Constitutive model and hot workability of 2195 Al-Li alloy based on stress correction

Abstract

The isothermal compression tests of 2195 Al-Li alloy annealed at 400 - 490 ℃ and strain rate 0.01-10s−1 were carried out. The true stress-strain curve obtained from the experiment was modified by friction force and temperature rise effects, and the constitutive relationship was established based on the modified true stress-strain curve. The results show that the correlation coefficient R is 0.99584, and the mean absolute error (AARE) is only 3.698%, which indicates that the constitutive model can well predict the flow stress of 2195 Al-Li alloy under different deformation parameters. Furthermore, based on the modified stress-strain data, the activation energy processing diagram (AEP) is established by coupling the rheologic instability diagram(conventional hot processing map，CHP) with the activation energy value Q, and the hot-working window of the alloy is optimized as follows: the strain rate is less than 0.4 s−1, and the temperature is 475-490 ℃. The constitutive relationship and activation energy thermal processing diagram of 2195 Al-Li alloy established based on the modified stress and strain can lay a good foundation for the finite element simulation of the 2195 Al-Li alloy rheological process and the formulation of processing parameters.

Keywords

• 2195 al-li alloy
• stress-strain correction
• rheological behavior
• constitutive equation
• activation energy processing diagram