A numerical simulation of super-plastic die forging process for Zr-based bulk metallic glass spur gear

Because of the high strength and hardness at room temperature, the processing of bulk metallic glasses (BMGs) is very difficult whether by machining or by plastic forming, and the applications of BMGs are restricted. The development of super-plastic precise forming technology, utilizing viscous flowing property of BMGs exhibited in super-cooled liquid region, will lead to wider applications of the alloys. In this paper, the different die forging processes and the deformation behaviors of Zr41.25Ti13.75Ni10Cu12.5Be22.5 BMG fine spur gear are analyzed by FEM simulation. The simulation results are compared with experimental ones. The results show that there is significant difference between the forming load–time curves and flow behaviors of the three processes; compared with the other two processes, the two-stage hole-forming process has lower forming pressure and better cavity filling effect, or has larger die cavity fullness and lower stress concentration under the same forming loads; when the two-stage hole-forming process is adopted, the inadequate filling state of cavity is helpful to decrease the hole-forming load in the second stage.