The Improved Arrhenius Model with Variable Parameters of Flow Behavior Characterizing for The As-Cast AZ80 Magnesium Alloy

In order to study the hot working behaviour of as-cast AZ80 magnesium alloy, a series of isothermal upsetting tests with height reduction of 60% were performed at the temperature range of 523-673 K and the strain rate range of 0.01-10 s(-1) on a servo-hydraulic Gleeble-1500 machine simulator. Based on the regression analysis for Arrhenius type equation of flow stress, the activation energy of deformation was determined to be Q = 168.6606 KJ.mol(-1), and material constants A, n and alpha in the equation also were calculated respectively to predict the peak stress during hot deformation. A 7th order polynomial was used to represent the influence of strain on these parameters (i.e Q, lnA, n and alpha). The Arrhenius equation was further developed by taking account of the effect of strain on the flow stress to describe the flow behavior during the whole experimental temperature and strain rate range. Then comparison between the predicted results and test results shows that the correlation coefficient and average absolute relative error is 0.99 and 6.63%, respectively. The flow stress predicted by developed equation can give an accurate and precise description of the flow behaviour for AZ80 magnesium alloy.