Scale Factor in Scratch Tests of the Materials with Different Elastic Volume

Abstract

Experimental study of the scale factor impact on determination of the mechanical characteristics of metals and alloys in scratch indentation tests with recording «scratch intensity - scratch length» deformation diagrams is presented. The advantages of using the scratching method with a constant preset depth for control of the mechanical characteristics of materials and coatings are shown. The effect of the scratch depth on the determined values of the mechanical characteristics -scratch hardness and specific energy of local destruction - is studied in scratching tests using the edge of the Vickers tetrahedral pyramid. It is shown that the scale effect in scratching tests is manifested rather clearly. As the scratch depth decreases, the strain resistance, scratch hardness and specific fracture energy grow due to a multiple reduction of the elastic volume of the metal. For this reason, we recommend to use a constant preset scratch depth in comparative scratch testing of several materials or coatings thus providing close values of the elastic volumes of the materials and the same impact of the scale factor on the results of measuring the mechanical characteristics of the material.