Effect of Pre-corrosion on the Fatigue Failure of Additive Manufactured AlSi10Mg Alloy

In this paper, the effect of pre-corrosion on the fatigue failure of additively manufactured (AM) AlSi10Mg alloy is studied via digital image correlation (DIC) and scanning electron microscopy (SEM). DIC strain fields were used to visually display the temporal and spatial characteristics of fatigue damage accumulation, macroscopic crack initiation and propagation in AM AlSi10Mg alloy. SEM fracture analysis was utilized to examine the micro-cracking features and fracture mechanism. The experimental results showed that pre-corrosion led to a significant reduction in the fatigue life. Two fracture modes were observed in both uncorroded and pre-corroded specimens, namely single crack fracture, multi-crack initiation and propagation. Randomly internal distributed pores with different shapes and sizes caused by AM manufacturing process were observed on the cross sections of all specimens. For uncorroded specimens, cracks originated from pore defects located in the 'L-T' surface or subsurface; for pre-corroded specimens, the localized corrosion in the 'L-T' surface or its combination with adjacent internal defects was the main mechanism for crack initiation. Pre-corrosion affected the nucleation position and propagate path of the crack, and accompanied by quasi-cleavage characteristics.