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Palmqvist method

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Materials testing
Palmqvist method

Determined crack lengths from a Vickers indention.
Technical information
Searched property Fracture toughness
Year developed 1962[1]
Practical use Determination of the fracture toughness for cemented carbides.
Website ISO-standard ISO 28079:2009, Palmqvist toughness test

The Palmqvist method, or the Palmqvist toughness test, (after Sven Robert Palmqvist) is a common method to determine the fracture toughness for cemented carbides. In this case, the material's fracture toughness is given by the critical stress intensity factor KIc.[2]

Approach

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The Palmqvist-method uses the lengths of the cracks from a number of Vickers indentions to determine the fracture toughness. The Palmqvist fracture toughness is given by[2]

in units of MPa,

where HV is the Vickers hardness in N/mm2 (or MPa) (i.e., 9.81 x numerical HV), P is the indentation load in N (typically 30 kgf is used) and T is the total crack length (mm) after application of the indenter.

Notes

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  1. ^ S. Palmqvist, Occurrence of crack formation during Vickers indentation as a measure of the toughness of hard materials, Arch Eisenhuettenwes, 33 (1962) 629-333.
  2. ^ a b Roebuck, Bryan; Bennett, Eric; Lay, Lewis; Morrell, Roger (2008). "Palmqvist Toughness for Hard and Brittle Materials" (PDF). National Physical Laboratory. Retrieved 15 April 2020.