Effect of SiC Addition on the Mechanical Properties of Twin-Roll-Cast AZ31 Sheet

Abstract

The effect of SiC addition on grain refinement of an AZ31 alloy was investigated. First preliminary casting tests were carried out. Different amounts between 0.25 wt% and 1,0 wt% of SiC-particles with a diameter of about 2 μm were added to an AZ31 melt and poured into a plate mould. The resulting microstructure was observed by optical microscopy. Best results were reached with the addition of about 0.25 wt% in terms of a homogeneous microstructure and a sufficient grain refinement. Higher amounts lead to coarsening and agglomeration of precipitations. Based on these results Twin-Roll-Casting (TRC) of an AZ31 alloy with the addition of SiC-particles was conducted. For the investigations a TRC-system in laboratory scale was used. This system is part of the Twin-Roll-Casting pilot plant at the Institute of Metal Forming, which is used in collaboration with the MgF Magnesium Flachprodukte GmbH. The produced TRC-strip was cut into plates, and samples for microstructure characterization and the determination of the mechanical properties were retrieved. Compared to TRC-strip without the addition of SiC-particles a microstructure with finer precipitations and a more homogeneous distribution can be observed. Furthermore, sheets with an addition of SiC offer improved mechanical properties in TRC-condition.