Measurement of residual thermal stress in WC–Co by neutron diffraction

The temperature dependence of residual stresses in a WC–17.8vol.%Co cemented carbide was measured by neutron diffraction. The comparison of the WC lattice parameter within the WC–Co and within stress-free WC reference provides a measurement of lattice elastic strains and, using Hooke’s law, stresses. WC is found to be under hydrostatic compressive stresses of about −400 MPa at room temperature, which decrease monotonically with temperature to a near-zero value at 800 °C. Residual stresses in cobalt also decrease with increasing temperature, but show an apparent increase above 800 °C, which is attributed to an increase in lattice parameter due to W dissolution in the Co phase.