Optimization of deformation parameters of dynamic recrystallization for 7055 aluminum alloy by cellular automaton
(1. College of Mechanic and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;
2. School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China)
2. School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China)
Abstract: In order to simulate the microstructure evolution during hot compressive deformation, models of dynamic recrystallization (DRX) by cellular automaton (CA) method for 7055 aluminum alloy were established. The hot compression tests were conducted to obtain material constants, and models of dislocation density, nucleation rate and recrystallized grain growth were fitted by least square method. The effects of strain, strain rate, deformation temperature and initial grain size on microstructure variation were studied. The results show that the DRX plays a vital role in grain refinement in hot deformation. Large strain, high temperature and small strain rate are beneficial to grain refinement. The stable size of recrystallized grain is not concerned with initial grain size, but depends on strain rate and temperature. Kinetic characteristic of DRX process was analyzed. By comparison of simulated and experimental flow stress–strain curves and metallographs, it is found that the established CA models can accurately predict the microstructure evolution of 7055 aluminum alloy during hot compressive deformation.
Key words: 7055 aluminum alloy; cellular automaton; dynamic recrystallization; hot compression; grain refinement