Unformatted text preview: The elongated diamond indenter and low test forces allows testing very small parts. Also only a very small sample of material is required for testing and it is valid for a wide range of test forces. Another reason Knoop is preferred is because its test allows for distinguishing the hardness between phases and microconstituents in the solid, as to where Rockwell testing only provides a bulk hardness of the solid. • The Knoop indenter makes a very small indentation that can only be measured under a microscope. The optical microscope is used to measure the longest diagonal of the diamond shaped indent. The long diagonal is approximately .001 to .200 mm. • Hardness number = 14229 * Test Force / (Long diagonal Length)^2 Test Force = Hardness Number * (Long diagonal Length)^2 / 14229 Test Force = 540 HK * (100 μm)^2 / 14229 Test Force = 379.5 gf...
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- Spring '10
- Rockwell scale, Knoop, Indentation hardness, Rockwell Hardness Testing, specific total test, test force