1. Rockwell hardness
test

2. AHMAD EJAZ
DEPARTMENT OF
MATERIAL SCIENCE

4. HARDNESS TEST

5. CONTENT
Hardness
General type of hardness test
Rockwell hardness test

6. HARDNESS:-
 Hardness is simply the resistance to plastic
deformation or permanent deformation of
material.
 The term hardness may also refer to
resistance to bending, scratching, abrasion
or cutting.
 Hardness is dependent
on ductility, elasticity plasticity, strain,
strength,

7. GENERAL TYPES OF HARDNESS MEASUREMENT
There are three general type of hardness
test:
 Scratch hardness test
 Indentation harness test
 Rebound hardness test

8. SCRATCH TEST
 Scratch hardness is the measure of how
resistant a sample is to
permanent plastic deformation due to
friction from a sharp object. The
principle is that an object made of a
harder material will scratch an object
made of a softer material.
 In scratch test Moh’s scale are usually
adopted.
 This consist of a list of materials

9. MOH’S SCALE ARRANGEMENT
 Mineral hardness number
 Talc 01
 Gypsum 02
 Calcite 03
 Fluorite 04
 Apatite 05
 Feldspar 06
 Quartz 07
 Topaz 08
 Corundum 09
 Diamond 10

10. INDENTATION TEST
 Indentation hardness measures the resistance
of a sample to material deformation due to a
constant compression load from a sharp object.
 They are primarily used in
engineering and metallurgy fields.
 it is most widely used for measurement of
harness
 it measure the brinell hardness , Rockwell
hardness, Vickers hardness etc.

11. ROCKWELL HARDNESS TEST
 The Rockwell Hardness test also uses a machine to
apply a specific load and then measure the depth of
the resulting impression.
 Rockwell hardness test devised in USA.
 It is useful for finished material testing .
 Hardness no. is indicated on dial.
 Test piece is place on table of the instrument.
 Indenter is brought into contact with surface of test
piece under light load(minor load).
 Scale is then adjusted to zero.
 Major load is applied ,hardness index is read from the
scale.

13.  Penetration depth “e” of impression is
messure by instrument.
 This penetration depth is convert into
harness value appear on dial.
 Rockwell hardness formula
 HR = E - e

14.  F0 = preliminary minor load in kgf
 F1 = additional major load in kgf
 F = total load in kgf
 e = permanent increase in depth of
penetration due to major load F1 measured
in units of 0.002 mm
 E = a constant depending on form of
indenter: 100 units for diamond indenter, 130
units for steel ball indenter
 HR = Rockwell hardness number

15. SCALE USE ON DIAL
 scale being determined by indenter and full load use .
 Scale A : which is use in conjunction with diamond
cone and 60kgf load .it is use for very hard material
such as tool steel.
 Scale B : which is use in conjunction with 1/16 inch
diameter steel ball and 100kgf load.it is use for soft
material such as copper alloy ,mild steel etc.

16.  Scale C: which is use in conjunction with
diamond cone 120 degree angle and 150
load .it is use for hardend steel , hard cast
iron.

17. ADVANTAGE/DISADVANTAGE
 Advantages of the Rockwell hardness include:
 The direct Rockwell hardness number readout
on the dial.
 Rapid testing time.
 Can be used for a very wide range of materials.
 Disadvantages include:
 Possible errors due to shifting of the sample under test
load during test cycle
 Quality of the indenter has a strong influence on the
test result