Step 1: Understanding the Concept:
Hardness tests usually involve pressing a standardized "indenter" into a material with a specific force and measuring the resulting mark.
Step 2: Key Formula or Approach:
* Brinell: Hardened steel ball indenter.
* Rockwell: Depth of penetration (cone or ball).
* Vickers: Diamond pyramid indenter.
* Mohs: Scratching.
Step 3: Detailed Explanation:
In the Brinell test, a hardened steel (or tungsten carbide) ball of a specified diameter is pressed into the surface of the metal under a fixed load. After the load is removed, the diameter (size) of the resulting circular indentation is measured. The Brinell Hardness Number (BHN) is then calculated as the load divided by the surface area of the indentation.
Step 4: Final Answer:
The Brinell hardness test measures hardness by the size of the indentation made by a steel ball.