In situ X-ray tomography of fracture behaviour in low-porosity L-PBF AlSi10Mg alloy with laser shock peening

In this study, we employed a novel hybrid AM process, in which periodic laser shock peening (LSP) treatments were added to the standard laser powder bed fusion (L-PBF) process, for fabricating the AlSi10Mg alloy. As a result, the porosity of the alloy was reduced by approximately 90%. To monitor damage evolution, we conducted in situ tensile tests using high-resolution synchrotron radiation X-ray micro-computed tomography. The results indicate that in the LSP-treated L-PBF AlSi10Mg alloy, with a porosity of around 0.05%, the plasticity of vertical tensile samples significantly increases, and the fracture strain closely resembles that of the horizontal sample. The reduction in porosity results in increased spacing between adjacent defects, which decreases the interaction between defects. Consequently, the rapid fracture caused by the merge of large defects is prevented. Notably, micro-cracks observed in the vertical samples before tensile fracture primarily originates at the molten pool boundaries rather than from defects.