ASTM B312-09

5.1 The green strength value determined under the conditions specified by this test method is influenced by the characteristics of the powder, how it compacts under the specified conditions (i.e., the particle to particle bonding that exists following compacting), and the lubrication system used.

5.2 Knowledge of the green strength value is useful to the production, characterization and utilization of metal powders in the manufacture of PM structural parts and bearings.

The test for green strength of a compacted metal powder can be used to:

Relate the resistance of a pressed compact to breakage or damage due to handling.

Compare the quality of a metal powder or powder mixture from lot to lot.

Determine the effect of the addition of a lubricant or other powders to a base powder.

Evaluate powder mixing or blending variables.

   Factors that are known to influence the green strength of a metal powder are particle shape, particle size distribution and compressibility of the metal powder.

5.5 The amount and type of lubricant or other additives and the mixing procedures have a strong effect on the green strength of specimens produced from metal powder mixtures.

1.1 This standard covers a test method that may be used to measure the transverse rupture strength of a compacted but unsintered (green) test specimen produced from lubricated or unlubricated metal powders or powder mixtures.

1.2 Green strength is measured by a quantitative laboratory procedure in which the fracture strength is calculated from the force required to break an unsintered test specimen supported as a simple beam while subjected to a uniformly increasing three-point transverse load under controlled conditions.

1.3 This test method is a companion standard to Test Method B 528 that covers the measurement of the transverse rupture strength of sintered PM test specimens.

1.4 With the exception of density values, for which the g/cm³ unit is the industry standard, and mass measurements used to calculate density, the values stated in inch-pound units are to be regarded as the standard. The SI equivalents shown in parentheses have been converted in accordance with IEEE/ASTM Standard SI 10, may be approximate and are only included for information.

1.5 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. ^REFERENCE:

ASTM Standards:

B 215 Practices for Sampling Metal Powders

B 243 Terminology of Powder Metallurgy

B 528 Test Method for Transverse Rupture Strength of Metal Powder Specimens

B 925 Practices for Production and Preparation of Powder Metallurgy (PM) Test Specimens

B 962 Test Methods for Density of Compacted or Sintered Powder Metallurgy (PM) Products Using Archimedes’ Principle

E 691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

SI 10 American National Standard for Use of the International System of Units (SI): The Modern Metric System