Palmqvist method

style="font-size:110%;text-align:center;;background:#DACAA5;" colspan="2" \| Materials testing
class="infobox" style="font-size:90%;width:24em;"
colspan="2" style="font-size:125%;text-align:center;"\| Palmqvist method
colspan="2" \| 265px Determined crack lengths from a Vickers indention.
style="background:#DACAA5;" colspan="2" \| Technical information

Searched property \| Fracture toughness
Year developed \| 1962S. Palmqvist, Occurrence of crack formation during Vickers indentation as a measure of the toughness of hard materials, Arch Eisenhuettenwes, 33 (1962) 629-333.
Practical use \| Determination of the fracture toughness for cemented carbides.
Website ISO-standard \| [http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=44495 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 K_Ic.{{cite web |url=http://eprintspublications.npl.co.uk/1566/1/mgpg9.pdf |first1=Bryan |last1=Roebuck |first2=Eric |last2=Bennett |first3=Lewis |last3=Lay |first4=Roger |last4=Morrell |title=Palmqvist Toughness for Hard and Brittle Materials |publisher=National Physical Laboratory |year=2008 |access-date=15 April 2020}}

Approach

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

: $K_{\text{Ic}} = 0.0028\sqrt{\text{HV}}\sqrt{\frac{P}{T}}$ in units of MPa $\sqrt{\text{m}}$ ,

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

Category:Materials testing

Category:Fracture mechanics