Passivation Behavior of Different Building Planes of Selective Laser Melting 316L Stainless Steel in 3.5% NaCl Solution

The passivation behavior of selective laser melting 316L stainless steel (SLM 316L SS) on different building planes is studied in 3.5% NaCl solution. The results show that the XOZ and YOZ planes have a semicircular molten pool structure, and the XOY plane shows a columnar molten pool structure. Meanwhile, the XOZ planes have relatively smaller grain sizes and higher low-angle grain boundaries (LAGBs) proportionate than that of YOZ and XOY planes. The electrochemical testing results illustrate that the XOZ plane has a lower corrosion tendency than that of YOZ and XOY planes, as the thicker passive film with higher content of Cr2O3 is detected on the XOZ plane. The XOZ plane, which has a higher Crox + hy/(Feox + hy + Crox + hy) ratio, has excellent passivation performance and better electrochemical properties than the other two planes.

Automated summary

The passivation behavior of selective laser melting 316L stainless steel on different building planes was studied. It was found that the XOZ and YOZ planes have a semicircular molten pool structure, while the XOY plane shows a columnar molten pool structure. The XOZ plane exhibits smaller grain sizes and a higher proportion of low-angle grain boundaries compared to the YOZ and XOY planes. The electrochemical testing results indicate that the XOZ plane has a lower corrosion tendency and a thicker passive film with a higher content of Cr2O3. The XOZ plane, with a higher Crox + hy / (Feox + hy + Crox + hy) ratio, demonstrates excellent passivation performance and better electrochemical properties than the other two planes.