Question

The Brinell hardness test measures hardness by:

• A. Depth of penetration of a cone
• B. Size of indentation made by a steel ball
• C. Scratch resistance
• D. Rebound height of a hammer

Hint:

Logic Tip: Brinell = Big Ball (measures width). Rockwell = Rock-hard Diamond Cone (measures depth). Vickers = Pyramid (measures diagonals).

Answer 1

The Correct Option is B

Concept:
Hardness testing quantifies a material's resistance to plastic deformation. Different standardized tests exist in metallurgy, each utilizing a unique type of indenter and a specific physical measurement (depth, area, or rebound) to calculate the final hardness number.

Step 1:
The Rockwell hardness test typically uses a diamond cone (or a small steel ball) and measures the physical *depth* of the penetration caused by the applied load. This corresponds to Option (A).

Step 2:
The Mohs scale evaluates hardness based purely on the ability of one material to visibly scratch another. This corresponds to Option (C).

Step 3:
The Shore Scleroscope drops a diamond-tipped hammer from a fixed height onto the material and measures the *rebound height* to determine hardness. This corresponds to Option (D).

Step 4:
The Brinell test presses a large, hardened steel or tungsten carbide ball (usually 10 mm in diameter) into the surface of the test material under a specific, heavy load (e.g., 3000 kg).

Step 5:
After the load is removed, the engineer uses a specialized microscope to measure the *diameter (size) of the resulting circular indentation* left on the surface. The Brinell Hardness Number (BHN) is calculated based on the surface area of this impression. Therefore, Option (B) is the correct answer.