oSIST prEN ISO/ASTM 52908:2022

Additive manufacturing of metals - Finished Part properties - Post-processing, inspection and testing of parts produced by powder bed fusion (ISO/ASTM DIS 52908:2022)

This standard covers the qualification, quality assurance and post processing for metal parts made by laser powder bed fusion. This standard defines methods and procedures for testing and qualification of
various characteristics of additively manufactured metal parts, in accordance to ISO 17296-3:2013 Classes H and M. The standard is intended to be used by part providers and/or customers of parts. This standard is a top-level standard in the hierarchy of additive manufacturing standards in that it is intended to apply to metallic parts made by additive manufacturing. The standard defines qualification procedures and  acceptance criteria where appropriate to meet defined quality levels.

Additive Fertigung von Metallen - Eigenschaften von Fertigteilen - Nachbearbeitung, Inspektion und Prüfung von Bauteilen hergestellt mittels pulverbettbasiertem Schmelzen (ISO/ASTM DIS 52908:2022)

Fabrication additive de métaux - Propriétés des pièces finies - Post-traitement, inspection et essais des pièces produites par fusion sur lit de poudre (ISO/ASTM DIS 52908:2022)

Dodajalna izdelava kovinskih izdelkov - Lastnosti končnih delov - Končna obdelava, kontrola in preskušanje delov, izdelanih s spajanjem prahu na podlagi (ISO/ASTM DIS 52908:2022)

General Information

• Status: Not Published
• Public Enquiry End Date: 02-Apr-2022
• ICS: 25.030 - Additive manufacturing
• Technical Committee: VAR - Welding
• Current Stage: 98 - Abandoned project (Adopted Project)
• Start Date: 02-Oct-2023
• Due Date: 07-Oct-2023
• Completion Date: 02-Oct-2023
• Ref Project: prEN ISO/ASTM 52908 - Additive manufacturing - Post-processing methods - Standard specification for quality assurance and post processing of powder bed fusion metallic parts

Overview

oSIST prEN ISO/ASTM 52908:2022 sets requirements for the post-processing, inspection, and testing of metallic parts produced by powder bed fusion additive manufacturing (AM). Developed by SIST, this standard is essential for ensuring that metal parts manufactured by laser powder bed fusion meet strict quality, safety, and performance requirements. It establishes procedures for part qualification, quality assurance, and post-processing in line with established ISO and ASTM additive manufacturing standards.

This standard targets both part providers and customers, serving as a top-level reference document in the hierarchy of international additive manufacturing standards for metal parts. It aligns with ISO 17296-3:2013 Classes H and M, ensuring compatibility with widely accepted categories in AM.

Key Topics

• Qualification Requirements: Defines the need for technical documentation, facility records, and quality assurance documentation. Manufacturers must demonstrate their ability to consistently meet purchase specifications through validated and traceable records.
• Post-Processing: Specifies critical post-build steps such as cooling, cleaning, removal from build platforms, heat treatments like stress relief and HIP (hot isostatic pressing), and various surface finishing techniques.
• Inspection and Testing: Covers metallurgical and mechanical tests, surface quality assessments, geometrical inspections, and non-destructive testing. Emphasizes the importance of controlling and recording these processes for effective quality management.
• Documentation and Traceability: Details the documentation requirements for both manufacturers and subcontractors. Includes calibration certificates, testing records, quality management documentation, and training records to ensure compliance and traceability.
• Procedures for Subcontractors: Outlines requirements for quality assessment and documentation when post-processing or testing is outsourced.
• Conformance with Other Standards: Requires cross-referencing with standards for powder lifecycle management, test methods, surface textures, and tensile testing.

Applications

Organizations engaged in additive manufacturing of metal parts by powder bed fusion will benefit from implementing this standard, including:

• Part Manufacturers: To establish and demonstrate robust quality assurance systems, consistent process validation, and reliable documentation for each produced component.
• Industrial Customers: For specifying acceptance criteria and verification procedures when sourcing additively manufactured metal parts.
• Quality Assurance Professionals: As a basis for auditing AM production lines, evaluating conformance, and ensuring traceability across production and third-party testing.
• Regulatory Compliance: Enables companies to align their practices with international best practices for additive manufacturing, supporting entry into regulated markets such as aerospace, medical devices, and automotive.
• Subcontractors and Service Bureaus: Helps standardize expectations and processes for subcontracted post-processing and testing services.

Related Standards

Implementing oSIST prEN ISO/ASTM 52908:2022 typically involves integration with several other important additive manufacturing and quality assurance standards, such as:

• ISO/ASTM 52900: General principles and vocabulary for additive manufacturing
• ISO/ASTM 52920: Qualification principles and requirements for industrial AM sites
• ISO/ASTM 52927: Main characteristics and test methods for AM products
• ISO/ASTM 52928: Powder life cycle management
• ISO/ASTM/TS 52930: Qualification of AM equipment
• ISO 1302: Indication of surface texture in technical documentation
• ISO 3369, ISO 6892-1, ASTM E8/E8M, DIN 50125: Standards for density determination and tensile testing

Summary

oSIST prEN ISO/ASTM 52908:2022 provides a comprehensive quality management framework for the additive manufacturing of metal parts via powder bed fusion, focusing on qualification, documentation, post-processing, and rigorous inspection procedures. Adopting this standard supports the delivery of high-quality AM metal parts that meet the needs of demanding industrial sectors, promoting supplier-customer confidence and enabling regulatory compliance.

Keywords: additive manufacturing, powder bed fusion, metal parts, post-processing, inspection, testing, quality assurance, ISO/ASTM 52908, industrial standards, AM documentation, qualification procedures.

Standards Content (Sample)

SLOVENSKI STANDARD
01-marec-2022
Aditivna proizvodnja kovinskih izdelkov - Lastnosti končnih delov - Končna
obdelava, kontrola in preskušanje delov, izdelanih s spajanjem prahu v postelji
(ISO/ASTM DIS 52908:2022)
Additive manufacturing of metals - Finished Part properties - Post-processing, inspection
and testing of parts produced by powder bed fusion (ISO/ASTM DIS 52908:2022)
Additive Fertigung von Metallen - Eigenschaften von Fertigteilen - Nachbearbeitung,
Inspektion und Prüfung von Bauteilen hergestellt mittels pulverbettbasiertem Schmelzen
(ISO/ASTM DIS 52908:2022)
Fabrication additive de métaux - Propriétés des pièces finies - Post-traitement,
inspection et essais des pièces produites par fusion sur lit de poudre (ISO/ASTM DIS
52908:2022)
Ta slovenski standard je istoveten z: prEN ISO/ASTM 52908
ICS:
25.030 3D-tiskanje Additive manufacturing
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT INTERNATIONAL STANDARD
ISO/ASTM DIS 52908
ISO/TC 261 Secretariat: DIN
Voting begins on: Voting terminates on:
2022-01-14 2022-04-08
Additive manufacturing of metals — Finished Part
properties — Post-processing, inspection and testing of
parts produced by powder bed fusion
ICS: 25.030
This document is circulated as received from the committee secretariat.
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
ISO/CEN PARALLEL PROCESSING
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/ASTM DIS 52908:2022(E)
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 SUPPORTING DOCUMENTATION. © ISO/ASTM International 2022

ISO/ASTM DIS 52908:2022(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 DIS 52908:2022(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviations .2
4.1 Symbols . 2
4.2 Abbreviations . 3
5 Qualification . 3
5.1 General . 3
5.2 Part Validation . 3
5.3 Technical documentation relating to part(s) produced . 3
5.4 Facility documentation . 4
5.4.1 Additive manufacturer documentation requirements . 4
5.4.2 Subcontractor documentation requirements . 4
5.5 Quality Assurance documentation . 4
6 Post processing . 5
6.1 General . 5
6.2 Post‑build activities . 5
6.3 Thermal treatment . 5
6.4 Separation from the built platform and support structures . 6
6.5 Surface finishing . 6
6.5.1 Surface finishing operations . 6
6.5.2 Machining allowances . 7
7 Inspection and testing .7
7.1 General . 7
7.2 Metallurgical testing . 7
7.2.1 Objective . 7
7.2.2 Specimen selection, design, and preparation for part characterization . 8
7.2.3 Test methods, parameters and specimens . 9
7.2.4 Metallurgical properties . 9
7.2.5 Determining the non‑metallic inclusion content . 9
7.2.6 Analysis and test report . 9
7.3 Mechanical testing . 10
7.3.1 General . 10
7.3.2 Orientation in the build space . 10
7.3.3 Specimen geometry and surface quality . 10
7.3.4 Density (Part). 10
7.3.5 Archimedean method.12
7.3.6 Image analysis of metallographic specimens .13
7.3.7 Static testing .15
7.3.8 Dynamic testing . 19
7.4 Surface quality inspection . 20
7.5 Geometrical inspection (form, dimension and tolerances) . 20
7.6 Non‑destructive testing . 21
Bibliography .22
iii
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM DIS 52908:2022(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 should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 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 Objective to create a common set
of ISO/ASTM standards on Additive Manufacturing.
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 DIS 52908:2022(E)
Introduction
This document is designed to complement ISO/ASTM 52900, which describes different additive
manufacturing processes using a variety of materials. This standard covers the testing of components
manufactured from metallic materials using additive technologies.
As with conventional manufacturing processes (e. g. casting and milling), metallic parts produced by
additive manufacturing technologies have critical‑to‑quality characteristics. These include in particular
density, strength, hardness, surface quality, dimensional accuracy, residual stresses, absence of cracks,
voids and structural homogeneity, which are typically tested in additively manufactured components.
The quality of additively manufactured components is essential if functional components are produced
on an industrial scale. Thus, it is necessary to qualify additive manufacturing processes according to
uniform criteria and to apply standardised in‑process and post‑process testing.
v
© ISO/ASTM International 2022 – All rights reserved

DRAFT INTERNATIONAL STANDARD ISO/ASTM DIS 52908:2022(E)
Additive manufacturing of metals — Finished Part
properties — Post-processing, inspection and testing of
parts produced by powder bed fusion
1 Scope
This document sets requirements for the qualification, quality assurance and post processing for
metal parts made by powder bed fusion. This document defines methods and procedures for testing
and qualification of various characteristics of additively manufactured metal parts, in accordance with
ISO 17296‑3, Classes H and M.
This document is intended to be used by part providers and/or customers of parts. This standard is a
top‑level standard in the hierarchy of additive manufacturing standards in that it is intended to apply
to metallic parts made by additive manufacturing. This document defines qualification procedures
where appropriate to meet defined quality levels.
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, Additive manufacturing — General principles — Fundamentals and vocabulary
ISO/ASTM 52920, Additive manufacturing — Qualification principles— Requirements for industrial
additive manufacturing sites
ISO/ASTM 52927, Additive manufacturing — General principles — Main characteristics and corresponding
test methods
ISO/ASTM 52928, Additive manufacturing — Feedstock materials — Powder life cycle management
ISO/ASTM/TS 52930, Additive manufacturing — Qualification principles — Installation, operation and
performance (IQ/OQ/PQ) of PBF-LB equipment
ISO 1302, Geometrical Product Specifications (GPS) — Indication of surface texture in technical product
documentation
ISO 3369, Impermeable sintered metal materials and hardmetals — Determination of density
ISO 6892‑1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
ASTM E8/E8M, Standard Test Methods for Tension Testing of Metallic Materials
DIN 50125, Testing of metallic materials — Tensile test pieces
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/ASTM 52900 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
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM DIS 52908:2022(E)
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
grain size
powder particle size
particle size
average diameter of powder particles under consideration
3.2
grain size
metallurgical grain size
average grain size in the metallurgical structure when viewed in cross-section
4 Symbols and abbreviations
4.1 Symbols
The symbols listed in Table 1 are used throughout this document.
Table 1 — Symbols
Symbol Term Unit
a specimen thickness (bending test) mm
b specimen width (bend test) mm
pb
d specimen diameter mm
d ISO metric threads mm
l
d roller diameter (bend test) mm
b
E volume energy density J/mm
V
F punch force N
b
F maximum force (bend test) N
max
h head heigth mm
h scan line spacing mm
s
notch impact energy
KU, KV J
U:U-notch, V:V-notch
L initial gauge length mm
L test length (L > L + d ) mm
c c 0 0
L total length mm
t
l roller spacing (bend test) mm
ab
l specimen length (bend test) mm
p
l layer thickness mm
z
N nominal dimension mm
P laser power W
L
R average surface roughness μm
Z
S punch path (bend test) mm
b
T tolerance mm
T transition temperature K, °C
T
VR volume rate mm /s
v scan speed mm/s
s
α angle of bend (bend test) °(degree)
β angle of bend (bend test) °(degree)
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM DIS 52908:2022(E)
4.2 Abbreviations
The abbreviations listed in Table 2 are used throughout this document:
Table 2 — Abbreveations
AM additive manufacturing
EDX energy‑dispersive X‑ray spectroscopy
SEM scanning electron microscope
CAD computer aided design
NDT non-destructive testing
QA quality assurance
COC certificate of conformance
ASL approved supplier list
HIP hot isostatic pressing
EDM electrical discharge machining
PBF powder bed fusion
5 Qualification
5.1 General
The manufacturer shall demonstrate the capability to produce AM parts to the requirements given in
the purchase specification. The inspection and testing described in the following clauses is performed
and assessed using the methods and acceptance criteria stated in the purchase specification.
NOTE Purchase specification requirements are developed at the design stage, as described in
ISO/ASTM 52927, and are in accordance with the relevant standards and regulations that are required for the
conformity of that part.
5.2 Part Validation
Validation that the part produced complies with the requirements of the purchase specification shall be
captured in a qualification record. A typical ‘qualification record’, shall consist of:
— Technical documentation relating to part(s) produced;
— Facility documentation;
— Quality assurance (QA) documentation.
5.3 Technical documentation relating to part(s) produced
The technical documentation relating to part(s) produced shall contain:
— Purchase specification in accordance with ISO/ASTM 52927, which includes inspection methods,
associated plans, acceptance criteria, and representative quality indicators where applicable;
— Feedstock specification, test results and declaration of conformity with ISO/ASTM 52907;
— Material specification (consolidated product material properties specification);
— Completed manufacturing plan;
— Records of destructive and non-destructive testing;
— Inspection record for the part (in accordance with the purchase specification);
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM DIS 52908:2022(E)
— Other documentation required by the purchaser, regulation or product standard (e. g. material
identification, labelling, product instructions).
NOTE 1 For some materials, there may be a singular specification that controls both feedstock and material
properties, such as metallurgical and mechanical properties.
NOTE 2 Technical specifications for metal powders are addressed in ISO /ASTM 52907.
5.4 Facility documentation
5.4.1 Additive manufacturer documentation requirements
Facility documentation requirements for industrial manufacturing sites are addressed in
ISO/ASTM 52920.
For the purpose of this document, an outline of the relevant manufacturing plant and equipment shall
be provided. The outline shall include the major items of equipment used for post processing, inspection
and testing (including details of geographical location).
The following facility documentation shall be provided:
— Records of equipment qualification (addressed in ISO/ASTM TS 52930);
— Records of powder lifecycle management (addressed in ISO/ASTM 52928).
The following quality management documentation shall be provided, where a certified quality
management system is not already in place:
— Records (e.g. calibration certificates) of inspection equipment used for measuring and testing;
— Records of equipment used for metallographic examinations, mechanical tests, non‑destructive
tests, hydraulic and gaseous testing (where appropriate, this is to include details of the testing
procedures used);
— Training records of manufacturing and inspection personnel;
— Developments that affect the supply shall be qualified and reported.
The items listed above are acceptable where a quality management system is in place (see 5.5.).
5.4.2 Subcontractor documentation requirements
Where the manufacturer subcontracts post-processing and/or testing activities, the manufacturer
shall state the conditions under which these activities are subcontracted and shall provide a purchase
specification for the operations involved.
The manufacturer shall assess and approve the subcontractors for their capability to perform the
subcontracted activity to the required quality level.
5.5 Quality Assurance documentation
General QA documentation requirements are considered to be met when the quality management
system (e. g. ISO 9001, ISO 13485) is certified by a recognised inspection body.
Additive manufacturing QA documentation requirements are addressed in ISO/ASTM 52920.
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM DIS 52908:2022(E)
6 Post processing
6.1 General
Post‑processing consists of activities performed after the completion of a build cycle but prior to final
inspection activities.
NOTE 1 Intermediate inspections can be performed between post-processing activities.
Post‑processing operations are typically performed to achieve the desired material properties, final
geometry and surface finish, and include the following steps:
— post-build activities (e. g. cool down, declamping, removal from the AM machine, part cleaning);
— thermal treatment;
— separation from the build platform and support structures;
— surface finishing.
NOTE 2 At the post‑processing stage there are also several system‑based operations performed (i.e. not
related to the AM part) to prepare for subsequent builds. These activities are covered within other standards and
include:
— recovery and reprocessing of unfused powder (see ISO/ASTM 52928);
— AM equipment cleaning and maintenance (see ISO/ASTM 52920).
6.2 Post-build activities
Following successful completion of the build, the chamber is allowed to cool and unfused powder is
recovered from the build chamber. Once the build chamber is opened, the build platform fasteners
can be removed, and care shall be taken to avoid deflection, which could induce cracking, due to the
build‑up of any residual stresses within the build.
Once the build assembly is removed from the AM machine, it can be cleaned and visually inspected (e. g.
for imperfections, discolouration, separation from support structures). Loose powder that remains
on the build assembly after exposure to atmosphere (i. e. no longer within an inert environment) may
be removed by various methods (e. g. compressed gas, brushing, vacuum, sonic or ultrasonic cleaning
methods). Loose powder removed at this stage shall be considered to be waste powder and disposed of
safely.
For some non-reactive materials, loose powder that is removed within a controlled environment (e. g.
glovebox, automatic depowdering unit), can also be reused where allowed by the manufacturer’s
procedures, subject to contamination and traceability controls.
6.3 Thermal treatment
Although it is not mandatory to apply any thermal treatment to additively manufactured parts, the
following points should be considered:
— reducing residual stresses
The build‑up of successive layers with rapid heating and cooling generates residual stresses in
the component, which can lead to distortion. Where used, support structures help to minimise this
distortion by providing stiffness within the build assembly to resist deflection due to these residual
stresses. Therefore, the build assembly is typically stress relieved prior to the removal of any support
structures, although this is not mandatory. The release of thermal stresses can lead to distortion, over
a short or prolonged period of time. Furthermore, local stress peaks may occur in the part, which can
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM DIS 52908:2022(E)
significantly reduce fatigue strength and lead to premature cracking. Stress‑relief reduces stresses in
the component in a controlled manner after manufacture, thereby preventing distortion.
— reducing anisotropy
The as‑built part can exhibit anisotropy, which may be normalised to minimise the orientation
and location dependence on the mechanical properties of the formed material and achieve the final
mechanical property requirements.
NOTE ISO/ASTM 52909 includes supplementary guidelines for the evaluation of finished part properties,
including orientation and location dependence, for metal parts produced by powder bed fusion.
— prepare material for mechanical post-processing
Processes such as annealing can reduce the hardness of the as‑built material to facilitate subsequent
machining operations. Annealing, followed by ageing, can also enable grain boundary carbides to enter
into solution and thus prevent unacceptable grain boundary carbide precipitation, which can lead to
intergranular corrosion and cracking.
— densification
hot isostatic pressing (HIP) can improve material properties through the reduction of porosity and
anisotropy.
NOTE ASTM A1080/A108M provides a standard practice for hot isostatic pressing of steels, stainless steels
and related alloys.
The particular thermal treatment specified depends on the material and desired mechanical properties,
as defined within the material specification and agreed between manufacturer and purchaser.
NOTE ASTM F3301 includes details of thermal treatments for various metals produced by powder bed
fusion.
Specimens used for destructive testing shall be representative of the part and therefore be subjected to
the same thermal post‑processing operations as the part they represent.
6.4 Separation from the built platform and support structures
Various items can be present within the build assembly, which require separation from the build
platform, from support structure and/or from other items (e.g. the part, test specimens). A suitable
method of separation shall be specified in the manufacturing plan, such that separation does not have a
detrimental effect on the integrity of the part or test specimens.
Separation is typically performed after thermal treatment, for the reasons described in 6.3, but may be
performed before thermal treatment where deemed appropriate by the manufacturer.
6.5 Surface finishing
6.5.1 Surface finishing operations
Suitable finishing operations shall be selected by the manufacturer and defined within the
manufacturing plan, to achieve the final geometry and surface finish requirements, specified in the
design.
NOTE Numerous finishing operations are available, examples of which are listed below:
— machining (e.g. turning, drilling, milling);
— electrical discharge machining (EDM);
— abrasive operations (e.g. grinding, polishing, vibratory finishing, abrasive slurries);
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM DIS 52908:2022(E)
— blasting operations (e.g. sand blasting, shot peening);
— chemical finishing (e.g. plating, dipping, degreasing);
— coating (e.g. painting, spraying, powder coating).
The selection will depend upon the material, geometry (e.g. size, complexity, accessibility), surface
finish (e.g. roughness, waviness, lay), tolerances, aesthetic and economic considerations.
6.5.2 Machining allowances
Depending on the requirements of an additively manufactured part, it may be necessary to machine one
or several areas to comply with the required tolerances. This typically requires a machining allowance
which comprises at least the maximum possible dimensional deviation.
Machining allowances are to be regarded as a “cutting allowance”, i.e. for machining solids of revolution
or for two-sided machining, allowances shall be applied twice. Chain dimensions shall be avoided and
when using finished part drawings, functional dimensions shall be indicated and areas with machining
allowance shall be denoted by symbols according to ISO 1302.
Consideration should also be given to the fact that, depending on the geometry, additively manufactured
parts may be subject to warpage. An additional machining allowance is required for this.
7 Inspection and testing
7.1 General
The following aspects shall be controlled and documented for quality assurance purposes (e.g. through
controlled procedures and records):
— Metallurgical testing;
— Mechanical testing;
— Surface quality inspection;
Geometrical inspection (Form, dimension and tolerances);
— Non-destructive testing.
NOTE Additional records, not covered in this standard:
— Machine build log report, see ISO/ASTM 52904;
— Powder cycle / reconditioning, see ISO/ASTM 52928;
— Equipment maintenance records, see ISO/ASTM TS 52930;
— Cleaning lenses / building chamber → quality specification, see ISO/ASTM TS 52930;
— Filter (quality, saturation, condensate), see ISO/ASTM TS 52930;
— In‑process monitoring (melt pool analysis, etc.), see ISO/ASTM 52920.
7.2 Metallurgical testing
7.2.1 Objective
Numerous methods have been developed in metallography to quantitatively and/or qualitatively
describe structural characteristics in metallic materials, including defects such as pores and cracks.
These can equally be applied to the analysis of beam‑melted test specimens and parts to provide
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM DIS 52908:2022(E)
information about manufacturing quality, material characteristics and behaviour. The structure
of a material is characterised by the type, size, shape, distribution and orientation of the structural
components. Numerous metallographic investigations can be carried out by examining the structure of
a polished cross‑section of a specimen or appropriately prepared part with the naked eye, a magnifying
glass or a microscope. While general metallographic procedures described in other standards are
typically sufficient for the preparation of metals produced in laser powder bed fusion, there are
structures and features specific to this production method that occur frequently enough to be of note.
7.2.2 Specimen selection, design, and preparation for part characterization
Metallographic characterization of parts produced by laser powder bed fusion is a common operation,
but there are process and material details that may not be immediately apparent to new users of the
technology. The two fundamental specimen types that are commonly processed are those cut from
actual parts and those specifically designed to be used for metallographic evaluation.
In the case of specimens cut from actual parts, a typical goal is to ensure that the specimen is free
from defects. In the powder bed fusion process, material is formed at the same time as the part, and
an approach akin to that taken in the characterization of cast materials is required, as opposed to the
approach taken in subtractive manufacturing processes where the material properties are already
known. Care shall be taken because many imperfections depend on the specific geometry that is
produced, so it can be difficult to extrapolate material quality characteristics from simple specimens to
complex parts, even when using the same powder and build parameters. For the purposes of sectioning
the part, the use of either metallographic saws or wire EDM is recommended over machining, to ensure
that the material is not adversely affected during sectioning. This is of particular concern with softer
materials.
The second case of processing parts designed for metallographic characterization allows for substantial
freedom to design the part to fit the need and ease the process of specimen preparation. A few
considerations for the design of the specimen geometry are listed in the following:
a) Specimen size: The specimen should be sized appropriately to fit in the metallographic mounting
cup or mold, or planned to be sectioned so that it will fit. Again, when possible, the parts should be
sectioned using a method that does not adversely affect the material. Metallographic saws or wire
EDM are commonly used for this purpose.
b) Polished face orientation: The polished face of the part may be in a plane parallel to the build
platform (XY), or in a plane parallel with the build direction (Z), and this will often be of great
importance for the types of structures that are visible in the specimen. For the characterization of
some effects, it can be beneficial to introduce a feature in the part to indicate the orientation of the
part within the XY plane as well.
c) Surface effects: Often the external surfaces of parts produced in laser powder bed fusion parts are
not representative of the bulk, internal material. Observation of this surface region may or may not
be the goal of the characterization effort, but users should be aware that characterization efforts in
near surface regions are subject to these effects.
d) Mounting method: If mounting fine structures, such as lattices or parts with thin walls, hot
mounting is not recommended as the pressure that is used during the mounting process can
substantially deform the part.
e) Labelling: In the case where a number of specimens from a single build will be mounted and
polished, it can be beneficial to label directly into the part such that labels are visible during
subsequent steps.
f) Required material response: For example, a part that is used for the characterization of bulk
material density may not be well suited to determining the level of near surface porosity. It is
recommended to consider the required material response.
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM DIS 52908:2022(E)
g) Thermal treatment: It may be desired to perform thermal post‑processing (see 6.3) in addition to
mechanical post‑processing. Specimens shall be subjected to have the same post‑processing as the
parts they represent.
The specimen shall be prepared according with the standard specified (e. g. ASTM E3). After the
specimen is mounted using either a hot mount press or cold mount mold, it is typical to grind and then
polish the specimen.
After fine polishing, there are a number of possible subsequent steps. This is the ideal time to measure
bulk porosity in the specimen by taking a digital photo and processing the image to determine the
relative density, as described in the following section. Subsequent to this analysis, the specimen may
be chemically etched to show additional structure and permit a more detailed examination of the
beam‑melted metallic structure. In the majority of cases etching is required to reveal the separate
microstructural constituents of a metal alloy. Various etching techniques exploit the diversity of
individual types of grain, e. g. crystallographic orientation, chemical composition, hardness, chemical
resistance. A wide variety of etching techniques can be used on metallographic specimens.
In certain materials, etching in the as‑build condition will also expose features unique to materials
produced by powder bed laser fusion. It is often possible to see evidence of each pass of the laser over
the material. In these materials, it is often possible to see the path of both the bulk scan and the contour
scan, which can be beneficial when diagnosing porosity problems due to insufficient overlap between
those scans.
7.2.3 Test methods, parameters and specimens
Refer to ISO/ASTM 52927 for examples of suitable test‑methods.
7.2.4 Metallurgical properties
The chemical composition shall be determined using methods stipulated in the material specification.
The grain size shall be measured in at least two orthogonal planes (e. g. horizontal and vertical planes
relative to the build direction) because of the potential for microstructure anisotropy.
7.2.5 Determining the non-metallic inclusion content
Non-metallic inclusion content shall be assessed using a method appropriate for the selected material
(refer to ISO/ASTM 52927 and the appropriate material specification).
7.2.6 Analysis and test report
When analysing metallographic specimens it is important to be aware of the micro‑structural
characteristics created by the layer‑on‑layer construction process of beam‑melted metal parts. The test
report shall contain at least the following information:
— reference to the applied standards;
— specimen type;
— specimen identification;
— material;
— any special remarks, e. g. thermal treatment;
— test conditions;
— orientation of specimen in the build space;
— relative location of specimen in the build space;
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM DIS 52908:2022(E)
— specimen derived from part or sample;
— results of the analysis (in accordance with the test standard);
— other information required by the selected test standard.
7.3 Mechanical testing
7.3.1 General
Appropriate test methods shall be selected, and specified in the manufacturing plan, to determine the
mechanical properties required by the material specification.
Refer to ISO/ASTM 52927 for examples of suitable test‑methods.
7.3.2 Orientation in the build space
Test specimens shall be located and oriented within the build space to mitigate the risk of variability in
mechanical properties due to position and/or orientation.
NOTE 1 The ISO/ASTM 52911 series provides technical design guidelines for positioning in the
build space, with consideration of orientation with respect to the build platform and the recoater.
NOTE 2 ISO/ASTM 52921 provides standard practice for part positioning, coordinates and
orientation.
7.3.3 Specimen geometry and surface quality
Specimen geometry and surface quality are defined in the standard for the particular test.
7.3.4 Density (Part)
The relative density of parts produced by beam melting is typically at least 99,8 % of the theoretical
material density.
Density can be tested by Archimedean methods, by gas pycnometry (see ISO 12154) or optically by
quantitative analysis of metallographic specimen images. Non‑destructive testing methods can also be
used for density evaluation via image processing of 2D or 3D images (see Section 7.3.6).
Archimedean methods are typically faster and provide information about overall porosity, whilst image
analysis methods yield more information about the type and distribution of porosities within a single
plane or in a volume. Archimedean methods are typically used to determine density in the early phases
of metallographic qualification testing. Determining density purely by gravimetric means (i.e using
measurements to calculate the volume and weighing a specimen) is not considered to be sufficiently
accurate.
Figure 1 and Figure 2 show typical microstructures of specimens with a density greater or less than
99 %.
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM DIS 52908:2022(E)
Figure 1 — Light micrograph of the micro-section (unetched) of 316L grade steel with a density
of more than 99 %
© ISO/ASTM International 2022 – All rights reserved

ISO/ASTM DIS 52908:2022(E)
Figure 2 — Light micrograph of the micro-section (unetched) of 316L grade steel with a density
of less than 99 %
7.3.5 Archimedean method
7.3.5.1 Objective
To determine density by the Archimedean method, a part is weighed in air initially, and then in liquid.
The advantage of this method compared with density determination by quantitative structural analysis
is that results can be obtained with comparative ease and cover the entire volume range of the part or
specimen. The disadvantage is that this method only determines the density. It provides no information
about the type, distribution and shape of structural porosities.
7.3.5.2 Test methods, parameters and specimens
Density is determined in accordance with the procedure described in ISO 3369, ASTM B962 or
ASTM B311. For specimens with relative densities less than 98 %, ASTM B963 may be used.
7.3.5.3 Specimen preparation
ISO 3369 stipulates a specimen volume of more than 0,5 cm . Thus, an optimal compromise between
cost‑effective specimen production, ease of handling, measurement accuracy and information value
of the microstructure is needed. Cube-shaped specimens which retain an edge length of 10 mm after
separation from the build platform are recommended. According to the standa
...