The Rockwell scale is a hardness scale based on indentation hardness of a material. The Rockwell test determines the hardness by measuring the depth of penetration of an indenter under a large load compared to the penetration made by a preload. There are different scales, denoted by a single letter, that use different loads or indenters. The result is a dimensionless number noted as HRA, where A is the scale letter.
It is typically used in engineering and metallurgy. Its commercial popularity arises from its speed, reliability, robustness, resolution and small area of indentation.
In order to get a reliable reading the thickness of the test-piece should be at least 10 times the depth of the indentation. Also, readings should be taken from a flat perpendicular surface, because convex surfaces give lower readings. A correction factor can be used if the hardness of a convex surface is to be measured.
Test range:
(20～88) HRA; (20～100) HRB; (20～70) HRC
Scales and values
Scale
|
Abbreviation
|
Load
|
Indenter
|
Use
|
A
|
HRA
|
120° diamond cone
| ||
B
|
HRB
|
100 kgf
|
1⁄16-inch-diameter (1.588 mm) steel sphere
|
Aluminium, brass, and soft steels
|
C
|
HRC
|
150 kgf
|
120° diamond cone
|
Harder steels >B100
|
D
|
HRD
|
100 kgf
|
120° diamond cone
| |
E
|
HRE
|
100 kgf
|
1⁄8-inch-diameter (3.175 mm) steel sphere
| |
F
|
HRF
|
60 kgf
|
1⁄16-inch-diameter (1.588 mm) steel sphere
| |
G
|
HRG
|
150 kgf
|
1⁄16-inch-diameter (1.588 mm) steel sphere
| |
Standards:
• International (ISO)
ISO 6508-1: Metallic materials -- Rockwell hardness test -- Part 1: Test method (scales A, B, C, D, E, F, G, H, K, N, T)
ISO 2039-2: Plastics -- Determination of hardness -- Part 2: Rockwell hardness
• US standard (ASTM International)
ASTM E18 : Standard methods for Rockwell hardness and Rockwell superficial hardness of metallic materials
EBP related products:
Any friends interested in purchase Rockwell hardness tester, please contact us at:
EBPu Electromechanical Equipment (Zhejiang) Co., Ltd.
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