INFLUENCE OF HEAT-TREATMENT ON TENSILE BEHAVIOR OF NEUTRON-IRRADIATEDMOLYBDENUM

Tensile specimens of stress-relieved and recrystallized molybdenum wer e irradiated at five temperatures between 646 and 1073 K in FFTF/MOTA cycle 11. The exposure levels were in the range of 6.8 to 34 dpa depen ding on the irradiation temperatures. After irradiation tensile tests and hardness test were carried out at room temperature, The total elon gation of stress-relived specimens irradiated at 792, 873 and 1073 K r anged from 9 to 13%, and those of recrystallized specimens irradiated at these temperatures were almost 0%. The fracture modes of the stress -relieved specimens irradiated at 646-873 K were transgranular type an d those of recrystallized specimens irradiated at 646-1073 K were inte rgranular type, Grain growth and intergranular fracture surface were o bserved in the stress-relieved specimen irradiated at 1073 K but it st ill has 9% total elongation. It is important that the stress-relived m olybdenum had enough ductility at room temperature after neutron expos ures up to relatively high fluences.