This paper describes the results of an investigation of the influence of irradiation temperatures from 150 to 750 C, and post-irradiation test temperatures of 25 to 850 C on the mechanical properties of AISI Type 304 and 347 stainless steels tested at various strain rates. The irradiations were conducted in an Oak Ridge Research Reactor core position. Subsize tension specimens were irradiated to 7 x 1020 nvt (fast) and 9 x 1020 nvt (thermal).
The yield stress was not affected by irradiation at any test temperature above 600 C. At lower irradiation and testing temperatures the yield and ultimate engineering tensile stresses are strongly dependent upon irradiation temperature. The true tensile and fracture stresses at test temperatures below 600 C were unaffected regardless of the irradiation temperature; they were slightly reduced at test temperatures above 600 C in the high strain-rate tests.
Increases in yield strength due to irradiation were associated with decreases in the uniform elongation, but not fracture strain for test temperatures below 600 C. At higher testing temperatures the radiation effect on the ductility parameters was strongly strain-rate sensitive. The ductility parameters decreased markedly with decreasing strain-rate and increasing deformation temperature.
At this neutron exposure the influence of irradiation at deformation temperatures less than 600 C is reflected only in the stress-strain relationship and not in the fracture stress or strain. However, the irradiation effect for deformation at 600 C and above concerns the fracture process and not the deformation relationship. The effect on the fracture process appears to be a result of changes in the grain boundary fracture behavior.