Brinell hardness Number Online
The Brinell scale characterises the indentation hardness of materials through
the scale of penetration of an indenter, loaded on a material test-piece. It is
one of several definitions of hardness in materials science.
Brinelling refers to surface fatigue caused by repeated impact or overloading.
It is a common cause of roller bearing failures, and loss of preload in bolted
joints when a hardened washer is not used. Engineers will use the Brinell
hardness of materials in their calculations to avoid this mode of failure.
Fretting corrosion can cause a similar-looking kind of damage and is called
false brinelling since the mechanism is different.
Proposed by Swedish engineer Johan August Brinell in 1900, it was the first
widely used and standardised hardness test in engineering and metallurgy. The
large size of indentation and possible damage to test-piece limits its
usefulness.
The typical test uses a 10 mm diameter steel ball as an indenter with a 3,000
kgf (29 kN) force. For softer materials, a smaller force is used; for harder
materials, a tungsten carbide ball is substituted for the steel ball. The
indentation is measured and hardness calculated as:
where:
P = applied force (kgf)
D = diameter of indenter (mm)
d = diameter of indentation (mm)
Common values
When quoting a Brinell Hardness Number (BHN or, more commonly, HB), the
conditions of the test used to obtain the number must be specified. The standard
format for specifying tests can be seen in the example "HBW 10/3000". "HBW"
means that a tungsten (chemical symbol W, from the German Wolfram) carbide ball
indenter was used, as opposed to "HBS", which means a hardened steel ball. The
"10" is the ball diameter in millimeters. The "3000" is the force in kilograms
force.
Brinell Hardness Numbers (standard test conditions unless otherwise stated)
Material Hardness
Softwood (e.g., pine) 1.6 HBS 10/100
Hardwood 2.6 to 7.0 HBS 1.6 10/100
Aluminium 15 HB
Copper 35 HB
Mild steel 120 HB
18-8 (304) stainless steel 1250 HB
Glass 1550 HB
Hardened tool steel 1500 - 1900 HB
Standards
International (ISO) and European (CEN) Standard
EN ISO 6506-1 : Metallic materials - Brinell hardness test - Part 1 : test
method.
EN ISO 6506-2 : Metallic materials - Brinell hardness test - Part 2 :
verification and calibration of testing machine.
EN ISO 6506-3 : Metallic materials - Brinell hardness test - Part 3 :
calibration of reference blocks
US standard (ASTM International)
ASTM E10 : : Standard method for Brinell hardness of metallic materials.
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