Effect of magnesium carbonate on microstructure and rolling behaviors of AZ31 alloy

The present study aims at investigating grain refinement and rolling behavior of a magnesium carbonate (MgCO3) added AZ31 alloy. MgO particles produced by decomposition of MgCO3 in an AZ31 melt act as effective heterogeneous nuclei, and decrease the grain size of the ingot from 310 to 117 μm. Grain refinement alters the hot deformation mechanism of AZ31 alloy from TDRX-dominance to CDRX-dominance. The twinned regions provide easy crack propagation routes and thus deteriorate workability. As a result, workability in hot rolling especially up to the intermediate stage is improved.