Completing a hardness test is a critical step in qualifying metal parts; these tests determine the various properties of a specific metal, such as resistance to wear, toughness, and formability.
Different test scales were created to assist engineers in selecting the appropriate metals and hardness for their specific application.
To help you understand the different test scales we’ve created a cross-reference table for three of the most popular hardness tests below.
Brinell Hardness Test
The first widely used standardized hardness test, the Brinell method determines the indentation hardness of metal materials and is typically used for materials with a coarse surface or a surface too rough to be tested through other methods.
The Brinell test is not useful for fully hardened steel or other hard materials, however, and often leaves a large impression on the metal. The Brinell test is also very slow.
Rockwell Hardness Test
Developed to provide a less destructive alternative to the Brinell test, this differential-depth method eliminates the errors associated with mechanical imperfections.
Quicker and cheaper than the Brinell and Vickers tests, the Rockwell test requires no material prep, and hardness value is easily readable without any extra equipment, making this one of the most commonly used methods of measuring metal hardness.
Vickers Hardness Test
Making use of a diamond indenter, the Vickers hardness test is done with less force and more accuracy than the Brinell test. By magnifying the surface of a metal, this test can target specific microstructural constituents like martensite or bainite, or assess the quality of heat treating or surface hardening operations.
Requiring an optical system and material prep, the Vickers test incurs higher costs and takes longer to complete than the Rockwell test.
Selecting the Right Hardness Test for Your Application
To assist you in understanding the most popular test scales, ESI has created a free Hardness Conversion Table, with approximate tensile strength in PSI and MPa as well as groupings of approximate fastener property classes compiled in one easy-to-read guide.