ISO 13947:2011

INTERNATIONAL ISO
STANDARD 13947
Second edition
2011-12-01
Metallic powders — Test method for the
determination of non-metallic inclusions
in metal powders using a powder-forged
specimen
Poudres métalliques — Détermination de la teneur en inclusions non
métalliques dans les poudres métalliques à l’aide d’une éprouvette
forgée de poudre
Reference number
©
ISO 2011
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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
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Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 13947 was prepared by Technical Committee ISO/TC 119, Powder metallurgy, Subcommittee SC 2,
Sampling and testing methods for powders (including powders for hardmetals).
This second edition cancels and replaces the first edition (ISO 13947:2007), of which it constitutes a minor
revision.
INTERNATIONAL STANDARD ISO 13947:2011(E)
Metallic powders — Test method for the determination of non-
metallic inclusions in metal powders using a powder-forged
specimen
SAFETY PRECAUTIONS — This International Standard does not purport to address all of the safety
problems, if any, associated with its use. It is the responsibility of the user of this International
Standard to establish appropriate safety and health practices and to determine the applicability of
regulatory limitations prior to use.
1 Scope
This International Standard specifies a metallographic method for determining the non-metallic inclusion
level in metal powders using a powder-forged specimen. The test method covers repress powder-forged test
specimens in which there has been minimal lateral flow (<1 %). The core region of the powder-forged test
specimen contains no porosity detectable at 100× magnification.
This test method can also be used to determine the non-metallic inclusion content of powder-forged steel parts.
However, in parts where there has been a significant amount of material flow, the near-neighbour separation
distance needs to be changed, or the inclusion sizes agreed between the parties need to be adjusted.
This test method is not suitable for determining the non-metallic inclusion level of parts that have been forged
such that the core region contains porosity. At the magnification used for this test method, residual porosity
is hard to distinguish from inclusions. Too much residual porosity makes a meaningful assessment of the
inclusion population impossible.
This test method can be applied to materials that contain manganese sulfide (admixed or prealloyed), provided
the near-neighbour separation distance is changed from 30 µm to 15 µm.
2 Normative references
The following referenced documents are indispensable for the application 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/TR 14321:1997, Sintered metal materials, excluding hardmetals — Metallographic preparation and
examination
ASTM B796, Standard test method for nonmetallic inclusion content of powders intended for powder forging
(P/F) applications
ASTM E3, Standard guide for preparation of metallographic specimens
ASTM E768, Standard guide for preparing and evaluating specimens for automatic inclusion assessment of
steel
3 Principles
A section representing the core region of the test specimen (part) is cut from the test piece (part) prior to
metallographic grinding and polishing (mounting the section is optional but strongly recommended).
The polished sample is examined microscopically at a magnification of 100× and a note is made of inclusions
greater than a predetermined size.
The maximum Feret’s diameter is used to determine inclusion size. A Feret’s diameter is a caliper diameter, as
illustrated in Figure 1.
The fragmented nature of some inclusions means that their size determination is somewhat complicated. The
concept of near-neighbour separation shall be used in determining inclusion size. According to this concept, if
an inclusion is within a certain distance of its neighbouring particles, it is considered a member of an inclusion
cluster or agglomerate. Detected features within 30 µm of one another are considered part of the same
inclusion. The concept is illustrated schematically in Figure 2.
The non-metallic inclusion level of the test specimen (part) is reported as the number of inclusions, per
100 mm , greater than or equal to the predetermined size.
4 Significance and use
4.1 The non-metallic inclusion
...