| The Rockwell and Superficial
Rockwell hardness test uses either a 120° diamond cone
with a 0.2mm radius spherical tip or a ball indenter of
a specified diameter. The indentor is pressed into the
surface of the test piece using a two step application -
a preliminary force P followed by an additional
test force. The preliminary force should be applied and
maintained for a duration that shall not exceed 3 s. The
increase in force from the preliminary force condition
to the total test force F should occur in between
1 and 8 s. This force is then maintained for a duration
of 4 ± 2 s. The additional force is then removed and,
while the preliminary force is maintained, the reading
is made after a short stabilisation time. The result of
the test is read directly from the machine as:
|
|
where: |
E = indenter
constant, and |
| |
e = the
permanent increase in penetration depth. |
|
Scale |
Indenter |
Preliminary
force
P (N) |
Total
force
F (N) |
Application |
| HRA |
Diamond cone |
98.07 |
588.4 |
Sheet steel: shallow
case-hardened |
| HRB |
Ball 1.5875 mm dia. |
98.07 |
980.7 |
Cu and Al alloys; annealed low
C steels |
| HRC |
Diamond cone |
98.07 |
1471 |
Hard steels; CI, deep
case-hardened |
| HRD |
Diamond cone |
98.07 |
980.7 |
Thin hard steel; med.
case-hardened |
| HRE |
Ball 3.175 mm dia. |
98.07 |
980.7 |
Cast iron; Al; Mg; and bearing
metals |
| HRF |
Ball 1.5875 mm dia. |
98.07 |
588.4 |
Annealed Cu alloys; thin soft
sheets |
| HRG |
Ball 1.5875 mm dia. |
98.07 |
1471 |
Malleable CI; bronzes; Cu-Ni
alloys |
| HRH |
Ball 3.175 mm dia. |
98.07 |
588.4 |
Soft materials; high ferritic;
Al; Pb; Zn |
| HRK |
Ball 3.175 mm dia. |
98.07 |
1471 |
Al and Mg alloys |
| HRL |
Ball 6.350 mm dia. |
98.07 |
588.4 |
Thermoplastics |
| HRM |
Ball 6.350 mm dia. |
98.07 |
980.7 |
Thermoplastics |
| HRP |
Ball 6.350 mm dia. |
98.07 |
1471 |
Thermosetting plastics |
| HRR |
Ball 12.70 mm dia. |
98.07 |
588.4 |
Very soft plastics and rubbers |
| HRS |
Ball 12.70 mm dia. |
98.07 |
980.7 |
- |
| HRV |
Ball 12.70 mm dia. |
98.07 |
1471 |
- |
| HR 15N |
Diamond cone |
29.42 |
147.1 |
Hardness tests
used for thin sheets,
foils, coatings, surface heat
treatments, and polymers including
their surface treatments |
| HR 30N |
Diamond cone |
29.42 |
294.2 |
| HR 45N |
Diamond cone |
29.42 |
441.3 |
| HR 15T |
Ball 1.5875 mm dia. |
29.42 |
147.1 |
| HR 30T |
Ball 1.5875 mm dia. |
29.42 |
294.2 |
| HR 45T |
Ball 1.5875 mm dia. |
29.42 |
441.3 |
| HR 15W |
Ball 3.175 mm dia. |
29.42 |
147.1 |
| HR 30W |
Ball 3.175 mm dia. |
29.42 |
294.2 |
| HR 45W |
Ball 3.175 mm dia. |
29.42 |
441.3 |
| HR 15X |
Ball 6.350 mm dia. |
29.42 |
147.1 |
| HR 30X |
Ball 6.350 mm dia. |
29.42 |
294.2 |
| HR 45X |
Ball 6.350 mm dia. |
29.42 |
441.3 |
| HR 15Y |
Ball 12.70 mm dia. |
29.42 |
147.1 |
| HR 30Y |
Ball 12.70 mm dia. |
29.42 |
294.2 |
| HR 45Y |
Ball 12.70 mm dia. |
29.42 |
441.3 |
|
|
| ASTM
standard |
|
BS EN ISO
2039-1:2003,
(BS 2782-3:Method 365D:1997) |
Plastics. Determination of
hardness. Ball indentation method |
|
BS EN ISO
2039-2:2000 |
Determination of Rockwell
hardness. |
BS EN ISO 6508-1:2005,
BS 891:Part 1:1962 |
Metallic materials. Rockwell
hardness test. Test method (scales A, B, C, D, E, F, G,
H, K, N, T) |
| ASTM D785-03 |
Standard Test Method for
Rockwell Hardness of Plastics and Electrical Insulating
Materials |
| (ASTM E1842-96) |
Standard Test Method for
Macro-Rockwell Hardness Testing of Metallic Materials |
| ASTM E18-05 |
Standard Test Methods for
Rockwell Hardness and Rockwell Superficial Hardness of
Metallic Materials |
