Question

Write an abstract about hardness test of metal, also Rockwell Hardness test and Vickers Hardness Test?

* please do not write it with hand.

Answer 1

HARDNESS OF METAL :   Abilitity to resist deformation, indentation or penetration, drilling and wear and scratch etc.

HARDNESS TEST : It measuring the hardness by using different tests by different scales.

ROCKWELL HARDNESS TEST :

It is widely used test due to its speed, small indentation and ability to identify small hardness differences.

The hardness is measured according to the depth of indentation hole under constant load.

ROCKWELL HARDNESS is measured in RHN (rockwell hardness number ).

In rockwell hardness test two types of loads applied on metal. One is minor load which ranges from 3kgf to 10 kgf and another one is major load which from 15kgf to 150kgf.

the difference between depth of minor load indentation to major load is considered as RHN.

Basically the indenter should have 10times harder than testing material.

VICKERS HARDNESS TEST :

In vickers hardness test square base diamond pyramid is used as indenter. The angel between opposite faces of pyramid is 136 degrees.

Vickers hardness is measured in VHN ( vickers hardness number ).

vickers hardness is load devided by the surface area.

  

Vickers hardness test uses the load ranges from 1-120 kgf applied between 10 to 15 seconds.

TYPES OF INDENTATIONS :

a) Perfect square indentation

b) Pincushion indendentation ( observed in annealed metals )

c) The barrel shaped indentation ? ( observed in cold working metals ).