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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 |
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