Tensile behaviour and fracture characteristics of die cast magnesium alloy AM50

Most of automotive magnesium applications are presently produced by high-pressure die casting processes. Understanding of tensile and fracture behaviours of die cast AM50 is critical for proper design of different applications. In the present study, magnesium alloy AM50 was high pressure die cast into rectangular coupons with section thicknesses of 2, 6 and 10 mm. Tensile and fracture behaviours of the die cast AM50 were characterized. The microstructure of die cast AM50 alloy was evaluated by optical microscopy. The results of tensile testing indicate that the tensile properties including yield strength (YS), ultimate tensile strength (UTS) and elongation (E-f) decreases with increasing section thicknesses of die cast AM50. The analysis of tensile behaviour shows that the straining hardening rates during the plastic deformation of the alloy increase with decreasing the section thicknesses. The observation via SEM fractography illustrates that the fracture behaviour of die cast AM50 is influenced by section thicknesses. As the section thickness increases, the fracture of AM50 tends to transit from ductile to brittle mode due to arising porosity content and coarsening microstructure. (C) 2007 Elsevier B.V. All rights reserved.