Effect of porosity on the fatigue life of a cast Al alloy

Abstract

A methodology has been developed to investigate the causes of fatigue fracture in the pressure-cast aluminium alloy Al Si9 Cu3 (Fe). Several samples have been tested. In each case porosity was the primary cause for failure. 3D tomographic images of the samples porosity at the initial state have been used as a basis for finite element analysis of the stress concentration around each pore above a minimal given size. Morphological assessment of the pores and Finite Element calculation allow investigating the correlations between, stress concentration and crack initiation. Results indicate that the pores causing failure have sizes located at the end-tail of the size distribution.