Direct strip casting and hot rolling of an AZ31 magnesium alloy

An AZ31 magnesium alloy was cast by the direct strip casting (DSC) process. Prior to casting, the melt was treated with a commercial Al–Ti–B refiner. By subsequently hot rolling the cast strip at 400 °C, a 1 mm thick sheet was produced. The microstructures of DSC and the hot rolled magnesium were examined by optical microscopy and the hardness was measured. The flow curves of the cast material were determined at 200 °C, 300 °C and 400 °C by compression tests with a deformation dilatometer and dynamic recrystallization was found to take place at 300 °C and 400 °C. The thermal stability of the hot rolled sheet was investigated by an isochronal annealing treatment over a wide range of temperatures between 100 °C and 460 °C.

Research highlights▶ Addition of a AlTiB master alloy leads to refinement of an AZ31 magnesium alloy cast by the direct strip cast (DSC) method. ▶ Hot deformation behaviour of DSC material exhibits no difference between longitudinal and transverse to casting direction. ▶ Isochronal annealing of hot rolled (69% and 92%) DSC material results in different recrystallization behaviours because of different initial microstructures.