Vickers Test
The test is similar to that of the Brinell in that the hardness no: is derived from the relationship between the applied load and the surface area of the indention. The test insists in forcing the square base diamond pyramid (with an angle 136o between the 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 impression produced by the test is of the form shown in the figure
The load is selected according to the thickness and hardness of the specimen. The Vickers or diamond pyramid hardness (DPH) is determined by load per unit area of the impression and is found from the formula
DPH = 1.8544P
d2
‘P’ is the load applied to the pyramid in kg and d is the diagonal of the impression in mn. Vickers hardness test is used for very hard material and parts of small cross section
According to the Loading the Tests are classified as:-
- Static load- When load is increased slowly and gradually and the material is loaded by tension, compression etc.
- Dynamic loading-When the load increases rapidly as in an impact test.
- Repeated or Fatigue [both static and dynamic]-When the load repeatedly varies in the case of test either in value or both in value and in direction
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