Effect of Subsequent Annealing Temperature on Dynamic Deformation and Fracture Behavior of Submicrocrystalline Al-4.4%Mg Alloy via Equal-Channel Angular Pressing

ECAP 가공된 초미세 결정립 Al-4.4%Mg 합금의 동적 변형 및 파괴거동에 미치는 후-열처리 온도의 영향

The influence of subsequent annealing treatment on the dynamic deformation and the fracture behavior of submicrocrystalline Al-4.4%Mg alloy is investigated in this study. After inducing an effective strain of 8 via equal-channel angular pressing at $200^{\circ}C$, most of the grains are considerably reduced to nearly equiaxed grains of $0.3{\mu}m$ in size. With an increment of various subsequent heat treatments for 1 hour, resultant microstructures are found to be fairly stable at temperatures up to $200^{\circ}C$, suggesting that static recovery will be dominantly operative, whereas grain growth is pronounced above $250^{\circ}C$. The results of tensile tests show that yield and ultimate tensile strength decrease, but elongation-to-failure and strain hardening rate increase with an increase in annealing temperatures. The dynamic deformation and the fracture behavior retrieved with a series of torsional tests are explored with respect to annealed microstructures. Such mechanical response is analyzed in relation to resultant microstructure and fracture mode.