ASTM B331-20 - 1.10.2020
Significance and Use

5.1 The compressibility value obtained by this test is a measure of a material characteristic of the powder.

5.2 The test method is useful in research and development projects, as a quality control test in the evaluation and manufacturing control of metal powder production, and as an acceptance test for shipment of metal powder lots.

5.3 In PM production operations, the test is helpful in determining pressing and tooling requirements for high density parts.

5.4 Results may be affected by test conditions such as the type, amount, and method of lubrication, dwell time during compaction, and die material. The compressibility values may not necessarily agree with results obtained under production conditions.

1. Scope

1.1 This laboratory test method covers the determination of the compressibility of metal powders and metal powder mixtures as measured by the extent to which a test portion can be densified under controlled conditions in a specified die.

1.2 Units—With the exception of the values for density and mass, for which the use of gram per cubic centermetre (g/cm3) and gram (g) units is the longstanding industry practice, the values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

1.3 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.

1.4 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


Practices for Production and Preparation of Powder Metallurgy (PM) Test Specimens


Terminology of Powder Metallurgy


Practices for Sampling Metal Powders


Terminology Relating to Quality and Statistics


Test Methods for Density of Compacted or Sintered Powder Metallurgy (PM) Products Using Archimedes Principle