Rolling and recrystallization behavior of pure zirconium and zircaloy-4

Abstract

Rolling and recrystallization of pure zirconium and zircaloy-4 have been studied comparatively in this paper. For the as-received condition, zirconium presented a recrystallized microstructure and the alloy a typical basketweave microstructure. Comparative rolling tests were performed, and reduction limit curves as a function of the rolling temperature were determined. At room temperature, pure Zr shows substantial plasticity and the alloy presents low ductility and many cracks. The ductility of both materials increases significantly with an increase in rolling temperature at the range between 300 and 500ºC. In static recrystallization studies, samples of the two materials with similar recrystallized grain size were cold-rolled with a thickness reduction of 55%. During annealing, pure Zr and the alloy soften by recovery and recrystallization, however the relative contribution of recovery is lesser pronounced in the alloy, for which the recrystallization temperature increases by about 60°C.

Stress relieved Zircaloy-4 recovery and recrystallization during fast anisothermal transients

“…The degree of recrystallization after each thermal transient was assessed via microhardness measurement. This method was used during previous studies [7] [8] [9] [10] [15] [19] [20] [21]. Experiments were therefore carried out to look for any difference in the recrystallization kinetics between rapid transients and long-time isothermal tests reported in the literature.…”