Spatter oxidation during laser powder bed fusion of Alloy 718: Dependence on oxygen content in the process atmosphere

In laser powder bed fusion (L-PBF), degradation is mainly driven by the accumulation of highly oxidized spatter particles in bed. Although amount spattering can be controlled melt pool stability, formation an unavoidable characteristic PBF processes. Oxidized risks defect printed components. However, factors influencing level oxidation during L-PBF processing are not yet fully understood. Herein, residual oxygen process atmosphere was reduced from traditionally applied 1000–20 ppm using partial pressure control system to Alloy 718 powder. Spatter accumulated on gas inlet were further analyzed reveal effect content scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Increasing increased surface coverage oxide phases rich Al Cr. The XPS analysis confirmed that covered with Al- Cr-based oxides, whose thickness atmosphere. bulk showed same trend approximately thrice spatters generated at 1000 O2 (608 O sample) compared 20 (206 sample). Thermodynamic simulations demonstrate a transition thick mixed corundum spinel-type oxides Al-based decreasing pressure, consistent findings.