ASTM B925-08

Test specimens are used to determine the engineering properties of PM materials, for example, tensile strength, ductility, impact energy, etc.; property data that are essential to the successful use of PM material standards. Processing PM test specimens under production conditions is the most efficient method by which to obtain reliable PM 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 PM test specimens under controlled conditions. The data obtained are important to both metal powder producers and PM parts manufacturers.

PM 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 PM parts, standard test specimens compacted from the production powder mix to the same green density can be processed with the production PM parts and then tested to obtain this information.

Material property testing performed for industrial or academic research and development projects uses standard PM 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.

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 PM test specimens and in ASTM PM 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 (PF) or metal injection molding (MIM). They do not pertain to cemented carbide materials.

1.5 Detailed information on PM 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.