Fatigue crack development from defects in a cast aluminium alloy

Experimental load and strain controlled data have shown that the fatigue life of cast 356 aluminium alloys can be significantly reduced by the presence of defects, such as pores. There is also considerable scatter in the data. The Paris Law can be used to describe the crack growth behavior, two different growth regimes being observed. The data have been applied to predict the fatigue life for an automobile component. The prediction was conservative in comparison with component test data. Better correlation would probably require consideration of the effect of crack closure.