February 2000

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Tech News

Revision of Brinell Hardness Standard to Require Use of Tungsten-Carbide Ball Indenters

A REVISION to ASTM E 10, Standard Test Method for Brinell Hardness of Metallic Materials, that will require the use of tungsten-carbide ball indenters for all Brinell hardness testing has been initiated by E28.06 on Indentation Hardness Testing, a subcommittee within ASTM Committee E28 on Mechanical Testing. The current version of E 10 requires tungsten-carbide balls only when testing materials having a hardness of HBW 450 and harder. Steel ball indenters are allowed for all softer materials. This change is expected to improve the accuracy of Brinell testing by reducing measurement error due to flattened steel balls, and should significantly increase the usable life of the indenter. In addition, the change will align ASTM E 10 with the ISO standard 6506, Metallic Material—Brinell Hardness Test.

Once approved, only tungsten-carbide ball indenters and test blocks calibrated with tungsten-carbide ball indenters will be allowed. Because of the difference in the elastic properties of steel and tungsten carbide, the Brinell hardness between HBW 300 and HBW 450 will change slightly if steel ball indenters have been used previously. The change will be greater as the hardness increases; however the shift is considered to be negligible.

For technical information, contact Robert A. Ellis, David L. Ellis Co., Inc., 310 Old High St., P.O. Box 592, Acton, MA 01720 (978/897-1795; fax: 978/ 897-0844). For Committee E28 membership or meeting information, contact Daniel Schultz, ASTM (610/832-9716; fax: 610/832-9666).