ASTM B923-21

Standard Test Method for Metal Powder Skeletal Density by Helium or Nitrogen Pycnometry

SIGNIFICANCE AND USE
5.1 Both suppliers and users of metals can benefit from knowledge of the skeletal density of these materials. Results of many intermediate and final processing steps are controlled by or related to skeletal density of the metal. In addition, the performance of many sintered or cast metal structures may be predicted from the skeletal density of the starting metal powder, for all or a portion of the finished piece.
SCOPE
1.1 This test method covers determination of skeletal density of metal powders. The test method specifies general procedures that are applicable to many commercial pycnometry instruments. The method provides specific sample outgassing procedures for listed materials. It includes additional general outgassing instructions for other metals. The ideal gas law forms the basis for all calculations.  
1.2 This test method does not include all existing procedures appropriate for outgassing metal materials. The included procedures provided acceptable results for samples analyzed during an interlaboratory study. The investigator shall determine the appropriateness of listed procedures.  
1.3 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3.1 State all numerical values in terms of SI units, unless specific instrumentation software reports volume or density, or both, using alternative units. In this case, present both reported and equivalent SI units in the final written report. Many instruments report skeletal density as g/cm3 instead of using correct SI units (kg/m3).  
1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Historical
• Publication Date: 31-May-2021
• ICS: 77.160 - Powder metallurgy
• Technical Committee: B09 - Metal Powders and Metal Powder Products
• Drafting Committee: B09.03 - Refractory Metal Powders

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: B923 − 21
Standard Test Method for
Metal Powder Skeletal Density by Helium or Nitrogen
1
Pycnometry
This standard is issued under the fixed designation B923; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 2. Referenced Documents
2
2.1 ASTM Standards:
1.1 This test method covers determination of skeletal den-
B215 Practices for Sampling Metal Powders
sity of metal powders. The test method specifies general
B243 Terminology of Powder Metallurgy
procedures that are applicable to many commercial pycnom-
E177 Practice for Use of the Terms Precision and Bias in
etry instruments. The method provides specific sample outgas-
ASTM Test Methods
sing procedures for listed materials. It includes additional
E691 Practice for Conducting an Interlaboratory Study to
general outgassing instructions for other metals. The ideal gas
Determine the Precision of a Test Method
law forms the basis for all calculations.
1.2 This test method does not include all existing proce-
3. Terminology
dures appropriate for outgassing metal materials. The included
3.1 Definitions:
procedures provided acceptable results for samples analyzed
3.1.1 Refer to Terminology B243 for additional definitions
during an interlaboratory study. The investigator shall deter-
relating to metal powders.
mine the appropriateness of listed procedures.
3.2 Definitions of Terms Specific to This Standard:
1.3 Units—The values stated in SI units are to be regarded 3.2.1 density, n—the mass per unit volume of a material.
as standard. No other units of measurement are included in this
3.2.2 density, skeletal, n—the ratio of mass of discrete
standard.
pieces of solid material to the sum of the volumes of the solid
1.3.1 State all numerical values in terms of SI units, unless
material in the pieces and closed pores within the pieces.
specific instrumentation software reports volume or density, or
3.2.3 outgassing, n—the evolution of gas from a material in
both, using alternative units. In this case, present both reported
a vacuum or inert gas flow, at or above ambient temperature.
and equivalent SI units in the final written report. Many
3 3.2.4 skeletal volume, n—the sum of the volumes of the
instruments report skeletal density as g/cm instead of using
solid material in the pieces and closed pores within the pieces.
3
correct SI units (kg/m ).
1.4 This standard does not purport to address all of the
4. Summary of Test Method
safety concerns, if any, associated with its use. It is the
4.1 An appropriately sized sample (to provide at least the
responsibility of the user of this standard to establish appro-
minimum skeletal volume required for reliable results for the
priate safety, health, and environmental practices and deter-
instrument or apparatus used) is outgassed under appropriate
mine the applicability of regulatory limitations prior to use.
conditions prior to analysis.
1.5 This international standard was developed in accor-
4.2 The sample is weighed to nearest 0.0001 g. It is impor-
dance with internationally recognized principles on standard-
tant to use an analytical balance to determine the sample mass.
ization established in the Decision on Principles for the
The pycnometer measures the total displaced skeletal volume
Development of International Standards, Guides and Recom-
of the sample under analysis. The sample mass is then used to
mendations issued by the World Trade Organization Technical
calculate the skeletal density of the metal. Any error in the
Barriers to Trade (TBT) Committee.
sample mass will affect the calculated density. Some cleaning
of the sample surface may take place inside the pycnometer.
1
This test method is under the jurisdiction of ASTM Committee B09 on Metal
Powders and Metal Powder Products and is the direct responsibility of Subcom-
2
mittee B09.03 on Refractory Metal Powders. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved June 1, 2021. Published June 2021. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2002. Last previous edition approved in 2020 as B923 – 20. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/B0923-21. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
B923 − 21
Therefore, it is best to reweigh the sample after analysis and 7. Apparatus
use the
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: B923 − 20 B923 − 21
Standard Test Method for
Metal Powder Skeletal Density by Helium or Nitrogen
1
Pycnometry
This standard is issued under the fixed designation B923; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method covers determination of skeletal density of metal powders. The test method specifies general procedures that
are applicable to many commercial pycnometry instruments. The method provides specific sample outgassing procedures for listed
materials. It includes additional general outgassing instructions for other metals. The ideal gas law forms the basis for all
calculations.
1.2 This test method does not include all existing procedures appropriate for outgassing metal materials. The included procedures
provided acceptable results for samples analyzed during an interlaboratory study. The investigator shall determine the
appropriateness of listed procedures.
1.3 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
1.3.1 State all numerical values in terms of SI units, unless specific instrumentation software reports volume or density, or both,
using alternative units. In this case, present both reported and equivalent SI units in the final written report. Many instruments
3 3
report skeletal density as g/cm instead of using correct SI units (kg/m ).
1.4 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2
2.1 ASTM Standards:
B215 Practices for Sampling Metal Powders
B243 Terminology of Powder Metallurgy
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
1
This test method is under the jurisdiction of ASTM Committee B09 on Metal Powders and Metal Powder Products and is the direct responsibility of Subcommittee B09.03
on Refractory Metal Powders.
Current edition approved May 1, 2020June 1, 2021. Published May 2020June 2021. Originally approved in 2002. Last previous edition approved in 20162020 as
B923 – 16.B923 – 20. DOI: 10.1520/B0923-20.10.1520/B0923-21.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
B923 − 21
3. Terminology
3.1 Definitions:
3.1.1 Refer to Terminology B243 for additional definitions relating to metal powders.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 density, n—the mass per unit volume of a material.
3.2.2 density, skeletal, n—the ratio of mass of discrete pieces of solid material to the sum of the volumes of the solid material in
the pieces and closed pores within the pieces.
3.2.3 outgassing, n—the evolution of gas from a material in a vacuum or inert gas flow, at or above ambient temperature.
3.2.4 skeletal volume, n—the sum of the volumes of the solid material in the pieces and closed pores within the pieces.
4. Summary of Test Method
4.1 An appropriately sized sample (to provide at least the minimum skeletal volume required for reliable results for the instrument
or apparatus used) is outgassed under appropriate conditions prior to analysis.
4.2 The sample is weighed to nearest 0.1 mg. 0.0001 g. It is important to use an analytical balance to determine the sample mass.
The pycnometer measures the total displaced skeletal volume of the
...