The flow stress of an aluminium-lithium alloy during plastic deformation at elevated temperatures

The behavior of the steady flow stress of 2091 aluminium-lithium alloy during high temperature plastic deformation is studied by isothermal compression of cylindrical specimens using a Gleeble 1500 heat-analogue machine. The results reveal that the 2091 Al-Li alloy is sensitive to positive strain rate. Anomalous steady state deformation is noted when the alloy is deformed in the temperature range of 300 degrees C similar to 500 degrees C at strain rates within the range of 10(-3)s(-1) similar to 10.0s(-1). The flow stress remains a constant during steady state deformation It does, however, increase with increasing of strain rate and decreasing of deformation temperature. These effects can be attributed to an equilibrium between dynamic softening and strain hardening during the steady state deformation. Further investigations, of?the flow stress indicate that the plastic deformation of the 2091 alloy at elevated temperature is controlled by thermally activated processes, in which the flow stress can be correlated to strain rate and temperature in terms of the so-called temperature-compensated strain rate, i.e. Zener-Hollomon parameter. Semi-empirical representations of the flow stress are derived from experimental data by linear regression analysis for the 2091 Al-Li alloy of interest during plastic deformation at elevated temperature.