Vickers Hardened Test ( Diamond Pyramid Method )

The test is similar to that of the Brinell in that the hardness number is derived from the relationship between the applied load and the surface area of the indentation . The test consists in forcing a square based diamond pyramid ( with an angle 136* between opposite faces ) into the ground or even polished surface to be tested. The applied load is 5, 10, 30, 50, 100 or 120 kg . The Load is selected according to the thickness and hardness of the specimen.

The Vickers hardness number or diamond Pyramid Hardness (DPH), determined in such tests is the load per unit area of the impression and is found from the formula :

DPH = 1.8544 (P / d^2).

where P = Load applied to the pyramid in kg.

d = diagonal of the impression in mm.

As a rule , Vickers Hardness Number is determined from special tables in accordance with measured value of d ( length of the diagonal). Vickers and Brinell hardness numbers are expressed in same units and coincide for hardness up to about 400. At higher hardness, the Vickers number is larger than the Brinell Number.

Vickers hardness test is used for very hard materials and parts of small cross section.

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Mechinopedia For Mechanical Engineers

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