Deformation Behavior and Cavitation of AA2017 at Elevated Temperatures

Abstract

In this work, deformation behavior of AA2017-T4 at elevated temperatures was studied employing uni-axial tensile and creep experiments. Tensile tests were carried out at temperatures varying 150–500 °C under different strain rates then, a combination of neural network and dynamic material modeling was utilized to construct the processing maps. Furthermore, creep experiments were conducted to assess inelastic deformation behavior of the alloy at temperatures between 150 and 225 °C and stresses in the range of 150 to 230 MPa. Microstructural evaluations were carried out for determination of microstructural changes and formation of voids and cavities within the samples. The results showed that dynamic precipitation could occur during deformation at temperatures 175–225 °C leading to negative strain-rate sensitivity at true strains larger than 0.1. The main softening process was detected as dynamic recovery at temperatures higher than 250 °C however, dynamic recrystallization could also occur at low strain rates and temperatures higher than 400 °C. The activation energies for hot deformation were computed as 380.6 kJ mole−1 at 250–350 °C and it was reduced to 224.7 kJ mole−1 for the range of 350–500 °C. This showed the hard particle could significantly change rate of flow softening. The creep activation energy was determined as 169.5 kJ while the stress-exponent varied between 5.5 and 10.1 at temperatures between 150 and 225 °C indicating that dynamic recovery controlled by dislocation climb could be the governing creep mechanism.