13th International Conference on Fracture June 16–21, 2013, Beijing, China -4- each angle. Before and after annealing, nominal stress and strain has different figure in each angle. In other words, strain-stress curve shows anisotropy in each annealing conditions. However, the strength of anisotropy differs by annealing. Figure 5. Strain-stress curve of (a) as-received specimen and (b) 450°C annealed specimen In order to analyze this result, ultimate tensile stress (σmax) and maximum strain ( ɛmax) are plotted in Fig. 6. From Fig. 6(a), ultimate tensile stress is high in 15° and 75°, and is especially low in 45°, so we can see strong anisotropy in as-received specimens. However, in 285° and 450°C annealed specimens, ultimate tensile stress become higher in 45°, and lower in other angles, so it can be said that anisotropy is weakened by annealing. Fig. 6(b) shows that strain also has anisotropy. Strain of as-received specimens is extremely high in 45° to 75°, but by annealing, strain of 0° to 30° becomes higher, on the other hand, strain of 45° to 75° becomes lower. By annealing, strain of 30° to 90° is flat, so it can be said that anisotropy is weaken by annealing. Figure 6. (a) Ultimate tensile stress and (b) Maximum strain of each specimen
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