Evaluating porosity differences in wrought and additively manufactured 316L stainless steel: a tensile deformation study via high-resolution X-ray nanotomography

This study uses a high-resolution (2 μm voxel size) X-ray nanotomography investigation into the dynamic evolution of porosity in additively manufactured 316L stainless steel during uniaxial tensile deformation. By quantifying a porosity increase from 0.24 to 3.96% and identifying void growth and coalescence, we provide novel insights into the failure mechanisms of additive manufacturing (AM) parts compared to wrought counterparts, advancing the understanding of AM material performance. Furthermore, voids that were nucleated owing to plastic deformation were identified. Pores with a coalescence close to the fracture surface were obtained compared to the initial state. Also, the average pore size was approximately eight times higher than the as-printed condition. On the other hand, the void formation levels were much lower in the wrought alloy than in the additively manufactured samples, as expected. Primary voids (associated with gas pores and keyholes) were observed on the fracture surface. The creation of additional voids during the deformation was then linked to the secondary voids. The current work highlights the critical role of the nucleation and growth of pores inside additively manufactured metal parts produced for different applications.