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Rockwell Hardness

Description
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:

HR = E - e

where:
E = indenter constant, and
e = the permanent increase in penetration depth

Standards
BS EN ISO 2039-1:2003,
(BS 2782-3:Method 365D:1997)
Plastics. Determination of hardness. Ball indentation method
BS EN ISO 2039-2:2000Determination of Rockwell hardness.
BS EN ISO 6508-1:2016,
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 D785-08Standard 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 E18-18Standard Test Methods for Rockwell Hardness and Rockwell Superficial Hardness of Metallic Materials
Indentec 4150LK Rockwell Hardness Tester
Indentec 4150LK Rockwell Hardness Tester
Standard Rockwell Scales
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