Twin-roll casting of wire of magnesium alloys

Christoph Kaden ^* Kristina Kittner Madlen Ullmann Ulrich Prahl

• Institute of Metal Forming, TU Bergakademie Freiberg, Freiberg, Germany

Twin-roll casting allows the production of end-contour semi-finished products in a single forming step. While successfully tested for flat products made of Mg alloys, twin-roll casting of long products represents a new research focus. This study examined the microstructure, texture and mechanical properties of twin-roll cast wires of the common wrought alloys AZ31 and AZ80, as well as the calcium-containing alloy ZAX210. The twin-roll casting method produces wires characterized by a central segregation zone, where small and large grains form a necklace-like structure. Addition of Ca notably reduces the extent of segregation in ZAX210. Scanning electron microscopy analysis reveals the presence of fine and large network-like intermetallic phases, primarily Mg17Al12, AlMn, and Ca2Mg6Zn3. Pole figures show a pole split or a shiftet basal pole but with low intensities below 2.5. Tensile tests at room temperature show that mechanical properties of AZ80 deteriorate due to increased addition of Al compared to AZ31. Both alloys exhibit low elongation at fracture attributed to prominent central segregation and brittle intermetallic phases. In contrast, the addition of Ca in ZAX210 results in a finer and more homogeneous microstructure, leading to the highest tensile strength and elongation at fracture.