The rotational speed notably influences both the stirring and mixing processes of the material. Furthermore, it affects the heat input during friction stir welding, subsequently impacting the recrystallization mode within the welding process. This study examined the impact of the rotational speed on grain morphology, grain orientation, texture type, and strengthening phase across various regions of the weld. The results show that the coarse grains of the base material are refined due to the occurrence of dynamic recrystallization during welding process. When the rotational speed reaches 700 rpm and 800 rpm, a (111) [1 \(\overline{1}\) 0] shear texture was formed by continuous dynamic recrystallization (CDRX). When rotates at 900 rpm, a necklace-like structure was formed due to the occurrence of geometric dynamic recrystallization (GDRX). As the rotation speed increases, there was a corresponding amplification in the strain rate. Consequently, the mode of recrystallization transitions from CDRX to GDRX. The weld nugget zone exhibited a (001) [100] cubic texture and (12 \(\overline{4}\) ) [211] texture, attributable to the process of discontinuous dynamic recrystallization. Additionally, with an increase in welding heat input, there was an increase in the volume of plastic metal. This resulted in a stronger degree of recrystallization and a weakening of the phenomenon of grain preferential orientation. Due to the eccentric movement of the tool, alternating grains with different orientations in the weld nugget zone form a band structure, and the width of band is equal to the distance traveled by the tool in one rotation. A rotation speed of 900 rpm stimulates the formation of a needle-like Mg9Si7Ag2Al3 phase within the welded joint. The tensile strength of the welded joint was increased to 245 MPa.
