2018 Volume 59 Issue 10 Pages 1551-1559
The effect of the soaking conditions of ingots on the rate of recovery and recrystallization in an A1050 hot-rolled sheet during annealing at 350°C was investigated. The rate of the recovery and recrystallization with no soaking and 600°C/8 h WQ (water quenching) was slower than that of 450°C/8 h FC (furnace cooling). Many dissolved impurities (Fe, Si), which were contained in the no soaking and 600°C/8 h WQ conditions cause the delay in the recovery and recrystallization. Particularly, in the no soaking condition, no precipitation was observed within the grains of the ingot and the hot-rolled sheet. On the other hand, in the 450°C/8 h FC condition, the recovery and recrystallization was too fast. Fine granular precipitates of less than 0.1 µm in diameter were observed and there were few dissolved impurities in the ingot and the hot-rolled sheet. Pinning of the subgrain boundaries by these fine precipitates was not observed. The normalized change in the Vickers hardness and electrical conductivity was divided into a recovery reaction and a recrystallization one, respectively, by a newly developed rate equation. The role of the impurities in the recovery and recrystallization was explained and clarified by the result of using this equation.
This Paper was Originally Published in Japanese in J. JILM 67 (2017) 284–291.