Materials Performance: Hardness

Understanding Hardness

Hardness is a measure of how resistant a material is to indentation, scratching, cutting or bending.
It’s an important property because it affects how a material interacts with its environment and other materials.
Hardness not only relates to a material’s strength but also its durability, how it wears, and the types of mechanical load it can handle.

Indentation Testing: This practical test measures hardness through indentation. Softer materials will show larger, deeper indents whereas harder materials will show smaller, shallower indents.
Hardness vs Toughness: Hardness should not be confused with toughness. Hardness is the resistance to scratching or indentation while toughness is a measure of how much energy a material can absorb before fracturing.
Heat Treating: Hardness can often be increased by heat treating techniques such as tempering and quenching.

Ceramics are extremely hard and resist wear, making them ideal for uses such as cutting tools and abrasives.
Metals like steel and titanium as well as alloys like stainless steel and carbide tools are often treated to increase their hardness and thus their performance in specific applications.

Hardness is a crucial property for manufacturing tools and equipment. The harder the tool, the longer it can be used before it wears out or deforms.
For consumer products, hardness is important for both aesthetic and functional reasons. It impacts everything from the product’s scratch resistance to its lifespan.
In construction and engineering, hardness can influence a material’s suitability for different applications. It affects how a material reacts to stress, strain, impacts, and wear.

Heat treatment can strongly influence the hardness of a material. By manipulating the temperature and cooling process, the hardness of a metal or alloy can be increased or decreased.
The grain structure of a material also plays a part in hardness. Finer grain structures often increase hardness and strength because they resist deformation better than coarser grain structures.