Volume 2, Issue 8 (September 2005)
Neutron Flux Effect on the Irradiation Hardening of Type 304 Stainless Steel
In order to investigate the neutron flux effect on the irradiation hardening of type 304 stainless steel, microstructure observation, tensile test, and micro Vickers hardness test were performed on the type 304 stainless steel irradiated to 1.6 × 1024−1.4 × 1026 n/m2 in LWRs, (flux 3.4 × 1015−5.6 × 1017 n/m2/s). The tensile test was carried out in air at 288°C, and the hardness test was also carried out in air, but at room temperature. The amount of irradiation hardening increased with increasing neutron flux. The amount of irradiation hardening was proportional to the 0.25th power of neutron flux. Dislocation loop density increased with increasing neutron flux, and mean diameter had hardly any dependence on neutron flux. From the above, the neutron flux dependence of dislocation loop density could be said to be the main factor controlling irradiation hardening under LWR irradiation conditions. The amount of irradiation hardening of type 304 stainless steel used in LWR is expected to be lower than the predicted amount from higher flux irradiated materials.