| 2024 aluminum alloy was deformed by extrusion over the temperature range of 300-443℃ and the strain rates between 0.07-2.7/sec. Flow stress and strain rates were calculated from the ram pressure and ram speeds. The stress (σ)-strain rate (ε·)-temperature (T) relationship was found to be similar to that in creep. The experimental data were shown to fit the relationship ε·=A[sinh(ασ)ⁿexp(-ΔH/RT) where A,α, and n are material constants. The activation energy, ΔH, for 2024 aluminum extrusion were determined to be 33.6 Kcal/mole. The dislocation substructures produced during hot extrusion were studied by transmission electron microscopy. The equilibrium subgrain size was found to vary inversely with the logarithm of the Zener-Hollomon parameter, ε·exp(ΔH/RT). |
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