Which of the following hardness tester uses Diamond cone type indenter?
Rockwell
Hardness Tester Indenter Types Explained
Hardness testing measures a material's resistance to localized plastic deformation. This is commonly done by pressing a specific shape, called an indenter, into the material's surface with a known force. Different hardness testing methods use different indenter shapes and testing procedures to measure hardness. Understanding the indenter type is key to selecting the appropriate test for a material.
Rockwell Hardness Test Method Analysis
The Rockwell hardness test is a common method that measures the depth of indentation caused by a specific indenter under a specific load. This test system is versatile because it uses different indenters depending on the material being tested:
- A diamond cone type indenter (specifically, a 120-degree cone with a rounded tip) is used for testing harder materials, such as hardened steels. This corresponds to scales like HRC, HRA, and HRD.
- A hardened steel ball of various diameters is used for testing softer materials, corresponding to scales like HRB and HRF.
Given that the Rockwell test employs a diamond cone indenter for many of its scales, it directly matches the condition mentioned in the question.
Indenter Comparison Across Hardness Tests
To clarify why Rockwell is the correct choice, let's look at the indenters used in the other options:
| Hardness Test Method | Standard Indenter Type | Notes |
| Brinell | Hardened steel ball (or tungsten carbide ball) | Measures the diameter of the indentation left by the ball. |
| Vickers | Diamond pyramid (square-based) | Uses a square-based pyramid shape made of diamond. |
| Knoop | Diamond pyramid (elongated, rhombic-based) | Uses a specific diamond pyramid shape that is longer than it is wide. |
| Rockwell | Diamond cone (120°) or Steel ball | Uses a diamond cone for hard materials and a steel ball for softer ones. |
From the table, we can see that while Vickers and Knoop tests use diamond indenters, they are specifically diamond *pyramid* shapes. The Brinell test uses a steel ball. The Rockwell hardness test is the method among the options that uniquely uses a diamond cone type indenter.
Important Questions from Hardening
The ductility of a material with work hardening
Hardenability of steel is a measure of
The ‘’Jominy test’’ is used to find
The true stress-strain relations of plastic deformation at which necking begins may be approximated. The value n for steel is \(\rm \sigma _ T= K \varepsilon _T^n\) The value n for low carbon steel is
Surface hardening is principally employed for
