What is Hardness?
The Hardness  has  a  variety  of  meanings. Generally speaking, the hardness is a measure of how difficult or easy it is for a material to be penetrated, indented, deformed or scratched, measured by hardness tests such as Brinell, Rockwell, or Vickers.
To the metals industry, it is the property of a metal, which gives it the ability to resist being permanently, deformed (bent, broken, or have its shape changed), when a load is applied. To the lubrication engineer, it means resistance to wear. To the design engineer, it is a measure of flow stress. To the mineralogist,  it  means  resistance  to  scratching,  and  to  the  machinist,  it means resistance to machining. Hardness may also be referred to as mean contact pressure.  Therefore, there are different measurements of hardness: scratch hardness, indentation hardness, and rebound hardness. 

According to the forces applied and displacements obtained the hardness measurement can be defined as “macro”, “micro” or “nano” scale.

Digital durometer Array of Hardness Test Methods:

  • The Shore Durometer Test is available to measure the hardness of polymeric materials.
  • Vickers and Knoop hardness testing are microhardness tests offered by our Metallurgical Laboratory to measure small samples or small regions in a sample. Vickers is also available on the macro scale to 50 km. These methods can measure surface or coating hardness on carburized or case-hardened parts, as well as surface conditions such as grinding burns or decarburization.
  • Rockwell, Brinell and Superficial Rockwell hardness testing are performed on castings, forgings and other relatively large metal products and samples because the tests produce a large visible indentation.

Hardness tests can be used for many engineering applications to achieve the basic requirement of mechanical property.

For examples:

  • surface treatments where surface hardness has been much improved.
  • Powder metallurgy
  • Fabricated parts: forgings, rolled plates, extrusions, machined parts.

  Hardness, however, cannot be considered to be a fundamental material property. Instead, it represents an arbitrary quantity used to provide a relative idea of material properties. As such, hardness can only offer a comparative idea of the material's resistance to plastic deformation since different hardness techniques have different hardness scales.

 


We would like to thank the following websites
for sharing their experience
and providing information for this guide.

References:
www.indentec.com , durometer.com , www.zianet.com , www.hegewald-peschke.com
www.calce.umd.edu ,  www.businessdictionary.com , wikipedia.org , hegewald-peschke.com
www.hardnesstesters.com ,  www.instron.com.es , gordonengland.co.uk , hardtester.net , imeko.org