Hot tensile deformation mechanism and constitutive equation of AZ61Ce magnesium alloy sheets

Abstract

To explore the hot tensile deformation characteristics of aged and homogenized AZ61Ce magnesium alloy sheets, the constitutive equation, initial condition of dynamic recrystallization (DRX) and microstructure are investigated in terms of uniaxial hot tensile testing in a temperature range of 473–723 K and a strain rate range of 0.003–0.1 s−1. Dynamic strain aging (DSA) is easily caused under low temperature deformation conditions for the homogenized AZ61Ce sheet, while its counterpart aged AZ61Ce is not sensitive to DSA under these conditions. The constitutive equations for both the aged and homogenized AZ61Ce alloy sheets under peak stress are established by regression analysis of an Arrhenius-type hyperbolic sine function. The activation energy, Q, of the homogenized AZ61Ce alloy sheet is higher than that of the aged one because of the higher amount of solved Al atoms in the homogenized alloy matrix. The study of critical strain (εc) reveals that Mg17Al12 particles precipitated by aging promote the DRX nucleation and grain refinement during tensile deformation. In addition, the softening mechanism of the AZ61Ce alloy sheets at temperatures below 573 K is primarily dynamic recovery, while at temperatures above 573 K, it is DRX.