ASTM B939 - 09

    Standard Test Method for Radial Crushing Strength, K, of Powder Metallurgy (P/M) Bearings and Structural Materials

    Active Standard ASTM B939 | Developed by Subcommittee: B09.04

    Book of Standards Volume: 02.05


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    ASTM B939

    Significance and Use

    The radial crushing strength test is a destructive procedure used to determine a material strength characteristic of PM bearings and hollow cylindrical test specimens. These data can be used to grade, classify, and evaluate the materials.

    The PM bearing Specifications B438 and B439 require the use of this test method as an acceptance test for the strength of oil-impregnated sintered bearings.

    This test method may be used by powder producers and parts manufacturers as a lot acceptance test for metal powders and lubricated powder mixtures intended for the production of porous parts.

    Companies in the PM industry use this test as a manufacturing control test because it is appropriate for production practices.

    Radial crushing strength is a property of the PM material but is not a design value. However, experience has shown that the radial crushing strength of a material is approximately twice the ultimate tensile strength.

    1. Scope

    1.1 This test method covers the equipment and laboratory procedure for the determination of the radial crushing strength of materials using either a plain powder metallurgy (PM) bearing or a thin-walled hollow cylindrical test specimen. This is a destructive test that produces quantitative results.

    1.2 Limitations:

    1.2.1 The principle of this procedure is based on the material being tested having minimal ductility. The permanent deflection of the cylinder during the test should not exceed 10 % of the outside diameter.

    1.2.2 The radial crushing strength test results should be used only as a guide if the test specimen has a wall thickness that is greater than one-third of the outside diameter. These test results should then only be used for comparison with data from the test specimens of like materials and similar dimensions.

    1.3 With the exception of density values, for which the g/cm3 unit is the industry standard, the values stated in inch-pound units are to be considered the standard. The values in SI units, shown in parenthesis have been converted in accordance with IEEE/ASTM Standard SI 10, may be approximate and are only included for information.

    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 and health practices and determine the applicability of regulatory limitations prior to use.


    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    MPIF Standard

    MPIFStandard55 Determination of Radial Crush Strength (K) of Powder Metallurgy (PM) Test Specimens

    ASTM Standards

    B243 Terminology of Powder Metallurgy

    B438 Specification for Bronze-Base Powder Metallurgy (PM) Bearings (Oil-Impregnated)

    B439 Specification for Iron-Base Powder Metallurgy (PM) Bearings (Oil-Impregnated)

    B925 Practices for Production and Preparation of Powder Metallurgy (PM) Test Specimens

    E456 Terminology Relating to Quality and Statistics

    E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

    IEEE/ASTM Standard

    SI10 American National Standard for Use of the International System of Units (SI): The Modern Metric System


    ICS Code

    ICS Number Code 77.160 (Powder metallurgy)

    UNSPSC Code

    UNSPSC Code


    DOI: 10.1520/B0939-09

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