Model of critical strain for dynamic recrystallization in 10%TiC/Cu-Al₂O₃ composite

Abstract

Using the Gleeble-1500D simulator, the hot deformation behavior and dynamic recrystallization critical conditions of the 10%TiC/Cu-Al₂O₃ (volume fraction) composite were investigated by compression tests at the temperatures from 450 °C to 850 °C with the strain rates from 0.001 s⁻¹ to 1 s⁻¹. The results show that the softening mechanism of the dynamic recrystallization is a feature of high-temperature flow true stress-strain curves of the composite, and the peak stress increases with the decreasing deformation temperature or the increasing strain rate. The thermal deformation activation energy was calculated as 170.732 kJ/mol and the constitutive equation was established. The inflection point in the ln θ-ɛ curve appears and the minimum value of −∂(lnθ)/∂ɛ-ɛ curve is presented when the critical state is attained for this composite. The critical strain increases with the increasing strain rate or the decreasing deformation temperature. There is linear relationship between critical strain and peak strain, i.e., ɛ_c=0.572 ɛ_p. The predicting model of critical strain is described by the function of ɛ_c=1.062×10⁻²Z^0.0826.

Keywords

10%TiC/Cu-Al₂O₃ composite / hot deformation / constitutive equation / dynamic recrystallization / critical condition

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