What does hardness testing measure?

Hardness testing primarily measures the resistance of a material to deformation, particularly permanent deformation, scratching, cutting, or penetration. This property is crucial in material science and engineering because it helps determine how a material will behave under mechanical stress or wear conditions.

In practical applications, materials with higher hardness values are typically more resistant to wear and can be advantageous in various manufacturing and industrial processes. Hardness is a key factor when selecting materials for specific applications, such as tools or structural components, where durability and wear resistance are essential.

The other options do not accurately reflect what hardness testing measures. Weight pertains to the gravitational force on an object, density relates to mass per unit volume, and visual appearance concerns aesthetic factors, none of which capture the mechanical resistance characteristic that hardness testing evaluates.