What is difference between hardness and toughness?

Hello Pals,

Hardness and toughess, there is always confusion about these terms. Difference is one measure of resistance to deformation  and other is ability of steel to absorb energy or impact prior to fracture.

Difference between Hardness & Toughness:

Simplest explanation for difference

Hardness – Measure of resistance to deformation 

Toughness- Ability to be absorb energy 

What Difference?

Hardness:

Measure of resistance of material to deformation or to surface indentation. It is function of stress required to produce specific deformation. Hardness is a property that represents an effect of complex elastic and plastic stress fields set up in the material being tested. To Express hardness quantitatively there are different hardness scale. Different hardness test methods like Brinell, Rockwell, Vickers etc. are used to measure hardness.  

Toughness:

 

Ability of material to absorb energy or impact and deform plastically prior to fracture.It can be measured by impact toughness and fracture toughness. Usually toughness of steel increases with decreasing hardness.

So the main difference between hardness and toughness one is ability to resist deformation other is measure of ability to absorb energy or impact and deform before fracutre