CEN/SS M11 - Powder metallurgy

This document specifies a metallographic test method for determining the non-metallic inclusion level in metal powders using a powder-forged specimen. This test method is applicable to repress powder-forged test specimens in which there has been minimal lateral flow (<1 %). The core region of the powder-forged test specimen must not contain porosity detectable at 100x magnification.
This test method can also be applied 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 applicable 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 also be applied to materials that contain manganese sulphide (admixed or prealloyed), provided the near-neighbour separation distance is changed from 30 µm to 15 µm.

This document specifies the dimensions of an unnotched impact test piece of sintered metal materials. The test piece may be obtained directly by pressing and sintering or by machining a sintered part.
This document applies to all sintered metals and alloys, with the exception of hardmetals. However, for certain materials (for example, materials with low porosity or materials with high ductility), it may be more appropriate to use a notched test piece which, in this case, will give results with less scatter. (In this case, refer to ISO 148-1.)
NOTE            For porous sintered materials, the results obtained from impact tests on unnotched specimens according to this standard are not fully comparable with results obtained from tests on solid metals tested on notched specimens.

This document is applicable to all sintered metals and alloys, excluding hardmetals.
This document specifies:
—    the die cavity dimensions used for making tensile test pieces by pressing and sintering, and by metal injection moulding (MIM) and sintering;
—    the dimensions of tensile test pieces machined from sintered and powder forged materials.

This document specifies a gas chromatography and a mass spectrometry method of detecting the presence of argon in metal powder produced components, consolidated by hot isostatic pressing.
This document specifies the calibration and functionality test for the equipment covered. It also specifies methods for sampling, sample preparation and sample test procedure of PM HIP components to detect argon presence.
Components produced by additive manufacturing are not covered in this document.

This document specifies a method for the determination of green strength by measuring the transverse rupture strength of compacts of rectangular cross-section.

This document specifies a method for the determination of the relative loss of mass which a metallic powder undergoes when heated in a stream of pure dry hydrogen under specified conditions.
The purpose of this test is to evaluate a chemical powder characteristic which is of importance to the powder metallurgical industry. The test is not intended as a means for the determination of the content of specific elements (see Annex A and ISO 4491-1).
The test method is applicable to unalloyed, partially alloyed and completely alloyed powders of the metals listed in Table 1 (see 7.2.1). It is not applicable to lubricated powders or to mixtures of metal powders.

This document is the first part of a series of standards dealing with the determination of oxygen content in metallic powders by reduction methods. It specifies general guidance to these methods and gives some recommendations for the correct interpretation of the results obtained.
The test methods are applicable generally to all powders of metals, alloys, carbides and mixtures thereof. The constituents of the powder shall be non-volatile under the conditions of test. The powder shall be free of lubricant or organic binder.
However, there exist certain limitations which depend upon the nature of the analysed metal. These limitations are discussed in Clause 4.

This document defines terms related to powder metallurgy.
Powder metallurgy is the branch of metallurgy which relates to the manufacture of metallic powders, or of articles made from such powders with or without the addition of non-metallic powders, by the application of forming and sintering processes.

This document specifies the requirements for the chemical composition and the mechanical and physical properties of sintered metal materials used for bearings and structural parts.

This document specifies a generic test method to determine the abrasion wear characteristics of hardmetals.
The test is appropriate for use in situations where test laboratories have a need to simulate abrasive damage. The procedure includes information which enables the test to be used in a variety of different conditions:
a)   with counterface wheels of different stiffness (for example steel and rubber);
b)   wet and dry;
c)   different abrasive sizes;
d)   different chemical environments.

This document gives guidelines for the measurement of hardmetal grain size by metallographic techniques only using optical or electron microscopy. It is intended for WC/Co hardmetals (also called cemented carbides or cermets) containing primarily tungsten carbide (WC[1]) as the hard phase. It is also intended for measuring the grain size and distribution by the linear-intercept technique.
This document essentially covers four main topics:
—     calibration of microscopes, to underpin the accuracy of measurements;
—     linear analysis techniques, to acquire sufficient statistically meaningful data;
—     analysis methods, to calculate representative average values;
—     reporting, to comply with modern quality requirements.
This document is supported by a measurement case study to illustrate the recommended techniques (see Annex A).
This document is not intended for the following:
—     measurements of size distribution;
—     recommendations on shape measurements. Further research is needed before recommendations for shape measurement can be given.
Measurements of coercivity are sometimes used for grain-size measurement, however, this document is concerned only with a metallographic measurement method. It is also written for hardmetals and not for characterizing powders. However, the method can, in principle, be used for measuring the average size of powders that are suitably mounted and sectioned.
[1] DE: Wolframcarbid, EN: tungsten carbide.

This document specifies the methods of metallographic determination of the microstructure of hardmetals using photomicrographs.

This document specifies a method for determining the flow rate of metallic powders, including powders for hardmetals and mixes of metallic powders and organic additives such as lubricants, by means of a calibrated funnel (Gustavsson flowmeter).
The method is applicable only to powders which flow freely through the specified test orifice.

This document specifies a method of determining the particle size distribution of metallic powders by dry sieving into size fractions.
The method is applicable to dry, unlubricated metallic powders, but not applicable to powders in which the morphology differs markedly from being equiaxial, for example flake-type powders.
The method is not applicable to metallic powders having a particle size wholly or mostly under 45 µm.

This document specifies a method of measuring the air permeability and the porosity of a packed bed of metal powder, and of deriving therefrom the value of the envelope-specific surface area. The permeability is determined under steady-state flow conditions, using a laminar flow of air at a pressure near atmospheric. This document does not include the measurement of permeability by a constant volume method.
Several different methods have been proposed for this determination, and several test devices are available commercially. They give similar, reproducible results, provided that the general instructions given in this document are respected, and the test parameters are identical.
This document does not specify a particular commercial test device and corresponding test procedure. However, for the convenience of the user, an informative annex has been included (see Annex A) which is intended to give some practical information on three specific methods:
—     the Lea and Nurse method, involving a test device which can be built in a laboratory (see A.1);
—     the Zhang Ruifu method, using a similar test device (see A.2);
—     the Gooden and Smith method, involving a test device which can be built in a laboratory but for which a commercial test device also exists. (Two types of commercial test device exist; one of these is no longer available for purchase, but is still being used, see A.3.)
These methods are given as examples only. Other test devices available in various countries are acceptable within the scope of this document.
This testing method is applicable to all metallic powders, including powders for hardmetals, up to 1 000 µm in diameter, but it is generally used for particles having diameters between 0,2 µm and 75,0 µm. It is not intended to be used for powders composed of particles whose shape is far from equiaxial, i.e. flakes or fibres, unless specifically agreed upon between the parties concerned.
This testing method is not applicable to mixtures of different metallic powders or powders containing binders or lubricant.
If the powder contains agglomerates, the measured surface area can be affected by the degree of agglomeration. If the powder is subjected to a de-agglomeration treatment (see Annex B), the method used is to be agreed upon between the parties concerned.

This document specifies procedures for sampling and testing of hardmetals for the determination of their physical and mechanical characteristics.

This document specifies procedures for the sampling and testing of powder mixtures for the manufacture of hardmetals, using sintered test pieces. It also covers the preparation of test pieces.

This document specifies a method for the determination of the total oxygen content of metallic powders by reduction-extraction at high temperature.
By agreement, this method is also applicable to the determination of the total oxygen content of sintered metal materials.
The method is applicable to all powders of metals, alloys, carbides, and mixtures thereof which are non-volatile under the test conditions. The sample can be in powder or compact form.
The analysis is carried out on the powder as supplied, but the method is not applicable if the powder contains a lubricant or binder. If such substances are present, the method may be used only if they can first be completely removed by a method not affecting the oxygen content of the powder.
This document is to be read in conjunction with ISO 4491-1.

This document specifies a method for the determination of the fluid permeability of permeable sintered metal materials in which the porosity is deliberately continuous or interconnecting, testing being carried out under such conditions that the fluid permeability can be expressed in terms of viscous and inertia permeability coefficients (see Annex A).
This document does not apply to very long hollow cylindrical test pieces of small diameter, in which the pressure drop of the fluid in passing along the bore of the cylinder might not be negligible compared with the pressure drop of the fluid passing through the wall thickness (see A.5).

This document specifies the funnel method for the determination of the apparent density of metallic powders under standardized conditions.
The method is intended for metallic powders that flow freely through a 2,5 mm diameter orifice. It can, however, be used for powders that flow with difficulty through a 2,5 mm diameter orifice but flow through a 5 mm diameter orifice.
Methods for the determination of the apparent density of powders that will not flow through a 5 mm diameter orifice are specified in ISO 3923‑2[1].

ISO 4490:2018 specifies a method for determining the flow rate of metallic powders, including powders for hard metals, by means of a calibrated funnel (Hall flowmeter).
The method is applicable only to powders which flow freely through the specified test orifice.

ISO 4506:2018 specifies a method of determining the ultimate strength and proof stress of cemented carbide under uniaxial compressive loads.

ISO 4492 specifies a method by which the dimensional changes associated with compacting and sintering of metallic powders are compared with those of a reference powder when processed under similar conditions (see Clause 4).
The method applies to the determination of three types of dimensional changes involved with the processing of metallic powders, excluding powders for hardmetals.

ISO 3927:2017 specifies methods for measuring the extent to which a metallic powder is compacted when subjected to uniaxial compressive loading in a confining die under specified conditions.
The method is not applicable to powders for hardmetals.

ISO 4496:2017 specifies methods for determining, in iron, copper, tin and bronze powders, the approximate content of non-metallic materials which are insoluble in the ordinary mineral acids.
The insoluble matter referred to is generally considered to be acid-insoluble silica and silicates, carbides, alumina, clays or other refractory oxides which are either present in the raw material from which the powders are manufactured or introduced during the manufacturing process.

ISO 3928:2016 specifies
-      the die cavity dimensions used for making fatigue test pieces by pressing and sintering, together with certain dimensions of the test piece obtained from such a die, and
-      the dimensions of the test pieces machined from sintered and powder forged materials.
ISO 3928:2016 is applicable to all sintered metals and alloys, excluding hardmetals.

ISO 4499-3:2016 gives guidelines for the measurement of microstructural features in Ti(C,N) based hardmetals and WC/Co hardmetals that contain additional cubic carbides by metallographic techniques only using optical or electron microscopy. It is intended for sintered hardmetals (also called cemented carbides or cermets) containing primarily inorganic carbides and nitrides as the hard phase. It is also intended for measuring the phase size and distribution by the linear intercept technique.

ISO 4499-4:2016 specifies methods for the metallographic determination of the presence, type, and distribution of porosity, uncombined carbon and eta-phase in hardmetals.

ISO 22068:2012 specifies the requirements for the chemical composition and the mechanical and physical properties of sintered metal injection-moulded materials.
It is intended to provide design and materials engineers with necessary information for specifying materials in components manufactured by means of the Metal Injection Moulding (MIM) process only.
It does not apply to structural parts manufactured by other powder metallurgy routes, such as press-and-sinter or powder-forging technologies.

ISO 7265:2012 specifies methods for preparing a sample from one or more sintered parts to be analysed for free or total carbon content. Combined carbon is determined as the difference between total and free carbon. This standard covers the preparation of samples for the determination of carbon by a chemical method, i.e. combustion in oxygen and measurement of the carbon dioxide produced, in accordance with ISO 437. It does not cover the preparation of samples for carbon determination by physical methods, such as metallography or spectroscopy.

ISO 13944:2012 specifies a method for the determination of the lubricant content of a powder mix. The method is also suitable for preparing samples for measuring the content of elements, e.g. graphite and oxygen, the determination of which is interfered with by the presence of a lubricant.
A condition of the application of the method is that a suitable solvent for the lubricant concerned is known and available.

ISO 2739:2012 specifies a method of measuring the radial crushing strength of sintered metal parts in the form of hollow cylinders, commonly known as bushings.
This method is applicable to sintered bushings composed of pure or alloyed metal powders.

ISO 3953:2011 specifies a method for the determination of tap density, i.e. the density of a powder that has been tapped into a container under specified conditions.

ISO 11876:2010 specifies a flame atomic absorption spectrometric method to be used for the determination of the mass fractions of copper, potassium, magnesium, manganese, sodium and zinc in cobalt metal powders in the range of 0,001 % to 0,01 %, calcium in the range of 0,002 % to 0,01 %, and iron and nickel in the range of 0,002 % to 0,05 %.

ISO 4498:2010 specifies methods of hardness testing of sintered metal materials, excluding hardmetals.
Procedure 1 determines the apparent hardness of the whole material.
Procedure 1
applies to sintered metal materials which have either not been subjected to any heat treatment, or which have been heat treated in such a way that the hardness is essentially uniform to a depth of at least 5 mm below the surface,
applies to the surfaces of sintered metal materials which have been treated in such a way that the hardness is not uniform in the section to a depth of 5 mm below the surface,
therefore applies to materials in which the hardness is obtained essentially by surface enrichment by carbon, or by carbon and nitrogen (for example, by carburizing, carbonitriding, nitrocarburizing or sulphidizing), and
applies to materials which have been induction hardened.
Procedure 2 determines the microhardness of the metal phase.
Procedure 2
applies to all types of sintered metal materials,
is used, in particular, to determine the hardness profile of case‑hardened or carbonitrided materials in accordance with the method described in ISO 4507, and
also applies to any sintered metallic materials which have been subjected to surface treatments such as electrodeposited plating, chemical coating, chemical vapour deposition (CVD), physical vapour deposition (PVD), laser, ion bombardment, etc. To determine the microhardness of treated surfaces, Procedure 2 applies.

ISO 3369:2006 specifies a method of determining the density of impermeable sintered metal materials and hardmetals.

Cancels and replaces ISO 3738:1976. Gives principle,symbols, designations and values of parameters, apparatus, test pieces, procedure, expression of results and test report.

ISO 3907:2009 specifies a gravimetric method for the determination of the mass fraction of total carbon in carbides and hardmetals.
This method is applicable to
carbides of chromium, hafnium, molybdenum, niobium, tantalum, titanium, vanadium, tungsten and zirconium,
mixtures of these carbides and binder metals, free of lubricant,
all grade of presintered or sintered hardmetals, produced from these carbides, and
having a mass fraction of total carbon exceeding 4 %.

ISO 3908:2009 specifies a gravimetric method for the determination of the mass fraction of insoluble (free) carbon in carbides and hardmetals.
This method is applicable to
carbides of hafnium, molybdenum, niobium, tantalum, titanium, vanadium, tungsten and zirconium,
mixtures of these carbides and binder metals, free of lubricant, and
all grades of presintered or sintered hardmetals, produced from these carbides,
having a mass fraction of insoluble carbon between 0,02 % and 0,5 %.

ISO 3327:2009 specifies a method for the determination of the transverse rupture strength of hardmetals.
This method is applicable to hardmetals of negligible ductility. If it is used for hardmetals showing significant plastic deformation before breaking, incorrect results may be obtained. In such cases, the method may be used for comparison purposes only.

ISO 3954:2007 specifies procedures for the sampling of powders for powder metallurgical purposes.
lt also covers the splitting of the sample into the quantity required for testing.

Migrated from Progress Sheet (TC Comment) (2000-07-10): Revision in ISO/TC 119 followed by UAP

Migrated from Progress Sheet (TC Comment) (2000-07-10): Revision in ISO/TC 119 followed by UAP

Specifies primary standard test blocks, secondary standard test blocks and working standard test blocks calibrated from master standard test blocks to be used for the verification of Rockwell hardness testing machines and indenters for testing hardmetals. This part of ISO 3738 should be read in conjunction with ISO 3738-1.

Gives a method for the determination of the transverse rupture strength of sintered metals, excluding hardmetals. Particularly suitable for comparing the sintered strength of a batch of metal powder with that of a reference powder or with a reference strength.

The method is applicable to carbide and binder metal powder mixtures, free of lubricant, and all grades of presintered or sintered hardmetals, with a titanium content exceeding 0,2 % (m/m). Specifies principle, interfering elements, reagents, apparatus, sample preparation, procedure, elimination of interferences, preparation of the calibration curve, expression of results and test report.

The method is applicable to carbides and binder metal powder mixtures, free of lubricant, all grades of presintered or sintered hardmetals, having a cobalt content exceeding 1 % (m/m). Gives principle, interfering elements, reagents, apparatus, sampling, procedure, expression of results and test report.

General requirements concerning the field of application, principle, interfering elements,aparatus, sampling and test report are given in ISO 7627-1.