Methods and Applications of Microindentation Hardness Testing

  • Peter J. Blau


There is a great deal of confusion in conceptions about penetration hardness. Part of the problem results from a popular misconception that “hardness” is a basic property of a material. This is not the case. Hardness numbers are, more accurately, measures of the response of given materials to various types of indentation processes. Microindentation hardness numbers depend on a combination of surface and bulk material properties. As indenter geometry and test loads are changed (particularly at loads below about 100 g), different combinations of surface and bulk properties may contribute to the net response of the material. Issues of impression size versus microstructural feature size (“scale effects”) are important. Also, at lower loads and with blunter indenters (e.g., Knoop), material is penetrated less deeply, bringing about an increased sensitivity to surface preparation technique. The metallographer should recognize this fact and take particular care in preparing polished samples that may be used for low-load microindentation studies.


Hardness Scale Hardness Number Indentation Process Indenter Geometry Taper Section 
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Copyright information

© Van Nostrand Reinhold Company Inc. 1986

Authors and Affiliations

  • Peter J. Blau
    • 1
  1. 1.National Bureau of StandardsUSA

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