| The deformation maps are constructed based on a dynamic material model for hot working of extruded Al 2024 composites reinforced with 15 vol. % SiC_p at the temperatures ranging from 320 to 520℃ and the strain rates ranging from 0.1 to 3.0/sec by torsion test. The values of strain rate sensitivity(m) of the composites were used for establishing the deformation maps. The efficiency of power dissipation, expressed as η= 2m/(2m＋1), is plotted as a function of temperature(T), pass strain(ε_i), and strain rate(ε`) to provide the optimum hot working condition for dynamic recrystallization (DRX). Also, the DRX domain of the composites has been analyzed from the relationship between the efficiency and deformed microstructure. With the increase in the deformation temperature and the decrease in the strain rate, the efficiency of the composites increased. The characteristics of these results have been investigated with the help of hot ductility measurement and Zener-Hollomon parameter(Z=ε` exp(Q/RT). It was found that the optimum hot working condition for DRX is 430∼450℃ and 0.5/sec. |
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