| The restoration processes that take place during and after hot compression of polycrystalline copper specimens, in the temperature range 673-1023 K and the strain rate range 7.4×10^(-4) - 4.55×10^(-2)s^(-1), have been investigated by means of an interupped technique and metallography. The specimens have two different average grain size, 11 ㎛ and 102㎛. All the specimens show the single or multiple peak stresses in the flow curves, which means that the dynamic recrystallization takes place. The multiple peaks in flow curves initiate at lower strain, lower temperature and higher strain rate in small grain sized specimens than in large ones. The static restoration after dynamic recrystallization during hot deformation proceeds on sequentially there distinct mechanisms, namely metadynamic recrystallization, recovery and recrystallization. Regardless of different grain sizes, the relative importance of contribution of the three mechanisms to the static softening is shown to be high1y sensitive to the fractional prestrain of the fast peak strain. There exists a critical fractional strain (-70%) below which no metadynamic recrystallization occurs. |
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