Influence of solution temperature on fatigue behavior of AM-SC1 cast magnesium alloy

The microstructure, tensile properties and high cycle rotary bending fatigue behavior of low pressure sand cast (LPSC) AM-SC1 Mg alloy, solution-treated at 525, 540 and 560 degrees C respectively and then aged at 215 degrees C, were studied. The solution temperature has little influence on the average grain size of LPSC AM-SC1 alloy, but decreases the size and content of the residual secondary compounds when solution temperature increases. Compared with the alloy solution treated at 525 and 540 degrees C, the alloy treated at 560 degrees C shows obviously higher yield strength (+19 MPa) and ultimate tensile strength (+24 MPa), comparable elongation, and higher rotary bending fatigue strength (+8 MPa). However, when the fatigue stress amplitude is higher than the fatigue strength, the 560 degrees C solution treated alloy shows an obvious lower fatigue life. The fatigue fracture behavior of LPSC AM-SC1 alloy was discussed as well in this paper. (C) 2012 Elsevier B.V. All rights reserved.