Regular Article

Dynamic recrystallization kinetics and microstructure evolution of 7055 aluminum alloy during hot compression

¹ College of Mechanic and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, PR China
² State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, PR China

^* e-mail: 297zhangtao@nuaa.edu.cn

Received: 4 March 2019
Accepted: 2 August 2019

Abstract

7055 aluminum alloy is widely used in manufacture of key components in fields of aerospace. Hot forming is the vital process for manufacture of components. Dynamic recrystallization (DRX) plays a significant role in grain refinement. Hot compressions and metallographic tests are conducted. Equations of DRX kinetics are fitted by least square method and finite element models (FEM) coupled with DRX kinetics equations are established to study the effects of forming parameters on microstructure evolution. The results show that true stress increases with ascending strain rate and decreases with ascending temperature. Large strain, small strain rate and high temperature are beneficial to sufficient DRX fraction and grain refinement. Deformation energy and thermally activated motion of atoms and molecules resulting from large strain and high temperature contribute to dynamic nucleation; meanwhile, small strain rate provides sufficient time for growth of recrystallized grains. The FEM results agree with experiments.