Development of a magnesium alloy sheet with enhanced formability for vehicle lightweighting

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With their low density and high specific stiffness, magnesium alloys offer great possibilities for vehicle lightweighting. One of the issues associated with their use is their low formability at room temperature. At higher temperatures, their formability is improved due to the activation of additional slip systems. However, forming at high temperatures involves additional tooling and energy costs and lengthens the cycle time. Another way to improve magnesium formability is to control its texture and microstructure. A random texture, as well as fine grains, lead to a reduction of twinning and an increase in formabilty. Typically, more random textures are obtained by the addition of rare earths elements (REEs) as alloying elements. However, these elements are costly and there are many environmental and health issues associated to their production, processing, and utilization. Recently, asymmetric rolling has been studied as a way to produce fine microstructures in various metal sheets. During this process, the difference in speed between the top and bottom rollers induces shear stresses that promote recrystallization, therefore producing sheets with finer grains. Sheets produced using this process show improved formability and good mechanical properties. In this project, the formability of magnesium sheets produced by asymmetric rolling will be studied. Two common alloys (AZ31 and ZEK100) will be used as a baseline, and compared with a new alloy that will be developed. This new alloy is being developed by German partners with the aim of offering, to the automotive sector, a light alloy with improved formability and mechanical properties (with an increased proportion of aluminium in the alloy). The formability studies performed in this project will allow our Canadian industrial partner to assess the potential uses of the baseline magnesium alloy sheets, as well as the new alloy sheets, for the production of automotive parts by stamping at room temperature and moderate temperatures (up to 250°C). With the growing demand for lightweight automotive components, research projects on new materials and technology are mandatory for our industries to maintain their leadership in this highly competitive market.