Constitutive Modeling and Understanding of the Hot Compressive Deformation of Mg-9.5Zn-2.0Y Magnesium Alloy With Reduced Number of Strain-Dependent Constitutive Parameters

초록

The hot compressive flow behavior of the cast Mg-9.5Zn-2.0Y alloy as a function of strain was analyzed, and the degree of dependence of the parameters (A: material constant, n(2): stress exponent, Q(c) : activation energy for plastic flow and a: stress multiplier) of the constitutive equation () upon the strain was examined in a systematic manner. This is to explore the possibility of representing the hot compressive deformation behavior of metallic alloys in a simple way by using a reduced number of strain-dependent constitutive parameters. The analysis results for several different cases can be interpreted as follows: (1) Q(c) can be treated as being strain-independent, which is physically sensible; (2) while only the microstructure changes as a function of strain at low flow stresses, as the flow stress increases, the power-law creep deformation and power-law breakdown mechanisms change; (3) the regime where only A is strain dependent expanded to higher strain rates and lower temperatures as the strain increased, suggesting that the number of the strain-dependent parameters decreases as the initial microstructure is refined by dynamic recrystallization, and the microstructure approaches a steady state.

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