CONSTITUTIVE BEHAVIOR OF WROUGHT MAGNESIUM ALLOY AZ61

摘要

The data on the hot workability of the magnesium alloy AZ61 available in the open literature are based on the tests over narrow ranges of temperatures and strain rates and thus are of limited use for bulk-forming processes. The objective of the present research was to perform a detailed constitutive analysis of the alloy, on the basis of the results obtained from uniaxial compression tests at temperatures from 250 to 450°C and strain rates from 0.01 to 100 s(-1). The shape of the flow curves suggested the occurrence of twinning followed by dynamic recrystallization. The alloy did not display steady-state flow stress behavior such that the constitutive analysis of the alloy using the hyperbolic equation must take strain into account. It was found that the constitutive constants were indeed strain dependent. A method to apply the hyperbolic constitutive equation at given strains was developed, with which an accurate strain-stress database for the alloy could be established.