What Does Diamond Pyramid Hardness (DPN) Mean?
Diamond pyramid hardness (DPH) is a measurement of a material's hardness, equal to the value of the load divided by the surface area of the indentation. In practice, this area is calculated from microscopic measurements of the lengths of the diagonals of the impression.
This testing can be used for all metals and has one of the widest scales among hardness tests. It has received wide acceptance for research work because it provides a continuous scale of hardness—from very soft metals with a DPH of 5 to extremely hard materials with a DPH of 1,500.
Diamond pyramid hardness is also known as Vickers hardness or the Vickers pyramid number.
Corrosionpedia Explains Diamond Pyramid Hardness (DPN)
Diamond pyramid hardness is the unit of hardness given by the Vickers test. The hardness number can be converted into units of pascals, not to be confused with the unit of pressure.
The diamond pyramid hardness test employs a pyramid-shaped diamond with an included angle of 136°, which is impressed into the specimen using loads of 5 to 120 kg, making a small square impression. This test is employed for finished or polished components because the impression can be very small. The diamond pyramid hardness number is obtained from a calculation based on measuring the diagonals of the impressions in the steel.
The test is often easier to use than other hardness tests, since the required calculations are independent of the size of the indenter, and the indenter can be used for all materials irrespective of hardness. The basic principle, as with all common measures of hardness, is to observe the questioned material's ability to resist plastic deformation from a standard source.