Optical microscope inspection of the fracture surfaces of specimens printed with different orientations are shown in Fig. 8. They show that failure has different origins. Although individual ABS layers have melted together, every layer can still be distinguished in these images, and the fracture was mainly caused by pulling and rupturing damage to the layers. Generally, the fracture of the additive manufactured specimens began in close proximity to the weakest layers, and the cracks propagated up to complete specimen’s failure. Comparison of fracture surfaces shows that the failure modes have changed according to the layer orientation. In particular, the 0° specimen gave rise to a more discontinuous surface area, resulting in reduced elongation to fracture, and it seems to be related to a higher observable amount of porosities on the fracture surface.