals —
Secretariat: DIN
Non-destructive testing and evaluation
Voting begins on:
2023-02-02 — Defect detection in parts
Voting terminates on:
Fabrication additive de métaux — Essais et évaluation non destructifs
2023-04-27
— Détection de défauts dans les pièces
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/DTR 52905:2023(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. © ISO 2023
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ISO/DTR 52905:2023(E)
FINAL
TECHNICAL ISO/ASTM
DRAFT
REPORT DTR
52905
ISO/TC 261
Additive manufacturing of metals —
Secretariat: DIN
Non-destructive testing and evaluation
Voting begins on:
— Defect detection in parts
Voting terminates on:
Fabrication additive de métaux — Essais et évaluation non destructifs
— Détection de défauts dans les pièces
COPYRIGHT PROTECTED DOCUMENT
© ISO/ASTM International 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. In the United States, such requests should be sent to ASTM International.

ISO copyright office ASTM International
RECIPIENTS OF THIS DRAFT ARE INVITED TO
CP 401 • Ch. de Blandonnet 8 100 Barr Harbor Drive, PO Box C700
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
CH-1214 Vernier, Geneva West Conshohocken, PA 19428-2959, USA
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
Phone: [phone] Phone: [phone]
DOCUMENTATION.
Fax: [phone]
IN ADDITION TO THEIR EVALUATION AS
Reference number
Email: [e-mail] Email: [e-mail]
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/ASTM DTR 52905:2023(E)
Website: www.iso.org Website: www.astm.org
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
Published in Switzerland
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
© ISO 2023 – All rights reserved
NATIONAL REGULATIONS. © ISO/ASTM International 2023
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ISO/ASTM DTR 52905:2023(E)
Contents Page

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

Introduction .............................................................................................................................................................................................................................. vi

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

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

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

4 NDT potential for authentication and/or identification ............................................................................................ 2

5 List of abbreviated terms ............................................................................................................................................................................ 2

6 Typical flaws/defects in AM .....................................................................................................................................................................4

6.1 Flaw origins/causes ........................................................................................................................................................................... 4

6.2 Flaw/defects classification .......................................................................................................................................................... 4

6.3 Defect classification strategies for AM ..........................................................................................................................12

7 NDT standards review ................................................................................................................................................................................13

7.1 Post-process NDT standards ................................................................................................................................................... 13

7.1.1 ISO review ............................................................................................................................................................................. 13

7.2 In-process NDT review .................................................................................................................................................................15

8 Standard selection structure for AM ...........................................................................................................................................18

9 NDT techniques potential for AM only defects .................................................................................................................19

10 AM artefacts ...........................................................................................................................................................................................................28

10.1 Design ..........................................................................................................................................................................................................28

10.1.1 Star artefact .........................................................................................................................................................................28

10.1.2 À la carte artefact ...........................................................................................................................................................34

10.2 Manufacturing .....................................................................................................................................................................................36

10.2.1 Star artefact ......................................................................................................................................................................... 36

10.2.2 À la carte artefact ........................................................................................................................................................... 37

11 NDT method trials and validation using star artefact .............................................................................................38

11.1 Experimental trials .........................................................................................................................................................................38

11.1.1 X-ray Computed Tomography – XCT (MTC & GE & EWI) .............................................................39

11.1.2 Neutron Imaging — NI and Synchrotron radiation — SX (HZB & ESRF) ..................... 42

11.1.3 Thermography Testing — TT (University of Bath) ..........................................................................50

11.1.4 Resonant Ultrasound Spectroscopy methods — RUS .................................................................... 59

11.1.5 Ultrasonic testing — UT and Phase Array UT — PAUT (EWI and NIST and

LNE) .............................................................................................................................................................................................74

11.1.6 Residual stress — RS (ILL) ..................................................................................................................................... 79

12 Defect built validation star artefact (Cut-off MTC) ......................................................................................................84

12.1 Summary of procedure by XCT .............................................................................................................................................84

12.1.1 Apparatus ..............................................................................................................................................................................85

12.1.2 Significance of data/interpretation of results ......................................................................................86

12.2 Summary of procedure by metallography ..................................................................................................................89

12.2.1 Apparatus ..............................................................................................................................................................................90

12.2.2 Significance of Data/Interpretation of Results ....................................................................................90

12.3 Comments/observations ............................................................................................................................................................92

13 NDT trials for à la carte artefact ......................................................................................................................................................92

13.1 Summary of procedure ................................................................................................................................................................ 92

13.2 Apparatus ................................................................................................................................................................................................. 93

13.3 Significance of data/interpretation of results......................................................................................................... 93

13.4 Comments/observations ............................................................................................................................................................96

14 Summary of the trials findings by material .........................................................................................................................96

15 Main conclusions........................................................................................................................................................................................... 101

iii
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ISO/ASTM DTR 52905:2023(E)

Annex A (informative) Causes and effects of defects in wire DED and PBF process .................................. 103

Annex B (informative) Review of existing NDT standards for welding or casting for

application of post build AM flaws ............................................................................................................................................. 105

Annex C (informative) Star artefacts using during the trials .............................................................................................110

Annex D (informative) Summary of star artefact manufacturing and NDT technologies for

trials ........................................................................................................................................................................................................................... 115

Annex E (informative) XCT parameters and XCT set up used for inspection and validation ............117

Annex F (informative) Parameters and set up for Neutron Image (NI) and Synchrotron (Sx)

inspection ............................................................................................................................................................................................................. 134

Annex G (informative) Set up for PT and SHT thermography inspection ............................................................. 140

Annex H (informative) Ultrasonic test ........................................................................................................................................................ 143

Annex I (informative) Residual stress characterisation of Ti6Al4V by Neutron diffraction............154

Bibliography ......................................................................................................................................................................................................................... 156

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ISO/ASTM DTR 52905:2023(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 non­governmental, 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.

The committee responsible for this document is 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, 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 DTR 52905:2023(E)
Introduction

In response to the urgent need for standards for Additive Manufacturing (AM), this document initially

indicates Non­Destructive Testing (NDT) methods with potential to detect defects and determine

residual strain distribution that are generated in AM processes. A number of these methods were

verified. The strategy adopted was to review existing NDT standards for matured manufacturing

processes which are similar to AM, namely casting and welding. This potentially reduces the number of

standards required to comprehensively cover the defects in AM. For identified AM unique defects, this

document proposes a two-level NDT approach: a star artefact as an Initial Quality Indicator (IQI) and

à la carte artefact where an example shows the specific steps to follow for the very specific unique AM

part to be built, paving the way for a structured and comprehensive framework.

Most metal inspection methods in NDT use ultrasound or X-rays, but these techniques cannot always

cope with the complicated shapes typically produced by AM. In most circumstances X-ray computed

tomography (CT) is a more suitable method, but it also has limitations and room for improvement or

adaptation to AM, on top of being a costly method both in time and money.

This document includes post­process non­destructive testing of additive manufacturing (AM) of

metallic parts with a comprehensive approach. It covers several sectors and a similar framework can

be applied to other materials (e.g. ceramics, polymers, etc.). In-process NDT and metrology standards

are referenced as they are being developed. This document presents current standards capability to

detect which of the Additive Manufacturing (AM) flaw types and which flaws require new standards,

using a standard selection tool. NDT methods with the highest potential will be tested.

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TECHNICAL REPORT ISO/ASTM DTR 52905:2023(E)
Additive manufacturing of metals — Non-destructive
testing and evaluation — Defect detection in parts
1 Scope

This document categorises additive manufacturing (AM) defects in DED and PBF laser and electron

category of processes, provides a review of relevant current NDT standards, details NDT methods that

are specific to AM and complex 3D geometries and outlines existing non-destructive testing techniques

that are applicable to some AM types of defects.

This document is aimed at users and producers of AM processes and it applies, in particular, to the

following:
— safety critical AM applications;
— assured confidence in AM;
— reverse engineered products manufactured by AM;
— test bodies wishing to compare requested and actual geometries.
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 11484, Steel products — Employer's qualification system for non-destructive testing (NDT) personnel

ISO/ASTM 52900, Additive manufacturing — General principles — Fundamentals and vocabulary

ASTM E1316, Terminology for Nondestructive Testing

EN 1330­2, Non-destructive testing — Terminology — Part 2: Terms common to the non-destructive

testing methods
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO/ASTM 52900, ASTM E1316,

EN 1330-2, ISO 11484, and the following apply.

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

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
flaw type
identifiable features that defines a specific flaw

Note 1 to entry: defect term, this word is used when a flaw that does not meet specified acceptance criteria and

is rejectable.

Note 2 to entry: Flaw term, an imperfection or discontinuity that is not necessarily rejectable

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ISO/ASTM DTR 52905:2023(E)
3.2
lack of fusion
LOF

type of process-induced porosity, in which the powder or wire feedstock is not fully melted or fused

onto the previously deposited substrate

Note 1 to entry: In PBF, this type of flaw can be an empty cavity, or contain unmelted or partially fused powder,

referred to as unconsolidated powder.

Note 2 to entry: LOF typically occurs in the bulk, making its detection difficult.

Note 3 to entry: Like voids, LOF can occur on the build layer plane (layer/horizontal LOF) or across multiple build

layers (cross layer/vertical LOF).
3.3
unconsolidated powder

unmelted powder that due to process failure was not melted and became trapped internally

3.4
layer shift

when it is disturbed by a magnetic field a layer or a number of layers are shifted away from

the other build layers
Note 1 to entry: see stop/start for PBF laser/E beam.
3.5
trapped powder

unmelted powder that is not intended for the part but is trapped within internal part cavities

3.6
porosity
presence of small voids in a part making it less than fully dense

Note 1 to entry: Porosity may be quantified as a ratio, expressed as a percentage of the volume of voids to the

total volume of the part.
[SOURCE: ISO/ASTM 52900:2019, 3.11.8]
4 NDT potential for authentication and/or identification

Some of the NDT methods in this technical report have the additional potential to extract authentication

and/or identification apparatus or design embedded in the design of the AM part. Such a potential clearly

depends on the material(s), geometry and process elected to fabricate the part, however the design

information and AM data file can embed in its geometry or texture ad-hoc devices that potentially could

be extracted by NDT techniques. ISO/TC 292 specifies and maintains a number of standards supporting

such devices within the ISO referential, and are fully applicable to AM digital information. The specific

requirements of design techniques, materials, processes, NDT modalities and applications, however,

still require careful evaluation, selection and classification.
5 List of abbreviated terms
AM additive manufacturing
BAE British Aerospace and Engineering Systems
EB­PBF electron beam powder bed fusion
ESFR European Synchrotron Research Facility
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ISO/ASTM DTR 52905:2023(E)
EWI Edison Welding Institute
FMC full matrix capture
GE­PD general electric powder division
HZB Helmholtz Zentrum Berlin
ILL Institute Laue­Langevin
IR infrared
IRT infrared thermography
J & J Johnson & Johnson
LNE Laboratoire National De Métrologie ET D'essais
PBF­LB laser powder bed fusion
DED­LB laser directed energy deposition
MTC The Manufacturing Technology Centre
ND neutron diffraction
NDE non­destructive evaluation
NDT non­destructive testing
NI neutron Imaging
NIST National Institute of Standards and Technology
NLA non­linear acoustic testing
NLR non­linear Resonance testing
PAUT phase array ultrasound Testing
PCRT process compensated resonance testing
PT pulse thermography
RAM resonance acoustic method
ROI Region of interest
SX X-ray synchrotron
SHT step heating thermography
TFM total focusing method
TMS the modal shop
UoB university of bath
XCT X-ray computed tomography
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ISO/ASTM DTR 52905:2023(E)
6 Typical flaws/defects in AM
6.1 Flaw origins/causes

The causes of defects across different types of AM processes can be quite different, but the defects that

they generate can be remarkably similar. Detecting the defects also does not depend on the cause, and

in general only the size and geometry (and potentially morphology) of the defect matters for detection.

The causes and effects of a number of AM flaws have been reported in the European project

[21]

AMAZE . Table A.1 and Table A.2 give explanations of the mechanisms by which these flaws are

generated and those mechanisms are linked to the process parameters selected and the resulting

processing conditions, see ISO 11484.Understanding the conditions under which flaws are generated

and simplifying the terminology used to describe these flaws will hopefully aid the drive for quality

improvement required for widespread implementation of the technology.

The flowchart displayed in Figure 1 gives an idea of the complexity of flaw generation within the

PBF process. As can be seen, the generation of one flaw type can result in an anomalous processing

condition, which in turn generates a second flaw. For example, the presence of a thick layer or low laser

(or electron beam) power can lead to under­melting, which in turn can lead to unconsolidated powder.

Coupled with the tendency of the power source to decrease the surface energy of unconsolidated

powder under the action of surface tension, ensuing ball formation may arise due to shrinkage and

worsened wetting, leading to pitting, an uneven build surface, or an increase in surface roughness, see

EN 1330­2.

Therefore, even when there are multiple causes, a single flaw type or conditions can be generated

(excessive surface roughness) causing failure by a single failure mode (surface cracking leading to

reduced fatigue properties). Alternatively, it is also conceivable that a single flaw type or condition can

cause failure by several different failure modes.
6.2 Flaw/defects classification

Post-built AM flaws have been identified based on a report from the FP7 European AMAZE project.

Potential flaws in directed energy deposition (DED) and powder bed fusion (PBF) are listed in Table 1

and Table 2 respectively. A brief description for each flaw type is also given in the tables.

Due to the similarity in manufacturing, defects from welding and casting bear some resemblance to

defects from AM processes such as PBF and DED. Defects in post-built PBF and DED parts are identified

and listed in EN 1330-2, ASTM E1316 and References [22]. As noted in Table 1 and Table 2, both

technologies have common defects such as porosity, inclusions, undercuts, geometry, LOF, and a rough

surface texture. However, the mechanisms for PBF and DED defect generation are very different, and

more importantly, the relative abundance of each defect type will be very different due to the melting

and solidification mechanisms involved (and the significantly higher thermal gradients present in DED).

DED involves imparting a momentum into the melt pool rather than melting the powder that is already

present. The important difference between the two methods is that of timescales.
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ISO/ASTM DTR 52905:2023(E)
Key
machine: inputs/choices
AM part: resulting defect/flaw
process: resulting condition
common type of failure

Figure 1 — Causes, mode of failures and defect formation in PBF AM (see ISO/ASTM 52900)

In PBF, there is a balance of timescales between melting and re-solidification. If the melt rate is too

low, then the melt pool can become unstable and break into multiple pools. If the melt rate is too high,

powder partially melts in front of the melt pool, which can cause defects or heat affected zones. In DED,

this balance is not relevant, but the powder (or wire) that is fed into the melt pool can melt sufficiently

quickly. The issue of adding cold material (with a given momentum) to a melt pool is not well understood,

but has a large effect on the Marangoni convection direction and thermal gradients present. It is likely

that the melt pool depth will be much shallower (which may reduce powder surrounding the melt pool)

and that the thermal gradients less severe (which cause a flatter melt pool), though this depends on the

wetting between substrate (which has no surrounding powder) and the melt pool. This difference in

the melt pool dynamics impacts its shape.

This has two important consequences, grain growth and bubble dynamics. Internal defects are

attributable to cracking, pores, or lack of material. Cracking has many causes, but is generally related

to the grain boundary (apart from solidification cracking). Note that the issue of “spattering” that is

believed to be prominent in DED (or indeed welding) is still a significant issue in PBF. For L-PBF the

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ISO/ASTM DTR 52905:2023(E)

issue is that of ablation at the surface of the melt pool caused by the large thermal gradients. For EB-

PBF the problem occurs from two mechanisms; ablation and charging of the powder.
Table 1 — Typical flaws in directed energy deposition
Flaw type Description

Poor surface The surface roughness on the part does not meet the target specification for the part.

finish Measurement of the surface roughness is considered out­of­scope for NDT however, visual

examination can be included.

Porosity Typically spherical in shape and contains gas. Porosities can grow in a line to form a cha

...