The Brinell hardness test method consists of indenting the test material with a 10 mm diameter hardened steel or carbide ball subjected to a load of 3000 kg.
The objective of harness test is define the hardness number which represents an arbitrary quantity used to provide a relative idea of material properties. The hardness number derived in this test is called Brinell harness number and is designated as BHN
For softer materials the load can be reduced to 1500 kg or 500 kg to avoid excessive indentation. The full load is normally applied for 10 to 15 seconds in the case of iron and steel and for at least 30 seconds in the case of other metals. The diameter of the indentation left in the test material is measured with a low powered microscope.
The Brinell harness number is calculated by dividing the load applied by the surface area of the indentation. The formula is shown in the picture shown below.
Where F = Force applied in kgF
D = diameter of indenter
This method is not used in industry since it is quite slow, deforms the specimen excessively and requires setup to calculate the depth of the indentaion..
The above information has been taken from www.gordonengland.co.uk. Please do refer to them for more info.
The above information has been taken from www.gordonengland.co.uk. Please do refer to them for more info.
with warm regards
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Hardness of materials has probably long been assessed by resistance to scratching or cutting. Relative hardness of minerals can be assessed by reference to the Mohs scale that ranks the ability of materials to resist scratching by another material.
ReplyDeletefor more please visit:http://www.ndtindia.org/portable-hardness.html
The rockwell hardness test method consists of indenting the test material with a diamond cone, hardened steel or tungsten carbide ball indenter.
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