ASTM B311-22 PDF

Overview

ASTM B311-22: Standard Test Method for Density of Powder Metallurgy (PM) Materials Containing Less Than Two Percent Porosity provides a reliable procedure for measuring the density of PM materials and cemented carbides with very low porosity. This test method is based on the water displacement technique, utilizing Archimedes’ principle to calculate density with high precision. Accurate density measurement is essential for quality assurance, research, and production in powder metallurgy and hard metal applications.

ASTM B311-22 is recognized internationally and developed in alignment with globally accepted standardization principles. The standard is widely used in industries involved with metal powders, cemented carbides, and metal injection molded (MIM) parts.

Key Topics

• Applicability: Intended for PM materials with less than 2% porosity and cemented carbides. Density measurement helps assess the degree of densification required for an application.
• Methodology: Utilizes water displacement, with an analytical balance for weighing the specimen in air and water. Special preparation and cleaning of test specimens are necessary for accuracy.
• Precision and Limits: The method cannot be used for samples with significant surface-connected porosity, as water absorption can cause incorrect results. For affected samples, an alternative method such as ASTM B962 is recommended.
• Cemented Carbides: Density measurement is particularly useful to monitor compositional deviations in cemented carbides, such as tungsten carbide-cobalt grades. However, density alone cannot confirm correct composition for complex grades.
• Units: Density is typically reported in grams per cubic centimeter (g/cm³), following industry standards.
• Quality Assurance: The procedure includes recommendations for calibration and repeatability within and between laboratories, ensuring reliable and reproducible results.

Applications

ASTM B311-22 is vital across sectors that produce or utilize powder metallurgy components, including but not limited to:

• Quality Control: Ensures PM parts, cemented carbides, and MIM components meet densification criteria and specification requirements.
• Material Characterization: Helps determine if manufacturing and processing steps achieve the targeted densification, directly influencing part performance and service life.
• Compliance and Certification: Used by manufacturers and testing laboratories for product certification and regulatory compliance in global markets.
• Component Evaluation: Useful in the automotive, aerospace, tooling, and industrial machinery sectors where high-density PM parts are critical for strength, durability, and wear resistance.

Related Standards

To ensure comprehensive and accurate evaluation of powder metallurgy materials and products, the following related standards are often referenced alongside ASTM B311-22:

• ASTM B243: Terminology of Powder Metallurgy
• ASTM B962: Test Methods for Density of Compacted or Sintered Powder Metallurgy (PM) Products Using Archimedes’ Principle - for materials with higher porosity or surface-connected pores.
• ASTM E456: Terminology Relating to Quality and Statistics
• ASTM E691: Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

Conclusion

ASTM B311-22 offers a rigorous and accurate method for determining the density of low-porosity powder metallurgy materials and cemented carbides. Its use of water displacement under precisely controlled conditions supports quality assurance in manufacturing and research. The standard plays a critical role in ensuring the integrity and reliability of high-performance PM parts and hard metals in demanding industrial applications. For materials with greater porosity or surface absorption, ASTM B962 provides an appropriate alternative test method.