Simulation Study Of Al-5.5Cu-0.3Mg Alloy During Multi-pass Hot Compression Process

Al-Cu-Mg alloy (Cu/Mg≥8) is an aluminum alloy that can be strengthened by heat treatments. Its rolling sheets with excellent mechanical properties, ballistic resistance, welding properties and stress corrosion resistance are widely used in aviation, spaceflight, and war industry. As the products escalating, the demand for the performance of products is higher and higher, therefore, it is necessary to optimize the production process. In order to optimize the rolling process parameters and obtain rolling pieces with good performance, researches of the deformation behaviors and the microstructure evolution during the material multi-pass deformation process become important.Axisymmetric compression tests for cylindrical samples of Al-5.5Cu-0.3Mg alloy were carried out on Gleeble-1500 system to study the flow stress behaviour of the alloy during multi-pass hot compression in the paper. The recrystallization kinetic model of Al-5.5Cu-0.3Mg alloy was obtained by calculating the flow stress curve of double-pass compression tests using softening method. In addition, under the four different experimental conditions, four-pass hot compression simulation experiments were carried out to collect the flow stress curves of four-pass hot deformation for calculating the softening rate between different passes. Results showed that in each pass the softening rate increased with the increase of passes and initial deformation temperature.The microstructure and mechanical properties were analyzed by observation of OM and TEM, and by measurement of hardness of hot compression deformed samples. Results showed that there was no dynamic recrystallization in the alloy in the first pass of deformation, while in the second pass there was dynamic recrystallization. Moreover, Static recrystallization occured in the four passes, and the hardness in the same pass became higher with the increase of final deformation temperature.By importing the constitutive equations and recrystallization mathematical model, and by re-programming on DEFORM-2D software with FORTRAN, it is realized to make a coupled thermo -mechanical simulation on the multi-pass hot compression of Al-5.5Cu-0.3Mg alloy. The simulation results show that the distribution of deformation temperature, effective stress, effective strain and strain rate, and are uneven. The values in the center and near the diagonal position are obviously higher than other location; and the recrystallization fraction in the center is larger than that near the surface of the sample. The recrystallization percentage of the whole sample increases as the passes increasing.