Extending the use of Indentation Tests

Abstract

Results are described of experiments performed using indenters of various geometries on a range of WC/Co hardmetals, with hardnesses ranging from 1000 to 1800 HV30.

The deformation characteristics of hardmetals show a similar dependence on indenter angle to that shown by other materials for lubricated and unlubricated pyramid indenters. As indentation temperature decreases, relative increases in hardnesses are similar, but Palmqvist cracking shows a greater temperature dependence in the coarse-grained cemented carbides. Stresscorrosion cracking, as measured by increases in the length of Palmqvist cracks and surface flaking, occurs in most acidic environments, and is dependent on the carbon content of the hardmetal.

When ball indentations are made at decreasing distances from the square edge of specimens, flakes break away from the edge. The mechanisms of crack growth change when hardness increases above 1375 HV30. Damage produced by flaking is small on the indented face but large on the side face: flake size increases with increase in hardness.