Effect of Precipitation of Impurities during Annealing on the Rate of Recovery and Recrystallization in 1050 Aluminum Hot-Rolled Sheets

Abstract

It is well known that the recovery and recrystallization of commercially pure aluminum are influenced by the dissolved impurities, iron and silicon. In this study, we assumed that the dissolved impurities precipitate on the cell boundaries and subgrain boundaries during annealing and control the rate of recovery and recrystallization in the commercially pure aluminum and adopted a new rate equation developed by Yamamoto, which contains the term of the particle number that exponentially changes. It was found that the entire reaction was divided into two reactions, i.e., the recovery and recrystallization, which processes were analyzed by this equation. The entire reaction was expressed by superimposing the two processes. For the recovery process, the value of the time exponent is 0.5, which means control of the dislocation pipe diffusion, by which impurities precipitate on the dislocation cell boundaries. For the recrystallization process, the value of the time exponent is 1, which means control of the grain boundary diffusion, by which impurities precipitate on the subgrain boundaries. Therefore, our assumption was verified by this new equation. Based on the activation energy, we consider that the precipitation of silicon during the recovery and that of iron during the recrystallization control the reaction rate.