Irradiation hardening of advanced tungsten grades: An experimental and inverse finite element method study

The effect of neutron irradiation on mechanical properties of various advanced W grades (pure, doped by K, alloyed by Re) was assessed by means of mechanical testing using miniaturized tensile and sub-miniaturized three-point bending (3PB) specimens. Different irradiation conditions in terms of temperature (400, 600, 800 and 1100 degrees C) and irradiation dose (0.2-0.25 dpa, 1.0-1.1 dpa) were considered. In order to extract the yield stress from the flexural load-displacement data, the empirical correlation between the flexural stress at a specific reference point on the flexural stress-strain curve and uniaxial tensile yield stress was established. The empirical ratio identified can be applied for the 3PB testing in a wide range of temperatures and plastic properties of un-irradiated and irradiated W alloys. The accuracy of the yield stress determination deduced using the empirical correlation from the 3PB tests was compared with the inverse FEM modelling procedure applied to the 3PB tests carried along with reference data extracted from the dedicated tensile tests. The information on the tensile yield stress and work hardening rate of all studied materials at different irradiation conditions was summarized and discussed in the view of the irradiation hardening.