Role of build orientation on quasi-static and dynamic fracture responses of additively manufactured AlF357 and AlSi10Mg alloys

In this work, a popular additive manufacturing (AM) aluminum alloy - AlSi10Mg and a new AM aluminum alloy - AlF357 are fabricated using Laser-Powder Bed Fusion ( L -PBF) approach to evaluate quasi-static and dynamic fracture behaviors. Four build orientations - horizontal, vertical, flat, and diagonal - are assessed. A Kolsky pressure bar apparatus along with ultrahigh speed photography is used to carry out the dynamic fracture experiments. In-plane surface displacements near cracks are measured using Digital Image Correlation (DIC) to evaluate the fracture parameters directly. A hybrid experimental-numerical approach that combines DIC measurements and finite element analysis is implemented to extract critical energy release rate and crack growth resistance behaviors. The effect of build orientation is found to be significant on the quasi-static fracture behavior with the horizontal and flat orientations having the best and worst fracture responses, respectively. Under dynamic loading conditions, however, the effects of build orientation are marginal. Both AlF357 and AlSi10Mg show strain-rate sensitivity and change in fracture mechanism under dynamic loading conditions with ~175% and ~200% increase in critical energy release rate. AlF357 consistently outperforms AlSi10Mg in both quasi-static (~30%) and dynamic (~10%) loading conditions.