A hybrid process for forming thin-walled magnesium parts

Weight reduction is one of the primary concerns in the automotive and electrical industries. As the lightest metal, magnesium is attracting more and more interests from both the industrial and academia researches. Conventionally, magnesium alloys are formed at elevated temperatures, at which thermally improved formability is sensitive to temperature and strain rate. Due to limitations in forming speeds, tooling strength and narrow processing windows, complex thin-walled parts cannot be made by traditional warm drawing or hot forging processes. A hybrid process, based on deformation mechanism at elevated temperature, is proposed that combines the warm drawing and hot forging modes to produce an aggressive geometry at acceptable forming speed. Process parameters, such as temperatures, forming speeds, etc., are determined by FEM modeling and simulation. Sensitivity analysis under the constraint of forming limits of Mg alloy sheet material and the strength of tooling material is carried out. The proposed approach is demonstrated on a conical geometry with thin walls, and with bottom features. Results show that designed geometry can be formed in about 8 s. This cannot be formed by conventional forging while around 1000 s is required for warm drawing. This process is being further investigated through controlled experiments.