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Bess MTI’s Materials Laboratory performs microhardness test. These tests concern static indentations made on a material with loads not exceeding 1 kgf. The indenter is either the Knoop elongated diamond pyramid, or the Vickers square diamond pyramid
The measurements are carried out with a microscope with at least 500X magnification. The surface of the material requires a highly polished finish.
Knoop Hardness
The Knoop indenter produces a diamond shaped indentation. The Knoop hardness number, KHN is the ratio of the load applied by the indenter to the unrecovered projected area, given by the equation:
where F is the load applied by the indenter, in kgf and A is the unrecovered projected area of the indentation in mm 2
Vickers Hardness
The Vickers indenter is ground in the form of a squared pyramid. The Vickers hardness, VH is the ratio of the applied load divided by the surface area of the indentation, given by equation:
where F is the load, in kgf and d is the arithmetic mean of the two diagonals, in mm.
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