Hot Compressive Deformation and Processing Maps of ZK60 and ZK60-1.0Er Magnesium Alloy

Abstract

The hot compressive deformation behavior of ZK60 and ZK60-1.0Er magnesium alloy occurring homogenization was investigated by Gleeble-1500D thermal simulator, analyzing the characteristics of the flow stress changes of the two kinds of magnesium alloys at the temperature 160-420℃, the strain rate 0.0001-1.0s-1. The experimental results show that the two kinds of magnesium alloys are deformation temperature and strain rate sensitive materials, with the decrease of deformation temperature and the increase of strain rate, the flow stress increases; meanwhile, flow stress value tends to be constant after flow stress reaches peak value. Rare earth Er reduces the average deformation activation energy from 183kJ/mol to 153kJ/mol, and the stress index n value is improved from 6 to 8; dynamical recrystallization critical stress σc value decreases, with the increase of deformation temperature and the decrease of strain rate, and at 420℃/1.0s-1, rare earth Er reduces the critical stress σc value of occurring dynamic recrystallization from 76MPa to 50MPa. According to the obtained processing map by material dynamic model, combining with microstructure observations, rare earth Er reduces instability areas of ZK60 magnesium alloy, and increases power dissipation efficiency value ηmax from 35% to 45% at safety zone, promotes dynamic recrystallization grain nucleation, but inhibits recrystallization grain growth.

Keywords

• zk60
• er
• hot compressive deformation
• constitutive equation
• processing map