Hardness is not a physical property of a material but a characteristic, one that can be measured through a variety of methods. The Brinell hardness test identifies the indentation hardness of a desired material. Guidelines for Brinell testing machines and the procedures for performing Brinell hardness tests are standardized through ASTM E10-23: Standard Test Method for Brinell Hardness of Metallic Materials.
What Is a Brinell Hardness Test?
As defined in ASTM E10-23, a Brinell hardness test is:
“an indentation hardness test using a verified machine to force an indenter (tungsten carbide ball with diameter D), under specified conditions, into the surface of the material under test.”
Following this initial step, the diameter of the resulting indentation D from the force is measured in at least two directions perpendicular to each other. The mean of these measurements is the Brinell hardness value. This differs from alternative indentation hardness testing methods such as the Vickers, Rockwell, and Knoop tests, as well as those practiced for assessing scratch and rebound hardness types.
Since this procedure involves the tested material undergoing a fixed force, it can be stated that the shallower the indentation, the harder the material is. For a general demonstration of the Brinell hardness test, please refer to the video below:
The adoption of Brinell hardness tests are useful for several reasons. With metallic materials, a measurement of the indentation hardness can shed insight on the materials’ tensile strength, wear resistance, and ductility, as these may correlate with the measured characteristic. In addition, Brinell hardness tests have a particular recognition in industry, as they are considered satisfactory for acceptance testing of commercial shipments. They have been used in industry extensively for this purpose.
What Is ASTM E10?
As for the ASTM E10-23 standard, there is a heavy focus on the background of and actions taken throughout the Brinell hardness test procedure. This includes requirements and thorough detail on measuring the indentation, verifying the testing machines, converting to other hardness values, and preparing a test report.
Explanatory information on verification, Brinell hardness standardization machines, standardization of indenters, and standardization of test blocks can be found in the annexes of ASTM E10-23. Two nonmandatory appendices deal with a table of Brinell hardness numbers and examples of procedures for determining uncertainty.
What Are the Changes to ASTM E10-23?
ASTM E10-23 revises the 2018 edition of the same standard. Notably it underwent the following changes:
- References were updated.
- Fahrenheit equivalents were added for the ambient temperature limits of Brinell hardness tests.
- New section 9.3, “Reporting Converted Hardness Values,” was added.
ASTM E10-23: Standard Test Method for Brinell Hardness of Metallic Materials is available on the ANSI Webstore.