Constitutive Behavior for Quenching of Al-Cu-Mg Alloy With Consideration of Precipitation

The deformation behavior of as-quenched 2024 Al-Cu-Mg alloy has been experimentally studied. The experiments are designed to cool specimens to the desired temperature with a constant cooling rate, i.e., 5 K/s. Isothermal tensile tests are performed over a range of 573-723 K temperature and (0.01, 0.1, and 1 s(-1)) strain rates to find out the flow stresses and microstructures after deformation. Due to the nonuniform deformation mechanisms (solid solution versus solid solution and precipitation), two types of Arrhenius model are established for the temperature range of 573-673 K and 673-723 K, respectively. For temperature between 573 and 673 K, the activation energy is dependent on temperature and strain rate, and the value of activation energy decreases with the increases of temperature and strain rate. Compared with the ideal variation trend with no consideration of precipitation, the largest difference of activation energy is found at the temperature of 623 K which is the nose temperature of 2024 alloy.