NEUTRON DOSE AND TEMPERATURE EFFECTS ON MECHANICAL PROPERTIES OF TITANIUM ALLOYS

摘要

The present paper summarises the work carried out on the effect of neutron irradiation up to a dose level of 0.3 dpa on the mechanical properties of the Ti6Al4V alloy in the temperature range from 22 to 350°C. Tensile properties of the Ti6A14V (α +β) alloy showed initial softening followed by hardening and lack of work hardening when neutron dose increased from 0.001 to 0.1 dpa at the ambient temperature. At a dose level of 0.3 dpa a clear change in tensile properties was observed when irradiated and tested at temperatures up to 150°C compared to those at 350°C. Hardening and decrease in uniform elongation were observed at temperatures up to 150°C whereas clear work hardening behaviour was observed at 350°C . Irradiation at 350°C seemed to have no effect on the low cycle fatigue behaviour of the Ti6A14V (α +β) alloy. Fracture toughness of the Ti6A14V (α +β) alloy showed continuous decrease with increasing dose level from 0.001 to 0.1 dpa at 150°C. At the dose level of 0.3 dpa the fracture toughness seemed to increase with increasing temperature reaching a maximum at about 250°Cand decreased again at 350°C. The large irradiation hardening and decrease of fracture toughness in the Ti6A14V (α +β) alloy appears to be related to radiation dose level, temperature and radiation-induced precipitation in the a-phase of the Ti6A14V alloy.