Improvement of Radiation-and Thermal Stress-Induced Springback Degradations in Invar Alloy Using Repeated Radiation Plus Hot-Then-Cold Treatments

Abstract

A method is proposed to improve both the gamma-ray radiation-and thermal stress-induced degradations of springback characteristics in Invar alloy. Invar foil was first subjected to a 30 kGy-irradiation followed by 60 cycles of hot-then-cold (radiation+hot-then-cold) treatments. It was found that both the radiation-and thermal stress-induced springback degradations in Invar foil tended to be stabilized after 5 cycles of radiation+hot-then-cold treatments. XRD analyses showed no difference between controls and experimental samples, thus excluding the possibility of structural or phase transformations. The weak bonds inside the foil possibly rearranged and recovered during the radiation+hot-then-cold processes, resulting in radiation-and thermal stress-hard springback behaviors.