Constitutive behaviors of magnesium and Mg–Zn–Zr alloy during hot deformation

• Constitutive analysis of pure magnesium and ZK60 alloy during hot compression.
• Hot deformation activation energy of 135 kJ/mol based on the self-diffusion of Mg.
• The theoretical exponent of 5 for the classical hyperbolic sine equation.
• A constitutive equation with physical and metallurgical backgrounds.
• A constitutive equation suitable for comparative hot deformation studies.

The flow stress of pure magnesium and ZK60 (Mg–6Zn-0.6Zr) magnesium alloy during high-temperature deformation were correlated to the Zener-Hollomon parameter through analyses based on the apparent and physically-based approaches. It was demonstrated that the theoretical exponent of 5 and the lattice self-diffusion activation energy of magnesium (135 kJ/mol) can be set in the hyperbolic sine law to describe the peak flow stress of either the pure Mg or highly alloyed one with zinc and zirconium. As a result, the influence of alloying elements upon the hot flow stress of the ZK60 alloy was characterized by the proposed approach based on the simple material's constants. One of the main prospects of the proposed approach, which is not possible by the conventional approach, is its ability to be utilized in the comparative hot working and alloy development studies.

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