Strain-Hardening and Fracture Behavior of Die Cast Magnesium Alloy AM50

Abstract

Understanding tensile and fracture behaviors of die cast magnesium alloys is of importance for proper design of various emerging automotive 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. Effect of section thicknesses on strain-hardening and fracture behaviors of the die cast AM50 was investigated. The results of tensile testing indicate that the tensile properties including yield strength (YS), ultimate tensile strength (UTS), and elongation(Ef)decrease with increasing section thicknesses of die cast AM50. The analysis of true stress versus strain curves shows that the straining hardening rates during the plastic deformation of the alloy increase with decreasing section thicknesses. The observation via SEM fractography illustrates that the fracture behavior 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 increasing porosity content and coarsening microstructure.

Microstructure, Tensile Properties and Fracture Behavior of HPDC Magnesium Alloy AZ91

“…This observation implies that, compared to the 6 and 10 mm thick samples, the die cast AZ91 alloy with the thin cross section (2 mm) is capable of spontaneously strengthening itself increasingly to a large extent, in response to extensive plastic deformation prior to fracture. The low porosity level and the even dispersion of fine intermetallic particles inside grains and around ground boundaries observed by Zhou et al [11], which resist slip in the primary phase should be responsible for the relatively high strain-hardening rate of the thin alloy in the early stage of plastic deformation, i.e., instantly after the onset of plastic flow as indicated in Fig. 11.…”

Experimental and numerical investigation of the effect of temperature on mixed‐mode fracture behaviour of AM60 Mg alloy

“…Other research works investigated the fracture of Mg alloys statistically . In a research, the effect of sample thickness on stress‐strain behaviour and fracture mechanism of AM50 alloy was explored, and by changing the sample thickness, a change of fracture mechanism from brittle to tough was reported . In 2007, the influence of crack‐tip angle on the fracture behaviour of AM60 alloy was studied, and it was observed that the influence develops a transition region from brittle to tough fracture .…”

“…23,24 In a research, the effect of sample thickness on stress-strain behaviour and fracture mechanism of AM50 alloy was explored, and by changing the sample thickness, a change of fracture mechanism from brittle to tough was reported. 25 In 2007, the influence of crack-tip angle on the fracture behaviour of AM60 alloy was studied, and it was observed that the influence develops a transition region from brittle to tough fracture. 26 Summing up the above-mentioned literature, three basic findings can be deduced: (a) In existing literature, only mode I fracture has been considered, with material behaviour under in-plane mixed-mode loading remained to be adequately studied.…”