## 3 Results and Discussion
### Texture Evolution of Alloy during Annealing
#### 3.2.2 Annealing Temperature Effect  
Figure 11 shows the \(\phi\)2 = 0\({}^{\circ}\) ODF sections of 80% cold-rolled samples after different annealing treatments. The texture change is minor after annealing at 330 \({}^{\circ}\)C for 0.5 h (Figure 11a,b). When the annealing temperature reached 380 \({}^{\circ}\)C (Figure 11c), and then exceeded 420 \({}^{\circ}\)C (Figure 11d,e) significant changes occurred. With increasing annealing temperature, the amounts of Brass, copper, and S textures decreased (especially Brass and S textures, Table 4), while the amounts of cube and Goss textures increased with increasing temperature (especially that of the cube texture, of which the volume fraction increased from 2.82% to 36.53% after annealing at 470 \({}^{\circ}\)C for 0.5 h). Figure 12a-c shows the EBSD-derived inverse pole figure (IPF) images of 80% cold-rolled samples, annealed at different temperatures for 0.5 h. There are several equiaxed \begin{table}
\begin{tabular}{c c c c c c} \hline
**Heat Treatment** & **Cube (\%)** & **Goss (\%)** & ** Brass (\%)** & **Copper (\%)** & **S (\%)** \\ \hline Before annealing & 2.82 & 3.06 & 35.46 & 8.63 & 25.80 \\
330 \({}^{\circ}\)C/0.5 h & 10.56 & 4.27 & 26.85 & 7.66 & 12.66 \\
380 \({}^{\circ}\)C/0.5 h & 17.65 & 7.67 & 15.64 & 5.56 & 8.47 \\
420 \({}^{\circ}\)C/0.5 h & 20.64 & 15.72 & 11.61 & 4.68 & 4.35 \\
470 \({}^{\circ}\)C/0.5 h & 36.53 & 17.33 & 8.43 & 3.15 & 2.82 \\ \hline \end{tabular}
\end{table} 
Table 4: Volume fractions of different textures, calculated based on the ODF of 80% cold-rolled samples after different annealing treatments (with a measurement accuracy of 0.05%). Figure 11: Sections (\(\varphi\) = 0\({}^{\circ}\)) of ODFs on the rolling plane of the cold-rolled sample after different annealing treatments: (**a**) before annealing; (**b**) 330 \({}^{\circ}\)C/0.5 h; (**c**) 380 \({}^{\circ}\)C/0.5 h; (**d**) 420 \({}^{\circ}\)C/0.5 h; (**e**) 470 \({}^{\circ}\)C/0.5 h.  
recrystallized grains with sizes of 5-10 \(\upmu\)m when the samples are annealed at 330 \({}^{\circ}\)C for 0.5 h (Figure 12a). With the increase in temperature, the recrystallized grains grow (Figure 12b,c). Figure 12d-f demonstrates the cube-orientated grains extracted from Figure 12a-c, respectively. Agreeing with the results in Figure 11, most of these recrystallized grains show a cube-like orientation, and, with the increase in temperature, cube-orientated grains grow faster and are thus much larger than grains with other orientations. Preparation and Fatigue Crack Propagation Behavior of 2524-T3 Aluminum Alloy with a Strong Brass Texture  
Based on the above analysis, reducing second-phase particles is conducive to the formation of a strong deformation texture (such as the Brass texture), while increasing the annealing temperature would weaken the deformation texture. Besides, increasing deformation will, on the one hand, increase deformation texturing during cold rolling, while on the other hand facilitating recrystallization during subsequent annealing. To produce a strong deformation texture in a T3-tempered sample, Sample 1 was pre-annealed at 495 \({}^{\circ}\)C for 2 h to minimize the number of second-phase particles. Then, it was cold-rolled to 10% deformation in each pass, and a staged annealing treatment was applied (330 \({}^{\circ}\)C/0.5 h + 380 \({}^{\circ}\)C/0.5 h + 420 \({}^{\circ}\)C/0.5 h) after each pass to limit the potential for recrystallization. After eight passes of cold rolling and annealing, the material was solution-treated at 500 \({}^{\circ}\)C for 0.5 h and then naturally aged for about 96 h to achieve a T3 temper. To assess the deformation texture effect on the fatigue properties of the alloy, a T3-tempered sample (Sample 2) with and without evident texture, which can be obtained following the same process as for Sample 1 except for rotating the rolling direction by 90\({}^{\circ}\) after each pass, was examined.