Extending the use of Indentation Tests
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.
KeywordsCrack Length Stress Corrosion Indentation Test Side Face Total Crack Length
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- 2.S. Palmqvist, Occurrence of crack formation during Vickers indentation as a measure of the toughness of hardmetals, Arch. Eisenhuttenwes. 33:629 (1962).Google Scholar
- 4.E. A. Almond and B. Roebuck, Some observations on indentation tests for hardmetals, in: “Conf. on Recent Advances in Hardmetal Production,” Loughborough U. of Tech. and Met. Powder Rep. (1979).Google Scholar
- 5.R. K. Viswanadham and J. D. Venables, A simple method for evaluating cemented carbides, Met. Trans. 8A:187 (1977).Google Scholar
- 7.H. Suzuki, T. Tanase, F. Nakayama and K. Hayashi, Low temperature transverse-rupture strength of WC-Co cemented carbide, J. Jap. Soc. Powder Metall. 25:32 (1978).Google Scholar
- 8.E. A. Almond and B. Roebuck, Precracking of fracture toughness specimens of hardmetals by wedge indentation, Met. Technol. 5:92 (1978).Google Scholar
- 9.E. A. Almond and B. Roebuck, Stress corrosion cracking of a 6% Co/WC hardmetal, J. Mater. Sci., 565:11 (1976).Google Scholar
- 10.B. Roebuck and A. T. May, A chemical spot test for the carbon content of Ni and Co-bonded hardmetals, Prakt. Metallogr. 31:18 (1981).Google Scholar
- 11.E. M. Trent, Private communication.Google Scholar
- 12.M. Dlouhy and J. Houdek, Testing of cemented carbides for dynamic toughness, Pokroky Práškové Met. 9 (1970).Google Scholar