The recrystallization of 99.997% chromium

Abstract

Recrystallization data were obtained on samples of warm worked 99.997% chromium that had been deformed 60% by rolling. The per-cent recrystallized as a function of time was obtained using quantitative optical microscopy techniques. Specimens in various stages of recrystallization yielded activation energies of about 80 kcal/mole. The recrystallization data were analyzed using the theory of Avrami. Deviations from the theoretical equations occurred in the initial part and latter stages of the recrystallization process. The initial deviation was attributed to the overlap of recovery with recrystallization, which was confirmed by transmission electron-microscopy studies, while the latter deviation was attributed to the lack of perfectly random nucleation. Isothermal grain-growth measurements were conducted on the growing, unimpinged, recrystallized grains. An initial decrease in the growth rates was attributed to a decrease in the strain energy by concurrent recovery and recrystallization processes occurring during the initial stages of recrystallization. When the recovery processes were essentially complete, the growth rates became constant until extensive impingement of the grains began to occur.