Deformation and fracture behavior of hot extruded Mg alloys AZ31

► Facture propagation mechanism is identified as dimpled rupture during deformation. ► The original elongated coarse grains are unable to coordinate plastic deformation. ► Contraction twins locate at boundary of elongated grains and interact with cracks. ► Suppressing elongated grains, inclusions and pores enhances plasticity of Mg alloys.