Improvement of bending formability of AZX612 magnesium alloy by surface texture control utilizing shot peening

Magnesium alloy is the promising light structural material, but the sheet formability is insufficient due to the basal texture. However, the basal texture is also the reason for the high strength of magnesium alloys. Therefore, a texture modification technique for localized volume is desired. In addition, bending deformation of a sheet requires tensile strain only at the outer surface. Therefore, weakening the basal texture only near the surface of one side can be sufficient to improve the bending formability. In this study, the authors attempted to improve the bending formability of AZX612 alloy by modifying texture near surface using shot peening process. Shot peening is normally regarded as the strengthening technique of the surface by introducing the plastic strain. However, this study attempts to recrystallize the deformation microstructure achieved by shot peening. Randomly oriented recrystallized grains were confirmed after the shot peening using alumina particles followed by annealing. The thickness of the texture-modified zone was thicker when the shot particle is larger. The 90-degree bending with the bending radius of 3 mm was successfully conducted without cracking after the suggested process, which was not possible for conventionally rolled and annealed sheet samples. • Recrystallization after shot peening produces random orientation distribution. • The randomly oriented zone increases as a function of the shot media size. • Bending formability improved by the suggested method.