Shot peening test on 2196 Al-Li alloy was carried out under the processing parameters (Table 2) by shot
peening machine. The machine movement speed was 404 mm/min. As shown in Fig. 2, there were four workpieces
peened in the test. The workpieces were “ T ” extrusions with a small Hook. The length of the workpieces was
1200 mm, the cross-sectional thickness was 2 mm. As described in the paper by Nouguier-Lehon et al. (2013),
they used confocal microscopy to study the surface morphology. In the present study, we used the JCM-6000
scanning electron microscope (SEM) to study the surface of Al-Li alloy before and after shot peening to get better
result, the samples were cut from the workpiece. In order to obtain better results and increase equipment life, we
used the secondary electron image mode. The electron beam mode was PC-std, the filament mode was Fil-std. The
setting of acceleration voltage mode was High-Vac, and the voltage setting was 10 kV, enlarged 40 times.