Elevated temperature fatigue testing of hardmetals using notched testpieces

Methods of fatigue testing hardmetals at elevated temperatures using notched test-pieces are described. Notches were used to promote deformation initiated in zones representative of the average microstructure rather than from macroscopic defects. By localising the stressed volume of the test-pieces, behaviour more characteristic of the material with less scatter is obtained compared with the use of straight-sided test-pieces. Test have been made in flexure with single-sided notches, and in push-pull using double notches. Controlled atmospheres were used to minimise the effects of oxidation at temperatures in the range 200–800 °C. It is considered that these new testing methods for hardmetals should provide useful information to rank materials for resistance to fatigue at elevated temperature or during temperature cycling.