"Hardness HB" indicates the ability of a material to resist hard objects pressed into its surface. It is one of the important performance indicators of metal materials. Generally the higher the hardness, the better the wear resistance. A hardened steel ball or carbide ball of a certain size (usually 10mm diameter) is pressed into the surface of the material with a certain load (usually 3000kg) and kept for a period of time. Then remove the load, the ratio of the load to the indentation area is the Brinell hardness value (HB).

The unit is kgf/mm² (N/mm²)

HB, HBS and HBW are all Brinell hardness symbols. What’s the difference between them?

HB is a unit of Brinell hardness, but it doesn’t specify what material the indenter is made of.

HBS indicates that the indenter is a hardened steel ball and is used to measure materials with Brinell hardness value below 450, such as mild steel, gray cast iron and non-ferrous metals.

HBW indicates the indenter is cemented carbide and is used to measure materials with Brinell hardness value below 650.

Tips:

The standard GB/T231.1-2009 <Metal Materials Brinell Hardness Test Part 1: Test Method> states that only carbide indenters are allowed to be used. The Brinell hardness symbol is HBW, which should not be confused with the previous HB and HBS. 

So now only carbide can be used as the indenter, only HBW can be used.

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