Formability and viscoplastic self-consistent simulations of Mg-4Zn-X-Ca alloys were carried out in an effort to understand the relationship between deformation behaviors and room-temperature formability. The microstructural, textural and mechanical properties of Mg-4Zn-X-Ca alloys were also investigated. All of the alloys showed a sound twin roll cast microstructure without the occurrence of inverse segregation. Annealed Z4 and ZSX400 alloys exhibited strong basal textures; however, the other Mg alloys showed weaker basal textures with splitting in the transverse direction resulting from their different types of static recrystallization. Among the Mg-4Zn-X-Ca alloys, the ZAX400 alloy exhibited a high yield strength value of 189.3 MPa and excellent formability of 7.5 mm with enhanced yield isotropy, comparable to those of Al alloys. The higher formability values of the Mg-4Zn-X-Ca alloys were closely related to the modified deformation behaviors resulting from the texture evolution. The ZX40, ZAX400, ZWX400 and Z
CX400 alloys, which were more formable, had higher relative activity of the basal <a> slip upon compression deformation, thus improving the yield isotropy. However, the Z4 and ZSX400 alloys in this study, had relatively low activity of the basal <a> slip in compression modes, as caused by their different CRSS ratios (tension twin/basal <a> slip).
