High-throughput surface characterization to identify porosity defects in additively manufactured 316L stainless steel

In the present study, a high throughput (HT) methodology is applied to rapidly assess the surface characteristics of 83 additively manufactured 316L stainless steel. The variation in surface roughness (S-a) showed a good correlation with a dimensionless number (pi) and provided direct linkages to the internal porosity defects. Lack-of-fusion regime relates to high surface roughness (S-a > 5 mu m), low dimensionless number (pi < 61), and the presence of cavities in between the melt pool tracks. Balling regime correlates to high surface roughness (S-a > 5 mu m), intermediate dimensionless number (61 <pi < 146), and non-uniform melt pool track width. Keyhole regime shows low surface roughness (S-a < 5 <mu>m), high dimensionless number (pi > 146), and a curved melt pool track. This approach accelerates the process parameter discovery and minimizes the porosity defects for the LPBF process. The impact of the defects on the as-processed tensile mechanical properties demonstrates that samples with porosity exhibit up to 10% less tensile strength and 30% less ductility than optimal samples.