Which of the following can affect the results in hardness testing?

The choice of the indenter used in hardness testing is crucial as it significantly influences the results obtained from the test. Different indenters, such as diamond, steel ball, or carbide, are designed with varying shapes and materials, which affect how they penetrate the test material. The hardness test relies on measuring either the size or depth of the resulting indentation made by the indenter, so using an indenter that is too soft or improperly shaped can lead to inaccurate measurements.

For example, a diamond indenter is typically used in Rockwell and Vickers hardness tests due to its ability to penetrate harder materials without deformation. In contrast, a softer indenter might yield larger or inconsistent indentation measurements on harder materials, leading to erroneous conclusions about their hardness. As such, ensuring the right type of indenter is employed is essential for achieving reliable and reproducible hardness test results.