High cycle fatigue behaviors of low pressure cast Mg-3Nd-0.2Zn-2Zr alloys

High cycle fatigue behaviors of Mg-3Nd-0.2Zn-2Zr (abbrev. NZ30K20) magnesium alloys were studied using porosity-free low pressure sand mold castings bars (abbrev. LSM). The results show that the LSM-NZ30K20 alloys show a significant response to heat treatment, achieving 51%, 39% and 17% increases in YS, UTS and fatigue strength (FS), respectively, in the peak-aged condition, compared with those of the as-cast alloy. The fatigue failure of the porosity-free LSM-NZ30K20 alloy is mainly originated from the localized shearing near the specimen surfaces during cyclic loading. In the T6 condition, the increased fatigue strength is attributed to the strong precipitation hardening in addition to the grain boundary constraints. The fatigue fracture behavior of the LSM-NZ30K20 alloy castings is well described by the Weibull modulus and the characteristic fatigue life. Fatigue lives of the LSM-NZ30K20 alloy can be quantitatively predicted using the classical Basquin equation.