High temperature deformation mechanisms in the 14% Cr ODS alloy

The stress relaxation behavior of the ODM401 ODS steel is tested at the temperature range 400-800 °C in order to investigate the deformation mechanisms. The repeated relaxation tests are performed on the tensile specimens within the plastic strain range 10−4-10−1. The deformation mechanisms are analyzed in terms of an activation volume, dislocation density and velocity, a thermal stress component and a strain rate hardening. The deformation is driven by the dislocation glide and climb. Dispersed particle-dislocation interactions is a dominant effect at temperatures 400-600 °C. Short-range interactions between dislocations and a lattice are most significant at 600 °C. The non-conservative motion of dislocations becomes active at temperatures above 600 °C. The majority of the mobile dislocations is not trapped and is able to move freely in the microstructure.