Rockwell Hardness Test

In this test a Hard Steel Ball or a Diamond Cone Indenter is pressed into the surface of the material being tested/ The result of the test is read directly from machine.

The indenter is forced into the test material under a preliminary minor load (98N)and after equilibrium are achieved an indicating device, which follows the movements of the indenter, is set to the datum position. An additional major load is then applied with resulting increase in penetration. The conditions are then allowed to stabilise and then the additional major load is removed,leaving the minor load in place. The resulting permanent penetration esulting from the application and removal of the additional major load is used to calculate the Rockwell hardness number.

HR = E - e

F1 = additional major

e = permanent increase in depth of penetration due to major load , measured in units of 0.001 mm

E = a constant of 100 units for diamond and ball indenters

HR = Rockwell hardness number

D = diameter of steel ball

Scale	Indenter	Major Load F1 N	E	Applications
A	120oDiamond cone	490.5	100	Sheet steel ; shallow case hardened
B	1/16" steel ball	882.9	130	Copper, Aluminium alloys, Low Carbon Steel
C	120oDiamond cone	1373.4	100	Most Widely Used -Hardened Steels, Cast irons etc
D	120oDiamond cone	882.9	100	Thin but hard steels, Ductile Iron (Pearlitic
E	1/8" steel ball	882.9	130	Cast Iron, Aluminium, Bearings alloys
F	1/16" steel ball	490.5	130	Annealed copper alloys , Soft thin metals
G	1/16" steel ball	1373.4	130	Phosphor bronze, beryllium copper, malleable irons, Lead etc
H	1/8" steel ball	490.5	130	Soft Metals Plastics etc
K	1/8" steel ball	1373.4	130	Soft bearing metals, Plastics, soft materials.
L	1/4" steel ball	490.5	130	Soft bearing metals, Plastics, soft materials.
M	1/4" steel ball	882.9	130	Soft bearing metals, Plastics, soft materials.
P	1/4" steel ball	1373.4	130	Soft bearing metals, Plastics, soft materials.
R	1/2" steel ball	490.5	130	Soft bearing metals, Plastics, soft materials.
S	1/2" steel ball	882.9	130	Soft bearing metals, Plastics, soft materials.
V	1/2" steel ball	1373.4	130	Soft bearing metals, Plastics, soft materials.