ASTM B925-03
(Practice)Standard Practices for Production and Preparation of Powder Metallurgy (P/M) Test Specimens
Standard Practices for Production and Preparation of Powder Metallurgy (P/M) Test Specimens
SIGNIFICANCE AND USE
Test specimens are used to determine the engineering properties of P/M materials, for example, tensile strength, ductility, impact energy, etc.; property data that are essential to the successful use of P/M material standards. Processing P/M test specimens under production conditions is the most efficient method by which to obtain reliable P/M material property data since in most cases it is impractical or impossible to cut test bars from sintered parts.
The performance characteristics of metal powders, for example, compressibility, green strength and dimensional changes associated with processing are evaluated using P/M test specimens under controlled conditions. The data obtained are important to both metal powder producers and P/M parts manufacturers.
P/M test specimens play a significant role in industrial quality assurance programs. They are used to compare properties of a new lot of metal powder with an established lot in an acceptance test and are used in the part manufacturing process to establish and adjust production variables.
In those instances where it is required to present equivalent property data for a production lot of P/M parts, standard test specimens compacted from the production powder mix to the same green density can be processed with the production P/M parts and then tested to obtain this information.
Material property testing performed for industrial or academic research and development projects uses standard P/M test specimens so the test results obtained can be compared with previous work or published data.
Powder metallurgy test specimens may have multiple uses. The dimensions and tolerances given in this standard are nominal in many cases. The user is cautioned to make certain that the dimensions of the test specimen are in agreement with the requirements of the specific test method to be used.
SCOPE
1.1 These standard practices cover the specifications for those uniaxially compacted test specimens that are used in ASTM standards, the procedures for producing and preparing these test specimens, and reference the applicable standards.
1.2 Basic tool design and engineering information regarding the tooling that is required to compact the test specimens and machining blanks are contained in the annexes.
1.3 This standard is intended to be a comprehensive one-source document that can be referenced by ASTM test methods that utilize P/M test specimens and in ASTM P/M material specifications that contain the engineering data obtained from these test specimens.
1.4 These practices are not applicable to metal powder test specimens that are produced by other processes such as cold isostatic pressing (CIP), hot isostatic pressing (HIP), powder forging (P/F) or metal injection molding (MIM). They do not pertain to cemented carbide materials.
1.5 Detailed information on P/M presses, compacting tooling and sintering furnaces, their design, manufacture and use are not within the scope of these practices.
1.6 Test specimen and die cavity dimensions shown in inch-pound units are to be regarded as standard and are applicable to the referenced ASTM test methods and material specifications. Values in SI units are shown in parentheses and result from conversion in accordance with IEEE/ASTM Standard SI-10. They may be approximate and are only for information.
1.7 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:B925–03
Standard Practices for
Production and Preparation of Powder Metallurgy (P/M) Test
Specimens
This standard is issued under the fixed designation B 925; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope A 34/A 34M Practice for Sampling and Procurement Test-
ing of Magnetic Materials
1.1 These standard practices cover the specifications for
A 341/A 341M Test Method for Direct-Current Magnetic
those uniaxially compacted test specimens that are used in
Properties of Materials Using D-C Permeameters and the
ASTM standards, the procedures for producing and preparing
Ballistic Test Methods
these test specimens, and reference the applicable standards.
A 596/A 596M Test Method for Direct-Current Magnetic
1.2 Basictooldesignandengineeringinformationregarding
Properties of Materials Using the Ballistic Method and
the tooling that is required to compact the test specimens and
Ring Specimens
machining blanks are contained in the annexes.
A 773/A 773M Test Method for dc Magnetic Properties of
1.3 This standard is intended to be a comprehensive one-
Materials Using Ring and Permeameter Procedures with
sourcedocumentthatcanbereferencedbyASTMtestmethods
Electronic Hysteresigraphs
that utilize P/M test specimens and in ASTM P/M material
A 811 Specification for Soft Magnetic Iron Parts Fabricated
specifications that contain the engineering data obtained from
by Powder Metallurgy (P/M) Techniques
these test specimens.
A 839/A 839M Specification for Iron Phosphorus Powder
1.4 These practices are not applicable to metal powder test
Metallurgy (P/M) Parts for Soft Magnetic Applications
specimens that are produced by other processes such as cold
A 904 Specification for 50 Nickel-50 Iron Powder Metal-
isostatic pressing (CIP), hot isostatic pressing (HIP), powder
lurgy (P/M) Soft Magnetic Alloys
forging (P/F) or metal injection molding (MIM). They do not
A 927/A 927M Test Method for Alternating-Current Mag-
pertain to cemented carbide materials.
netic Properties of Torroidal Core Specimens Using the
1.5 Detailed information on P/M presses, compacting tool-
Voltmeter-Ammeter-Wattmeter Method
ing and sintering furnaces, their design, manufacture and use
B 215 Practices for Sampling Finished Lots of Metal Pow-
are not within the scope of these practices.
der
1.6 Test specimen and die cavity dimensions shown in
B 243 Terminology of Powder Metallurgy
inch-pound units are to be regarded as standard and are
B 312 Test Method for Green Strength for Compacted
applicable to the referenced ASTM test methods and material
Metal Powder Specimens
specifications. Values in SI units are shown in parentheses and
B 328 Test Method for Density, Oil Content, and Intercon-
result from conversion in accordance with IEEE/ASTM Stan-
nected Porosity of Sintered Metal Structural Parts and
dard SI-10. They may be approximate and are only for
Oil-Impregnated Bearings
information.
B 331 TestMethodforCompressibilityofMetalPowdersin
1.7 This standard may involve hazardous materials, opera-
Uniaxial Compaction
tions, and equipment. This standard does not purport to
B 438/B 438M Specification for Sintered Bronze Bearings
address all of the safety concerns, if any, associated with its
(Oil-Impregnated)
use. It is the responsibility of the user of this standard to
B 439 Specification for Iron-Base Sintered Bearings (Oil-
establish appropriate safety and health practices and deter-
Impregnated)
mine the applicability of regulatory limitations prior to use.
B 528 Test Method for Transverse Rupture Strength of
2. Referenced Documents
Metal Powder Specimens
B 595 Specification for Sintered Aluminum Structural
2.1 ASTM Standards:
Parts
B 610 Test Method for Measuring Dimensional Changes of
This practice is under the jurisdiction of ASTM Committee B09 on Metal
Powders and Metal Powder Products and is the direct responsibility of Subcom-
mittee B09.02 on Base Metal Powders. Annual Book of ASTM Standards, Vol 03.04.
Current edition approved April 10, 2003. Published June 2003. Annual Book of ASTM Standards, Vol 02.05.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
B925–03
Metal Powder Specimens 5.2 The performance characteristics of metal powders, for
B 612 Specification for Iron Bronze Sintered Bearings (Oil- example, compressibility, green strength and dimensional
Impregnated) changes associated with processing are evaluated using P/M
B 715 Specification for Sintered Copper Structural Parts for test specimens under controlled conditions. The data obtained
Electrical Conductivity Applications are important to both metal powder producers and P/M parts
B 782 Specification for Iron Graphite Sintered Bearings manufacturers.
(Oil-Impregnated) 5.3 P/M test specimens play a significant role in industrial
B 783 Specification for Materials for Ferrous Powder Met- quality assurance programs. They are used to compare prop-
allurgy (P/M) Structural Parts erties of a new lot of metal powder with an established lot in
B 817 Specification for Powder Metallurgy (P/M) Titanium an acceptance test and are used in the part manufacturing
Alloy Structural Components process to establish and adjust production variables.
B 823 Specification for Materials for Nonferrous Powder 5.4 In those instances where it is required to present
Metallurgy (P/M) Structural Parts equivalent property data for a production lot of P/M parts,
B 853 Specification for Powder Metallurgy (P/M) Boron standard test specimens compacted from the production pow-
Stainless Steel Structural Components der mix to the same green density can be processed with the
E 8 Test Methods forTensionTesting of Metallic Materials productionP/Mpartsandthentestedtoobtainthisinformation.
E 9 Test Methods of Compression Testing of Metallic Ma- 5.5 Material property testing performed for industrial or
terials at Room Temperature academic research and development projects uses standard
E 18 Test Methods for Rockwell Hardness and Rockwell P/M test specimens so the test results obtained can be com-
Superficial Hardness of Metallic Materials pared with previous work or published data.
E 23 Test Methods for Notched Bar Impact Testing of 5.6 Powder metallurgy test specimens may have multiple
Metallic Materials uses. The dimensions and tolerances given in this standard are
E 228 Test Method for Linear Thermal Expansion of Solid nominal in many cases. The user is cautioned to make certain
Materials with a Vitreous Silica Dilatometer that the dimensions of the test specimen are in agreement with
E 1876 Test Method for Dynamic Young’s Modulus, Shear the requirements of the specific test method to be used.
Modulus and Poisson’s Ratio by Impulse Excitation of
6. Powder Metallurgy Test Specimens
Vibration
2.2 IEEE/ASTM Standard:
POWDER COMPRESSIBILITY TESTING
SI-10 Standard for Use of the International System of Units
(SI): The Modern Metric System 6.1 Cylindrical Powder Compressibility Test Specimen:
2.3 MPIF Standard: 6.1.1 Description and Use—This solid cylindrical test
Standard 56 Method for Determination of Rotating Beam specimen, see Fig. 1, is produced by compacting a test portion
FatigueEnduranceLimitinPowderMetallurgyMaterials of powder mix in laboratory powder metallurgy tooling similar
to that shown in Fig. A1.1 in the Annex. An alternative test
3. Terminology
specimen for measuring powder compressibility is the trans-
3.1 Definitions—Definitions of powder metallurgy terms verse rupture test specimen. These test specimens are not
can be found in Terminology B 243. Additional descriptive
information is available in the Related Materials section of Vol
02.05 of the Annual Book of ASTM Standards.
4. Summary of Practice
4.1 Thesepracticesdescribetheproduction,bypressingand
sintering metal powders, and the preparation, by machining
sinteredblanks,oftestspecimensusedtomeasurepropertiesof
metal powders and sintered materials.
5. Significance and Use
5.1 Test specimens are used to determine the engineering
properties of P/M materials, for example, tensile strength,
ductility, impact energy, etc.; property data that are essential to
the successful use of P/M material standards. Processing P/M
testspecimensunderproductionconditionsisthemostefficient
method by which to obtain reliable P/M material property data
since in most cases it is impractical or impossible to cut test
bars from sintered parts.
Dimensions
in. mm
D—Diameter 1.00 25.4
T—Compact thickness 0.280 6 0.010 7.11 6 0.25
Annual Book of ASTM Standards, Vol 03.01.
Available from MPIF, 105 College Road East, Princeton, NJ 08540. FIG. 1 P/M Cylindrical Powder Compressibility Test Specimen
B925–03
sintered. The compressibility of the metal powder mix or a 6.2.2.2 See the following P/M Material Specifications:
compressibility curve showing the green density as a function A 811, A 839/A 839M, A 904, B 783, and B 823.
of compacting pressure is determined according to the proce-
RADIAL CRUSHING TESTING
dures in Test Method B 331.
6.3 Radial Crushing Strength Test Specimen:
6.1.2 Applicable ASTM Standards:
6.3.1 Description and Use—The radial crushing strength
6.1.2.1 See Test Method B 331.
test specimen shown in Fig. 3 is compacted to size in tooling
(Fig.A2.3) suitable for the production of a thin-walled hollow
TRANSVERSE RUPTURE, DIMENSIONAL CHANGE
cylinder within the range of the dimensions listed. The testing
AND GREEN STRENGTH TESTING
procedure involves the application of a compressive force
6.2 Transverse Rupture Strength Test Specimen:
perpendicular to the central axis of the test cylinder and
6.2.1 Description and Use—The pressed-to-size transverse
calculating the radial crushing strength from the breaking load
rupture test specimen, Fig. 2, is produced by compacting metal
and test specimen dimensions. Radial crushing strength is the
powder in tooling similar to that shown in Fig A1.2.
material property that is used to quantify the mechanical
6.2.1.1 This rectangular test specimen has multiple uses in
strength of sintered metal bearings, (oil impregnated).
P/M. Primarily, it is designed to determine the transverse
6.3.1.1 Thistestspecimeniswidelyusedinaqualitycontrol
rupture strength of sintered or heat treated compacts by
test to determine the sintered material strength of powder
breaking the test specimen as a simple beam in three-point
mixes that are to be used for the production of any metal
loading following Test Method B 528. But, it is also used to
powder product because it is a quick, easy test and gives
measure the dimensional changes of metal powder mixes due
reliable and reproducible results. Laboratories testing powder
to pressing and sintering or other processing steps according to
mixes intended for the manufacture of porous bearings have
Test Method B 610, and it is used in both a 0.250 and 0.500 in.
recognized that breaking an unsintered test specimen by
(6.35 and 12.70 mm) thick version to determine green strength
diametrical loading will give a green strength value that is
using the procedure in Test Method B 312.
relevant in production.
6.2.1.2 It is an acceptable alternative test specimen to the
6.3.2 Applicable ASTM Standards:
cylindrical compact to determine powder compressibility ac-
6.3.2.1 See the following P/M Bearing Specifications:
cording to Test Method B 331. The sintered or heat treated
B 438/B 438M, B 439, B 612, and B 782.
specimen may be used to generate data for the elastic con-
stants. Young’s Modulus is determined by impulse excitation
of vibration and Poisson’s ratio may then be calculated. This
test specimen is also a convenient compact on which to
measure macroindentation hardness after various processing
steps.
6.2.2 Applicable ASTM Standards:
6.2.2.1 See the following Test Methods: B 312, B 331,
B 528, B 610, E 18, and E 1876.
Dimensions
in. mm
W—Width 0.50 12.7 Dimensions
L—Length 1.25 31.8 in. mm
R—Corner radius 0.01 0.3 D—Outside diameter 0.80 to 2.00 20 to 51
T—Thickness (thin) 0.250 6 0.005 6.35 6 0.13 d—Inside diameter 0.50 to 1.00 13 to 25
T—Thickness (thick) 0.500 6 0.005 12.70 6 0.13 T—Thickness 0.25 to 1.00 6 to 25
NOTE—Thickness shall be parallel within 0.005 in. (0.13 mm). NOTE—Wall thickness (D-d) shall be less than D/3.
FIG. 2 P/M Transverse Rupture Strength Test Specimen FIG. 3 P/M Radial Crushing Strength Test Specimen
B925–03
TENSION TESTING
6.4 Flat Unmachined Tension Test Specimen:
6.4.1 Description and Use—The unmachined flat tension
test specimen shown in Fig. 4 is commonly referred to in the
industry as “the dogbone.” It is compacted directly to size and
shape using tooling similar to that shown in Fig. A2.4 in the
Annex. This test specimen has been designed to have a
2 2
convenient 1.00 in. (645.2 mm ) pressing area to simplify
compacting calculations.
6.4.1.1 It is intended for determining the tensile properties
Dimensions
and ductility of P/M materials that have not been heat treated
in. mm
(not quenched and tempered nor sinter-hardened). The testing
procedures for this unmachined P/M test specimen can be G—Gage length 1.000 6 0.003 25.40 6 0.08
D—Diameter at center of gage section 0.187 6 0.001 4.75 6 0.03
found in Test Method E 8.
H—Diameter at ends of gage section 0.191 6 0.001 4.85 6 0.03
6.4.1.2 The flat tension test specimen is not normally used
R—Radius of gage fillet 0.25 6.4
with heat treated P/M materials because it may produce
A—Length of reduced section 1.875 6 0.003 47.63 6 0.08
J—Radius of shoulder fillet 0.05 1.3
unreliable test results and it has a tendency to slip in the grips.
L—Compact length 3 nominal 75 nominal
Slippagecanbepreventedbytheuseofhydraulicgrips,butthe
B—Length of end section 0.310 6 0.005 7.87 6 0.13
square corner design of the flat specimen will give rise to stress W—Compact thickness 0.394 6 0.005 10.00 6 0.13
C—Compact width 0.39 10.0
concentrations that may result in scattered test values. The
E—Length of shoulder 0.250 6 0.005 6.35 6 0.13
machined 190-Round tension test specimen, Fig. 5, is recom-
F—Diameter of shoulder 0.310 6 0.001 7.87 6 0.03
mended for use with heat treated P/M materials.
6.4.2 Applicable ASTM Standards: NOTE 1—Specimen diameters, 0.191 and 0.187 in. (4.85 and 4.75 mm),
to be concentric within 0.001 in. (0.03 mm) T.I.R.
6.4.2.1 See Test Methods E 8.
NOTE 2—Test section shall be free of nicks, scratches, and toolmarks.
6.4.2.2 See the following P/M Mat
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