Effect Of Irradiation At 588 K On Mechanical Properties And Deformation Behavior Of Zirconium Alloy Strip

Irradiation tests conducted for the Advanced Fuel Assembly (AFA) grid development allowed the measurement of the mechanical characteristics, growth, and relaxation of the following materials: stress-relieved, ?-annealed, and ?-quenched Zircaloy-4, and ?-annealed Zr-3Sn-1Mo. The mechanical characteristics of the zirconium alloys approached a limit value as early as 5 x 1024 n m-2, except for the ?-quenched Zircaloy-4 for which the limit value was reached later at about 5 x 1025 n m-2. Uniform elongation at 588 K showed a minimum at about 5 x 1024 n m-2; beyond this fluence, stress-relieved Zircaloy-4 presented the most marked tendency to increase. Longitudinal direction growth of annealed Zircaloy-4 and longitudinal and transverse direction growth of stress-relieved Zircaloy-4 may be expressed by the formula ? = A(?t)n where n = 0.67 (stress-relieved Zircaloy-4) and n = 0.4 (annealed Zircaloy-4). It is doubtful that the growth is associated with a density change. The stress-relaxation of the zirconium base materials is nearly complete for 4 x 1025 n m-2, with the exception of Zr-1Nb which has an intermediate behavior between those of Zircaloy-4 and Inconel 718.