Use at your own risk. Verify inputs, assumptions and results independently before applying them.
Calculate Knoop hardness number from the applied load and longest indentation diagonal.
Method notes
See the description of the Knoop Hardness test below. The following equation is used to calculate Knoop Hardness number (HK): HK = 1.451 x F / D^2.
- For background on the Knoop hardness test, see the TriboNet Knoop hardness reference page: Knoop hardness number.
- Use applied load in newtons and the longest indent diagonal D in millimeters.
Input definitions
- Applied load
- Normal load applied by the Knoop indenter during the hardness test. Unit: N.
- Longest indent diagonal D
- Measured length of the longest diagonal of the Knoop indentation. Unit: mm.
Worked example
Enter applied load 1 N and longest indentation diagonal 0.1 mm. The result is HK = 1.451 × 1 / 0.1² = 145.10. Measure the long diagonal, not the short diagonal, and keep the input in millimetres. Compare specimens only with an appropriate, consistently applied indentation test procedure.
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