BS ISO 22394:2010 Hardmetals. Knoop hardness test
Many metallurgical problems require the determination of hardness over very small areas.
The special shape of the Knoop indenter makes it possible to place indentations much closer together than with a square Vickers indentation, e.g. to measure a steep hardness gradient.
For a given long diagonal length, the depth and area of the Knoop indentation are known to be only 15 % of what they would be for a Vickers indentation with the same diagonal length.
Both Vickers and Knoop hardness tests were performed for a range of hardmetals, in order to investigate whether a specific International Standard is really required and if it compensates the limitations of the Vickers hardness test currently used. Knoop hardness tests were carried out independently in three institutes (KATS, Jinil Co., Seoul University) over a period of four months.
The results of this test showed that a new International Standard regarding the Knoop hardness test was necessary.
BS ISO 22394 is the resulting international standard. it specifies the method of the Knoop hardness test for hardmetals.
Contents of BS ISO 22394;
Foreword
Introduction
1 Scope
2 Normative references
3 Principle
4 Symbols and designations
5 Apparatus
6 Test pieces
7 Procedure
8 Expression of results
9 Test report
10 Significance
Annex A (informative) Investigation regarding the demand of an International Standard for a Knoop hardness test for hardmetals
Annex B (informative) Comparison of important test procedures in Vickers and Knoop hardness tests
Bibliography
