Y V R K Prasad
Articles written in Bulletin of Materials Science
Volume 5 Issue 5 December 1983 pp 459-464
Variations in the grain size and basal texture in magnesium hot-rolled in the temperature range 570–770 K have been studied and compared with those observed in specimens hot-rolled at 570 K and annealed at different temperatures in the range 570–770 K. In specimens hot-rolled temperatures higher than 670 K, a rapid increase in grain size and a weakening in basal texture have been observed. The yield stress of the specimen is lower than that predicted by the Hall-Petch relation and this result is interpreted in terms of the reduced basal texture. The dependence of yield stress on grain size in magnesium hot-rolled at different temperatures lower than 670 K matches with that observed in specimens annealed at different temperatures.
Volume 14 Issue 5 October 1991 pp 1241-1248
The influence of stacking fault energy (SFE) on the mechanism of dynamic recrystallization (DRX) during hot deformation of FCC metals is examined in the light of results from the power dissipation maps. The DRX domain for high SFE metals like Al and Ni occurred at homologous temperature below 0·7 and strain rates of 0·001 s−1 while for low SFE metals like Cu and Pb the corresponding values are higher than 0·8 and 100 s−1. The peak efficiencies of power dissipation are 50% and below 40% respectively. A simple model which considers the rate of interface formation (nucleation) involving dislocation generation and simultaneous recovery and the rate of interface migration (growth) occurring with the reduction in interface energy as the driving force, has been proposed to account for the effect of SFE on DRX. The calculations reveal that in high SFE metals, interface migration controls DRX while the interface formation is the controlling factor in low SFE metals. In the latter case, the occurrence of flow softening and oscillations could be accounted for by this model.
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